>Does anyone know the genotype of OP-50?
I once wrote to Brenner to ask this question. I then lost his
response (brilliant!), but I think I remember the gist: it is a
uracil auxotroph of a non-K12 E coli strain (E coli B, I think). So,
it is not a genetically well-characterized strain. As Brenner's 1974
paper explains, a uracil auxotroph was chosen because prototrophs
tend to produce inconveniently thick lawns. I also remember from
conversation in the Horvitz Lab some 15 years ago that OP50 is a bit
leaky -- the idea was that it would be able to grow slowly in the
absence of uracil, rather than being completely blocked. OP50 tends
to produce snakes, a known characteristic of E coli unable to make
thymine (because growth continues while replication is blocked), and
spontaneous faster-growing colonies that I isolated from NGM plates
did not have this characteristic. However, they also failed to grow
on minimal medium, to my surprise.
--
Leon Avery (214) 648-4931 (voice)
Department of Molecular Biology -1488 (fax)
University of Texas Southwestern Medical Center
6000 Harry Hines Blvd leon at eatworms.swmed.edu
Dallas, TX 75390-9148 http://eatworms.swmed.edu/~leon/
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