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Drosophila notation

Anesthetizing Flies need to be sexed and sorted both for making the matings and for counting their subsequent offspring. To immobilize flies for sorting and counting, we will use FlyNap®, a safe anesthetizing agent that will knock the flies out for an hour or so. To use FlyNap, first tap the flies out into a clean, dry vial with a foam plug, then wet a felt wand with FlyNap and insert the felt end beneath the foam plug so that the wand handle extends above the vial rim. Make sure the cap is always tightly screwed down on the FlyNap bottle. The flies should be sufficiently anesthetized in about two minutes. Immediately remove the wand and tap the immobilized flies unto a sorting card. Flies can be sorted under 15X magnification with a dissecting microscope. Use a fine-bristled, artist’s paint brush to gently move the flies, and make sure the flies are not left exposed to the illuminator heat for more than a few minutes as this can kill them. Unused flies can be discarded in the Fly Morgue. Sexing Careful sex determination is essential in preparing matings for genetics studies. Sexes can be distinguished soon after emergence and, with practice, even in the pupal case. There are only two features that are reliable for determining sex in all fruit flies: 1) the genitalia, and 2) the presence or absence of sex combs. Place anesthetized flies ventral side up on a card and view them with a dissecting microscope at 30X or higher magnification. The posterior-most abdominal segments of male flies have a darker, scleritized genital arch, penes, and divided anal plate; whereas females lack these features. Instead, females have a light-colored, subterminal vaginal plate with a small, medial slit running lengthwise that is barely visible at 30X.