I don't know anything about M. conductrix, but does it typically have flagella, an eyespot, and a cell wall (appears to be present in the EM images)?

I'm wondering if these features exist & are lost when they become endosymbionts, like Tetraselmis convoluta when they become symbionts of the acoel Convoluta roscoffenis (10.1111/j.1529-8817.1966.tb04603.x)

Do you think the high concentration of BPA is impacting Tetraselmis swimming, preventing them being taken up by the acoels? or that the Acoels are impacted, preventing them from eating?

Further, since they're obligate, do you think the acoel swimming defects and miRNA expression could be impacted by the reduced number of tetraselmis cells in the host body?

Futher, do acoels maintained in high conc. of BPA remain viable through adulthood?

This is a very neat paper taking advantage of a really cool system! Thanks for sharing!!!!

This is very cool! But since you also show a lack of uptake of Tetraselmis, do you think there could be an issue with the 5 µM BPA treated acoels not taking up the miRNA? I think it would be useful to add a control miRNA that shows expression of an uneffected pathway is detectable in the 5 µM BPA treated animals.

This is a really beautiful work that answers a lot of important questions about the evolutionary diversity of an essential process, and leads to even more exciting question! Thank you for sharing this work!

Are there any physiological conditions that correlate with this finding?

Given the similar shape & size of U. maydis and S. pombe, I would have naively guessed that they'd have similar invagination lengths. Also, the short lifetime of endocytic proteins in U. maydis is consistent with shorter invaginations, but it looks like S. cerevisiae patch lifetimes are longer than S. pombe, but this doesn't correlate w/ invagination length.

Does the invagination depth scale with the turgor pressure? Or maybe the growth rate?

minor error: missing space

This is a beautiful visualization of the protein dynamics across species! It hammers home how the different modules of the machinery have such different effects across species! Breathtaking!

Beautiful images!

It looks like U. maydis consistently has a lot of cytoplasmic fluorescence, compared to the other yeasts.

Is their cytoplasm auto-fluorescent in untagged cells? If so, is it equally bright when grown in their preferred medium or could the synthetic medium be stressing them out?

or is it just a lot of tagged-protein that isn't localized to endocytic sites.

Was the growth rate of each species similar on the synthetic medium compared to the preferred medium?

Is this synthetic medium also supposed to be EMM? Table S2 does not have a recipe for SD medium but indicates S. cerevisiae grows on EMM.

Thank you for sharing this important work. It seems that there are innumerable variables involved in the frequency of HABs and climate change will undoubtedly impact each of these. It seems these experiments were run at ambient temperature in the lab, correct? I assume the temperature in the estuary is wildly different in the spring & autumn (and throughout the day) which will impact the nutrients available in the DOM sample drastically. The NCMA collection center indicates this species can be maintained from 14-22 C. Have you tried maintaining the strains in the DOM while mimicking the temperatures of the seasonal samples?

I didn't see this in the text, but are HAB in the Changjiang Esturay more common in the spring or autumn?

Sorry, the text in this figure (and to a lesser extent fig 6) is very hard to read. The text and image is very pixelated.

Just out of curiousity, how does the growth in DOM compare to growth in standard culture mediums like L1 or F/2?

Will the newly isolated strains be deposited in any collection centers? These are very cool cells!!!

Figure 14 & Fig 15 are swapped

It would be nice to have the scale bars on all of the images, especially since there are multiple strains & species

The scale bars aren't defined for many of your figures. The first definition comes in Figure 5, despite the earlier figures having scale bars. Very beautiful images though!

Very fascinating work! I'd never heard about these mysterious fungi before so it was fun to learn about them! Its amazing how these microbes thrive in wildly different environments! I'd be very interested to see if y'all are able to replicate the yeast-like morphology in lab settings by mimicking the marine environment. Dissecting the Atlantic vs Pacific impact further would be very cool for future studies! Thanks for sharing this neat work!

Do you think the morphological distribution would be different when taken from different ocean depths? I imagine the pressure differences could lead to morphological changes/adaptations.

Also, are the yeast forms ever found in apples? or are those organisms most always elongated hyphae?

I'm a bit confused. A few sentences above you said the yeast-like form never occurs in culture and now that the hyphae form is only in pacific waters. Does this mean neither morphologies are found in cultured cells?

The cultured cells in Fig 1 appear to be elongated hyphae as well? Sorry if I'm misreading things.

