How to determine gene copy number?

[Scott C. Johnson]

Trypanosomes are typically diploid. Therefore to knockout the expression of
a given gene, both copies need to be disrupted. This is accomplished by
recmobination of two unique selectable markers into the coding regions. In
my case, I have performed the first knockout, and the recombinants are
unable to divide. They survive the drug selection, and live for about 3-4
more days. This is surprising as I expected the other copy to take up the
slack. Is there another copy? What is the best way to determine the number
of genomic copies of a given gene? There are many different explainations
for the observed result, but knowing if there are 1 or 2 copies would help.
Thanks

Scott

-- 
Scott C. Johnson
UW-Madison
scj at calshp.cals.wisc.edu