A stock solution of xylose (1 mg mL-1) was prepared in distilled water. A dilution series ranging from 100-1000 μg mL-1 was prepared from the stock solution. To 1 mL of solution, 1mL of DNSA was added and kept in a boiling water bath for 10 min and then 400 μL of sodium potassium tartrate solution was added and kept it for cooling. The absorbance was recorded in a spectrophotometer (Shimadzu, UV-VIS) at 540 nm

Preparation of standard curve of xylose

Transformation of calcium-competent cells was carried out by the procedure detailed below: •The competent bacterial cells were thawed briefly and 200 μL of cells was mixed rapidly with plasmid DNA (10-50 ng) in fresh, sterile microcentrifuge tubes and maintained on ice for 30 min. A negative control with competent cells only (no added DNA) was also included. •Cell membranes were disrupted by subjecting cells to heat-pulse (42 °C) for 90 sec. •After heat shock, cells were incubated on ice for 5 min. •Cells were then mixed with 1 mL LB medium and incubated with shaking at 37 °C for 1 h. •For blue/white screening 40 μL of X-gal solution (20 mg mL-1 in dimethylformamide) and 4 μL of the IPTG (200 mg mL-1) was spread on LB-ampicillin (LB-amp) plates with a sterile glass rod. The plate was allowed to dry for 1h at 37 °C prior to spreading of bacterial cells. •Bacterial cells (100-200 μL) were spread and the plate was incubated at 37 °C for overnight. •White colonies were picked from the plates and suspended into LB-amp broth and cultivated to OD600=0.5

Transformation procedure

PurifiedDNA fragments of size 2-8 kb were ligated to the treated vector using a 1:3::vector :insert ratio in a volume of 10 μL. The total amount of DNA was about 0.5 μg. Vector and insert DNA was heated to 45 °C for 10 min and the immediately chilled on ice for 5 min prior to addition of ligase and buffer. T4 DNA ligase (NEB, England) was added to a final concentration of 0.125 UμL-1 and reactions were incubated at 16 °C for overnight in a ligation chamber. Reaction mixture incubated under same condition without addition of the enzyme was used as control. A ligation reaction was also set up under condition with linear plasmid DNA containing the

Ligation of insert DNA with dephosphorylated vector

In order to minimize self ligation of vector during cloning experiments, the digested DNA was subsequently treated with calf intestinal phosphatase (CIP) [NEB, UK]. The reaction conditions and amount of CIP were optimized and varied from (0.06-1) unit/picomole DNA termini. The dephosphorylation reaction was carried out in 50 μL reaction as follows. Reaction mixture containing no restriction enzyme was treated as control. Reaction was incubated for 1 h at 37 °C and stopped by heat inactivation at 65 °C for 20 min. 2.5.5. Composition of restriction mixture (50 μL) Linearized Plasmid DNA X μL (1 μg) CIP 1 μL (0.06-1 U μL-1) Reaction buffer (10X) 5.0 μL Distilled water Y μL Total volume 50 μL Linearized and dephosphorylated plasmids from each reaction were purified from low melting agarose gel using gel extraction method according to the manufacturer’s protocol (Qiagen gel extraction kit, Germany). 100 ng DNA from each reaction was then ligated in15 μL reaction volume containing 1.5 μL of 10X ligation buffer (NEB, England) and 0.2 μL of T4 DNA ligase to check the efficiency of self ligation after dephosphoryaltion. The ligation mixture was incubated at 16 °C for overnight and transformed into E. coli DH5αcompetent cells.

Dephosphorylation of the restricted plasmid

The vector isolated as above was digested with BamHI to generate the cohesive ends. The reaction was performed in 1.5 mL Eppendorf tubes as described below. Composition of restriction mixture (100 μL) Plasmid DNA X μL (20 μg) Bam HI 8 μL (10 U μL-1) NEB buffer 4 10.0 μL BSA (100X) 1 μL MQ water Y μL The reaction mixture was incubated at 37 °C for 3 h. The digestion was stopped by heat inactivation at 65 °C for 20 min. The digestion of plasmid was checked using 1.2 % (w/v) agarose gel electrophoresis for linearization of the plasmid. The digested plasmid was purified from low melting agarose gel using gel extraction method according to the manufacturer’s protocol (Qiagen gel extraction kit, Germany).

Restriction digestion of plasmid DNA

Two hundred μL of alkaline-SDS solution was added to the above suspension, mixed by inverting the tubes up and down 3 times and incubated for 5 min at room temperature. ƒTo the above mixture, 250 μL of 3 M Na-acetate (pH 4.8) was added, mixed by inverting the tubes up and down 3 times, and centrifuged at 12,000 x g for 10 min. ƒThe supernatant was collected in another micro centrifuge tube (MCT), 200 μL of phenol:chloroform solution was added, inverted two times and centrifuged at 12, 000 x g for 8 min at room temperature. ƒThe aqueous phase was transferred to new tubes and 500 μL of chilled (-20 °C) ethanol (96 %) was added. ƒThe tubes were centrifuged at 13,000 x g for 25 min at 4 °C, supernatant discarded and pellet dried for 15 min at room temperature. ƒThe pellet was washed with 500 μL of chilled 70 % (v/v) ethanol and centrifuged at 13, 000 rpm for 4 min at 4 °C. ƒThe pellet was dried at room temperature and dissolved in 50 μL of 1X TE buffer (pH 8.0) containing RNase and stored at -20 °C till further use.

The cells of E. coli DH10B having p18GFP vector were cultivated for overnight at 37 °C in LB medium containing ampicillin (100 μg mL-1). ƒThe E. coli culture having p18 GFP vector (~1.5 mL) was taken in Eppendorf tubes and centrifuged at 10, 000 x g for 5 min. ƒThe pellet was homogenized by vortex mixing in 100 μL of homogenizing solution

Plasmid isolation from miniprep method

The metagenomic DNA extracted from above defined protocol was digested with Sau3A1 at conditions optimized to generate maximum fragment in the size range of 2-6 kb. Different concentration (0.05 to 1 unit) of enzyme was used to optimize the digestion of 1 μg of DNA. Reactions were carried out in a final volume of 30 μl each in an Eppendorf of 1.5 mL. Reaction mixture (1 μg DNA having 3 μL NEB buffer 3 and 0.3 μL of 10X BSA) were kept at 37 °C for 10 min and stopped by heat inactivation at 80 °C for 20 min. Different digested reactions were checked for the desired fragments using 0.8 % (w/v) agarose gel electrophoresis. After optimization of DNA fragments for the appropriate size, a large scale digestion was carried out and the fragments (2-8 kb) were purified from low melting agarose gel using gel extraction method according to the manufacturer’s protocol (Qiagen gel extraction kit, Germany)

Insert DNA preparation

CONSTRUCTION OF METAGENOMIC LIBRARY

An attempt was made to study the effect of storage of DNA extracts on DNA yield and purity. The DNA extracts were centrifuged and the supernatants were dispensed into 2.0 mL Eppendorf tubes and stored at -20 oC for a month. DNA precipitation and its quantification were carried out at a week intervals.

Effect of storage on soil/sediment DNA extracts

The isolated DNA was diluted (1:100) with MQ. The concentration (mg mL-1) of the DNA [N] was determined spectrophotometrically by recording absorbance at 260 nm (A260) as: A260 = ε 260[N]where ε 260 is the extinction coefficient of DNA (50 for ds DNA) [N] = concentration (mg mL-1) of DNA The concentration of ds DNA [N] was calculated as [DNA] (mg mL-1) = A260/ε 260 [DNA] (μg mL-1) = A260 × 50 × dilution factor Purity of DNA was checked by measuring absorbance at 260 and 280 nm and calculating the A260/A280 ratio (Sambrook et al., 1989). A DNA sample was considered pure when A260/A280 ranged between 1.8-1.9. An A260/A280 < 1.7 indicated contamination of the DNA preparation with protein or aromatic substances such as phenol, while an A260/A230 < 2.0 indicated possible contamination of high molecular weight polyphenolic compounds like humic substances.

Determination of DNA quantity and purity

as well as commercial methods (MN kit, Germany; Mo-Bio kit, CA, USA; Zymo soil DNA kit, CA, USA) according to the manufacturer’s protocols and compared in terms of DNA yield and purity.

The soil DNA from Pantnagar and Lonar soil samples were also extracted by various manual (Desai and Madamwar, 2007; Agarwal et al., 2001; Yamamoto et al., 1998

Alternatively metagenomic DNA was extracted from the alkaline soil samples by using different commercial kits (UltraClean™, PowerSoil™ [Mo Bio Laboratories Inc., Carlsbad, CA, USA], Nucleospin kit [Macherey-Nagal, Germany] and Zymo soil DNA isolation kit [CA, USA]). The DNA was finally suspended in 100 μL of sterile Milli Q water for further analysis.

Commercial kits

Comparison of yield and purity of crude DNA

Soil (1 gm) was suspended with 0.4 gm (w/w) polyactivated charcoal (Datta and Madamwar, 2006) and 20 μL proteinase K (10 mg mL-1) in 2 mL of modified extraction buffer [N,N,N,N cetyltrimethylammonium bromide (CTAB) 1% w/v, polyvinylpolypyrrolidone (PVPP) 2% w/v, 1.5 M NaCl, 100mM EDTA, 0.1 M TE buffer (pH 8.0), 0.1M sodium phosphate buffer (pH 8.0) and 100 μL RNaseA] [Zhou et al., 1996] in 20 mL centrifuge tubes to homogenize the sample and incubated at 37 °C for 15 min in an incubator shaker at 200 rpm. Subsequently, 200 μL of 10% SDS was added to the homogenate and kept at 60 °C for 2 h with intermittent shaking. DNA was precipitated by adding 0.5 V PEG 8000 (30 % in 1.6 M NaCl) and left at room temperature for an hour (Yeates et al., 1998). The precipitated DNA was collected by centrifugation at 8000 x g at 4 °C. The supernatant was discarded and pellet was dissolved in 1 mL of TE buffer (pH 8.0) and then100 μL of 5 M potassium acetate (pH 4.5) was added and incubated at 4 °C for 15 min. The supernatant was collected after centrifugation at 8000 x g and treated with equal volumes of phenol: chloroform (1:1) followed by chloroform: isoamylalcohol (24:1) at 8000 x g for 15 min

PROTOCOL FOR OPTIMIZATION OF HUMIC ACID-FREE DNA FROM ALKALINE SOILS

cycles at 94°C for 30 s, 45°C for 30 s, 68°C for 2 min and final extension at 72°C for 10 min (see table 3.1). PCR products were cloned in pGEM-T easy vector (Promega) and the sequence for the cloned PfCDPK4 gene was obtained by automated DNA sequencing

The PCR reaction was carried out usmg Hi-fi Platinum Taq polymerase (Invitrogen) and primers PfCDPK4_F and PfCDPK4_R (see list II) with the following cycling parameters: 94°C for 2 min initial denaturation followed by 3

To obtain PfCDPK4 gene sequence, BLAST search was done usmg either i TgCDPK1 or the published sequence of other CDPKs in the P. Jalciparum genome sequence. An ORF on chromosome 7 exhibited significant sequence homology with other PfCDPKs. Subsequently, PlasmoDB annotation appeared in the public domain and the gene sequence PF07 _0072 matched with the PfCDPK4 sequence! identified by us. For PCR amplification, primers were designed on the basis of' nucleotide sequence of PFb7 _0072. Total RNA from asynchronous P. Jalciparum, cultures was isolated using RNA easy Kit (Qiagen, Germany) and was used to' synthesize cDNA for reverse transcription (RT). Both complimentary and genomic DNA were used as template.

Molecular Cloning of PfCDPK4

sodium sulphate, filtered and concentrated. The product was reconstituted in methanol and desalted using LH-20 sephadex column. The identity of the aldehyde was confirmed by TOF-MS and tandem mass spectrometric analysis using ESI-MS (API QST AR Pulsar i MSIMS, Applied Biosystems). Purification of peptide was performed using RP-HPLC. The aldehyde could be resolved from other impurities (including traces of alcohol, valeryl-FTAAlaninol) on Cl8 RP-HPLC column (7.8 x 300 mm, 125A, Waters) using a gradient of 0-48% B in 20 mins, 48% B in 40 mins and 90%B in 50 mins (A: water with 0.1% TF A and B: acetonitrile with 0.1% TF A) using a flow rate of 2 mllmin. The elution profile was monitored at 220 nm and the identity of the aldehyde was confirmed by mass spectrometric analysis

The aldehyde valery I-L-Phe-L-Thr-L-Ala-L-Alaninal (valery!-FT AAlaninal) was synthesized by Fmoc-solid phase solid phase chemistry using the Weinreb AM resin (Novabiochem, 0.63 mM/g) and automated peptide synthesizer (Advanced Chemtech. USA). Fmoc protecting groups of amino acids were removed by 20% piperidine in double distilled dimethyl formamide (DMF). A fourfold excess of respective amino acids were preactivated using HoBt (2 equivalents) in DMF and the coupling was catalyzed by diisopropylcarbodiimide (DIPCDI, 2 equivalents). After synthesis resin was dried with dichloromethane/DCM (3 X) and MeOH (3 X). The Thr side chain protecting group (tertiary butyl) was removed by treatment with 60:40, TF A: DCM, twice. The filtrates were discarded and resin was washed with DCM (3 X) and MeOH (3 X). The dried resin was suspended in tetrahydrofuran (3 ml) in a glass reaction flask (25 ml) under nitrogen, swelled with gentle stirring for 1 h, and then cooled to 0 °C. Cleavage of the peptide aldehyde from the resin was performed by adding lithium aluminium hydride (Aldrich. 2 M equivalents dissolved in THF) drop wise for 30 min at 0°C with constant stirring. The reaction was quenched with careful addition of KHS04 (saturated solution) and stirred until the solution reached room temperature. The resin was then filtered off and washed with DCM (3 X) and MeOH (3 X). The filtrate was treated with sodium potassium tartrate (saturated solution) and organic layer was extracted. This organic layer was dried over

