Lethalphasedetermination 1.PickabunchofheterozygoteL4hermaphroditestoanewplate. 2.Thenextday,therewillbeeggsontheplate;pickexactly20ofthesetoeachofafewplates.Makesuretousefirstdayeggslikethis:wild-typeanimalseventuallyrunoutofspermandlayunfertilizedeggsthatdon"tdevelop,andyouwanttoavoidconfusingthesewithdeadfertilizedeggs.Lineupthesetsof20eggsinarowjustbeyondtheedgeoftheseededportionoftheplate. 3.Thenextdayandsucceedingdays,examinetheplatesforunhatchedeggs,deadworms,andliveworms. 4.Ifthewormshatch,butmaybedyingasyounglarvae,itcanbedifficulttodistinguishbetweenwormsbeing"gone"becausetheydiedandthedeadlarvaearehardtofind,orbecauselivewormsjustcrawledupthesideofthedishanddisappeared.Tohelpthisproblem,youcankeepthewormsfromcrawlingoffthebacteriallawnbyusingaP-20toringthelawnwithalineof10mg/mlpalmiticacidinEtOH,whichprecipitatesontheplateandformsabarrierthewormswon"tcross.
