[Drosophila] Mutation not as described

Gae,

It seems to me that perhaps two things have happened:

1 - The stock (prior to or while at Bloomington) became contaminated
with a X chromosome that did not contain the mutation.
Alternatively, the coverage of FM6 does not include the location of
your mutation. The latter explanation may be possible, since FM6 has
the same problem as FM4: funny double-crossover genetics (see the
Redbook). Either way, this would explain why you were able to obtain
homozygotes and hemizygotes that did not express the phenotype.

2 - After you recovered the mutation, you probably also got another
mutation on the same chromosome (either from a contaminating
chromosome or as a spontaneous mutation). This second mutation may
confer the subviable/subfertile phenotype.

Now that you have your mutant, but the rest of the chromosome is
suspect, you should "clean it up." Cross females mut/FM6 to yw/Y
males and collect mut/yw virgins. Backcross a few generations to yw/
Y males to get rid of secondary mutations by recombination. Each
generation, set up a few dozen vials with individual females, and
always monitor the presence of the mutation by its expression in
sibling males. After a few generations, unless the second mutation
is closely linked, you should be able to cross females to FM/Y for
two generations to rebalance it. I'd recommend a different
chromosome 1 balance. FM7 is always in season.

Hope this helps,


Keith Maggert



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Keith A. Maggert, Ph.D. Assistant Professor
Texas A&M University office (979) 845-6610
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