Clzemical synthesis and purification of aldehyde valeryl-FTA-Aianina

released from the para-ovarian pad of fat as well as from the peritoneal reflections while care was taken to avoid injury to the ovarian vessels. A ligature was tied around the distal end of the fallopian tube including the ovarian vessels following which the ovary was excised. Hemostasis was secured before the stump of the tube was pushed back into the peritoneal cavity. The peritoneum was closed by continuous sutures using 2-0 silk. The same protocol was followed to perform oophorectomy on the contralateral side. The muscular layer and skin were closed together using surgical clips

The anesthetized mice were operated under strict aseptic conditions inside a laminar flow hood. The mouse was placed over layers of sterile tissue paper and the skin overlying the dorsal flanks was sterilized by wiping with 70% ethanol. The flank was palpated gently to identify the kidney, and an incision(~ 5 mm) was made using a pair of scissors on the overlying skin which penetrated the skin, sub-cutaneous tissue and the muscle layer with the parietal peritoneum being exposed and intact. The para-ovarian pad of fat was identified through the intact peritoneum and a small incision was made on the peritoneum overlying it. The ovarian tissue along with the fallopian tube was mobilized and delivered through the incision site. The ovary was

Bilateral oophorectomy

Leishmania major strain (MHOM/Su73/5ASKH) was a kind gift from Dr. Satyajit Rath, Immunobiology Laboratory, National Institute of Immunology, India. L.major promastigotes were cultured at 23°C in modified DMEM (DMEM (1 L) supplemented with sodium bicarbonate (3.7 g), HEPES (5.96 g), hemin (5 mg), biotin (1 mg), adenine (13.36 mg), xanthine (7.6 mg), triethanolamine (0.5 mL), and tween 80 (40 mg)) supplemented with 10% FCS. It is known that long term culture of L.major promastigotes results in loss of their virulence (2). Hence, to maintain the virulence of these parasites, they were propagated in mice footpad. Towards this end, the stationary phase L.major promastigotes were resuspended in Hank's balanced salt solution and 2x106 promastigotes were injected into the footpad of female BALB/c mice. 6 weeks post-infection, the infected footpad was dissected and the lesion harvested. The obtained lesion was minced and resuspended in modified DMEM supplemented with 10% FCS and placed in 23°C incubator to allow differentiation of intracellular amastigotes to promastigotes. This cycle of harvesting promastigotes from footpad lesions was performed every 6 weeks to maintain the virulent phenotype of this parasite

Protocol for propagation and maintenance of Leishmania major promastigotes

simultaneously uses all symmetry operators, resulting in a single peak with an improved signal-to-noise ratio which directly gives the position of the model in the unit cell. In addition, the TF is coupled with a PF to remove false maxima which correspond to interpenetrating molecules. Both the TF and PF allow the incorporation of a second model already placed in the cell. The TF solution may be subjected to rigid-body refinement incorporated in MOLREP. Non crystallographic symmetry may be imposed on the model in order to restrain the refinement. Pseudo-translation is automatically detected from analysis of the Patterson map. A significant off-origin peak gives the pseudo-translation vector, which is used to modify structure factors in the TF calculation (Navaza et al., 1998). In MOLREP multiple copies of the macromolecule in the unit cell can be searched (Vagin, 2000).

MOLREP is an automated program for molecular replacement that utilizes a number of original approaches to rotational and translational search and data preparation. MOLREP can perform a variety of tasks that require rotational and/or positional search: standard MR, multi-copy search, fitting a model into electron density, heavy-atom search and model superposition. The arsenal of rotation (RF) and translation (TF) functions includes self-RF, cross-RF, locked cross-RF, phased RF, full-symmetry TF, phased TF, spherically averaged phased TF and packing function (PF).The program is general for all space groups. The output of the program is a PDB file with the atomic model ready for refinement and a text file with details of the calculations. The rotational search is performed using the RF of (Crowther, 1972), which utilizes the fast Fourier transform (FFT) technique. The default radius of the integration sphere is derived from the size of the search model and is usually two times larger than the radius of gyration. The RF solutions are refined prior to positional search using a rigid-body technique. The refinement is performed in space group PI and the outcome is evaluated by the correlation coefficient. It

Automated molecular replacement program (MOLREP)

merging data, and symmetry equivalent positions, space group-specific systematic absences, total percentage of data collected and the linear Rmerge for data reduction. Finally, truncate program was used to obtain structure factor or amplitudes from averaged intensities (output from SCALA, or SCALEPACK) and write a file containing mean amplitudes and the original intensities. If anomalous data is present then F(+), F(-), with the anomalous difference, plus I(+) and 1(-) are also written out. The amplitudes are put on an approximate absolute scale using the scale factor taken from a Wilson plot. For all the Fab-peptide complexes and unliganded Fab of BBE6.12H3 antibody, the diffraction data were collected and processed using MOSFLM and subsequently merged using SCALA. For all the Fab-peptide complexes of 36-65 Fab, the diffraction data were collected and processed using DENZO and subsequently merged using SCALEPACK. The cell dimensions and space groups were unambiguously determined for each crystal. The solvent content and Matthews's constant were calculated (Matthews, 1968). The merged and scaled intensities were used for structure determination.

parameters using the whole data set. It is also used for merging different data sets and carrying out statistical analysis of the measurements related by space group symmetry. SCALEPACK also provides the detailed analysis of the merged data, and symmetry equivalent positions, space group-specific systematic absences, total percentage of data collected and the linear Rmerge for data reduction. MOSFLM is a package of programs with an integrated graphical user interface for processing data collected on any detectors. The programs cover all aspects of data reduction starting from the crystallographic pattern recorded on an image to the final intensities of observed reflections. In MOSFLM this entire process of integration of diffraction images is subdivided into three steps. The first is the determination of the crystal parameters, in particular the crystal lattice (unit cell) and its orientation relative to a laboratory axial system (usually based on the X-ray beam direction and the rotation axis)_ This is usually referred to as autoindexing. Knowledge of these parameters then allows an initial estimate of the crystal mosaicity. The second step is the determination of accurate unit-cell parameters, using a procedure known as post-refinement. This requires the integration of one or more segments of data with a few images in each segment. The final step is the integration of the entire set of diffraction images, while simultaneously refining parameters associated with both the crystal and the detector. After integration of the data, next step is to scale and merge the data set. Scaling and merging are done with the program SCALA. This program scales together multiple observations of reflections, and merges multiple observations into an average intensity. The merging algorithm analyses the data for outliers, and gives detailed analyses. It generates a weighted mean of the observations of the same reflection, after rejecting the out:iers. SCALA also provides the detailed analysis of

therefore only partially recorded on any individual image. For each predicted reflection, the background-subtracted diffracted intensity must be estimated. Although straightforward in principle, defects and limitations in both the sample (the crystal) and the detector can make this difficult in practice. Complicating factors include crystal splitting, anisotropic and/or very weak diffraction, high mosaicity, diffuse scattering, the presence of ice rings or spots, unresolved or overloaded spots, noise arising from cosmic rays or zingers, backstop shadows, detector blemishes, radiation damage and spatial distortion. These experimental factors will be important in determining the final quality of a data set. The HKL2000 (Otwinowski, 1997) is GUI based suite of programs for the analysis of X-ray diffraction data collected from single crystals. The package consists of three programs: DENZO, XDISPLA YF and SCALEPACK. HKL is the program that converts the raw X-ray diffraction data, collected from an image plate and reduces it to a file containing the hkl indices, intensities of the spots on the image plate along with estimates of errors involved. DENZO initially performs peak searching. The autoindexing algorithm carries out complete search of all the possible indices of the reflections picked by peak search using a fast Fourier transformation (FFT) software module. After search for real space vectors is completed, the program finds the three best linearly independent vectors, with a minimal unit cell volume, that would index all of the observed peaks. After refining the initial cell dimensions and detector parameters, the determined values are applied to the rest of the frames and the parameters are refined for each frame. The diffraction maxima are also integrated by DENZO_ The program XDISPLA YF (W., 1993) enables visualization of the peak search and processing procedures. SCALEPACK finds the relative scale factors between frames and carries out precise refinement of crystal

The collection of macromolecular diffraction data has undergone dramatic advances during the last 20 years with the advent of two-dimensional area detectors such as image plates and CCDs, crystal cryocooling and the availability of intense, monochromatic and highly collimated X-ray beams from synchrotron sources. These technical developments have been accompanied by significant advances in the software used to process the resulting diffraction images. In particular, autoindexing procedures have improved the ease of data processing to the point that in many cases it can be carried out automatically without any user intervention. However, the procedure used to collect the diffraction images, the screenless rotation method, has remained essentially unchanged since it was first suggested for macromolecular crystals by Xuong et al. (Nguyen-huu-Xuong, 1968) and by Arndt and coworkers and popularized by the availability of the Arndt-Wonacott oscillation camera (Arndt, 1977; U. W. Arndt, 1973). In this procedure, each diffraction image is collected while rotating the crystal by a small angle (typically between 0.2 and 2°) about a fixed axis (often referred to as the cpaxis). The only development of the method has been the use of very small rotation angles per image (the so-called fine cp-slicing technique) to provide improved signal to noise for weakly diffracting samples. Since, virtually all macromolecular diffraction data are collected in this way (with the exception of data collected using the Laue technique). The starting point for data integration will therefore be a series of such diffraction images and the desired outcome is a data set consisting of the Miller indices (hk/) of all reflections recorded on these images together with an estimate of the diffracted intensities I(hkl) and their standard uncertainties al(hkl). This requires the prediction of which reflections occur on each image and also the precise position of each reflection on each image (note that typically most reflections will be present on several adjacent images and

X-ray intensity data processing

Fab purification from the digestion mixture was carried out by ion-exchange chromatography using SPW-DEAE (60xl50 mm) column on a Waters3000 preparative HPLC (Waters, USA). In:tially, a blank run was carried out thereafter the column was allowed tore-equilibrate with the wash buffer (10 mM Tris-Cl, pH 8.0). A salt gradient of 0 to 0.2 M NaCI over a period of 120 minutes was used to elute the Fab. An aliquot from all the collected fractions were precipitated by using chilled acetone and were analyzed on a SDS-PAGE gel to ascertain which fraction corresponds to Fab. Fab, which has low or zero net negative charge at pH 8.0, was eluted out as the first major peak early in the gradient. The Fe portion and any undigested IgG which have a higher net negative charge at pH 8.0 would elute out later in the gradient. The Fab fractions collected from various HPLC runs for both the antibodies were pooled, concentrated and dialyzed against their respective crystallization buffer (50 mM Na-cacodylate pH 6.7, 0.05% sodium azide and SOmM Tris-Cl pH 7.1, 0.05% sodium azide).

Purification of Fab fragment

band has completely disappeared and only the 25 kDa doublet is clearly visible. Optimal w/w ratios of protein/enzyme and time of incubation were ascertained and preparative digestions were carried out using 20-50 mgs of IgG. The digestion mixture was then dialyzed against 10 mM Tris-Cl, pH 8.0 for Fab purification.

The concentration of the purified IgG was estimated usmg micro bicinchoninic acid (BCA) method of protein estimation (Micro BCA Protein Assay Kit , Pierce). To ascertain the optimal ratio of IgG to papain and time of incubation for proteolytic fragmentation of the antibody, an initial analytical digestion was carried out. 1 mg/ml solution of papain (Sigma, St. Louis, USA) was first pre-activated using rJ-mercaptoethanol (2.0m\1) for one hour. The reaction mixtures for digestion constituted 400 J.lg of IgG, rJ-mercaptoethanol (2.0mM) and EDTA (2.0mM) appropriate volumes of the activated papain solution were added so as to obtain various ratios of lgG:papain. The digestion reaction was monitored for 10 hours and 20 Ill aliquots were collected every hour. The proteolysis reaction was stopped with addition of 75 mM iodoacetamide and all the aliquots were analyzed on reducing SDS-PAGE. Initially the lgG appears as two bands, one at 50 kDa and the other at 25 kDa, corresponding to the heavy and light chains, respectively. The intensity of the 50 kDa band decreases and instead, a doublet starts appearing at 25 kDa as the reaction proceeds. The Fe portion may or may not be visible as a band just above the 25 kDa doublet. The digestion is deemed complete when the 50 kDa

Generation of Fab fragment

solution was injected into the HPLC. A salt gradient of 0 to 0.2 M NaCl over a period of 120 minutes was run and fractions for each peak, as detected by measurement of UV absorbance at 220nm, were collected. An aliquot of each fraction was subjected to acetone precipitation and the obtained precipitate was analyzed on SDS-PAGE to ascertain which fraction corresponds to IgG. The IgG fractions from different runs were pooled and concentrated to -1 mg/ml which was then dialyzed against the digestion buffer (0.15 M NaCl, O.lM Tris-Cl, pH 7.1).

The collected ascitic fluid was centrifuged to remove cell debris and fat. Mouse monoclonal ascites, was filtered through glass wool to remove lipid like material left over after centrifugation. The supernatant was then subjected to (Nr4)zS04 fractionation. Saturated (Nlit)zS04 solution (SAS) at pH 7.0 was gradually added to the ascites in an ice bath with continuous stirring till a concentration of 40% (v/v) was achieved. The mixture thus, obtained was centrifuged to get the protein pellet and the pellet was re-suspended in buffer (0.01 M Tris-Cl, pH 8.5). The crude antibody solution obtained from ammonium sulfate fractionation was dialyzed against the wash buffer (0.0 1 \1 Tris-Cl, pH 8.5) and then subjected to ion-exchange chromatography using 5PW-DEAE (60x150 mm) column on a Waters3000 preparative HPLC (Waters, L:SA), to purify IgG. All solutions used during chromatography were filtered (0.451-lm) and then degassed. Following equilibration of the column with wash buffer, a 2 ml aliquot of the crude antibody

Antibody purification

secrete antibody which gets collected in the peritoneal fluid. Ascites is thus a good source of monoclonal antibody. The hybridoma cells, from two different hybridoma, which were secreting IgGs, 36-65 and BBE6.12H3, were injected into the peritoneal cavity of male Balb/c mice irradiated with a dose of 400 RAD and primed with Freund's incomplete adjuvant 72 hours prior to injecting the hybridoma cells suspended in 500 111 of Dulbecco's phosphate buffered saline (DPBS). Approximately 5 x 105 to 5 x 106 hybridoma cells were injected into each mouse. Ascitic fluid could be tapped from the peritoneal cavity of mice after approximately 4-5 days.