Edit: Oh! I see! Are you stating that, when in marine environments, the hyphae are only observed in the Pacific Ocean? In Fig 4 you show that there are no elongated morphotypes in the Atlantic Ocean and they are mostly observed in the Pacific Ocean; however, you do show their presence in the Indian Ocean as well, correct? I think this could be reworded for clarity

Amazing images in this paper! How long was this fixation step at 4C? Does the cold temp prevent contraction?

Thank you for sharing this impressive piece of work! It is amazing how the entire function and morphology of a cell can change based on its environment! The use of multiple high-resolution techniques all converging on a consistent conclusion is very convincing!

This is very striking and interesting! We noticed a similar phenotype in the species Chlamydomonas smithii when we grew them in nutrient rich marine broth (https://doi.org/10.57844/arcadia-35f0-3e16). The cells became much larger compared to when grown in standard low-nutrient TAP media. Do you think this could have anything to do with increased nutrient availability within the host cell?

Is this the same bacterized volvic natural mineral water supplemented w/ protozoan pellets that the P. bursaria are grown in? or liquid HSM? or different media? just wondering if there are any external nutrients contributing to any of the differences.

Interesting! Since the average volume of the symbiotic algae was ~43 um, do you think you're selecting for smaller cells from the start?

For the symbiotic algae in the study, were the isolated M. conductrix cultures re-introduced into vacant P. bursaria cells to correct for any inadvertent size selection?

In your FIB-SEM, did you notice any differences in the cell wall of the free-living vs symbiotic algae? Has the 5.6-fold larger cell lost the wall, which might not be as necessary anymore since it has a protective host?

Very cool! Did you see Pak1 at endocytic sites along the side of the cell? If not, were the success rates similar at the side & at the tip of the cell? It would be neat if the Myo1 in the tip patches are phosphorylated and the Myo1 in the side patches aren't. I know there are a lot of other factors that could contribute to differences in side & tip patch internalization (membrane curvature/hardness, crowdedness, etc) but could be interesting to see!

Can you expand on how this analysis is done?

Was there a consistently sized ROI used in each cell? The LatA treated cells seemed to favor CRIB localization on the side of the cell instead of the proper tip so I'm curious what fraction of the image goes into the analysis.

Are these images maximum intensity projections or just single z-planes? If its a max intensity, it looks like scd1 might go to endocytic sites in the absence of Myo1?!

Oh wow! The nuclear localization of Scd1 in CK-666 goes away in the pak1-ts mutant!!!

Very cool! It also looks like there is more localization of Scd1 in the nucleus in CK-666 treated cells! Is this true across the dataset or just in the representative images?

I found the S1 figure VERY helpful in understanding these claims. You've got such great signal that it is hard to see the differences the in polar signal intensities through the fluorescent images alone. I think it could be a lot easier to interpret with the temporal quantification from S1 shown in the main figure

Can you provide more context on how you know this is the site of Cdc42 activation when there is dense CRIB-3xGFP localization on both ends of the cell? and in many places theres no visible fluctuation from the earlier cells to the marked cells

Very Interesting! Did you ever notice THATCH dimers associated at cables when expressed at endogenous levels? Would this indicate something in the THATCH domain is contributing to patch localization? Do the (1-856) and THATCH fragments co-localize? If so, could the 2 fragments be re-associating (infrequently)?

Really nice & convincing work! I really enjoyed reading this paper. Its fascinating how these mutations can have such a broad impact on different parts of the endocytic machinery but with no measurable impact on the accumulation of actin in patches or the internalization of vesicles! Thank you for sharing it on here!

Did you compare the intensity of tagged Pan1? it looks like it might be brighter in the bsp1 mutant compared to WT.

Its probably worth noting that in Drees 2001 they state "Ypr171w also interacted with Cap1, the α subunit of the yeast actin filament capping protein", but the evidence you provide is definitely much more convincing.

Very cool! Did you try to make the 408-470 peptide in vivo as well? Since the inclusion of the WH2-like domain enhances patch localization, it'd be neat to see if the domain is sufficient to recruit the peptide to the patches. Meaning it could be recruited through both the proline-rich region and the WH2-like domain. Or alternatively if the WH2-dependent enhancement is because of a feedback loop of sorts.

