Agar freezing strains

[Raja Rosenbluth]

24 June, 1997

We would appreciate hearing from people who use the agar
freeze method (i.e. not the M9-glycerol one)  for storing
their strains.

We have been having some difficulties in recovering live
worms when we go back to a tube for a second time.

Since we store our tubes in Liquid N2 and the agar is at
first very hard, we wonder whether the repeated slight
thawing and freezing is what is killing the worms.

We think that maybe we should be storing the agar tubes at
-80 C,  and for Liquid N2 we should only use the old
glycerol-M9 method.  This is what Theresa Stiernagel does at
the stock center.

Is that what most people do?
Any advice you may have would be appreciated.

Raja Rosenbluth, (Baillie Lab)   E-mail rosenblu at sfu.ca