Is the actin twist the highest resolution feature that can be observed in a raw tomogram? Maybe the protofilaments of microtubules? #teamtomo - ThreadSky

baradlab.com • 175 days ago

Is the actin twist the highest resolution feature that can be observed in a raw tomogram? Maybe the protofilaments of microtubules? #teamtomo

Reposted from hamid13r.bsky.social

Why do I like seeing actin filaments in my tomograms so much?
- bunch of actins passing by in between two mitos in a dendrite!
#cryoEM #cryoET #TeamTomo

Comments

dabiophysicist.bsky.social•174 days ago

The inner and outer edges of lipid bilayers, I think

baradlab.com•174 days ago

Lipid bilayers are typically 3.2-3.4nm apart (we do that measurement these days!). Actin rise is a bit finer than that, but not much... ~2.7nm.

dabiophysicist.bsky.social•174 days ago

I don't mean the whole membrane, I mean the edges themselves (must be the head groups, they are very dense)

dabiophysicist.bsky.social•174 days ago

Two dark edges, less dense within - do you think I'm misinterpreting? The pixel size is 8.22 Å, the CtC distance is about as expected I think

baradlab.com•174 days ago

Fair enough! Typically fwhm of 1.5 nm or so for those w 4 micron defocus...

dabiophysicist.bsky.social•174 days ago

Gary however may have another opinion
https://www.nature.com/articles/s41467-024-52914-1

hamid13r.bsky.social•175 days ago

Very good Q! In my experience, seeing actins like this is limited to non-milled and very thin tomograms... do you think we can have a leap in tomogram resolution in any way?

baradlab.com•175 days ago

I am not sure if its fair to ask for a jump in resolution from the highest resolution cellular imaging technique to date! With that said, I think there are improvements to be made in tilt series alignment and tomogram reconstruction. If not, M wouldn't be as huge an improvement for STA as it is!

hamid13r.bsky.social•175 days ago

I want higher resolution everywhere all the time 😄😄

daddea.bsky.social•174 days ago

I completely agree with you. Eman2 has a subtilt refinement, similar to M --not so good, maybe--, with the opportunity to correct the subtle local misalignments back to the tomograms to improve the visualization

dabiophysicist.bsky.social•174 days ago

Chromatic aberration (Cc) correctors. One day...🙏

hamid13r.bsky.social•174 days ago

daddea.bsky.social•174 days ago

I’m curious about the laser phase plate coupled with the Apollo detector

uermel.bsky.social•174 days ago

Depends on your definition of 'observe', 'raw', and the type of sample, I'd say. Observe visually? Does raw include CTF deconv?

e.g. one can easily spot single DNA strands in tomograms of in vitro chromatin. In cellular cryoET it's harder, but sometimes you can spot the turns in nucleosomes.

baradlab.com•174 days ago

Honestly I meant raw as opposed to averaged, any postprocessing short of that seems like fair play to me. DNA would def be the record from my end, and you're in a position to see more tomos than almost anyone!

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