making males

Leon Avery leon at
Thu Oct 30 09:15:21 EST 1997

Heat shock is a very touchy protocol.  You have to get the time
exactly right: half an hour too long, and the worms are sterile, half
an hour too short, and there's no nondisjunction.  Furthermore, the
correct time depends very sensitively on the temperature, and you
seldom know the temperature accurately enough.  So I do as follows:
put 5 L4 hermaphrodites on each of 6 plates at 30C.  Take out two
plates after 5.5 hours, two more after 6 hours, and two more after 6.5
hours.  One of those pairs should work.  You'll have advance warning
which, because you'll usually see some vulval abnormalities in the
parents, and they will produce small broods.  If all your plates are
sterile or if all are normal, adjust your incubator accordingly.  The
frequency of males is still not high -- you have to hunt for them.

Leon Avery                                       (214) 648-4931 (voice)
Department of Molecular Biology and Oncology              -1488 (fax)
University of Texas Southwestern Medical Center
5323 Harry Hines Blvd                            leon at
Dallas, TX  75235-9148        

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