It could be useful to sight its reported interactions with Bzz1, CAP1, Las17, Lsb3, RSV161, RSV167, Sla1, and YSC84 (several sources logged at yeastgenome.org)

This was also shown in Wicky et al 2003 where they also showed actin patch defects when BSP1 was overexpressed. (https://doi.org/10.1016/S0014-5793(03)00067-X)

minor punctuation error

Thank you for running this experiment and reporting the concentration gradient! I was a bit confused why 20 ug/ml was selected for the worms in the last paragraph until reading this. Thank you for making it clear!

Is this the same concentration of nanoalgosomes that were used in the colocalization studies? I see in the materials & methods that 2 ug were added to cells in 12-well plates which can usually hold 1-2 mL, so I assume its the same concentration, but the actual concentration is not currently clear. Sorry if I missed it somewhere.

In panel A the algosome signal looks pretty ubiquitously dispersed. While the colocalization w/ CD63 is clear, I think the figure could benefit from showing the individual channels like in panel b. Its hard to tell if the algosome signal is excluded at sites of Lamp1 & Calnexin or if its just ubiquitous signal that isn't enriched at these sites.

Thank you for sharing this work as an open access preprint! It is a fun read and I learned a lot!

Each condition has 3 dots representing QS1, QS6, and QS9, correct? Are these strains maintained on K. pneumoniae in the lab, explaining their quickest doubling time on Kp?

There was a recent paper that showed differences in growth of a heterotrophic algae when fed different strains of the same genus! It would be interesting to see the variability of Dicty growth when fed different strains of the same species!

https://doi.org/10.1080/00318884.2021.1941567

While not statistically significant as a whole, it does look like the Fg-Sm & Pv-At effects observed in Figure 3 are conserved after undergoing spore formation. Do you think certain bacterium might induce these genetic changes?

Were all 22 species of bacteria maintained in the same media? I could imagine different bacterial media components (even though low concentration) could impact Dicty's growth.

Similarly, do all 22 bacteria have similar doubling times? If Kp doubles 2x faster than Po, that could impact why amoeba double quicker on Kp than Po

Interesting! Do you think this picky-eating theory could explain delayed growth? It takes longer to eat because they have to sort through the less-profitable prey to find their favorite meal?

Thank you for sharing this work as an open source preprint! I'm very intrigued by the nutrient-dependent changes in buoyancy and I'm excited to see the future use of this technique!

I love the inclusion of a diverse panel of algal species. The P. tricornutum strain used in this study (CCMP632) was reported to be fusiform 95-100% of the time (DOI: 10.1111/j.1529-8817.2007.00384.x). It'd be interesting to see how buoyancy is impacted by morphology of the same species. In my hands, I always find triradiate cells to be harder to pellet.

It would be really cool to see how the presence of silica is impacting the buoyancy. P. tricornutum (which looks like one of the slowest sinkers measured here) can survive without the presence of silica. It would be interesting to see if there are notable differences in P. tricornutum buoyancy in L1-Si compared to standard L1.

I think this is a typo? According to wikipedia, the only member of the Phaeodactylum genus is P. tricornutum and P. traceroute isn't mentioned again in the text.

This is a very thorough study that uses clever techniques to describe the function of a protein from a Rhizarian species that doesn't have developed genetic tools. The data tells a convincing story and supports the claims made in this paper. Thank you for sharing this work as an open access preprint

Was S. sclerotiorum also tested like in the PbE3-2 overexpression plants?

Figure 4 provides very convincing evidence that pbE3-2 interacts with RD21A in vivo. A minor point would be Fig4E could be improved by displaying the mCherry signal in magenta rather than red for color blind readers who can't distinguish the yellow-green differences in the merge. But very convincing figure!

Do you know that PbE3-2 expression isn't impacting actin expression? If you normalized to 3 random "house-keeping" genes would the data look the same? The data makes sense and fits nicely with the other experiments but actin is highly involved in plant immunity so might not be the best control?

It could be helpful to define BAX at some point. It can be difficult for non-plant scientists (myself included) to understand what it means that PbE3-2 confers BAX resistance without having this information readily available.

Very interesting and convincing phenotype. Do you think the lack of a cell wall contributes to the amount of cell death? If this experiment were done in cells with cell walls, would you miss out on this observation?

Also, why do you think ii-23 is so much more susceptible to heat than ii-9, since they're essentially the same strain, right?

This was done on the the uvm4 strain, correct? Just confirming since the Picariello et al 2020 paper doesn't use uvm4. Have you found this Crispr/Cas9 protocol to be more effective on the uvm4 strain, compared to the strains used in Picariello et al 2020?

