[3dem] Leica plunger users

[Garry P Morgan]

Olga,


I wonder if anyone has a good experience with Leica cryo-plunger for single particle EM applications.
half my users have been pretty happy with our GP2 plunge freezer, but for the other half the delay between blotting and actually plunging (even when set to auto-plunge) is too long. it’s only 1-2 seconds, but that is long enough for some samples to fall apart. we have also had some intermittent issues with the blotting paper not rotating properly after blotting.  if you are not paying attention and looking for this, you may not even notice.  i would advise putting a pen mark on the filter paper so it’s pretty obvious. the Leica engineer looked at this for us, and of course it worked without fail while he was here so he couldn’t find anything to fix.

The one I have in my possession now did not cool down to 4C for nearly 3 hrs, and the humidity was going up and down.
Is it the normal behaviour?
we had this exact same problem with a unit still under warranty.  Leica sent an engineer and he replaced the peltier coolers…it now cools down to 4º in 20-30 minutes. if that did not solve the problem, he was going to try replacing the control board for the unit next. i suggest you get new peltiers.

Also, what is the good regime for protein solutions blotting? Could it be compared to Vitrobot?
i have found that this is comparable to the settings i used on our old vitrobot. in general i would say that i blot 1-2 seconds longer than i did on the vitrobot for any given sample. i think the GP2 chamber maintains humidity better and therefore needs longer blot times (but it could also be the fact that it’s only blotting on one side).

cheers,
Garry


Thank you!
Olga


=======
Yours sincerely,
Olga Sokolova, PhD, D.Sc.
Professor RAS, Faculty of biology Moscow State University
phone +7-495-938-0005
cell +7-916-4841251
http://proteom-msu.org/en/index.html
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