2,340 Matching Annotations
  1. Dec 2019
    1. CRISPRi-ME prevents evolutionary failure of a burdensome plasmid in E. coli.

      It reduces the rate of evolutionary failure but does not prevent

    1. 50 μg/ml RNase (ThermoFisher #EN053) freshly added. 2 ml of lysis buffer

      Fresh RNAse is really critical. Otherwise this will result in 10 fold more RNA contaminant than DNA; which implies the nanodrop reading and gel visualized DNA will be 10 - 100 fold different. (from personal experience of 1 prep only)

    1. deep-well plates, require a faster shaking speed for proper aeration

      Deepwell plates (24 well plates with 3ml cultures as well as 96 well with 1 ml) require 800 rpm shakers

      • by Bennett Biodesign lab @ Rice University
    1. we recommend calibrating OD using serial dilution of silica microspheres, which readily produces highly precise calibration (95.5% of teams having residuals less than 1.2-fold), is easily assessed for quality control, and as a side effect also assesses the effective linear range of an instrument.
    1. Bacteria are less likely to develop resistance against a pro-drug as it becomes active only after getting inside the bacteria. The active components formed from the pro-drug are potent and short-lived, thus not giving the bacteria sufficient time to develop resistance.

      Would like to see some evidence for this!

    1. which ends up being much less efficient

      Has this been quantified properly? I see a lot of new methods relying on in-vivo homologous recombination now-a-days - ex: FastCloning: a highly simplified, purification-free, sequence- and ligation-independent PCR cloning method

    1. “death phase,” where at least 99% of the cells in the culture lose viability

      So the 'death' in death phase is only loss of viability?

      I thought the cells lyse and are eaten up by neighbours; while reducing the OD (due to cell lysis)

    1. To add a data mask so you can refer to variables in a data frame as if they are variables in an environment.

      Similar to a with() function?

    1. plasmid-based circuits suffer from multiple limitations: high intercellular variation in gene expression, genetic instability from random partitioning of plasmids during cell division, and plasmid loss in environments for which antibiotic use could disrupt native microbial communities or is economically infeasible
  2. Nov 2019
    1. , science proceeds by the falsification and refinement of hypotheses. Thus, for most papers, the only way is down.

      That one nails it!

    2. despite Blatt’s carefully worded insinuations, PubPeer does not allow “hearsay”, “allegations” or invite “innuendo” (and we aim to act on all reports of such comments)

      Blatt does mention that the pubpeer site moderators are anonyomous in contrast to the journal editors. This somehow reduces their credibility on effective moderation of abusive or trolling comments. This sounds like a recursive argument: A central authority brings credibility but also corruptibility. I can see parallels in the debate about Bitcoin cryptocurrency vs federally backed currency and about the trustworthiness vs corruptibility of a central authority as compared to a distributed crowd authority.

    3. authors, journals and institutions are all unquestionably exposed to conflicts of interest when it comes to correcting problems

      A retraction once published does not reflect well on all of these parties and is clearly a conflict of interest even though they may claim that it is in their benefit. Somehow a pre-publication review is being given more importance than a post-publication review because of this reason.

    1. in much of biology, readers have to trust the authors to describe their experiments accurately, and there are many more opportunities for mistakes and dishonesty

      Good point

    1. alleging their negative appraisals of his work had resulted in a university rescinding a job offer

      Oh, and what does he have to say about the 20 retractions he as so far then?

      I is like a real wrongdoer criticising the police for investing in the first place.

    1. Commenting on a scientific paper, in particular when the comments are not positive, is risky business for academics

      Could someone elaborate on this? Why exactly does negative commenting cause a researcher to be discriminated against?

    1. That means gram-negative bacteria cannot change the BamA protein without losing their ability to infect.

      It 'suggests' that would have been better. There might also be other resistance pathways that might retain infectivity. This will depend on the environment used for the resistance evolution experiment

    1. Ina Schuppe Koistinen, Abhishek Krishnagopal, Sangeetha Kadur, Pooja Gupta etc gave me the inspiration to do what I wanted to do. Along the way I got exposed to more art and science creators like Gemma Anderson, Monica Zoppe, Drew Barry, Ina S. Koistinen, Christian Sardet, Sandra Black Culliton, Amanda Phingbodhipakkiya

      science communication - art + science

    1. required removal of salts results in osmotic stress - particularly challenging for a notoriously temperamental marine bacterium like Prochlorococcus

      Electroporation buffers cause osmotic stress and need osmoprotectants like glycerol

    2. the 6-month multi-step procedure is vulnerable to user variability

      The doubling time is 3.3 days!

