ive ▁le th al ▁" bal ancer ▁chrom os om es " ▁carrying ▁visible ▁gen etic ▁markers ▁can ▁be ▁used ▁to ▁keep ▁stock s ▁of ▁le th al ▁alle les ▁in ▁a ▁heter o zy g ous ▁state ▁without ▁recom bin ation ▁due ▁to ▁multiple ▁in versions ▁in ▁the ▁bal ancer . ▁The ▁development ▁of ▁this ▁organ ism — from ▁fert il ized ▁egg ▁to ▁m ature ▁adult — is ▁well ▁understood . ▁Gen etic ▁transformation ▁techniques ▁have ▁been ▁available ▁since ▁ 1 9 8 7 . ▁Its ▁complete ▁gen ome ▁was ▁sequ enced ▁and ▁first ▁published ▁in ▁ 2 0 0 0 . ▁Sex ual ▁m osa ics ▁can ▁be ▁readily ▁produced , ▁providing ▁an ▁additional ▁tool ▁for ▁studying ▁the ▁development ▁and ▁behavior ▁of ▁these ▁f lies . ▁ ▁Gen etic ▁markers ▁ ▁Gen etic ▁markers ▁are ▁commonly ▁used ▁in ▁D ros oph ila ▁research , ▁for ▁example ▁within ▁bal ancer ▁chrom os om es ▁or ▁P - element ▁inser ts , ▁and ▁most ▁phen ot ypes ▁are ▁easily ▁ident ifiable ▁either ▁with ▁the ▁n aked ▁eye ▁or ▁under ▁a ▁mic ros cope . ▁In ▁the ▁list ▁of ▁a ▁few ▁common ▁markers ▁below , ▁the ▁alle le ▁symbol ▁is ▁followed ▁by ▁the ▁name ▁of ▁the ▁gene ▁affected ▁and ▁a ▁description ▁of ▁its ▁phen ot ype . ▁( Note : ▁Rec ess ive ▁alle les ▁are ▁in ▁lower ▁case , ▁while ▁dominant ▁alle les ▁are ▁capital ised .) ▁Cy 1 : ▁Cur ly ; ▁the ▁wings ▁curve ▁away ▁from ▁the ▁body , ▁flight