Performing Drosophila Crosses

-Collect virgin females with appropriate marker and put into a new vial -When not collecting, keep the vials from which virgins are collected at 18 degrees celsius -The vials from which males are collected are stored at room temperature -Once 10 virgin females from a strain have been collected, add 4 males with the appropriate marker from another strain -Label the vial to indicate the cross type and generation (A1 = the first generation of the first cross) -Store the crosses in an incubator -After 5 days, flip the 14 flies into a new vial (there should be eggs visible at the surface of the food) -Label the vial appropriately (A2 = the second generation of the first cross) -Repeat this cycle until enough progeny from the crosses have been produced or until there are no parent males left - After about 10 days, the progeny from the crosses will start eclosing - Record the date that the flies begin eclosing - Once there are at least 20 flies in the vial, collect the progeny and sort according to phenotype -Record the number of flies of each phenotype born - Place the males and females into separate vials - There should be 5 - 15 progeny flies in each vial - if necessary, further separate them according to phenotype - Label the vial with: Cross type/generation, gender, # of flies, phenotype, date born, and date added to vial - Keep the progeny vials in an incubator - Repeat this process during the six days following the date they first eclosed, waiting each time until there are at least 20 flies in the vial (usually 2 to 3 times per vial) -After six days, toss the vial - Flip all progeny vials twice a week