      • Genetic Manipulation of Prochlorococcus Strain MIT9313: Green Fluorescent Protein Expression from an RSF1010 Plasmid and Tn5 Transposition
    3. Such projects are not suitable for graduate students or post-docs because of the high risk involved, nor are they easily funded

      that is wisdom!

    4. To avoid the pursuit of unproductive paths, we report here what has not worked in our hands, as well as our progress developing a method to screen the most efficient electroporation parameters for optimal DNA delivery into Prochlorococcus cells

      negative results

    1. key attributes needed to produce a worthy PhD thesis are a readiness to accept failure; resilience; persistence; the ability to troubleshoot; dedication; independence; and a willingness to commit to very hard work — together with curiosity and a passion for research
    1. Hemicellulase activity was elevated in pairwise mixtures of communities that placed interacting phylotypes together (interactions, n = 9 mixtures) but not in communities that did not place interacting phylotypes together (no interactions, n = 56 mixtures)

      Very interesting way to validate correlative phenotypes in communities

    1. For F-1 and J-1 students, on-campus work is limited to part-time (20 hours or less per week) during the fall and spring semesters when school is in session

      Does RA count for 20 h?

    1. When you present information visually (using slides, a poster, video, handout, etc.), you must provide a full written citation.

      citing sources

      • When you present information visually (using slides, a poster, video, handout, etc.), you must provide a full written citation.
        • A parenthetical citation should directly accompany images, videos, quotes, or anything that is directly referenced in your presentation.
        • works cited or references list should appear at the end of your presentation for all sources.
      • When you present information orally, you must provide an abbreviated citation that should include the name of the creator, title, and publication date.
    1. these two highly active enzymes were functionalized with an affinity binding motif through the genetic fusion of a carbohydrate binding module (CBM) from Cellulomonas fimi with specificity to cellulose (CBM2a)

      Why should the enzyme be functionalized to bind cellulose, should the carbohydrate binding be on the phage capsid?

    2. EPA Method 1603 is an approved drinking water assay that quantifies generic E. coli

      This drinking water assay contains a membrane (0.45 µm) filtration step to remove bacteria from the water sample prior to enrichment on selective and differential media. The bacteria CFUs are quantified directly on the filter following a lengthy enrichment

    1. known to introduce biases in composition estimates due to, for instance, variations in 16S rRNA gene copy numbers per genome

      Are the other marker genes known to be single copy?

  3. facultypatchbook.pressbooks.com facultypatchbook.pressbooks.com
    1. Students who are less exposed to what we propose here may resist at first, simply because it is unfamiliar, but it is our experience that, overall, students will embrace and appreciate these modifications to the way assessments are conducted.

      The initial student resistance is a very good point

    1. opening new paths for side effect control

      This is a tall claim. Is the microbiome's contribution to side effects well studied? Is it a significant contribution compared to off target human pathways and pleiotropic effects?

    Annotators

    1. SDS affects the oligomerization state of Aβ42 oligomers, thus providing flawed information on their order and distribution.

      The fact that SDS affects protein structures and oligomerization seems to be well known.

      I thought people did a variant called 'native PAGE' where SDS is not added and the protein is treated in non-denaturing conditions. Did you compare your method to this?

  4. Oct 2019
    1. includes creation of innovative solutions for bio energy, resource recovery, and emerging public health concerns by leveraging synthetic or molecular biology tools, novel biological systems (genetic circuits, enzymes, genetically engineered microbes), fundamental biological and chemical concepts, artificial intelligence, and big data science, as well as collaborations in Computer Science, Public Health, Plant Biology, or related fields.
    1. biofilm

      Wrong use of words. You should call it a layer of immobilized bacteria. Biofilm is when cells deliberately stick to a surface and secrete a matrix

    1. values measured by using luminous E. coli had tendency of about 30–40% lower than that of BOD5, it could be observed an apparent correlation between the two values

      I don't think this is robust correlation. It will depend on the organic composition of the BOD

    1. is dosed with seed microorganisms and stored for 5 days in the dark room at 20 °C to prevent DO production via photosynthesis

      Does the BOD measurement and interpretation depend on the organism the sample is seeded with?