Ascites is the intra-peritoneal fluid collected from mice that have developed peritoneal tumor. Hybridoma cells, when injected into the peritoneal cavity of mice,

Generation of ascites from mice

conditions used for purificatior and crystallization. Therefore, in any attempt at crystallization, the homogeneity of the preparation and its stability in solution is of paramount importance. lgG molecules possess a net negative charge, at pH 8.5. At this pH, IgG molecules, can therefore, bind to positively charged chemical moieties, an association that can be reversed using low concentrations of sodium chloride. Hence, it is possible to purify IgG using anion-exchange chromatography with a salt gradient. Since this method does not involve harsh conditions it represents an ideal way to purify IgG to be ultimately used for crystallization experiments. Ammonium sulphate fractionation prior to chromatography improves the resolution of peaks during IgG purification. The mouse IgG molecules are known to precipitate in the range of 33% to 40% (v/v) saturated ammonium sulphate. lgG molecules have three major domains, each of which are mobile with respect to the other. Consequently, the molecule is highly flexible and not easy to crystallize. Although entire immur.oglobulin molecules have also been crystallized (Harris et a!., 1998), the proteolytic fragments of IgG molecules have been observed to be more amenable to crystallization. Papain, a non-specific proteolytic enzyme obtained from papaya, cleaves antibodies at the hinge region to release one Fe and two Fab domains. Proteolysis by papain, if carried out carefully, followed by purification can yield a homogenous preparation of Fab. This pure preparation of Fab can be used for crystallization experiments.

A prerequisite for collection of X-ray diffraction data for structure determination is availability of well-ordered single crystals. Protein crystallization is considered to be an art and there are no universally applicable methods for obtaining crystals suitable for X-ray diffraction studies. However, it is unlikely that good crystals will not be obtained if attention is paid to the purity and stability of the molecule of interest. A high degree of purity is essential for successful crystallization of most proteins. Also, the molecule must be stable under the

Preparation of Fab fragment

I 0.0 J.Ll 16.0 J.LI I 0.0 J.Ll 4.0J.Ll 4.0J.Ll 0.5 J..ll 55.5 J.LI I 00 J.L

lOX PCR buffer 1.25 J.LM dNTP mix Template DNA (I 0 J.Lg/ml) Primer #I (25 nmoles/ml) Primer #2 (25 nmoles/ml) Taq DNA polymerase (5 U/J.Ll) Sterile water Total volume

The reaction was started by an initial hot start at 94 °C for 5 min., followed by a three-step amplification cycle. The amplification cycle consisted of a 1 min. denaturation at 94 °C, followed by a 2 min. annealing at 48 °C and an extension at 72 °C for 2 min. The cycle was repeated 30 times and the reaction mixture was incubated at 72 °C for additional 7 min. to allow for primer extension. The PCR amplified product was separated from the primers on a 1% agarose gel. A well was carved ahead of the required fragment and filled with 15% PEG-T AE solution (Zhen and Swank, 1993). The DNA was electro-eluted in 15% PEG-TAE solution, and purified further by phenoVchloroform extraction and ethanol precipitation.

A standard PCR was set up as described below.

Polymerase Chain Reaction

Microtitration plates were coated with r-bZP3 at a concentration of 200 ng/well in 50 mM PBS, pH 7.4 for I hr at 37°C and then at 4oc overnight. Plates were subsequently washed once with PBS and blocked with 1% BSA for I hr at 370C in PBS to reduce non-specific binding. Blocking was followed by three washes of 5 min each with PBS containing 0.05% Tween-20 (PBST). Plates were incubated with varying dilutions of preimmune and immune sera for 1 h and bound Ab was revealed with the anti rabbit-HRPO conjugate used at an optimized dilution of 1:5000 in PBS. After washing to remove unbound anti-rabbit-HRPO conjugate, the enzyme activity was estimated with 0.1% orthophenylenediamine (OPD) in 50 mM citrate phosphate buffer, pH 5.0 having 0.06% of hydrogen peroxide as the substrate. The reaction was stopped by adding 50 J..fllwell of 5 N H2S04 and the absorbance read at 490 nm in a microplate reader (Molecular Devices Corporation, California, USA). The Ab titer was calculated by regression analysis and is represented by Ab units (AU) as the reciprocal of the dilution of the Ab giving an A490 of I .0

Titration of Rabbit Anti-bZP3 Sera

Sf9 cells infected with AcNPV, VI, V2, V3, or V4 were harvested 72 h pi, washed twice with 10 mM PBS, air dried on a slide and fixed in chilled methanol for 15 min. Cells were incubated with MA-451 culture supernatant and N-terminal anti-peptide serum ( 1 :500) at 37°C for 1 h, washed with PBS and further incubated at 37oc for 1 h with I :50 dilution of anti-mouse FITC or I :2000 anti-rabbit FITC. Slides were washed extensively, mounted in 90% glycerol in PBS (50 mM, pH 7.4) and examined under Optiphot fluorescent microscope (Nikon, Tokyo, Japan).

Immunocytochemical Localization of Recombinant Proteins in Infected Cells

Cells and supernatant collected 72 h pi were analyzed on a 0.1% SDS-I 0% PAGE and Western blot using polyclonal Abs generated in rabbit against peptide-DT conjugates using (i) 23-45 aa residue N-terminal peptide with an extra lysine at the N-terminus (KQPFWLLQGGASRAETSVQPVLVE), (ii) 300-322 aa residue C-terminal peptide (CSFSKSSNSWFPVEGPADICQCC) corresponding to the bZP3 sequence (iii) MA-451 and (iv) goat anti-GST Ab. The C-terminal anti-peptide Ab was used for determining whether or not the full length bZP3 was being expressed by the cells infected with the different viruses. Anti-mouse (I :500), anti-rabbit ( 1 :500) or anti-goat ( 1 :500) Abs conjugated to HRPO were used for revealing bound Ab.

Analysis ofr-bZP3 in VI, V2, V3 and V4 Infected Cells and Supernatant

Cells ( 1.5X to6) infected with AcNPV, V 1, V2, V3 or V 4 were grown for 72 h pi followed by starvation for methionine (Met) in Met-free medium for I h. 25 J.1Ci of 35s Met was added and cells were pulsed for 2 h. Cells were harvested and proteins resolved on a 0.1% SDS-I 0% PAGE as described above. The gel was dried and exposed to X-ray film. The signal was quantitated and analyzed using the molecular imager (GS 250, BioRad, USA). The intensity of the polyhedrin band was compared with that of the r-bZP3 proteins expressed by virus constructs V 1, V2, V3 and V 4.

Radiolabeling of Recombinant Proteins in Infected S/9 Cells

Expression conditions for bZP3 under the polyhedrin promoter were standardized using the Northern blot and Western blot analysis of cells infected with the VI virus. Sf9 cells, seeded at a density of 1.5 million in a 35 mm petridish were allowed to attach for I h at 27oc. The medium was removed and the cells were infected with AcNPV (Autographa californica nuclear polyhedrosis virus) or VI at -10 MOl for 1 h. The infected cells were harvested at different time points from 0-84 h pi. The cells (-2X I o6) were washed with chilled PBS and resuspended in I ml of denaturing solution ( 4 M GITC, 25 mM sodium citrate, pH 7, 0.5% sarcosyl, and 0.1 M BME) followed by addition of 50 Jll of 2 M sodium acetate (pH 4) and 500 Jll water saturated phenol and 1 00 Jll chloroform:isoamyl alcohol ( 49: 1 ). The suspension was mixed thoroughly after the addition of each reagent, vortexed for 1 0 sec and cooled on ice for 15 min. The aqueous and the phenol phases were separated by centrifugation at 12,000 rpm for 20 min in a refrigerated microfuge. The aqueous phase was transferred to a fresh tube and 500 Jll isopropanol was added. RNA was precipitated at -20°C for 1 h, and pelleted at 12,000 rpm for 20 min at 40C. The RNA pellet was dissolved in 300 Jll denaturing solution followed by addition of 300 Jll of isopropanol. RNA was reprecipitated at -2ooc for 1 h, washed with 75% ethanol and the pellet collected by centrifugation at 12,000 rpm in a refrigerated microfuge. RNA was dissolved in 25 Jll of 0.5% SDS by heating at 65°C for 10 min and stored at -700C. RNA was quantitated and 5 Jlg of RNA corresponding to each time point was resolved on a 1.2% agarose formaldehyde gel, transferred to a nylon membrane and probed with 32p labeled bZP3 probe. Cells harvested at different time points from -2X 106 cells 12-84 h pi were pelleted down, washed with 10 mM PBS, pH 7.4, and lysed in reducing buffer and resolved on a 0.1% SDS-10% PAGE as described earlier. The supernatant was concentrated to lOX for loading on the gel.

Expression 'Of bZP3 in BEVS

For analysis of viral DNA by dot blot, I X I o5 cells were seeded in each we11 of the 9~ well plate and infected in duplicate with 50 J.Ll of the plaque pick for I h, followed b: addition of 50 J.Ll of CM to each well. Infected cells were incubated for 5 days, afte which the culture supernatant was saved and ce11s were processed for dot blot analysi~ Ce11s were lysed with 200 J.LI of 0.5 M NaOH. The alkali was neutralized by addition o 50 J.LI of 4 M ammonium acetate. The nylon membrane was wetted in warm water an( washed in dot blot solution (1 M ammonium acetate, 0.02 N NaOH) and the cell lysatt was blotted on to the membrane using a dot blot apparatus (Bio-Rad), dried, UV eros: linked and processed for prehybridization and hybridization. For the isolation of total genomic DNA, cells infected in a 35 mm culture dish wen harvested 72 h post infection (pi) and treated with 400 J.LI of DNA extraction buffer(]( mM Tris HCI, pH 8, 0.6% SDS, 10 mM EDTA)·and 50 J.Ll of 20 mg/ml proteinase K a 37°C for 12-I6 h. The DNA was extracted twice with phenol:chloroform:isoamy alcohol (25:24: 1) and once with chloroform. For each extraction, the suspension wa! mixed by inverting the eppendorf and separated by centrifugation at 2,000 rpm for 3 mir in a microfuge. DNA was precipitated with I ml of 95% ethanol at -20°C for 4 h anc pelleted at 4,500 rpm for 20 min. The pellet was washed with 70% ethanol, dried anc resuspended in 50 J.LI of TE. DNA was digested with Hind III, resolved on a 0.8% agarose gel and processed for Southern blotting. Positive clones were amplified b) infecting cells at a multiplicity of infection (MOl) of ~1 for 10 days and the amplifiec virus. was titrated using a plaque assay. Sf9 cells were infected at -I 0 MOl fo1 expression of the r-proteins.

Screening of the Recombinant Viruses

The staining solution was aspirated and the plates left at 27°C 0/N. Plaques whicl appeared as clear zones, were identified, marked and verified under the microscope Plaques were picked up using a sterile 200 J.Ll tip and viruses were allowed to diffuse ou 0/N in 200 J.LI of CM to make the plaque pick stock virus.

Sf9 cells ( 1.8x 1 o6) seeded in a 35 mm culture dish were infected in duplicate with 100 J!l of the serial dilutions (1 oO to w-2) of the transfection supernatant for I h. The viral inoculum was aspirated and 1.5 ml of the cooled agarose overlay (1.5% LMP agarose, 0.5X CM) was added to each dish and allowed to set. 1 ml of CM was added to each dish and the plates were incubated at 270C for 5 days. Medium was removed and cells were stained with 2 ml of staining solution (0.03 % neutral red in 10 mM PBS) for 1 h.

Plaque Assay for Isolating Viruses

Lipofectin-mediated transfection and in vivo homologous recombination was used to introduce foreign DNA into the AcNPV genome at the polyhedrin locus for making the V 1, V2, V3 and V 4 recombinant virus constructs using the BacPAK™ baculovirus expression system or the Baculogold™ transfection kit (Pharmingen) according to the manufacturer's instructions.

Construction of Recombinant Viruses

AcNPV and recombinant baculoviruses were isolated, grown and assayed in confluent mono layers of Spodoptera frugiperda (Sf9) cell line maintained in TNMFH which is Grace's insect cell culture medium supplemented with 3.33 giL Lactalbumin hydrolysate, 3.33 giL Yeast autolysate. Complete medium (CM) was prepared by supplementing TNMFH with 10% heat inactivated FCS and 1 OOX antibiotic-antimycotic.

Cell Culture Techniques

650C in 0.2X SSC, 0.1 % SDS for I 0 min. The membrane was wrapped in Saran wrap and exposed to an X-ray film. The colonies that were positive by colony hybridization were inoculated in a 3 ml culture and used for preparing DNA for analysis by restriction digestion and Southern blotting. The digested DNA was resolved on a 0.8% agarose gel as described above. The gel was soaked in 4 volumes of denaturing solution (1.5 M NaCI and 0.5 M NaOH) for 1 h at RT with shaking followed by neutralization (1 M Tris HCI, pH 8 and 1.5 M NaCI) for 1 hat RT. The DNA was transferred to a Nylon membrane, UV crosslinked and hybridized with the full length 32p labeled· bZP3 probe as described above.

