Today you'll get the adult flies out of the new vial that you made on Tuesday (the Sept. 15 vial). Since we've had problems with the flies clinging to the inside of the vial so hard that they won't come out without knocking out the gloopy food, today try putting the vials on ice first. Put the vial on its side in the ice chest, with ice piled part way up the side. After about 5 minutes, the flies should be so cold that they're motionless. Quickly dump the flies into an empty vial. Use a brush to get them out, if you have to. Be quick, and don't let the vial warm up in your hand, as the flies will revive as soon as they warm up.
Once you've got all the adults into the empty vial, put a foam plug in it (and the vial with food and larvae, of course). Warm the empty vial with your hand until the flies are starting to move, then put a Flynap wand in with them. (You want them to be warmed up, so you can tell when the Flynap puts them back to sleep). Count the number of male mutants, female mutants, male wild type, and female wild type.
Get the adults out of the Sept. 1 vial and count them, using the same technique. These are flies that emerged from their pupal cases between Tuesday afternoon and today, so they may be flies with a longer development time.
Estimate the allele frequencies in the adults from the Sept. 15 vial and the adults you got out of the Sept. 1 vial today. For sex-linked genes, count the alleles in the males and use the Hardy-Weinberg relationship to estimate the allele frequency in females, and keep the allele frequencies separate. For autosomal genes, pool the number of males and females and then use the Hardy-Weinberg relationship. Is there a difference in allele frequency between the flies you got out of the Sept. 1 vial on Tuesday and the ones you got out of that vial today?
Unfortunately, I didn't have time to read your preliminary proposals in detail. I'll e-mail you detailed comments on them, including suggestions for additional papers to look at, over the weekend. For today, I'll talk to each of you briefly about your proposed research and make some suggestions for things to think about.
The next thing you need to turn in will be a revised proposal for your individual experiment, based on the suggestions I e-mail you this weekend. It will be due on Thursday, Sept. 24. If I tell you "more background," I'll want to see more basic information about your gene, like what chromosome it's on, what the protein the gene makes does, what the phenotype of your mutant is, etc. If I tell you "more detail" about some part of the experiment, I want you to describe your proposed experiment in more detail--what kind of results you're going to be looking for, how many flies you'll use, etc. If I say "more on literature," I want you to describe the results of previous lab selection experiments (and last year's term paper) on your mutant in more detail--not just what they found, but how they did their experiments.
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This page was last revised September 17, 2009. Its URL is http://udel.edu/~mcdonald/geneticslab5.html