    2. The generally lower values in the U.S. derive from the much greater water use per capita than in other parts of the world

      Wow, that is amazing to know. Wonder how this cultural shift started historically?

    1. ఎప్పటికైనా Knowledge Centric Value Based Education రావాలని కోరుకుందాం

      I like the problem statement, but what is this knowledge centric value based education? Is this a good solution?

      It is essential to realize that there is no magic bullet that can solve such a complex problem that is so central to our life, livelihood and the urban upper middle class (shall I call brahminical!?) way of life. There must be many solutions working together towards the same idea. But first we should be clear on the problem and acknowledge it!

    1. the best way to correct for the analyte signal suppression or enhancement is to co-elute a stable isotope labelled (SIL) analogue of the analyte

      It is not straight forward to get isotope labelled standards for every compound

    1. Perhaps we ultimately need to be prepared to accept less standardised and slightly more expensive food in order to accommodate less intense and more diverse agriculture. You might never be quite sure what to expect when you peeled a banana, but the result could be a more robust and sustainable food system without a major crisis every few decades.
    1. To investigate how ciprofloxacin 35resistance is affected by the presence of metals,

      Ciprofloxacin's activity (MIC, IC50 etc.) could also depend on Zn presence, was this investigaged before going into selection and evolution?

    1. new toolkits for chronic labeling of active ensembles will provide a much awaited experimental basis to interrogate various aspects of neuronal circuits underlying long-term plastic changes of the brain, such as during nervous system development, during establishment of long-lasting remote memory over months, or in association with age-related neuronal changes over several years.
  5. sackler.tufts.edu sackler.tufts.edu
    1. improvement of soil health should be a priority agenda in India’s agricultural policy. We need steps to check wind and water erosion of soils. We need innovative technologies to minimise physical degradation of soils due to waterlogging, flooding and crusting. We need to improve the fertility of saline, acidic, alkaline and toxic soils by reclaiming them
    2. Indian soils are poor in organic matter content. About 59% of soils are low in available nitrogen; about 49% are low in available phosphorus; and about 48% are low or medium in available potassium. Indian soils are also varyingly deficient in micronutrients, such as zinc, iron, manganese, copper, molybdenum and boron
    1. Detection of AHL by LC-FTMS was much more sensitive than by TLC bioassay, because TLC bioassay was implied to be affected by the presence of quorum quenching molecules in activated sludge.

      does not make sense

    1. they are induced in a way that correlates well with the AHL species produced by the strain

      This is a baseless statement, made from only 1 strain p. aerofaciens, which makes C6-AHL

      • Two strains P. Putida and E. coli do not produce AHLs (you mention this)

      How does it correlate well then with 1 data point?

    2. After 8 days of incubation, we detected cells that were only green fluorescent, indicating that the sensor plasmid had been transferred to indigenous AHL-producing organisms

      It could also just mean that there are some AHL producers in the viscinity, just like the explanation given for yellow donor cells.

    3. QS systems have been experimentally analyzed in more than 50 different bacterial species and shown to control expression of a wide spectrum of functions, including bioluminescence, virulence, symbiosis, different forms of motility, biofilm formation, production of antibiotics and toxins, and conjugation (49).
    1. Images were prepared for publication using CorelDraw (Corel Corporation) and PowerPoint (Microsoft) software.

      Great that you cite the software

    2. PpuI, which directs the biosynthesis of the two AHLs 3-oxo-C10 and 3-oxo-C12 as major products; PpuR, the AHL receptor; and RsaL a repressor of ppul

      P. putida IsoF, isolated from tomato rhizosphere - quorum sensing

  6. Sep 2019
    1. placed at a 45° angle, nylon-mesh side up. Roots grew downward, collided with the bottom slide of the microcosm, and traveled along it. This method allowed observation of the root system by epifluorescence microscopy

      well explained!