If so, were the CrMCA genes effected by the UV mutagenesis used to generate the uvm4 strain?

Thank you for including this! Its nice to see such clear membrane localization in a more "normal" cell line with flagella! While this does have a cell wall, its still a cw15 mutant. I'm guessing this was necessary to get sufficient mVenus expression? I'd be super interested to see if this strain (and a fully intact cell wall strain) with MCA-II deletions are able to survive after HS

Are these over-expression cells more resistant to HS than WT cells?

Such an exciting and striking effect!!!! This paper is a lot of fun! Thank you for sharing!

There are still some faint myo1-mNG puncta visible. Do you think this would go away with higher expression of Ank1? or do you expect there is another mechanism that allows some Myo1 to get to the membrane / evade Ank1?

This is super cool! I love the 3 species inclusion in this paper! I'd be interested to see if Ank1/OSTF1 are interchangeable between species (expressing OSTF1 in Ank1 delta pombe)! Given its small size it might be an easily purifiable myosin "inhibitor"!

Was the Myo1 mutant localized to the contractile ring in the ank1 delta strain? One of the representative max intensity projections in Fig 2C looks like it has the beautiful elliptical ring!!!

This is really fun work! Thank you for sharing all of the neat images/movies! Very exciting observations that will surely bring about a ton more questions!

Thank you for including this information!!! Being able to see the actual collection site / environment provides a lot of information that is often never publicly reported and gets lost with time!

Did the DAPI staining not work? It isn't included in any of the figures.

What are the components of these solutions? or if unknown, what is the source?

Has this type of cooperative motility between clonal diatoms been shown before?

Very interesting! Was the difference between agar & SW-air in the SW-overlay statistically significant?

Is this on the 1 or 2% agarose medium?

Just curious, do motile Nitzschia cells move on glass or inorganic substrates?

Should this be referencing Figure S4? Also, is Fig S5 just showing more examples of this? If so, Awesome and thank you for providing these images!! If not, its unclear to me what additional information is shown in Figure S4.

Is this stained with BODIPY like cells in Figure S4?

This is wild! How do you distinguish between gliding movement and simply drifting in the liquid?

Is the EPS trail visible after the seawater is removed / dried up? My limited understanding is that the EPS is a sort of mucusal "slip-n-slide" but if the entire surface is wet, there'd be no need for EPS trails, right?

Also, did you notice any changes in the directionality of these cells at the different substrates?

Did the cells at the SW-air interface also show a bump-induced cooperative motility mechanism?

Very cool! In the bright-field image, is the structure on the left an EPS trail? or a pipette tip like in Fig 6?

Will a TNT fuse to another cell's TNT or will it attach directly to the membrane?

It would be helpful to include a heat map gradient/scale/legend under subpanels in C. It took me a while to realize that it was a heat map LUT and not a blue marker and a magenta marker.

In Fig 4 C,F) It would be helpful to have these fluorescent images merged with a brightfield image so we can see the outline of the TNTs and where these fluorescent proteins are localized in the cell.

It might be a good idea to also cite Fig 2C here since Fig 1e shows 0% TNTs so 'fewer' TNTs was a bit confusing

The TNTs in the WT here look drastically different from the WT/control TNTs in previous figures In both the GFP/mCherry and the Eps8-IRSp53, the TNT actin looks thinner when treated with CK-666 compared to Mock/DMSO. Have you done any diameter measurements of the TNTs?

Also ARPC3 disappeared, based on the STRING figure

If I understand correctly, the figure shows that IPSp53 and Eps8 interact and localize to these extension, but not that they are responsible for forming the longer protrustions, right? The figure text suggests they are responsible which isn't shown until Fig 5

Fig 4 C & F) does the 00:00 time point indicate the time when the cells were plated? In the earlier experiments, cells were allowed to adhere for 4-6 hours before treatment for 16-18 hours. Do TNTs form within 30 min of plating?

Also, minor point, but C is in hh:mm:ss time stamp, but F is hh:mm time stamp. Since all of the timepoints in C end it 00 sec it would be good to make C/F consistent as hh:mm (or hh:mm:ss)

Also, after 30 min, CK-666 is added and the extended protrusions form shortly after. For the control quantified in d and g, was DMSO added at the 30 min mark? It would be nice too see the control images as well. The force from the flow of added liquid could cause morphological changes

Have you done any experiments where you pre-treat with CK-666 before adhering the cells? Its possible the branched actin networks are necessary for the initial membrane deformation, but after the TNT is formed, Arp2/3 complex inhibition frees up more G-actin which goes the the linear filaments in the TNT?

