[3dem] Is there an asymmetric biological sample out there that reveals handedness at CET resolution?

Mike Strauss mikestrauss13 at crystal.harvard.edu
Tue Aug 7 11:33:08 PDT 2012


Hi Christian,

you could use a helical particle and look at the rise and rotation of the subunits.  Perhaps microtubules, or a helical virus.

If you want to see if a sample is loaded in the reverse direction, you could reconstruct a plastic section with fiducially on a known side (i.e. always on top), and then see where they end up in the program.

good luck.

mike


On Aug 7, 2012, at 2:27 PM, Christian Geiss <geiss at biophysik.org> wrote:

> Hello,
> 
> I am a Phd student, do cryo electron tomography and have a problem determining the handedness of my sample, because viewers for tomograms like Amira, Matlab-based scripts can invert the handedness depending if you look at your tomogram from top to bottom or vice versa. Since those programs behave to some extent like black boxes, the easiest would be to have a nice asymmetric biological sample where you know the handedness and that the latter can be judged quite easily from a reconstruction, meaning without further processing like subtomogram averaging.
> 
> So far, I can only think of bacterial ribosomes since they are asymmetric and quite big, but for cryoET the resolution would be not reasonable to resolve the handedness at all. Thus I could need in the ideal case e.g. something like a large complex that links each other to repetitive units with a known handedness.
> 
> I know its a tough question, but maybe someone can give creative input here? I would highly appreciate it!
> 
> Best regards,
> 
> C. Geiss
> 
> 
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Mike Strauss
Harvard Medical School - Dept. BCMP
240 Longwood Ave. - Bldg C2 Rm 125A
02115 Boston, MA, USA
(617) 432 1216
mikestrauss13 at crystal.harvard.edu





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