The ligation mixture was used for transformation of DH5a cells as described earlier. Transformed bacterial colonies growing on LB Amp plates were screened by colony hybridization. Briefly, colonies were grown for 6-8 h on a Nylon membrane placed on a LB Amp plate. The colonies were lysed by placing the membrane on a Whatman® 3MM paper soaked in I 0% SDS for 3 min, followed by treatment with denaturing solution (0.5 N NaOH, I.5 M Nael) for 5 min and neutralization solution (0.5 M Tris Hel pH 8, 1.5 . M Nael) for 5 min in the same manner. The membrane was dried, UV cross linked (Ultraviolet crosslinker, Amersham) and processed for prehybridization and hybridization. Stocks of 20X sse (174 giL NaCI, 88.2 giL sodium citrate, pH 7.0) and 50X Denhardt's (I% ficoll, I% PVP, I% BSA) were prepared. The membrane was prehybridized for 4-6 h in the prehybridization solution (5X SSe, 5X Denhardt's, 0.5% SDS, I 0 J..Lg/ml sheared and denatured salmon sperm DNA). The bZP3 DNA was labelled using the Multiprime DNA labeling system using 50 ng of purified bZP3 DNA. For hybridization with the probe, I o6 cpm/ml of the denatured 32p labeled bZP3 probe was added to the prehybridization solution and incubation was further carried out for I4-I6 h. For removing the non specifically bound probe, the membrane was washed successively at RT in 2X sse for 10 min, at 55°e in 0.2X sse, 0.1% SDS for 10 min and finally at

Screening of the Recombinant Transfer Vector

(gp67) signal sequence in the pAcSecG2T vector. bZP3 was amplified using the VI transfer vector as a template in a PeR reaction using forward primer eGGGATCCeAAeeeTTeTGGeTeTTG incorporating a BamH I site and reverse primer GeGAATTCeAGAAGeAGAeeTGGAeeA incorporating an EcoR I site. Amplified DNA was digested and ligated with the digested pAcSecG2T vector. A dinucleotide deletion at nt position 239-240 resulted in premature termination of the protein after aa residue 76 and was used for expression of the V3 protein. DNAs from the transfer vector clones were purified using the Plasmid Midi kit DNA purification system.

Constructs were designed to express bZP3 in insect cells under the late polyhedrin promoter. The full length bZP3 I-424 aa residues (construct VI encoding a 47 kDa polypeptide) including the native eukaryotic N-terminal signal sequence (aa 1-22) and the C-terminal region after the furin cleavage site which includes the transmembrane-like domain (aa 349-424) was digested from pBluescript-bZP3 clone 401 using Kpn I and Sac I restriction enzymes and subcloned in the pBacPAK8 vector. A second construct V2 was designed containing a truncated version of the gene (aa 1-348), excluding the C-terminal transmembrane domain giving a protein with a calculated mass of 39.8 kDa. The insert was amplified by PCR using the forward primer TGCAGGTACCATGGAGCTGAGGC incorporating a Kpn I site (restriction site shown in bold) and the reverse primer CCGAGCTCAGAAGCAGACCTGGACCA incorporating a Sac I site using 10 ng of 401 template DNA. The amplified fragment was digested with Kpn I and Sac I, and ligated with a similarly restricted pBacPAK8 vector. Two more constructs were designed to express bZP3 aa 23-76 (V3 encoding a polypeptide 36.6 kDa) and aa 23-348 (V4, encoding a polypeptide 67.3 kDa) inframe as GST fusion proteins with a replacement of the native signal sequence with an insect

Plasmid Construction

EXPRESSION IN BACULOVIRUS

The cell pellet obtained from l ml culture was solubilized by boiling for 5 min in 100 J..Ll of 2X sample buffer (0.0625 M Tris, pH 6.8, 2% SDS, 10% glycerol, 5% BME and 0.001% bromophenol blue) and the proteins were resolved on a 0.1% SDS-10% PAGE (Laemmeli, 1970). The gel was stained with Coomassie brilliant blue for staining total cellular proteins. For immunoblotting, the proteins were electrophoretically transferred to 0.45 J..Lm nitrocellulose membrane overnight at a constant voltage of 15 V in Tris glycine buffer with 20% methanol (Towbin et al., 1979). Nonspecific sites on the membrane were blocked by incubation with 5% BSA in 50 mM phosphate buffered saline (PBS), pH 7 .4, for 1 h followed by 3 washes (15 min each) with PBS containing 0.1% Tween-20 (PBST). For detection of bZP3, a murine monoclonal antibody (MAb), MA-451, generated against the pZP3P and recognizing a cross reactive epitope (166-171 aa residues) within the bonnet sequence was used (Afzalpurkar and Gupta, 1997). The membrane was incubated for 1 h with a 1 :5 dilution of MA-451 culture supernatant, followed by 3 washes in PBST. Horseradish-peroxidase (HRPO) conjugated goat anti-mouse immunoglobulin (lg) was used to reveal bound Ab. Colour was developed with 0.6% (w/v) 4-chloronaphthol in 50 mM PBS, pH 7.4, containing 25% methanol and 0.06% H202. The reaction was stopped by washing the membrane with PBS.

SDS-PAGE and Immunoblot

All bacterial cultures were grown in Luria Bertani (LB) medium (NaCl 1%, Yeast extract 0.5%, and tryptone I%, pH 7.0) at 37oc with shaking. The medium was sterilized by autoclaving at 15 lbs/inch2 for 20 min. Solid growth medium was prepared by adding 1.5% agar to LB prior to autoclaving. Antibiotics were added after cooling the medium to 50°C.

Media Composition and Bacterial Culture

Lipofectin was kindly provided by Syntex, Inc., USA as an aqueous solution containing 1 mg I ml of 1 ipid ( DOTMA DOPE; 50 50 ). The procedure used was as described by Feigner et al., 1987 with appropriate I modifications as suggested in the user s notes. Lipofection was done with 0.5 x 106 cells seeded on a 60 mm plate. For each plasmid, the lipofection was performed in duplicate. The amount and quality of the plasmid DNA used ranged from 400 ng of crude DNA prepared by the mini prep method, to 5 ug of highly purified, cesium banded DNA. The appropriate amount of DNA was suspended in 1.5 ml of serum free DMEM. In another tube, 30 ug of lipofectin was suspended in 1.5 ml of serum free DMEM. The two solutions were mixed. The cells were washed twice with HBSS to totally wash off all traces of serum. The DNA 1 lipofectin mix was then applied to the cells and the cells incubated for 4 hours at 37°C. Next, 3 ml of media containing 10 % FCS was added and the incubation continued at 3 7°C for 16 hours. The culture supernate was then aspirated off and fresh medium added to the cells. The selection for stable clones was started after 48 hours by the procedure described below.

Using lipofectin.

mixed with the sample by vortexing, and the DNA loaded on a preparative agarose gel. When digesting vector DNA in preparation for a ligation, the DNA was first purified from the digestion reaction as described in 3.2.4.8. This DNA was then treated with bacterial alkaline phophatase as described by Maniatis et al., 1982 ) • The dephosphorylated DNA was run on a preparative agarose gel to purify the linearised, dephosphorylated vector DNA. The efficiency of dephosphorylation was monitored by self ligation, followed by transformation of competent E.coli cells. Only after achieving efficient dephosphorylation of the vector DNA, was it used for ligation with the insert DNA.

For digestions aimed at purification of restriction fragments, 10 -20 ug of DNA was digested in a reaction mixture of about 100 -200 ul volume. Aliquots from the digestion reaction were checked on a minigel after one hour to monitor the extent of digestion. After the digestion was complete, one tenth volume of the 10 X tracking dye was

Digestions involving more than one restriction endonuclease were carried out with 2 - 4 ug DNA in a final reaction volume of up to 50 or 100 ul. In these cases, if the two enzymes had radically different optimal assay conditions, the DNA was digested first with the enzyme requiring a lower salt concentration. After incubating for one hour, a 5 ul aliquot from the digestion reaction was electrophoresed on a mini gel to monitor the extent of digestion. Once the digestion was complete, appropriate amount of salt and the

second enzyme were added and the incubation continued in an increased final reaction volume, to offset any increase in the glycerol concentration in the new reaction. Alternatively, the DNA was extracted once with phenol/chloroform, once with chloroform, and then precipitated with one half volume of 7.5 M ammonium acetate and two volumes of ethanol. The precipitation was done for 30 minutes at room temperature, and the DNA spun down for 30 minutes at room temperature. The supernate was discarded, pellet washed with 70% ethanol, recentrifuged, dried briefly under vacuum and finally resuspended in 18 ul distilled water. The DNA purified in this manner could then be used for setting up digestion with a second enzyme or for setting up a ligation. For those double digestions where one of the enzymes was known to be active over a broad range of ionic strength conditions, including those required for the optimal activity of the second enzyme, both the enzymes were added simultaneously in the digestion reaction, which was carried out using the optimal conditions of the second enzyme having more stringent assay requirements.

All fine chemicals and the thermal cycler used for PCR, were kindly provided by Cetus Corporation, California, USA. 3.2.4. Digestion of DNA with restriction enzymes. DNA samples were digested with restriction endonucleases in the appropriate digestion buffers as recommended by BRL. The digestion buffers were in most cases, supplied by BRL. Composition of the 1 X buffers is given in Table 4.

Figure !• Thermal cycle profile of a typical polymerase chain reaction ( PCR ). A typical PCR consists of repititive cycles of multiple temporal segments ( designated here as A - G ) with distinct target temperatures. After making the desired cocktail of template DNA, primers, Taq polymerase and the enzyme buffer, the reaction tube is incubated in a programmable thermal cycler, to incubate the reaction contents at pre-set temperatures for designated periods of time. Segments A -B, template denaturation; c -D, primer annealing; E -F, strand synthesis; G, ramp to the completion of the first cycle prior to the start of the next cycle ( dotted line ) . The duration and target temperature for each segment in an amplification cycle can be varied to suit the desired objectives.

plasmid DNA in a 100 ul mixture having 10 ul of 10 X PCR buffer, 10 ul of 10 mM dNTPs, 3 ul of each primer to give a final primer concentration of 1 uM, and 2.5 units of the Thermus aquaticus thermostable DNA polymerase. PCR reaction buffer ( 10 X ) contains 500 mM KCl, 100 mM Tris. Cl, pH 8 . 3 ' 15 mM MgC12 and 0.1 9.,-0 gelatin. The mixture was subjected to PCR amplification in a programmed thermal cycler block set for 3 0 cycles. The procedure is diagramatically outlined in Fig. 1 and involved four steps : a) The reaction was heated to 95°C for 30 seconds to separate the two strands of the target DNA; b) the reaction was then cooled to 37°C for one minute to allow annealing of the two primers to the template DNA to occur ; c) next, the temperature was raised to 72°C and the reaction maintained at this temperature for 10 minutes, for primer extension to occur; d) at the end of the cycle, the temperature was again raised to 95°C as in step (a) to start a new cycle. In between the steps (a) to (d), one minute ramp times were used to allow the efficient realisation of the set temperature. In the last cycle, the duration of step (c) was extended to ensure the conversion of all single strands into double stranded DNA. At the end of 30 cycles of PCR, a 10 ul aliquot from the PCR reaction was electrophoresed on a 1 % SeaKem I 3 % NuSieve agarose gel in TBE buffer, to resolve the PCR products. The amplified DNA was purified by electrophoresing the entire PCR mixture on a 1 % preparative agarose gel in TAE buffer.

Polymerase chain reaction was carried out as described by Scharf et al., ( 1986 ) , witD. some modifications. 23 mer oligonucleotide pri~ers synthesised by the solid phase triester method were designed to flank the target DNA desired to be amplified. A primer was designed to be complementary to , the 5 end of the phCG eDNA (+) strand and I was termed 5 primer ( also see Fig. 20 ) . Another primer was designed to be complementary to the sequence flanking the translation termination codon ( TAA ) of HBsAg (-) strand and this was I 1 I , termed 3 pr1mer. The 5 pr1mer also included the recognition sequence for restriction endonuclease Sal I as an overhang, while the I 3 primer included the recognition sequence for Hind III as an overhang. In addition, two extra bases ( G or C ) flanking the restriction site were included in the sequence of the primers, to improve the enzyme digestion. Thus, the nucleotide sequence of I the 5 primer read as : I I I 5 -GGCGTCGACATGGAGATGTTCCA-3 , while that for the 3 primer read I I as : 5 -CCAAGCTTTTAAATGTATACCCA-3 . A standard PeR· reaction contained 500 ng to 1 ug

Polymerase chain reaction ( PCR 1·

ingredients were present except N-acetylglucosamine. This value represented the galactose released. The difference in the counts between the tube in which acceptor was present and control represented transferase activity.

A mixture of sodium cacodylate (20 ~L, 0.2 M, pH = 6.5 adjusted with Hel) , MnCI2 (3 ~L, 1 M), mercaptoethanol (3 ~L, 1 M) and Triton X-100 (5 ~L, 10% w/v) was added to a solution containing N-acetylglucosamine (3 ~L, 1 M) and protein (1 00 ~g). The reaction was started with the addition of UOP-galactose (15 ~L, 10 mM with 1 ~Ci of eH] UOP-galactose). The mixture was incubated at 37°C for 60 minutes after which the reaction was stopped by the addition of EOTA (17 ~L, 0.3 M, pH = 7.4 adjusted with NaOH) and placing the tube on ice. The mixture was then passed through a column of Oowex 2X8 (200-400 mesh in cr form) already washed thoroughly with water. The unreacted UOP-galactose remained bound to the column while galactose which had been transferred to N-acetylglucosamine to form lactosamine, as well as free galactose, was eluted out with 1.5 mL of distilled water. One tenth of volume was taken for scintillation counting. For each assay, a control tube was run in which all

1,4 ~ Galactosyl transferase assay 96

(1 ml) was added palladium on charcoal (10%, 176 mg) and formic acid (100 Ill). The mixture was stirred at 50°C for 3h after which the catalyst was filtered off and the solvent was evaporated. The residue was taken in a mixture of CH30H:water:triethylamine (5:3:2, 1.6 ml) and stirred for 2 days at rt. The reaction mixture was concentrated and the residue was repeatedly lyophilized to yield 82; ESMS (mlz): 387.34 (M-H)'. Guanosine 5'-diphospho-6-deoxy-6-fluoro-a-D-mannose (mono-triethylamine salt) 83. Mixture of 4-morpholine-N,N'-dicyclohexylcarboxaminidium guanosine 5'-monophosphomorpholidate (43 mg, 0.054 mmol ) and 82 (16 mg, 0.034 mmol) was coevaporated with dry pyridine (3 x 500 Ill). 1 H-tetrazole (8 mg, 0.108 mmol ) and dry pyridine (1 ml) were added and the mixture was stirred under argon atmosphere for 2 days. Water was added and the mixture was concentrated under reduced pressure to yield 83; ESMS (mlz): 606.11 (M-Hr.