Would it be possible to develop a similar pipeline that uses alphafold to predict protein-drug interactions? Meaning I have a chemical structure and I want to determine which proteins it might bind to in a species.

If you add purified CLASP2a-GFP to Phalloidin-stabilized F-actin, will the CLASP bind & coat F-actin? and if so, could you then add the MTs and see if they coat the stable F-actin filament? Basically, does this go both ways? or does it need to be MT -> CLASP2a -> Actin?

It might be cool to see the rearrangement of the MTs in a single channel (or w/ DAPI) like Actin is shown in A-C. It looks like the Tubulin in F-G is whacky compared to the control, but its hard to tell if this is true with the actin overlay. From the whole cell view, it looks like MTs are localized more centrally in the knockdowns, compared to the cortical localization in the Control, but i didn't see any mention of this in the text (but I might have missed it and I'm not up to date on the CLASP-literature so it might already be known).

Very cool!!!! Strangely, it looks like the signal in the MT and F-actin channels are comparable between Full Length and truncated CLASP2as, but it looks like there is less GFP signal in the truncated version, compared to full-length. This can be seen with the increased blue signal in the merged channel. While the colocalization quantifications are awesome and needed, it could be nice to have some intensity quantifications / linescans as well, like you did for F-actin signal in Figure 2

This is weird, right? Is truncated CLASP2a better at binding F-actin (and maybe worse at binding MTs) than FL? Even though you cite a paper saying that TOG1 (which is deleted in this construct) also binds to F-actin?

Is it possible that microtubules are required for CLASP2a's F-actin bundling abilities? You show it can bind F-actin in the absence of MTs (Sup Fig 1) but its binding & function could be different in the presence of MTs

Just curious, is silanization essential for these assays to work? I recently saw some literature that silica nanoparticles can mess up actin dynamics / localization (https://doi.org/10.1007/s00204-020-02694-6 ; doi:10.1021/nn103344k). I know that basically all actin dynamics have been measured in the presence of glass/silica, and the 30 min on silanized glass likely wouldn't impact anything substantially, and there really aren't any good alternatives to silica-based coverslips, so definitely not expecting anything else, but I was just curious what the extra silanization does?

This is amazing!!! I'd love to see if this is happening with the truncated CLASP2a as well! Since the 2 actin binding TOGs are right next to each other, do you think both of those are both binding actin monomers helping to form stable dimers? helping to initiate non-spontaneous actin nucleation? Maybe even TOG3 binds actin?

Interesting finding! How many filopodia angles were measured? Panels B-D, F-G all have n= cells or filopodia, but Panel E has n = 3 experiments but doesn't specify the number of filopodia.

Did Cdc42 inhibition reduce the number of / length of filopodia, or just the viral entry?

Very cool! Have you ever observed VLPs moving back up a filopodia? or is endocytosis at the base of filopodia so frequent that it would be internalized before reaching the filopodia?

Did the particle ever attach midway to the filopodia or is it always starting at the tip? Also, how often are these behaviors observed? I see the % surfing vs % grabbing, but of all of the VLP entries, what percent are dependent on these 2 mechanisms?

It looks like blebbistatin is having a similar effect as the other drugs on filopodia length, number, and dynamics, but isn't reducing VLP internalization? If that is the case, the length & dynamics of filopodia don't matter for viral entry? Or do you think that the reduced internalization of VLP is because the overall cell morphology is so messed up in Blebbistatin treated cells?

Worth noting the lack of specificity of SMIFH2 for formins

https://doi.org/10.1242/jcs.253708

Still a useful drug to test with though!

Very cool! It'd be neat to see if cdc42 is upregulated in covid patients to a similar degree!

But internalization of VLP in SMIFH2 treated cells is still reduced compared to untreated cells, so do the dynamics of the filopodia not matter on viral entry?

Very cool work! I really enjoyed reading through this preprint! Thank you for sharing your work!

Very cool results! With the # of VLP internalized, did you make any distinctions between surface-bound VLPs and Filopodia-dependent internalization? Could these results be related to decreased endocytic efficiency?

