[3dem] "leopard skin" ice

[Bob Grassucci]

I am getting a chuckle out of the image of a Leopard shaving ;)  That 
being said that is why turtle ice may be more accurate.
Bob
On 11/21/2013 10:45 PM, Joachim Frank wrote:
> 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
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>>>>
>>>>
>>>
>>>
>>>
>>> -- 
>>> Paul Chipman
>>> Assistant Director of Research
>>> Biochemistry and Molecular Biology
>>> University of Florida
>>> 352-294-1790
>>>
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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
>>
>
>
>