[3dem] "leopard skin" ice

Sun Nov 24 22:55:12 PST 2013

Hi all,

I believe the reason is minor exposure to warm & moist air, typically  
during the transfer of the cryo holder.
We see similar thing every now and then (on rare occasions), but in  
the past we were occasionally pestered by the "cobblestones" (term  
coined by someone in Boulder, I believe).
Our problem was linked to design of the original version of 914  
cryotomo holder that left a tiny physical slit in the tip open even  
when the hatch was closed. After we got a small upgrade that blocked  
the slit the problem was solved.

A lively thread!
-Pasi

Quoting Dianne Taylor <dianne at bio.fsu.edu>:

> Here in Florida it has long been and will always be alligator, gator  
> for short, ice.
>
>  As the many good comments suggest, there may well be more than one  
> source of the problem. I would echo the observation that transfer of  
> the cryoholder is likely the most common one. We see it frequently  
> on the CM120 but not usually on the Titan. We see it with both  
> manual and Vitrobot freezing irrespective of ethane tank age or  
> fullness. Some samples seem to be more susceptable than others, our  
> lipid monolayer samples are very prone to the "dried mud" appearance.
>
> Dianne Taylor
> At 08:53 AM 11/22/2013, Bob Grassucci wrote:
>
>> 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
>>>>>> 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>_______________________________________________
>>>>> 3dem mailing list
>>>>> 3dem at ncmir.ucsd.edu
>>>>>
>>>>> 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
>>>
>>>
>>
>>
>> _______________________________________________
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>
> Dianne W. Taylor
> Associate in Research
> Institute of Molecular Biophysics
> Florida State University
> Tallahassee, FL 32306-4380
> Phone: (850) 644-4104
> E-mail:  dianne at bio.fsu.edu _______________________________________________
> 3dem mailing list
> 3dem at ncmir.ucsd.edu
> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem

<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>
Pasi Laurinmäki  Laboratory Engineer

Institute of Biotechnology
Electron Microscopy Unit
P.O.Box 56
FIN-00014 University of Helsinki
Finland

tel. +358 9 191 59502
fax. +358 9 191 59498
E-mail. pasi.laurinmaki at helsinki.fi
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