Was there altered expression of other myosins? or cytoskeletal proteins?

Is there a reason the +Suc propidium iodide staining is so much brighter than +Mock WT? is Propidium iodide staining just pretty inconsistent in these cells?

Just a minor point. I think y'all meant fluorescence.

What is marked in red? is that propidium iodide like in Fig 2D?

Wow! This is a very striking and exciting finding! Was the cell/layer count consistent across 100% of roots? It'd be great to see quantification of that as well. the Recovered number when sucrose is added is super cool!

The first image in Panel E has 2 asterisks instead of the 3. Not sure if intentional.

Is this just redundant w/ Fig 2 BC? I see that the values are a lot higher in Fig 2 BC and those were 6-day old, instead of the 5-day old plants shown here. Sorry if it's an ignorant question.

Very cool process! Have you taken the MA cells through several passages an they continue to retain this phenotype?

I really appreciate the consistency of phenotype across both cell types! I'm curious if a similar phenotype would occur in non-cancerous cells as well!

Were the MA cells in suspended culture for at least 24 hours (like the recovered ORM cells)?

Interesting! Is this something that would be happening in living tissue? I'd be curious to hear if y'all tried different membrane materials or numbers of passages!

Wow! That's a big change in 3 days!!! I'd be interested in seeing images of more than just the nucleus. Are there cell shape changes in the MA cells compared to the control?

Also, I'd be interested to see a comparison between control, ORM, and MA cells! Since the ORM cells can revert back to "normal" cells, it'd be interesting to compare the expression in revertable and non-revertable cells to get more insight into the genes responsible for this reversion!

Very cool! I'm guessing "expanded" means the cells were split/passaged, right? It could be helpful if this is clearly defined since expand could be interpreted as expansion microscopy preparation which would lead to larger nuclei. It is super cool that these phenotypes persist!

The Y-axes aren't consistent here so its hard to tell, but it seems like there is much stronger whole nucleus lamin signal in MA cells compared to control. Is this correct? Have y'all quantified the whole cell levels of lamin in MA & control cells?

I'm curious why <2 foci is the measurement here. It seems whole cell intensity or a full # of foci count would show greater variation between the conditions (based solely on the representative images). Sorry if this is a common assay that is frequently done.

That is wild! Have y'all looked at other inducers of apoptosis? Is it possible that the methotrexate just isn't getting into the nucleus as much (since MA cells seem to have so much more lamin surrounding & throughout the nucleus).

Oh! I see you used staurosporine which is listed as an apoptosis inducer! Did y'all notice any changes in survival rate when treated with Staurosporine?

Interesting! So the MA cells will migrate more than control cells through collagen, but are less capable through animal tissue! Also it is incredibly strange that the Jurkat MAs are found significantly less in BM and Liver (but not Spleen), but the CCRF-CEM MA cells are significantly less in Spleen an Liver (but not BM), right!??!

Very cool & elegant work!!!

Very cool! Do you think there are 2 Nck molecules binding to each A36 protein, or that half of the A36 proteins aren't binding Nck?

Could this be confirmed with a Grb2 or Intersectin mutant? Right now this claim is based on the A36 mutants, correct? But the A36 mutations could have many effects beyond loss of Grb2/Intersectin recruitment, right?

I think this text was left in on accident

Are the cell lines in Akamatsu et al 2020 able to be infected by the virus? It'd be neat to one day have this direct molecule count to confirm the 2 NPFs per Arp2/3 complex in vaccinia motility!

Is the entire CEV-Actin machinery known? While Nck is altered, there is probably a lot more happening, right?

Very cool & elegant work!!!

Is the entire CEV-Actin machinery known? While Nck is altered, there is probably a lot more happening, right?

Are the cell lines in Akamatsu et al 2020 able to be infected by the virus? It'd be neat to one day have this direct molecule count to confirm the 2 NPFs per Arp2/3 complex in vaccinia motility!

Could this be confirmed with a Grb2 or Intersectin mutant? Right now this claim is based on the A36 mutants, correct? But the A36 mutations could have many effects beyond loss of Grb2/Intersectin recruitment, right?

Very cool! Do you think there are 2 Nck molecules binding to each A36 protein, or that half of the A36 proteins aren't binding Nck?

I think this text was left in on accident

Interesting! So the MA cells will migrate more than control cells through collagen, but are less capable through animal tissue! Also it is incredibly strange that the Jurkat MAs are found significantly less in BM and Liver (but not Spleen), but the CCRF-CEM MA cells are significantly less in Spleen an Liver (but not BM), right!??!

