X-Message-Number: 9190
Date: Mon, 23 Feb 1998 01:44:57 -0800 (PST)
From: Doug Skrecky <>
Subject: testing cryoprotectants with flies

 Goal: Test the effect of various cryoprotectants on the freeze/thaw
 survival of drosophilia melanogaster flies.

 Procedure: Add cryoprotectant to commercial 4-24 fly food. Feed this to
 flies for several days. Then freeze the flies overnight in
 refrigerators's freezer. Thaw the next day and look for survivors.

 Note: With glycerol half the water added to the fly food was replaced by
 this liquid. With the other cryoprotectants, which are solid at room
 temperature, equal volumes of cryoprotectant and 4-24 fly food were mixed
 together, prior to addition of water.

 Results:
    Toxicity of cryoprotectant was roughly judged based on mortality prior
 to freezing. Based on this the substances used can be ranked in order of
 decreasing toxicity as follows: alanine, glycine > glycerol, proline >
 glucose, glutamine.
    Percentage survival after freezing/thawing is as follows:

    alanine: 0%
    glucose: 0
  glutamine: 0
   glycerol: 0
    glycine: 0
    proline: 0

 Conclusions:

    Drosophilia melanogaster is not an appropriate experimental model for
 testing cryoprotectants. Possibly a more freeze resistant insect might be
 useful for ranking the effectiveness of various cryoprotectants.

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