solution of compound 80 and 1 H-tetrazole (7 mg, 0.102 mmol) in anhydrous CH2CI2 was added dibenzyl-N,N'-diisopropylphosphoramidite (42 Ill, 43.8 mg, 0.127 mmol) and the mixture was stirred under argon atmosphere for 2 h at rt. Subsequently, the reaction mixture was cooled to -40°C and m-CPBA (30 mg, 0.17 mmol) was added and stirring was continued for another 30 minutes at rt. The reaction was quenched by the addition of a solution of saturated sodium bicarbonate. The mixture was extracted with CH2CI2. The organic phase was thoroughly washed with water, dried over Na2S04 and concentrated to afford 81, which was purified by running a silica coated preparative TlC plate; R, = 0.12 (twice run in 30% ethyl acetate in hexane); 1H NMR: characterstic () 5.6 (1 H, dd, JHP = 6.3 Hz and JHH = 1.8 Hz); 13C NMR: () 20.50, 20.53, 20.60, 64.75, 68.11, 68.58, 69.86, 70.67, 70.93, 81.87, 95.01, 128-128.72, 169.38, 169.50, 169.67; 31 P NMR () -3.11; ESMS (m/z): 591.34 (M+Nat. 6-Deoxy-6-fluoro-a-D-mannosyl phosphate (82). To a solution of 81 (20 mg, 0.035 mmol) in CH30H

Methyl-S-deoxy-S-difluoro-a-D-mannopyranoside (78). DAST (134 Ill, 1 mmol) was added with stirring at -40 °c, to a suspension of methyl-a-D-mannopyranoside S2 (200 mg, 1 mmol) in anhydrous CH2Cb (4 ml). The mixture was stirred at -40 °c for another 30 minutes and then at rt for 3h. After cooling to -20°C, the excess of reagent was destroyed by addition of CH30H (600 Ill) and sodium bicarbonate (200 mg). The cooling bath was removed, and the mixture was filtered once effervescence ceased. The filtrate was concentrated and purified by silica column chromatography (3% CH30H in CH2CI2) to yield 78; Rf = 0.21 in 12.5% CH30H in CH2CI2• 1 ,2,3,4-Tetra-O-acetyl-S-deoxy-S-fluoro-a-D-mannopyranoside (79). To compound 78 (100 mg, 0.51 mmol) was added 2% sulfuric acid solution in acetic anhydride (1.2 ml). The mixture was stirred at rt for 90 minutes. The contents were diluted with saturated sodium bicarbonate solution. The mixture was extracted with ethyl acetate. The organic phase was thoroughly washed with water, dried over Na2S04and concentrated to afford 79; Rf = 0.35 in 50% ethyl acetate in hexane. 2,3,4-Tri-O-acetyl-S-deoxY-S-fluoro-a-D-manno-di-O-benzyl phosphate (81). Compound 79 ( 30 mg, 0.085 mmol) was dissolved in anhydrous acetonitrile saturated with dimethylamine (5 ml ) at -20°C and stirred for 3 h after which TlC confirmed the disappearance of starting material. Excess of dimethylamine was removed under reduced pressure at 30°C and the reaction mixture was concentrated to afford 2,3,4-tri-O-acetyl-6-deoxY-6-floro-a-D-mannopyranoside (80). To a stirred

Synthesis of [6-Deoxy-6-fluoro]-GDP Mannose95 (Scheme 17 of Results and Discussion)

substrate (49). The contents were lyophilized and 250 III of membrane suspension (1.4 x 108 cell equivalent in incorporation buffer) were added to each tube. The tubes were incubated at 28°C for 20 minutes, cooled to 0 °C and the membranes were pelleted at 4 °C for 10 minutes in a microcentrifuge. The [3H] mannosylated products, that were recovered in the supernatant, were mixed with 0.5 ml 100 mM ammonium acetate and applied to a C18 Sep-pak cartridge that had been washed with 5 ml 80% propan-1-01 and 5 ml 100 mM ammonium acetate. The cartridge was washed with 1.5 ml of 100 mM ammonium acetate and then the eluate was reapplied to the same cartridge. The cartridge was subsequently washed with 5 ml of 100 mM ammonium acetate, after which the bound material was eluted with 5 ml of 60% propan-1-01. The final eluate was concentrated and redissolved in 100 III of 60% propan-1-01. One tenth of this volume was taken for scintillation counting.

The membranes were suspended (1.4 x 108 cell equivalent) in 250 J..ll of incorporation buffer (50 mM HEPES, pH = 7.4, 25 mM KCI, 5 mM MgCb, 5 mM MnCI2, 0.1 mM TlCK, 1 J..lg/ml leupeptin, 1 mM ATP, 0.5 mM dithiothreitol and 0.4 J..lg/ml tunicamycin). Each assay tube was prepared by adding 12.5 J..ll of 1% Chaps, 28 J..ll of 200 J..lM GDP-Man, 10 J..ll of GDP-[3H]Man (1 J..lCi) and 25 nmol of synthetic

Elongating mannosyl phosphate transferase (eMPT) assay45

Cultured promastigotes were harvested by centrifugation of suspension culture (500 ml) in falcon tubes at 3000 g for 10 min at 20°C in a cooling centrifuge (Rota 4R; Plastocraft). The clear spun media was carefully decanted and the pellet was resuspended in ice-cold phosphate buffered saline (PBS, 20mM, pH = 7.2). Centrifugation was done again as earlier and washings were collected in a separate falcon. The washing step with PBS was repeated twice. The promastigotes in PBS were then counted using a Neubauer chamber. For this an aliquot was taken and diluted with PBS (normally 10 J..ll original suspension was mixed with 60 J..ll PBS) and then formaldehyde was added to this (30 J..ll to give a final dilution of 1:10). After 10 minutes of fixing in formaldehyde, 10 J..ll of this diluted suspension was put under the coverslip on Neubauer chamber and counted. Total cell count was determined using the standard formula. For breaking cells to get membrane preparation,93 the cell pellet (6.5 x 109 cells) was suspended in 5 ml of hypotonic buffer (0.1 mM TlCK and 1 J..lg/ml leupeptin) and sonicated in ice (6 x 10 s pulses with 3 s intervals). Breaking of cells were assessed by a light microscope. The membrane protein was further processed as per the requirement of the experiment.

Preparation of Cell-free system of L.donovani

incubated at 23°C in a cooling incubator (CI-12S; Remi). Fresh passaging was done weekly in a similar fashion. After about 15 passages, a fresh cryostock from liquid nitrogen was expanded and passaging done as mentioned before. Random samples from culture flasks free from any visible microbial contamination and full of all healthy, motile parasites under microscopic examinations formed the basis of selection of the culture suitable for further use. After culturing, used flasks, pipettes, glassware etc were decontaminated by immersing them in 5% formaldehyde solution and then discarded. All other routine standard cell culture practices were observed.

For both routine as well as bulk culture of L.donovani 008 strain promastigotes, medium dMEM was used. This media was prepared by dissolving one sachet of powdered media dMEM (GIBCO BRl) in 800 ml of distilled water. To this was added 25 mM HEPES and other supplements (0.05 mM adenosine, 0.05 mM xanthine, 1 mg biotin, 0.04% tween 80, 5 mg hemin, 0.5% triethanolamine, 0.3% bovine serum albumin, 50 mg gentamycin sulfate). pH of the media was adjusted to 7.2 , volume made upto one litre and the media was sterilized using bell filter (0.22 Il, Sterivex GV; Millipore). The media was used within two months of preparation. To this media, as per requirement of routine culture, heat inactivated fetal bovine serum (HI-FBS) was added @ 10%. In the present study Leishmania donovani, 008 strain, promastigotes were used throughout obtained from Prof. K.P.Chang, Chicago Medical Centre, USA. These were initially isolated from patients native to central Bihar. Upon arrival these promastigotes were expanded in medium 199 and cell bank was raised where -107 viable parasites were taken in 1 ml of complete medium 199 containing 10% glycerol. These were stored in liquid nitrogen. The revival capacity of these frozen cells was checked after one week storage by snap thawing the contents of one vial at 37°C, inoculating 50 ml of dMEM media with the entire contents and incubation at 23°C for one week. A luxuriant growth with healthy viable parasites was observed under the microscope. Routinely, L.donovani promastigotes were cultured in T-125 culture flasks having 50 ml of dMEM media each supplemented with 10% FBS. Media was inoculated with 100 III of a previous culture containing _106 promastigotes. These flasks were

Maintenance and revival of L.donovani culture

Preparation of Microsomal Membranes of L.donovani parasite

N-Butyl-4-~-galactopyranosyl-a-D-glucopyranosyl ~-amino lactam (61). To a solution of 5 (12 mg) in CH30H (1 ml) was added palladium on carbon (10%, 35 mg) and formic acid (100 Ill). The mixture was stirred at 50°C overnight. The catalyst was filtered off and solvent was evaporated to afford 61; 1H NMR: 80.72-0.77 (t, 3H, CH2-CH3), 1.14-1.22 (m, 4H, CHz-CHz-CH3),1.40-1.45 (t, 2H, N-CH2), 4.31 (d, J = 7.8 Hz, 1H, H-1'), 5.38 (d, J = 4.2 Hz, 1H, H-1); 13C NMR: 8 12.72,19.69,28.77,40.65, 52.84, 61.09, 67.48, 68.50, 70.88, 72.56, 75.17, 77.66, 79.12, 103.19, 169.83; ESMS (mlz): 430.37 (M+Nat.

3,6··Di-O-benzyl-4-(2,3,4,6-tetra-O-benzyl-~-galactopyranosyl)-a-D-glucopyrano syl ~ amino lactam (58). To a solution of hexa-O-benzyl lactal (32, 300 mg, 0.36 mrnol) in CHCI3 (0.36 ml) was added trichloroacetyl isocyanate (90 Ill, 0.74 mmol). The mixture was stirred at rt for 18 h to afford the intermediate 57. This intermediate was characterized by 1 H NMR: 06.04 (1 H, d, J = 5.4 Hz, H-1, gluco isomer), 5.96 (1 H, d, J = 3.3 Hz, man no isomer). The reaction mixture was then cooled to -20°C and treated with benzylamine (0.13 ml, 1.17 mmol) and the flask was gradually brought to rt. The organic phase was thoroughly washed with water, dried over Na2S04 and concentrated. The residue was purified by silica column chromatography 1,30% ethyl acetate in hexane) to afford 58 (275 mg, 87%); Rt = 0.33 in 50% ethyl acetate in hexane; 1H NMR: & 3.37-3.46 (m, 5H, H-2,6,6'), 3.58-3.7 (m, 3H, H-3,4,5), 3.77-3.89 (m, 3H, H-2',3',5'), 4.34 (d, J = 4.2 Hz, 1 H, H-1 '),4.44 (d, 1 H, H-4'), 5.4 (d, J = 4.5 Hz, H-1), 6.24 (s, 1 H, NH), 7.22-7.36 (m, 30H, Ph); 13C NMR: & 54.27,68.43, 69.39, 71.48, 72.65, 73.06, 73.12, 73.37, 74.56, 75.05, 75.35, 75.95, 79.47, 82.31, 102.98,127.42-128.33,138.07-138.83,166.90; ESMS (mlz): 914.5 (M+Nat. 4-~-Galactopyranosyl-a-D-glucopyranosyl ~ amino lactam (59). To a solution of 58 (30 mg, 0.035 mmol) in CH30H (3 ml) was added palladium on carbon (10%, 170 mg) and formic acid (

Synthesis of anomeric ~-Iactam analogues of eMPT substrate91•92 (Scheme 14 of Results and Discussion)

mg, 0.03 mmol) in 95% aqueous pyridine (1 ml) was added. After 30 min CH2Cb was added and the solution was washed successively with cold 1 M Na2S203 (2 x 5 ml) and cold 1 M TEA hydrogen carbonate (2 x 5 ml), dried over Na2S04 and concentrated. The residue was purified by silica column chromatography (1.5% CH30H in CH2Cb with 0.1 % Et3N); Rf = 0.54 in 20% CH30H in CH2CI2; 1 H NMR: 8 -0.01 (s, 6H, Me~iCMe3), 0.84 (s, 9H, Me2SiCMe3), 1.95-2.11 (m, 18H, OAc), 3.62 (m), 3.88 (m), 4.2 (m), 4.5 (m), 4.9 (m, 2H, H-2', 3'), 5.28 (m, 3H, H-1, 2, 3), 5.44 (m, 1 H, CH=CH2); 31 P NMR .8-2.68; ESMS (mlz) : 925.3 (M-Et3N-H)". Dec-9-enyl-6-dihydroxyl-4-~-D-galactopyranosyl-a-D-mannopyranosyl phospha te triethylammonium salt (55). A solution of aqueous HF (48%) in CH3CN (5:95, 400 Ill) was added to compound 54 (10 mg, 0.009 mmol) at 0 aC. The solution was stirred at 0 aC for 2 h. The reaction was quenched by the addition of the aqueous NaHC03 solution until effervescence ceased and diluted with CH2CI2. The organic layer was extracted with water and TEAS solution thoroughly, dried over Na2S04 and concentrated to give dec-9-enyl-2,3,4-tri-O-acetyl-4-~-D-galactopyranosyl-a-D­mannopyranosyl phosphate triethylammonium salt; ESMS (m/z): 811.4 (M-EtsN-H)". A solution of oxalyl chloride (0.38 mg, 1.5 Ill, 0.003 mmol) in anhydrous CH2CI2 (50 Ill) was cooled to -78 aC and DMSO (0.47 mg, 1.7 Ill, 0.006 mmol) was added, followed by the addition of a solution of dec-9-enyl-2,3,4-tri-O-acetyl-4-~-D­galactopyranosyl-a-D-mannopyranosyl phosphate (7 mg, 0.007 mmol) in CH2CI2 (100 Ill). The mixture was stirred for another 30 minutes and then triethylamine (10 Ill) was added. The solution was brought to rt, water was added and the mixture was extracted with CH2Cb. The organic layer was dried over Na2S04 to give the aldehyde 55. Dec-9-enyl-6-dihydroxyl-4-~-D-galactopyranosyl-a-D-mannopyranosyl phosphate triethylammonium salt (56). The residue was taken in a mixture of CH30H:water:triethylamine (5:3:2, 1.6 ml) and stirred for 2 days at rt. The reaction mixture was concentrated and the residue was repeatedly lyophilized to yield 56.

