[3dem] Gatan 914 Holder Woes

Benoit Zuber bzuber at mrc-lmb.cam.ac.uk
Wed Oct 8 03:26:16 PDT 2008

Hi Cindi,

I cannot download the pictures but it sounds like you could have a leak 
in the column vacuum when you transfer the specimen. Your specimen would 
warm up shortly and devitrify. Then it would cool back down. All this 
happening fairly quickly, so that you would not be able to monitor the 
change in temperature.

Hope this helps,

Cindi Schwartz wrote:
> Hello List,
> We are having problems with plunge-frozen cryo grids only when using 
> our 914 holder. Basically, we are getting what I like to call, the 
> cauliflower effect. Sometimes it's very subtle and sometimes it's 
> blatant. Here are the facts:
> 1. This is happening to multiple people with multiple sample types
> 2. This happens when using the vitrobot or by hand-blotting
> 3. Grids from the same freezing session viewed with a Gatan 626 holder 
> do not have bad ice
> 4. Temperature measurements of the 914 holder during all phases of 
> loading the holder and inserting it into the microscope never get 
> above -170C
> 5. Grids have this regardless of which of 2 tanks of ethane we use
> Any ideas of what may be causing this would be greatly appreciated.
> The pictures were too big to send to the list (although quite small by 
> my standards). They are posted on our ftp site:
> ftp://bio3d.colorado.edu/914
> Thanks,
> Cindi
> **********************************
> Cindi L. Schwartz
> University of Colorado, Boulder
> Dept. MCDB
> O: 303-492-7980
> F: 303-735-0770
> **********************************
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> 3dem at ncmir.ucsd.edu
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Benoît Zuber
MRC Laboratory of Molecular Biology
Hills Road
United Kingdom
+44 1223 402209
bzuber at mrc-lmb.cam.ac.uk

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