    2. The rhizosphere is the volume of soil directly under the influence of plant roots; it is bounded by the root surface on one side and extends millimeters into the soil. It is populated with a high density of bacteria, fungi, protists, and nematodes supported by relatively labile organic compounds, such as sugars, amino acids, organic acids, and polysaccharides. These compounds are actively and passively lost from living and dying root tissues (12, 13). This rhizodeposition allows 5–100 times more organisms per unit volume to be supported in the rhizosphere than in nearby bulk soil, where the microbial community is thought to be carbon limited
    1. Chemically, the differencebetween the DI water and the 0.25×M9 EPS solution aresome simple salts and just 14.5μg/ml glucose equivalent ofEPS

      Should have compared with M9 + equivalent glucose (un-polymerized) as a better control for osmolarity reasons

    1. A narrative weaves together otherwise isolated bits of information into a meaningful whole, linking them in important ways but also chunking the information so that it takes up less space in working memory and connects to existing threads in long-term memory
    2. make the entire course relevant to students’ daily lives. All of the labs center around chemicals and materials that students interact with regularly. For instance, they evaluate bottled water versus tap water, test both for pH, conductivity, and taste, and then debate why so many people choose bottled over tap
    1. essential goal for me in every course has always been to make students feel comfortable participating in class, and to encourage as many of them as possible to speak up. Peer instruction, aided by electronic polling, gave me an opportunity to invite quiet students to engage more actively in class, both through the polls and through the subsequent discussions
    1. When new knowledge is integrated with and connected to existing knowledge, that new knowledge is easier to understand and to remember. A professor’s job is to build scaffolding from existing knowledge on which to hang incoming new knowledge. Using a concept map is one way to build that scaffolding.
    1. R markdown has the possibility of executing R code inline (and rendering the result to html) or rendering graphs inline. That saves time and makes the documentation maintainable as you don't need to manually prepare the output of that function or manually prepare and save a graph since it's rendered on the fly.

      R markdown makes documentation of code easy

    1. enzymatic quenching mechanism of AHL signals is also present in enzyme-producing bacteria, such as Anabaena sp. PCC7120, Ralstonia sp. XJ12B, P. aeruginosa PAO1, Agrobacterium tumefaciens C58, Bacillus sp. strain 240B1, Rhodococcus erythropolis strain W2
    2. Membrane biofouling remains to be one of the most serious operational problems for MBR applications, which results in permeate flux and water quality decline, trans-membrane pressure (TMP) and operating costs increase, frequent membrane cleaning and replacement necessary
    1. it has been assumed that the effectiveness of Pseudomonas sp. 1A1 in mitigating membrane biofouling could be expected to be more significant, given that the QQ enzyme that it produces (acylase) is extracellular

      The acylase might not be functional or stable in the extracellular wastewater environment

    1. different fouling patterns were observed for replicate MBRs seeded with the same inoculum and maintained under identical operating conditions, with similar levels of biomass, soluble microbial products, and extracellular polymeric substances

      The reactors were not maintained under the same conditions - 1 had backpulsing and the other was subjected to relaxation

    1. Figure 2. TMP profiles during the operation of two one-stage MBRs in two phases.

      Fouling seems to happen exponentially once it starts => following a first order reaction. What is the mechanism behind this?

    1. Next, a microfluidic device is used to co-encapsulate these clusters with gel beads, each containing uniquely barcoded forward 16S rRNA amplification primers

      Isn't the spatial information lost while encapsulation? Is the barcode capturing the spatial information in some way? It is not clear

    1. These carboxylated AHLs facilitated the transition from a short cell to filamentous growth, with an altered carbon metabolic flux that favoured the conversion of acetate to methane and a reduced yield in cellular biomass

      Carboxylated AHL signalling favours methanogenesis in Methanosaeta herundinacea 6Ac

    1. Instead, most particle-attached bacteria may be secondary consumers that recycle waste products from primary degraders.

      What factors determine their relative abundance then?

    1. co-occur out of cooperative relations or a similar niche preference

      similar niche evokes competition rather than cooperation, this is contradictory

    1. antibodies against siderophores in the intestine, which hindered proliferation of the gut pathogen Salmonella

      What about normal gut microbiota? I presume they need iron too

    1. At the micrometer-centimeter scale, electrochemical and optical probes have been productively used to profile gradients in pH, redox, and oxygen; however, these probes and their associated equipment are intrusive to the ecosystem and often expensive, limiting their application to only a few point measurements or limited time series, and their fragile nature makes them best suited for laboratory use