Dec-9-enyl-2,3,4-tri-O-acetYI-[6-0-(t-butYldimethYlsilyl)-4-~-D-galactopyranosyl] -a-D-mannopyranosyl phosphate tri ethylammonium salt (54). A mixture of H-phosphonate 6 (from scheme 1, 50 mg, 0.057 mmol) and dec-9-en-1-01 (30 Ill, 0.172 mmol) was dried by evaporation of pyridine (2 x 0.5 ml). The residue was dissolved in anhydrous pyridine (1 ml), pivaloyl chloride (22 Ill, 0.172 mmol) was added, and the mixture was stirred at rt for 1 h whereafter a freshly prepared solution of iodine (6

(Scheme 13 of Results and Discussion)

Synthesis of S'-hemiacetal analogue90 of Gal 1,4~-Man-a­phosphate acceptor

Design and Synthesis of mechanism based inhibitors of elongating MPT enzyme of LPG biosynthesis

was diluted with water and the aqueous layer was thoroughly extracted with ethyl acetate (15 ml x 2). The organic layer was dried over Na2S04, concentrated and dried to yield C4C] labelled stearyl alcohol 51. [14C]-Stearyl-2,3,6-tetra-O-acetyl-4-0-(2,3,4 ,6-tretra-O-acetyl-~-D-gal actopyrano syl)-a-D-mannopyranosyl phosphate triethylammonium salt (52). A mixture of H-phosphonate 47 (296 mg, 0.37 mmol) and [14C] stearyl alcohol (51,100 mg, 0.37 mmol) was dried by evaporation of pyridine (2 x 3 ml). The residue was dissolved in anhydrous pyridine (5 ml), adamantane carbonyl chloride (160 mg, 0.8 mmol) was added, and the mixture was stirred at rt for 1 h whereafter a freshly prepared solution of iodine (160 mg, 0.63 mmol) in 95% aqueous pyridine (5 ml) was added. After 30 min CH2Cb was added and the solution was washed successively with cold 1 M Na2S203 (2 x 10 ml) and cold 1 M TEA hydrogen carbonate (2 x 10 ml), dried over Na2S04 and concentrated. The residue was purified by silica column chromatography (2.5% CH30H in CH2CI2 with 1 % Et3N) to afford 52. [14C]-Stearyl-4-~-D-galactopyranosyl-a-D-mannopyranosyI phosphate triethyl ammonium salt (53). To a solution of compound 4 (75 mg, 0.07 mmol) in anhydrous CH30H (12.5 ml) was added anhydrous sodium carbonate (80 mg, 0.75 mmol). The mixture was stirred at rt for 2 h, whereafter sodium carbonate was removed by filtration. The solvent was evaporated and residue concentrated to yield 53; R,= 0.55 in 10: 1 0:3 CH30H:CH2CI2:O.25% KC!.

[14C]-Stearyl alcohol (51). Stearic acid (50,100 mg) in anhydrous THF (1 mL) was diluted with C4C] stearic acid (1.2 mL, 120 !lCi). To this was added THF-borane complex (4 mL). The mixture was refluxed at 90°C for 36 h. The contents were then poured onto CH3COOH:H20 (8 mL, 1:1), taken in a separating funnel. The mixture

Synthesis of [14C] labeled Stearyl linked Gal 1,4 f3 Man phosphate (Scheme 12 of Results and Discussion)

5.2 (m, 3H, H-1, 4, 3), 5.28 (dd, J = 2.1 and 3.6 Hz, 1 H, H-2), 7.95 (d, JHP=637 Hz, 1 H); 31 P NMR f> 0.129; ESMS (mlz) 699.27 (M-Et3N-H)" Stearyl-2,3,6-tetra-O-acetyl-4-0-(2,3,4,6-tetra-O-acetyl-~-D-galactopyranosyl)-a­D-mannopyranosyl phosphate triethylammonium salt (48). A mixture of H-phosphonate 47 (25 mg, 0.031 mmol) and stearyl alcohol (11 mg, 0.04 mmol) was dried by evaporation of pyridine (2 x 0.5 mL). The residue was dissolved in anhydrous pyridine (1 mL), adamantane carbonyl chloride (16 mg, 0.08 mmol) was added, and the mixture was stirred at rt for 1 h whereafter a freshly prepared solution of iodine (16 mg, 0.063 mmol) in 95% aqueous pyridine (3 mL) was added. After 30 min CH2CI2 was added and the solution was washed successively with cold 1 M Na2S203 (2 x 5 mL) and cold 1 M TEA hydrogen carbonate (2 x 5 mL), dried over Na2S04 and concentrated .The residue was purified by silica column chromatography (2.5% CH30H in CH2CI2 with 1 % Et3N) to afford 48; Rt = 0.46 in 20% CH30H in CH2CI2; 1H NMR: 8 0.84 (t, 3H, CH3), 1.23-1.45 (lipid protons), 1.85-2.12 (m, 21 H, OAc), 3.84-4.16 (m), 4.51 (d, J = 7.8 Hz, 1H, H-1'), 4.85-5.01 (m, 2H, H-2', 3'), 5.25 (m, 3H, H-1, 4, 3), 5.52 (dd, J = 2.1 and 3.6 Hz, 1 H, H-2), 5.69 (dd, 1 H, JHP = 6.8 and J1,2 =1.9 Hz, H-1); 13C NMR: 8 13.99, 20.48-20.77, 22.56, 27.8-29.59, 31.80, 36.44, 38.78, 52.82, 60.69, 68.99, 69.48, 70.23, 70.91, 76.52, 93.26, 100.93, 168.99-170.42; 31p NMR: 8 -2.90; ESMS (mlz): 967 (M-Et3N-H)' Stearyl-4-~-D-galactopyranosyl-a-D-mannopyranosylphosphate triethylammo nium salt (49). To a solution of compound 48 (15 mg, 0.014 mmol) in anhydrous CH30H (2.5 mL) was added anhydrous sodium carbonate (16 mg, 0.15 mmol). The mixture was stirred at rt for 2 h, whereafter sodium carbonate was removed by filtration. The solvent was evaporated and residue concentrated to yield 49 in quantitative yield; Rt= 0.55 in 10:10:3 CH30H:CH2CI2:O.25% KCI; 31p NMR.8 -1.72; ESMS (mlz): 673 (M-Et3N-H)'

1 ,2,3,6-Tetra-O-acetyl-4-0-(2,3,4,6-tetra-O-acetyl-~-D-galactopyranosyl)-a.-D­mannopyranose (46). Acetic anhydride (4 ml) was added dropwise to a stirring solution of Gal (1-4)~ Man (45, 700 mg, 2.04 mmol) in anhydrous pyridine (6 ml) at 0 °C. The reaction mixture was gradually brought to room temperature and stirred for 16 h. After completion of the reaction, the mixture was poured over ice and the product crystallized out to afford 46 in quantitative yield. Triethylammonium 2,3,6-tri-O-acetyl-4-0-[2,3,4,6-tetra-O-acetyl-~-D-galacto pyranosyl]-a.-D-mannopyranosyl hydrogen phosphonate (47). Compound 46 (600 mg, 0.89 mmol) was dissolved in anhydrous CH3CN saturated with dimethylamine (40 mL) at -20°C and stirred for 3 h after which TLC confirmed disappearance of the starting material. Excess of dimethylamine was removed under reduced pressure at 30°C and the reaction mixture was concentrated to provide 2,3,6-tri-O-acetyl-4-0-(2,3,4,6-tetra-O-acetyl-~-D-galactopyranosyl)-a.-D-mannopyra nose. To a stirred solution of imidazole (1 g, 14.68 mmol) in anhydrous CH3CN (20 mL) at 0 °C was added phosphorus trichloride (0.8 ml, 9.14 mmol) and triethylamine (2.4 mL, 0.86 mmol). The mixture was stirred for 20 min, after which a solution of the above anomeric deprotected compound (500 mg, 0.786 mmol) in anhydrous CH3CN (20 mL) was added dropwise. The mixture was stirred at 0 °C for 2 h and quenched with 1 M triethylammonium (TEA) hydrogen carbonate solution (pH=7.2, 10 mL). The clear solution was stirred for 15 min. CH2CI2 was added and the organic layer was washed with ice cold water (2 x 10 ml) and cold 1 M TEA hydrogen carbonate solution (2 x 10 ml), dried over Na2S04 and concentrated to yield 47 (500 mg, 86.2%); Rt = 0.35 in 20% CH30H in CH2CI2; 1H NMR: 8 1.9-2.08 (m, 21 H, 7 x OAc), 3.84-4.13 (m, 6H, H-5, 5', 6, 6'), 4.35 (d, J = 4.5 Hz, 1 H, H-4), 4.47 (d, J = 7.8 Hz, 1 H, H-1 '), 4.9 (dd, J =3.3 and 7.8 Hz, 1 H, H-3'), 5.05 (dd, J = 2.1 and 7.8 Hz, 1 H, H-2'),

Synthesis of Stearyl linked Gal 1,4 ~ Man phosphate (synthetic substrate for elongating-MPT activity)

Synthesis of Radiolabeled Exogenous Precursor of Phosphoglycan Biosynthesis

Design, Synthesis and Evaluation of Inhibitors of Phosphoglycan biosynthesis

Polycondensation. Compound 26 (25 mg, 0.033 mmol) was dried by evaporation of pyridine (500 III x 3) therefrom. The residue was dissolved in 10:1 pyridine:triethylamine (40 Ill), and pivaloyl chloride (9 Ill, 0.073 mmol) was added. Another lot of pivaloyl chloride (6 Ill, 0.04B mmol) was added in 45 min. After 3 h, the mixture became viscous, and a freshly prepared solution of iodine (220 Ill, 35 mg, 0.137 mmol in pyridine-water, 95:5) was added. After 2 h, CHCI3 was added and the organic layer was successively washed with cold 1 M aqueous Na2S203 solution and 1 Mice-cold TEAB buffer, dried over Na2S04 and concentrated to dryness to afford 27. For final deprotection, above residue was dissolved in 0.1 M NaOMe solution in CH30H (440 Ill), 1,4-dioxane (BOO Ill), and CHCI3 (BOO Ill). The mixture was stirred at rt for 7 h and left at 4 °C for 16 h, then diluted with CH30H, deionized with Dowex 50W-X4 (H+) resin, filtered and immediately neutralized with drops of triethylamine. The mixture was concentrated to dryness to afford fully deprotected phosphoglycans (28). 31 P (D~O): 8 -1.73, O.BB. Preliminary CD analysis of Phosphoglycans. The above polycondensation product (28) was lyophilized repeatedly and then redissolved in H20 (400 Jll). This solution was taken in a glass cuvette (300 Ill, 1 mm pathlength). It's CD spectra was recorded on a spectropolarimeter (JASCO, J-710) between 175-250 nm at 25°C. For reference, the CD spectra of agarose (15% W/V)87 was also recorded under the same conditions as mentioned above.

Triethylammonium 2,3,6-tri-o.acetyl-4-o.(2,3,4-tri-o.acetyl-~-D-galactopyrana syl)-a-D-manno pyranosyl hydrogen phosphonate (26). Compound 6 (30 mg, 0.034 mmol) was dissolved in a mixture of acetic acid-water-THF (3:1:1,2.5 ml). The mixture was stirred at 40°C for 9 h, after which the solvent was evaporated off under vacuo at rt. To remove excess of acid, water (1 ml) was added and evaporated off twice to afford 26 in quantitative yield; 1H NMR (CDCI3, 300 MHz) 0 1.95-2.09 (m, 21 H), 3.49-3.68 (m, 4H), 3.88 (m, 1 H), 4.14 (m, 1 H), 4.36 (d, J = 4.5 Hz, 1 H), 4.47 (d, J = 7.8 Hz, 1 H), 4.95 (dd, J = 3_3 and 7_8 Hz, 1 H), 5.05 (dd, J = 2_1 and 7.8 Hz, 1 H), 5.21 (dd, J = 2.1 and 3.6 Hz, 1 H), 5.41 (d, J = 3.3 Hz, 1 H), 5.48 (dd, J = 2.1 and 7.8 Hz, 1 H), 7.99 ( d, JH,p = 637_0 Hz, 1 H); 13C NMR (CDCI3, 75 MHz) 0 20.48-20.76, 60.10, 62.42, 66.57, 69.36, 69.53, 69.69, 71.20, 73.30, 73.86, 91.59, 92.54, 101_09, 169.13-170.49; 31p (CDCI3): 00.22; ESMS mlz657.3 (M-EhN-Hr.

Synthesis of phosphoglycans by polycondensation

d) Particle delivery using the Helios gene gun A day prior to immunization, hair were removed from the abdominal region of mice using a commercial depilatory agent (Anne French cream). Two cartridges/mouse ( ~ 2 Jlg DNA) were shot under pressurized helium gas ( 400 psi) intradermally at the shaven area of the abdomen of mice using the Helios gene gun. Two boosters comprising of two cartridges each were given on days 21 and 35. On day 45, mice in each group received i.m. injection of E. coli expressed recombinant protein (20 Jlglmouse in saline). Mice were bled retro-orbitally on days 0, 45 and 52 for analysis of antibody response.

tubing, which was cut into 0.5 inch pieces (cartridges). These cartridges were used to deliver DNA into epidermis of male/female mice. a) Preparation of DNA-gold microcarrier suspension Twenty five mg of gold microcarriers were weighed in a 1.5 ml eppendorf tube to which 100 J..Ll of 0.05 M spermidine was added and vortexed for 10 sec. To the above mixture 100 J..Ll of DNA (0.5 mg/ml) was added and vortexed for another 10 sec. While vortexing, 100 J..Ll of 1 M CaCh was added dropwise to the mixture and left at RT for 10 min to allow precipitation of DNA onto gold microcarriers. The DNA-gold pellet was collected by centrifuging at 12,000 X g for 1 min at RT. The pellet was washed thrice with 100% ethanol (freshly opened bottle), resuspended in 3 ml of 0.1mg/ml polyvinylpyrollidone (PVP) in ethanol and stored at -20°C till further use. b) Loading the DNA/microcarrier suspension into gold-coat tubing using the tubing prep station A 25 inch length of tubing was cut and fixed on tubing prep station, air dried by passing nitrogen gas through it for 15 min. The DNA/microcarrier suspension was vortexed and injected into the tubing using a 5 ml syringe and the microcarriers allowed to settle in the tubing for 3 min. Ethanol from the tubing was removed by slowly sucking into the syringe. The tubing was rotated, while passing the nitrogen gas, using the tubing prep station, for 20-30 sec to allow the microcarriers to evenly coat the inside of the tubing. c) Preparation of cartridges using the tubing cutter The tubing was cut into 0.5 inch long pieces (cartridges) by using the tubing cutter and cartridges stored at 4°C in vials containing desiccant pellets till further use.