That is wild! Have y'all looked at other inducers of apoptosis? Is it possible that the methotrexate just isn't getting into the nucleus as much (since MA cells seem to have so much more lamin surrounding & throughout the nucleus).

Oh! I see you used staurosporine which is listed as an apoptosis inducer! Did y'all notice any changes in survival rate when treated with Staurosporine?

I'm curious why <2 foci is the measurement here. It seems whole cell intensity or a full # of foci count would show greater variation between the conditions (based solely on the representative images). Sorry if this is a common assay that is frequently done.

Wow! That's a big change in 3 days!!! I'd be interested in seeing images of more than just the nucleus. Are there cell shape changes in the MA cells compared to the control?

Also, I'd be interested to see a comparison between control, ORM, and MA cells! Since the ORM cells can revert back to "normal" cells, it'd be interesting to compare the expression in revertable and non-revertable cells to get more insight into the genes responsible for this reversion!

The Y-axes aren't consistent here so its hard to tell, but it seems like there is much stronger whole nucleus lamin signal in MA cells compared to control. Is this correct? Have y'all quantified the whole cell levels of lamin in MA & control cells?

Were the MA cells in suspended culture for at least 24 hours (like the recovered ORM cells)?

Very cool! I'm guessing "expanded" means the cells were split/passaged, right? It could be helpful if this is clearly defined since expand could be interpreted as expansion microscopy preparation which would lead to larger nuclei. It is super cool that these phenotypes persist!

I really appreciate the consistency of phenotype across both cell types! I'm curious if a similar phenotype would occur in non-cancerous cells as well!

Very cool process! Have you taken the MA cells through several passages an they continue to retain this phenotype?

Interesting! Is this something that would be happening in living tissue? I'd be curious to hear if y'all tried different membrane materials or numbers of passages!

Is this just redundant w/ Fig 2 BC? I see that the values are a lot higher in Fig 2 BC and those were 6-day old, instead of the 5-day old plants shown here. Sorry if it's an ignorant question.

The first image in Panel E has 2 asterisks instead of the 3. Not sure if intentional.

What is marked in red? is that propidium iodide like in Fig 2D?

Wow! This is a very striking and exciting finding! Was the cell/layer count consistent across 100% of roots? It'd be great to see quantification of that as well. the Recovered number when sucrose is added is super cool!

Is there a reason the +Suc propidium iodide staining is so much brighter than +Mock WT? is Propidium iodide staining just pretty inconsistent in these cells?

Just a minor point. I think y'all meant fluorescence.

Was there altered expression of other myosins? or cytoskeletal proteins?

Very cool work! I really enjoyed reading through this preprint! Thank you for sharing your work!

Very cool! It'd be neat to see if cdc42 is upregulated in covid patients to a similar degree!

Very cool results! With the # of VLP internalized, did you make any distinctions between surface-bound VLPs and Filopodia-dependent internalization? Could these results be related to decreased endocytic efficiency?

But internalization of VLP in SMIFH2 treated cells is still reduced compared to untreated cells, so do the dynamics of the filopodia not matter on viral entry?

It looks like blebbistatin is having a similar effect as the other drugs on filopodia length, number, and dynamics, but isn't reducing VLP internalization? If that is the case, the length & dynamics of filopodia don't matter for viral entry? Or do you think that the reduced internalization of VLP is because the overall cell morphology is so messed up in Blebbistatin treated cells?

Worth noting the lack of specificity of SMIFH2 for formins

https://doi.org/10.1242/jcs.253708

Still a useful drug to test with though!

Very cool! Have you ever observed VLPs moving back up a filopodia? or is endocytosis at the base of filopodia so frequent that it would be internalized before reaching the filopodia?

Did the particle ever attach midway to the filopodia or is it always starting at the tip? Also, how often are these behaviors observed? I see the % surfing vs % grabbing, but of all of the VLP entries, what percent are dependent on these 2 mechanisms?

Did Cdc42 inhibition reduce the number of / length of filopodia, or just the viral entry?

Interesting finding! How many filopodia angles were measured? Panels B-D, F-G all have n= cells or filopodia, but Panel E has n = 3 experiments but doesn't specify the number of filopodia.

