growth of N. crassa

[Deborah B. Pedersen]

We have found transformants of N. crassa stored on Vogel's minimal plates
containing 200ug/ml hygromycin do not survive for longer than 2 months. The
plates were kept at 4C and parafilmed.  Colonies from the stored plates were
picked onto slants with or without hygromycin and nothing grew. Does anyone
have any ideas of why this would be? We do not have this problem with stored
slants, and have used them for up to a year.  Thanks for any advice.