Suspension of DNA adsorbed onto gold microcarriers at 0.5 Microcarrier Loading Quantity (MLQ; 50 J.lg DNA/25 mg gold microcarriers) was prepared and coated inside Tefzel

Plasmid DNA adsorbed onto gold microcarriers

For use in enzyme linked immunosorbant assay (ELISA), r-bmZP1, r-dZP3 and r-rG, expressed in E. coli were purified under denaturing conditions. For purification of r-bmZP1, as described previously, the pRSET-bmZP1 clone, encoding bmZPl, excluding the SS and the TD (22-462 aa) was used (Govind et al., 2001). Similarly, the pQE30-dZP3 and pQE30-rG clones encoding dZP3 and rG, excluding the SS and the TD were used for purification of r-dZP3 (26-352 aa) (Santhanam et al., 1998) and r-rG (20-457 aa) (unpublished. observations) respectively. For T cell proliferation assays, the above recombinant proteins were purified from inclusion bodies in the absence of chaotropic agents in refolded form as described below. The above clones were inoculated in 10 ml of LB containing appropriate antibiotics and grown 0/N at 3 7°C. Following day, the cells were subcultured (I: 100 dilution) in I liter of LB (250 mllflask) containing appropriate antibiotics and grown at 37°C until the A600

To investigate if the expressed protein was membrane bound or cytosolic, cells were fixed in 3. 7% paraformaldehyde followed by all washings and incubations with primary and secondary antibodies either in presence or absence of 0.1% Saponin and processed for indirect immunofluorescence as described above.

Localization of the expressed recombinant protein in COS-1 cells

described for bmZP1 except that for rGVR, rGVRt and rGVRst an annealing temperature of 45°C and for rGVRs an annealing temperature of 50°C was used.

To obtain the optimum expression of rG in mammalian cells and to study the influence of the SS and the TD on the immune response generated by DNA vaccine, four different constructs of rG eDNA in VR1020 vector were made (Table 1). For cloning rG, BHK21 cells were infected with PMIO strain of rabies virus. Total RNA from the infected cells was prepared at various time period post-infection using TRIZOL reagent. Total RNA was directly used to amplify the eDNA corresponding to rG without the SS and the TD, by RT-PCR, following the manufacturers instruction provided in the kit (Promega). The RT-PCR resulted in amplification of a 1.314 kb fragment. The fragment was cloned in pPCR-Script Amp SK (+) cloning vector and from there into pQE30 expression vector. One of the positive clones (pQE30-rG) expressing rG in E. coli was used as a template to PCR amplify rG eDNA, without the SS and the TD, using BamH I restriction site in the forward primer and Bgl II restriction site in the reverse primer (Table 1 ). For amplification of rG eDNA to prepare rGVRt (-SS, + TD), rGVRs (+ SS,-TD) and rGVRst (+ SS, + TD) constructs, the pKB3-JE-13 clone {ATCC) encoding the full length rG from the Challenge Virus Standard (CVS) strain of the rabies virus was used as a template. The DH5a strain of E. coli was transformed with pKB3-JE-13 plasmid DNA and one of the positive clones was used to PCR amplify' different rG eDNA fragments (for rGVRt, rGVRs and rGVRst constructs) using respective forward and reverse primers as shown in Table 1. All the PCR reactions were carried out with Taq DNA polymerase using the same reaction conditions as

PCR amplification of rG cDNAs

Theheadkidneywasusedasasourceofphagocytesforchemiluminescence (CL)andmigrationassays.Cellsfromthehomogenizedheadkidneywereseparatedwithatwo-stepPercollgradient.Granulocyteswerecollectedatthe1.070-1.090g/cm3interfaceandafterwashingwithrHBSSresuspendedinphenolred-freerRPMl.

Headkidney

Theacetylcholineconcentrationinthetissueswasestimatedspectrophotometricallyat540nmbythemethodofHestrin(1949)usingformicacid-acetonemixture(0.15mformicacidacetone,3:17V/V)astheextractionmediumAchconcentrationwascalculatedintermsofnmolAch/mgtissue

Acetylcholine(Ach)

Immediatelyafterisolation,thetissueswereweighedandsubjectedtolipidextractionthatwascarriedoutinduplicateaccordingtoFolchetal.(1957)

Totallipids

Meancorpuscularhaemoglobinconcentration(MCHC)istheaverageHbconcentrationperunitvolume(100)ofpackedredcells(W/V).Henceitisexpresseding/1whichisthesameaspercent(%).ItiscalculatedbythefollowingformulaHbMCHC=—......x100(g/dl)PCV

MCHC

Thepackedcellvolumeorhaematocritisthevolumeoccupiedbythepackedredcells,afteravolumeofanticoagulatedvenousbloodisfullycentrifuged.Thevolumeofpackedcellisexpressedasapercentageoftheoriginalvolumeoftheblood.ThePCVisusedtoestimatehaematologicalindices,includingthemeancellhaemoglobinconcentration(MCHC)andmeancorpuscularvolume(MCV).PCVdetermination followedthemethodsofBlaxhallandDaisley(1973).Thehaematocritvaluewasdeterminedbycentrifuging(3000rpm)aknownvolume ofincoagulantbloodkeptinWintrobe’stubes

PackedCellVolume(PCV)orHaematocrit(Ht)

Theexperimentalsetup(Figure8and9)forthedeterminationofO2uptakesimultaneouslyfromairandwaterwassimilartothatusedearlierbyNatarajan(1972),Rani(1994)andVijayalakshmi(1996).Aclosedglassrespirometerof5litrecapacitywasfilledwith3.5litrefreshtapwater.Athermocolfloatwithasemicircularholeatitsperipherywasplacedoverthewater,whichseparatedtheair-waterinterphaseoftherespirometer.Theair-phaseoftherespirometerwasattachedtoafluidmanometer.Asthefishcomestothewatersurfaceandtakesair-gulp,thereisapressurechangeintheair-phasecausinganimbalanceinthemanometricfluid.AgraduatedsyringefilledwithpureO2(takenfrommedicalO2cylinder)isusedtorestoretheimbalanceofthemanometricfluid.TheamountthusneededshowstheaerialO2uptakeofthefish.TheexpiredCO2wasabsorbedbythepelletsofKOHinthepetridishoverthemanometricfluid.Theconcentrationofdissolvedoxygenoftheambientwaterwasestimatedbefore andaftertheexperimenttomeasuretheaquaticO2uptakebythefish.ThedifferenceintheDOandtheamountofwaterindicatestheactualaquaticO2uptake.Winkler’svolumetricmethod(Welch,1948)wasusedtoestimatetoDOofthewatersamples.Darkenedrespiratorychamberswereusedwithdimensionsthatwereclosetothoseofthefishinorderthatthefishshouldremaininmoreorlessthesamepositionbut havesufficientroomtomoveitsopercula.Theflowofwaterthroughtherespirometer wasregulatedandmeasuredbymeansofaflowmeter.APhilipsO2electrode(PI1056)waskeptinawaterjacketmaintainedatthesametemperatureastheclosedcirculation.SamplesoftheinflowandoverflowwatercouldalsobeledovertheO2electrode

Bimodalrespiration

Thefisheswerefedadlibitumwithboiledhen’seggsontwodaysinaweekandearthwormsontheremainingdays.Feedingwasstopped24hrpriortoexperimentation.Noprophylactictreatmentforanydiseaseproblemwasnecessaryatanytimeduring acclimationandtest

Feeding

smiFISH: The smiFISH protocol was performed as described by Tsanov et al., 2016with modifications for use in the Drosophila embryo. Briefly, a minimum of 50μl of embryos were transferred to Glass V-vials (Wheaton) and transitioned from 100% Methanol to PBT in 50% increments, followed by several 10min PBT washes. Subsequently, embryos were washed at 37°C in stellaris wash buffer(1x SSC (150 mM NaCl and Sodium Citrate at pH 7.0), 10% deionised formamide) pre-warmed to 37°C. Hybridisation was performed using 4uM of labelled probes mixtures, as described above, incubated in stellaris hybridisation buffer (1x SSC, 100mg dextran sulphate, 10% deionised formamide) for a minimum of 14 hours at 37°C. Following hybridisation excess probes are removed with washes in stellaris wash buffer, pre-warmed to 37°C and subsequently washed with PBT. During the pen-ultimate PBT wash DNA and the nuclear membrane were stained using 1:1000 of DAPI (5mg/ml) and 1:1000 of wheat germ agglutinin (WGA) conjugated to Alexa 555 (5mg/ml, ThermoFisher Scientific), respectively. Embryos were subsequently mounted with ProLong Gold AntiFade (ThermoScientific).Alkaline Phosphatase Immunostaining: For immunostaining, a minimum of 50μl of embryos were gradually transferred from methanol to PBT and washed in PBT for 30mins with repeated changes of PBT. Embryos were blocked for 2hrs in 10% BSA in PBT and subsequently washed in PBT. Following this, embryos were incubated with monoclonal mouse anti-Hindsight-IgG1 (1:20, DSHB) primary in 1% BSA in PBT overnight at 4°C. To remove excess antibody, embryos were washed for 2hrs in 1% BSA in PBT. Next, polyclonal goat anti-mouse-IgG (H+L) AP Conjugate (1:500, Promega) was added in 0.1% BSA in PBT and incubated for 2hrs at room temperature. This was followed by washes with PBT and staining solution (defined above). Following staining, washing and mounting was performed as above. Image Acquisition: Images from alkaline phosphatase staining were acquired on a Leica DMR. Fluorescent images were acquired using a Leica TCS SP5 AOBS inverted confocal. Whole embryos were viewed using a20x 0.70 HXC PL APO Lambda Blue Immersion objective and embryo sections viewed with a 63x 1.40 HCX PL APO Lambda Blue Oil objective, with a maximum of 3x confocal zoom. Additional confocal settings were as follows: pinhole diameter of 1 airy unit, 400Hz unidirectional scan speedwith all images collected at 1024 x 1024. Images were collected sequentially usingPMTdetectors with the following mirror detection settings:DAPI (420-470nm), Alexa 488 (490-525nm), Alexa 555 (570-620nm) and Alexa 647 (650-780nm). The respective fluorophores were detected using the blue diode (20%) and the following laser lines: 488nm (50%), 555nm (50%) and 633nm (40%). When acquiring 3D optical stacks the confocal software was used to determine the optimal number of Z sections based on a Z section depth of 1μm at 20x and 0.3μm at 63x. Only themaximumintensity projections of these 3D stacks are shown in the results

fluorescently conjugated secondary antibodies, also at a ratio of 1:400. Secondaries used included: donkey anti-mouse-IgG-Alexa 488, donkey anti-sheep-IgG-Alexa 555 and donkey anti-rabbit-IgG-Alexa 647 (all from ThermoFisher Scientific). Following incubation, excess secondaries were removed with PBT washes over 2hrs, including a 40 min incubation with 1:1000 wash with DAPI (5mg/ml, ThermoFisher Scientific). Finally embryos were resuspended in ProLong Gold AntiFade (ThermoScientific) and mounted. smiFISH Probe Design: CustomsmiFISH probes were designed using the Biosearch Technologies Stellaris RNA FISH Probe Designer ver 4.2 (Biosearch Technologies, Inc., Petaluma, CA), (available online at www.biosearchtech.com/stellarisdesigner(last accessed: 18/05/2017)) against the Drosophila genome. Probes were designed with the following parameters; masking level of >=3, oligo length between 18bp to 22bp, a minimum of 2bp spacing between probes with a minimum of 24 probes per gene. Sequences complementary to the Y and Z flaps based onTsanov et al., 2016were added to the 5’ end of the probes. 250pmoles of labelled flap sequences were hybridised to 200pmoles of smiFISH probes in 1x NEB Buffer 3 (NEB) and incubated in a thermocycler at a final concentration of 4uM in the following conditions: 85°C for 3min, 65°C for 3min and 25°C for 5min.Details of target regions, number of probes and flap sequence are shown below in Table 2.2with details of fluorescent-labelled flap sequences shown in Table 2.3. Individual probe sequences for Ance, peb and ush are available in the following supplementary tables: Table S1.1, Table S1.2 and Table S1.3, respectively. ProbeProbe TargetTarget Region(s)FlapNumber of ProbesAnceExon 1;Intron 1;Exon 2chr2L:13905733-13906413;chr2L:13906591-13907163;chr2L:13907608-13907958Y48PebIntron 1;Intron 2chrX:4512107-4513998;chrX:4514915-4515168Z48UshIntron 3;Intron 4chr2L:524083-525382;chr2L:525516-535905Z48Table 2.2. | smiFISH target probes target regions, including: flap sequence and total number of probes per regionsFlapSequenceFluorophore (nm)YAATGCATGTCGACGAGGTCCGAGTGTAAAlexa 488ZCTTATAGGGCATGGATGCTAGAAGCTGGAlexa 647Table 2.3. | Fluorescently labelled Flap sequences complementary to probes flaps, including fluorophore for smiFISH