Just curious, is silanization essential for these assays to work? I recently saw some literature that silica nanoparticles can mess up actin dynamics / localization (https://doi.org/10.1007/s00204-020-02694-6 ; doi:10.1021/nn103344k). I know that basically all actin dynamics have been measured in the presence of glass/silica, and the 30 min on silanized glass likely wouldn't impact anything substantially, and there really aren't any good alternatives to silica-based coverslips, so definitely not expecting anything else, but I was just curious what the extra silanization does?

It might be cool to see the rearrangement of the MTs in a single channel (or w/ DAPI) like Actin is shown in A-C. It looks like the Tubulin in F-G is whacky compared to the control, but its hard to tell if this is true with the actin overlay. From the whole cell view, it looks like MTs are localized more centrally in the knockdowns, compared to the cortical localization in the Control, but i didn't see any mention of this in the text (but I might have missed it and I'm not up to date on the CLASP-literature so it might already be known).

This is amazing!!! I'd love to see if this is happening with the truncated CLASP2a as well! Since the 2 actin binding TOGs are right next to each other, do you think both of those are both binding actin monomers helping to form stable dimers? helping to initiate non-spontaneous actin nucleation? Maybe even TOG3 binds actin?

Is it possible that microtubules are required for CLASP2a's F-actin bundling abilities? You show it can bind F-actin in the absence of MTs (Sup Fig 1) but its binding & function could be different in the presence of MTs

Very cool!!!! Strangely, it looks like the signal in the MT and F-actin channels are comparable between Full Length and truncated CLASP2as, but it looks like there is less GFP signal in the truncated version, compared to full-length. This can be seen with the increased blue signal in the merged channel. While the colocalization quantifications are awesome and needed, it could be nice to have some intensity quantifications / linescans as well, like you did for F-actin signal in Figure 2

This is weird, right? Is truncated CLASP2a better at binding F-actin (and maybe worse at binding MTs) than FL? Even though you cite a paper saying that TOG1 (which is deleted in this construct) also binds to F-actin?

If you add purified CLASP2a-GFP to Phalloidin-stabilized F-actin, will the CLASP bind & coat F-actin? and if so, could you then add the MTs and see if they coat the stable F-actin filament? Basically, does this go both ways? or does it need to be MT -> CLASP2a -> Actin?

Also ARPC3 disappeared, based on the STRING figure

The TNTs in the WT here look drastically different from the WT/control TNTs in previous figures In both the GFP/mCherry and the Eps8-IRSp53, the TNT actin looks thinner when treated with CK-666 compared to Mock/DMSO. Have you done any diameter measurements of the TNTs?

Have you done any experiments where you pre-treat with CK-666 before adhering the cells? Its possible the branched actin networks are necessary for the initial membrane deformation, but after the TNT is formed, Arp2/3 complex inhibition frees up more G-actin which goes the the linear filaments in the TNT?

It might be a good idea to also cite Fig 2C here since Fig 1e shows 0% TNTs so 'fewer' TNTs was a bit confusing

Fig 4 C & F) does the 00:00 time point indicate the time when the cells were plated? In the earlier experiments, cells were allowed to adhere for 4-6 hours before treatment for 16-18 hours. Do TNTs form within 30 min of plating?

Also, minor point, but C is in hh:mm:ss time stamp, but F is hh:mm time stamp. Since all of the timepoints in C end it 00 sec it would be good to make C/F consistent as hh:mm (or hh:mm:ss)

Also, after 30 min, CK-666 is added and the extended protrusions form shortly after. For the control quantified in d and g, was DMSO added at the 30 min mark? It would be nice too see the control images as well. The force from the flow of added liquid could cause morphological changes

In Fig 4 C,F) It would be helpful to have these fluorescent images merged with a brightfield image so we can see the outline of the TNTs and where these fluorescent proteins are localized in the cell.

It would be helpful to include a heat map gradient/scale/legend under subpanels in C. It took me a while to realize that it was a heat map LUT and not a blue marker and a magenta marker.

If I understand correctly, the figure shows that IPSp53 and Eps8 interact and localize to these extension, but not that they are responsible for forming the longer protrustions, right? The figure text suggests they are responsible which isn't shown until Fig 5

Will a TNT fuse to another cell's TNT or will it attach directly to the membrane?

Would it be possible to develop a similar pipeline that uses alphafold to predict protein-drug interactions? Meaning I have a chemical structure and I want to determine which proteins it might bind to in a species.