[3dem] "leopard skin" ice

Joachim Frank jf2192 at columbia.edu
Thu Nov 21 19:45:17 PST 2013


Hi all,
just a note on the terminology:
You mean leopard fur, maybe?
Because the animal, shaved down to the skin, looks quite different for sure.

--Joachim.

Quoting Stefan Bohn <Stefan.Bohn at ucsf.edu>:

> Hi,
>
> sometimes this ice was appearing, when the ethane bottle was nearly empty.
> Sometimes, ethane bottle was full and it still appeared (open plunger, F20,
> identical(!) sample - 20mM Hepes, 20mM NaCl, 10mM MgCl2, ~15% glycerol) -
> in those instances I attributed it to not having filled the nitrogen high
> enough in the dewar, maybe not cooling the ethane long enough. Sometimes
> only part of the grid showed this ice, other parts were normal - particles
> were distributed evenly on those grids.
>
> But, in general, it was not reproducible. I couldn't correlate it to the
> phase of the moon, as was suggested to me several times...
>
>
>
> Most importantly, we referred to it as "turtle-ice" (from Schildkroete =
> plate toad).
>
> Hope that helps,
>
> Stefan.
>
>
>
>
> On Thu, Nov 21, 2013 at 1:26 PM, Jacob Brink <jbrink at jeol.com> wrote:
>
>> Hi Paul and Frank,
>>
>> We've also seen this type of ice in Flu particle preps at NIBSC during the
>> cryo-EM course, but we'd see it in the middle of the ice, away from
>> particles (see below). The ethane tank had not been moved. So, we never
>> really could attribute it to anything unless the ice would get really thin?
>> Open air plunger (!) and imaged in a 2100-LaB6 TT.
>>
>> Jaap
>>
>>
>>
>> On Nov 21, 2013, at 2:36 PM, Paul Chipman <pchipman at ufl.edu> wrote:
>>
>> Hi Frank,
>>
>> At Purdue we called this "alligator ice" and would see it from time to
>> time, occasionally when an ethane tank was nearing empty.  As such we
>> attributed to impurities that impeded freezing.  It could also be just
>> something in the buffer or sample that alters the freezing.  The recent
>> image below displays this type of ice but only near the viral particles.
>> Most of the ice was great except in areas of high particle concentration.
>> When I told the student the name we gave this type of ice, I got a laugh.
>>
>> Go Gators! (Florida)
>>
>> Cheers,
>> Paul
>>
>>
>> On Wed, Nov 20, 2013 at 1:54 AM, <frankpolzer at physik.hu-berlin.de> wrote:
>>
>>> Dear all,
>>>
>>> During the last weeks, I frequently observe what I believe is so-called
>>> leopard skin ice in my vitrified samples (plunge frozen in ethane using
>>> Mark IV Vitrobot).
>>>
>>> What again is the reason for this type of ice and how can this be avoided?
>>>
>>> Thanks for your help in advance,
>>>
>>> Frank
>>>
>>>
>>> Dr. Frank Polzer
>>>
>>> TEM Group
>>> Insitute of Physics
>>> Humboldt Universität zu Berlin
>>> Newtonstraße 15
>>> 12489 - Berlin
>>> Tel.: +49 30 2093-4995 (office)
>>> Tel.: +49 30 2093-7829 (TEM)
>>> Fax: +49 30 2093-7886
>>>
>>>
>>> _______________________________________________
>>> 3dem mailing list
>>> 3dem at ncmir.ucsd.edu
>>> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem<http://cp.mcafee.com/d/2DRPoArhpuvKUU-ejdTdFET73AhOtXCQQrzxO8VcsedFEIEIffzDS3qqdTAnQTQSjoygza1k52fRfVsS8_k_BPoVyUXTAT-LObbVEVKNRXBQn76ejouppjVqWtAklrTjVkffGhBrwqrhdECXYyMCY-ehojd79KVIDeqR4IMjW5BphVKR4eZ1L1dnoovaAVgtHza7GCSkflbAaJMJZ0l2OIEYTqy7uwSruud79EVsjdwLQzh0qmSkfldbFEwd4h_RmSa1EwElB0Qh6y2lLdTdCt0VWq79>
>>>
>>
>>
>>
>> --
>> Paul Chipman
>> Assistant Director of Research
>> Biochemistry and Molecular Biology
>> University of Florida
>> 352-294-1790
>>
>>  <alligator_ice.tif>_______________________________________________
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>> 3dem at ncmir.ucsd.edu
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>> http://cp.mcafee.com/d/5fHCNAedEILfTssv79CXCQQrzxO8VeZPqqdNMV4sCe76QQmkm7DNPX1Jd6XObWrWr9Ih8hB0G2x7WDYKr4vGvOVIsNstXOr_nV5BYQsToWZOWbzz79IfcIFYJteOaaJXFYG7DR8OJMddECQjt-hojuv78I9CzATsSjDdqymo9Z2OIEYTqy7uwTwCHIcfBisEeRNB3Rjra7GBO5mUm-waxpmkurJh3LgrdLf6zAQsK9CMnWhEwdbra7GCBQQg6y8_WHr50QgkaOwq8zh1aTCXCZuhzHyMKD70s
>>
>>
>>
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>>
>
>
> --
> Dr. Stefan Bohn
> Department of Cellular and Molecular Pharmacology
> University of California
> 1700 4th Street, Box 2530
> San Francisco, CA. 94158
>
> Phone: +1 (415) 476 - 2980
> Fax: +1 (415) 514 - 9736
>



-- 
Joachim Frank, Ph.D.
Howard Hughes Medical Institute Investigator,
Professor, Department of Biochemistry and Molecular Biophysics,
and Department of Biology, Columbia University,
650 West 168th Street, P&S Black 2-221
New York, NY 10032
(T) 212 305-9510  (F) 212 305-9500  Admin Asst: Masgan Saidi 212 305-9512
(E) jf2192 at columbia.edu
http://www.hhmi.org/research/investigators/frank.html



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