[3dem] Re: Ice contamination

[Bob Grassucci]

Hi Liz,
Definitely not ethane.  The contrast of blobs is too low.  It could be 
coming from the humidifier in the Vitrobot.  Try turning off the 
humidifier when you are making the grids and see if they disappear.  I 
am thinking they are getting deposited from the spray while plunging.
Bob

On 9/27/2011 6:46 PM, Wright, Elizabeth R. wrote:
> Dear All,
>
> For those of you patient enough to look at a larger image, please find 
> it located at the following link:
> http://dl.dropbox.com/u/23095990/Caulobacter_2sept2011.tif
>
> The contamination is the small globular looking material distributed 
> throughout the ice. There are 10 nm gold fiducials and a bacterial 
> cell. To our eyes, when we generate the 3D reconstructions, the 
> 'blobs' appear to be in the ice, albeit at or close to the surface. It 
> does not look like frost or particles that have landed on the surface 
> of a frozen specimen.
>
> Thank you all for your help.
>
> Sincerely,
>
> Liz
>
> From: Elizabeth Wright <erwrigh at emory.edu <mailto:erwrigh at emory.edu>>
> Date: Tue, 27 Sep 2011 16:38:47 -0400
> To: <3dem at ncmir.ucsd.edu <mailto:3dem at ncmir.ucsd.edu>>
> Subject: Ice contamination
>
> Dear 3D EM friends,
>
> We are experiencing a problem with ice contamination within the ice of 
> our plunge-frozen samples (frozen with an FEI Vitrobot). We have 
> purchased new hoses, regulators, ethane (99.999% pure) and liquid 
> nitrogen tanks, attempted chloroform or methanol treatment of the 
> grids, glow discharged the grids with different units, and still seem 
> to be unable to remove this contaminant. It is not specimen dependent 
> as we use different buffering systems for the samples. It is also not 
> microscope dependent, we have seen it when using a variety of instruments.
>
> Has anyone observed this before (image below)? Has anyone found a way 
> to remove it? Any thoughts or suggestions would be greatly 
> appreciated. If the image does not come through, please let me know.
>
> Thank you all for your help.
>
> Sincerely,
>
> Liz
>
>
>
> ----
> Elizabeth R. Wright, PhD
> Assistant Professor
> Emory University
> erwrigh at emory.edu <mailto:erwrigh at emory.edu>
> Ph: (404) 727-4665
>
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