[3dem] Unrecognised CryoEM contaminant 2

[Gabriel Lander]

It would help if you posted some images of the same sample in negative stain. Is there a possibility that this is condensed RNA? It would be almost invisible in negative stain, but show up very nicely in cryo.
Otherwise I'm inclined to say that these are microscopic hobgoblins that have infested your plunging device.

On Mar 28, 2014, at 9:42 AM, "Xinghong Dai" <bestdz at gmail.com> wrote:

> Hi Daniel,
> To me, it looks like phantom caused by too thin ice. Especially black patches around the hole in up-left panel, they look like almost-dry areas. Try to increase the humidity, and wait shorter time before, and after, you blot. Also try shorter blot time.
> Good luck!
>  
> Best regards,
>  
>  
> Xinghong Dai
> 
> 发件人: 3dem-bounces at ncmir.ucsd.edu [mailto:3dem-bounces at ncmir.ucsd.edu] 代表 Daniel Luque
> 发送时间: Friday, March 28, 2014 5:52 AM
> 收件人: 3dem at ncmir.ucsd.edu
> 主题: [3dem] Unrecognised CryoEM contaminant 2
>  
> Hello
>  
> Before a couple of days waiting for the list moderator approval to attach the images in the list , I do not have received any response (either positive or negative) and I do not have find a mail/way for contact. Thus, I have made the images available at our server at:
>  
> http://halley.cnb.csic.es/~virus/3DEM/Example_images.pdf
>  
> Bellow is text of the original question:
>  
> We are doing CryoEM of viral particles. When we check the sample by negative staining, a field of intact homogeneous particles without significant contaminants is observed. However, when we visualize the same sample by CryoEM, additionally to a lower-than expected number of particles, we observe an unexpected contaminant mostly located in the holes (see attached document with some example images). Does anybody see this class of contaminants? Any idea about its origin?
>  
> Thanks in advance!
>  
>  
> Daniel Luque
>  
>  
>  
>  
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