GenePrimer DirectionSequence (5’-3’)Intronic or ExonicAnceForwardAAACAAGTCATTCGCTTTAGGGCIntronicReverseCGCATTTTCGGATGACTCTGGKek1ForwardGCAGATTCGCACGGATGAACIntronicReverseTTTGCGTGGCAAAATGTGCTNetForwardATTCACCCAATTCCAACGACExonicReverseGTGGCAATGGACGGTACGGATupForwardCGGGAAAAGCAGCCTTGGATIntronicReverseTAGCTACAGCGAGTGCGAAATable 2.1. | Primer sequences for FISH.Alkaline Phosphatase RNA In-situ Hybridisation: For in situ hybridisations, a minimum of 50μl of embryos were washed with 100% ethanol, transitioned to 100% methanol, and then to PBT (1x PBS, 0.1% Tween-80). Embryos were then transferred to hybridisation buffer (previously described) and incubated at 55°C for 1hr, followed by overnight incubation in 0.5-2μl of the RNA probe in 50μl of hybridisation buffer. Sequential washes were then performed with hybridisation buffer and PBT, after which the embryos were incubated overnight at 4°C with anti-Digoxigenin-AP Fab fragments (1:250, Roche), pre-absorbed prior use against fixed embryos, in 500μl PBT. Excess primary antibody was removed with sequential several PBT washes, followed by two 5min washes in staining buffer (100mM NaCl, 50mM MgCl2, 100mM Tris pH 9.5, 0.1% Tween 80). The antibody bound RNA probe was visualised using 0.27mg Nitro-Blue tetrazolium and 0.14mg 5-Bromo-4-Chloro-3-indolyphosphate in 400ul. Staining was stopped by washing with PBT, followed by repeated washes with 100% ethanol over 1hr. Lastly embryos are briefly treated with 100% xylenes prior being mounted in Permount mounting medium (bioPLUS).Fluorescent RNA In-situ Hybridisation: For FISH, a minimum of 50μl of embryos were transferred from 100% methanol to 100% ethanol, as above. Embryos were washed for 1hr in 90% xylenes with 10% ethanol, followed by ethanol washes until complete removal of xylenes. Subsequently, embryos were washed with methanol and underwent post-fixation for 25mins using PBT with 5% formaldehyde. Following this embryos were pre-hybridised using hybridisation buffer (previously described) for 1hr at 55°C. Hybridisation was performed in 100ul of hybridisation buffer overnight at 55°C with 2μl of denatured RNA probe. Excess probes were removed through washes with hybridisation buffer and PBT. Prior to addition of primary antibodies, embryos were blocked for 30mins in 1x Blocking Reagent in PBT (Western Blocking Reagent, Roche). For detection of labelled RNA probes, the following primary antibodies were used: mouse monoclonal anti-Biotin-IgG (1:400, Roche), sheep polyclonal anti-DIG-IgG (1:400, Roche), rabbit polyclonal anti-DNP-IgG (1:400, ThermoFisher Scientific). Primary detection was performed overnight at 4°C in 400μl of 1x Blocking Buffer in PBT. Following incubation, excess primaries were removed with PBT washes and embryo re-blocked with 1x Blocking Reagent for 30mins. Subsequently, embryos were incubated for 1hr 30mins at room temperatur

Embryo Collection: Embryos were collected at 25°C on apple juice agar plates from cages withapproximately 5ml of well-fed young flies. Collections were performed every 2hrs with plates aged at 18°C or 25°C After Egg Laying (AEL), as appropriate, resulting in a pool of embryos between 2-4hrs (Stage 5 to 9), unless otherwise stated.After ageing, collected embryos were washed with 1x NaCl/Triton X (68nM NaCl, 0.03% (w/v) Triton X-100) and loosened from plates with a brush. Embryos were subsequently dechorionated in 50% bleach for 2min and thoroughly washed, alternating between dH20 and 1x NaCl/Triton X. For RNA In-situ hybridisations, embryos were fixed with 4.625% formaldehyde for 20mins with 50% heptane and Fixing Buffer (0.5x PBS, 25mM EGTA pH 8.0). Following fixation, embryos are devitellinised using methanol, transferred to 100% ethanol and stored at -20°C. For Immunostaining, overnight plates with a maximum 12hrs of ageing were collected and dechorionated as above. Fixing was performed for 12mins with 1.85% formaldehyde, 50% heptane, and Buffer B (4.5mM KPO4, 6.75mM NaCl, 20.25mM MgCl2, 4.5mM NaP). Embryos were devitellinised as previously described, but stored in 100% methanol at 4°C.RNA Probe Synthesis: RNA probes for RNA in-situ hybridisation were synthesized using gene specific primers, flanked by the T3 and T7 promoters to transcribe sense or anti-sense probes respectively, except for the AncecDNA probes. All probes were designed against approximately 1kb of the target RNA unless otherwise constrained by sequence or target limits. All primers used to generate RNA probes are described in Table 2.1, including intronic or exonic position of probes. Anti-sense probes for Ancewere derived from Ance cDNA cloned between T3 and T7 promoters within pBluescript KS plasmid. Template is produced through PCR of the plasmid template using primers against the T3 and T7 promoters. Approximately 1ug of DNA template was used to generate labelled anti-sense RNA in a transcription reaction. Probes were either labelled with Biotin, Digoxigenin (DIG) or Dinitrophenol (DNP) labelled UTP in a mix with other nucleotides. The transcription reaction was carried out for 2 hrs at 37°Cusing, 1x transcription buffer (0.06M MgCl2, 0.1M NaCl, 0.02M Spermidine-HCl, 0.4M Tris pH 7.5), 10 Units RNAse inhibitor (Roche), 20 Units T3/T7 polymerase (Roche), 1x nucleotide mix (10mM ATP, 10mM GTP, 10mM CTP, 6mM UTP and 4mM Biotin, DIG or DNP labelled UTP (Roche)) and dH2O. The probes were then hydrolysed in 1x carbonate buffer (60mM Na2CO3, 40mM NaHCO3, pH 10.2) and incubated for 5mins at 65°C. Following hydrolysis, the reaction was stopped by the addition of 40μl dH2O, 50μl STOP solution (0.2M NaAc, pH6.0) for 5min and precipitated overnight at -20°C with 2μg of tRNA in 0.1M LiCl, and 100% ethanol. The sample was then centrifuged for 20mins at 13,000g and the pellet resuspended in 150ul of hybridisationbuffer (50% formamide, 750mM NaCl, 75mM sodium citrate, 100μg/ml ssDNA, 50μg/ml heparin, 0.1% Tween-80).

Expression analysis of Drosophila Embryos

The PCR products were ligated with T-tailed vectors (pGEM-T Easy, pTARGE-TfM from Promega or pcDNA3.1 from Invitrogen). In general, the ligation was carried out at a vector: insert molar ratio of 1:3 or 1:4 in a 10pl reaction volume finally containing 1X T4 DNA ligase buffer (300mM Tris-HCl, pH 7.8, 100mM MgCh, 100mM DTT, lOmM dATP) and lU of T4 DNA ligase (Promega, U.S.A.). The reaction mix was incubated at 160C for 16 hrs (overnight). Following the reaction, the ligated DNA was transformed into Calcium Chloride treated E.coli-DH5a or XL-Blue1 competent cells with a high transformation efficiency. The transformed cells were plated on to Luria-Bertani-Agar plates containing 100p.g/ml of ampicillin. Additionally, for blue-white screening of the colonies, 20pl of SOmg/ml of X-Gal (5-bromo-4-chloro-3-indolyl-a-D-galactopyranoside) and 10pl of 0.1M IPTG (lsopropyl-J3-thiogalactopyranoside) (Promega, U.S.A.) was used. The plated cells were incubated at 370C for 8-10 hours

Ligation and Transformation:

Cell surface membrane proteins were separated using a method by Snapp and Landfear (1997). 4 X 107live cells/mL were resuspended in MME buffer (10mM MPOS, 0.1mM EGTA, 1mM MgS04, 0.1%v/v Triton X-100 and protease cocktail) and incubated at 4°C for 1 hr. on an end to end rotor. This was followed by centrifugation at 3000 x g for 4°C for 10 min. The pellet obtained was washed with PBS and then lysed in 2X sample buffer and run on an SDS-PAGE followed by western blotting

Separation of cell surface proteins

1258 x g for 10 min at RT and washed 2X with PBS to remove all traces of media and FBS. D1e pellet was finally resuspended in 200p.L of resuspension solution provided in the kit. 20p.L of RNase A solution was added and incubated at RT for 2 min. 20p.L of Proteinase K and 200p.L of lysis solution were added and the cell suspension was vortexed for ~15s. This was followed by incubation at 70°C for 10 min. Pre-assembled GenElute MiniPrep Binding column was equilibrated with 500p.L of column preparation buffer by centrifugation at 12000 x g for 1min. Following incubation at 70°C, 200p.L of ethanol was added to the lysate and the vortexed for 5-10s. This lysate was then transferred to the equilibrated column and centrifuged at 6,500 x g for 1min. The column was washed 2X with 500p.L of wash buffer, by centrifugation at 6,500 x g for 3 min. To collect the genomic DNA, the column was incubated at RT with 200p.L of elution buffer for 5 min followed by centrifugation at 6,500 x g for 1 min. The genomic DNA was aliquoted and stored at -20°C for long term and 4°C for short term storage

Genomic DNA of Leishmania donovani was obtained using GenElute™ a mammalian genomic DNA Miniprep kit from Sigma Aldrich (St. Louis, MO). Briefly, 108 parasites were harvested by centrifugation at

Preparation of genomic DNA from Leishmania donovani culture

0% FBS and cultured as described above. The cells usually regain motility by 24 to 48 hrs and the culture is ready for use after splitting them once

For long term storage, Leishmania donovani were stored as Dimethyl Sulfoxide (DMSO) containing frozen stocks (freeze downs). Parasites in mid to late log phase were taken and dead and agglutinated cells removed by centrifugation at 129 x g for 10 min. The supernatant was centrifuged at 1258 x g for 10 min to pellet cells which were then washed 2X with plain medium followed by resuspension in FBS containing 10% DMSO as the cryoprotectant. These were transferred to a labelled cryogenic vial and immediately transferred to -20°C for a few hours, followed by incubation at -70°C overnight. The following day, the stocks were transferred to liquid nitrogen (liq N2). To revive a frozen stock, the stock was retrieved from liq N2 and transferred to a beaker containing water at ~37°C. Once the stock has thawed, the cells were immediately transferred to lOmL plain mDMEM and centrifuged at 217 x g for 10 min. The pellet was washed three to four times with plain medium followed by resuspension in mDMEM containing

Preparation and revival of frozen stocks of Leishmania donovani

A total of 150 fungal and 150 bacterial isolates were screened qualitatively and quantitatively for their ability to produce the enzyme, tannase.

Screening and selection of potential tannase producers

Viewing slides under microscope

A drop of immersion oil was put on top of the cover-slip before viewing it under microscope. The cells were viewed at 100X resolution of Nikon Eclipse 80i microscope.Thedifferential interference contrast images of the cells were captured using NIS-Elements D3.0 software also used to find out mean cell size using at least 100 randomly selected cells.Fluorescence images were captured on Zeiss LSM 710 Meta inverted confocal microscope

The RNA was cross-linked onto the membrane after transfer by exposing it to the UV light of 200KJ/cm2 energy in a UV-crosslinker

UV-crosslinking of the RNA

Band intensities in gel autoradiogramswere determined by densitometry with the aid of the Fujifilm Multi Gauge V3.0 imaging system. Equal areas of radioactive bands were boxed and the PSL (Photo stimulated luminescence) values were further considered. Background signal (obtained from equal area as that of the radioactive band but from other part of the gel/blot) is subtracted from the signal intensities obtained from radioactive bands to get the final values

Densitometry

Oligonucleotides and PCR products were end-labelled using phage T4-polynucleotidekinase (PNK, New England Biolabs or Fermentas or Sigma) with 32P-γ-ATP. The radiolabelling reaction mixture (20μl) contained 1X of buffer provided by the company, 10 units of T4-PNK and 40μCi of 32P-γ-ATP. The reaction mix was incubated for 1 hrat 37ºC and the reaction was heat-inactivated at 65oC for 20 minutes. The labelled oligonucleotides and DNA fragments were purifiedby the Qiagen nucleotide removal kit. Labelling efficiency was checkedeither by using Geiger-Muller (GM) counter orusing liquid scintillation counter.For scintillation counting, 1μl of radioactive sample wasadded to the 5ml scintillation cocktail, and radioactivity count was determined in the 32P channel of scintillation counter (Perkin Elmer, Liquid Scintillation analyzer, Tri-Carb 2910 TR, USA). Liquid scintillation cocktail consists of 5g PPO (2,5-diphenyloxazol) and 0.3g POPOP (1,4-bis (5 phenyl 1,2-oxazole) Benzene, adjusted to a volume of 1L in toluene

Radiolabelling of oligonucleotides

DNA sequencing

Automated DNA sequencing on plasmid templates or on PCR products was carried out with dye terminator cycle sequencing kits on an automated sequencer following the manufacturer's instructions byan outsourced sequencing facility

The semi-quantitative reverse transcription-PCR (RT-PCR) involves the synthesis ofcomplementary DNA (cDNA)from RNA. For this, 1μgof RNAwas treated with 1μl (1 unit) DNase I enzyme (Sigma, amplification grade) for20 min to remove DNA contamination. DNase I was inactivated by heating at 70oC for 10 min. Next, 5pmol reverse primer wasadded along with dNTPs and volume made to 10μlwith DEPC-treated water; the mix washeated at 65oC for 5 min and incubated on ice forat least 1 min. The reverse transcription reaction was set up with this mix using the Superscript III RT kit (Invitrogen) as per manufacturer’s protocolto obtain cDNA. The cDNA servedas the template for setting up a PCR for requirednumber of cycles. The samples were finally run on agarose gels

Reverse transcription(RT)-PCR

Concentrations of DNApreparations were estimated by nanodrop or by gel electrophoresis followed by densitometric analysis.Concentration of RNA preparations were estimated by nanodrop

Estimation of DNA and RNA concentrations

Total RNA extraction from E. colicells was doneusing Qiagen RNeasy minikit. Cells were grown to an A600of 0.6 and harvested(amaximumof107cells)at 6000rpm for 5min at room temperature to prevent cells for encountering any stress in cold. Rest of the steps were followed exactly as mentioned in the manufacturer’s protocol. The quality of RNA preparations was assessed following electrophoresison 1.4% agarose-formaldehyde-MOPS gels.Ingeneral,forawild-typestrainRNAyieldwouldbe~0.5-1μg

Isolation of total cellular RNA

For high fidelity PCR, Herculase II fusion DNA polymerase (AgilentTechnologies)was used. Approximately 0.5μg of chromosomal DNAwas used as a template in a 50μl reaction volume