An X chromosome locus in Drosophila melanogaster that enhances survival of the triplo‐lethal genotype,Dp‐(Tpl)

摘要

AbstractOnly a single locus(Tpl)is known in the Drosophila melanogaster genome that leads to early lethality when present as a heterozygous duplication (three doses) or deficiency (one dose). We report the recovery of third instar larvae (and of occasional adults) carrying a duplication for the triplo‐lethal locus,Dp(Tpl).Karyotype analysis of the larvae showed that the individuals surviving were almost entirely 3X;2A metafemales. We examined the question of whether the entire X or a single X locus was a major factor permitting survival. X‐Y translocations were used to produce females hyperploid for different portions of the X and carryingDp(Tpl). Analysis of metaphase chromosomes by quinacrine fluorescence pattern indicates that the X chromosome region between 6D and 7DE must be present in an extra copy to enhance the survival ofTplduplication‐bearing females. Another type of experiment suggests that it is the region between 7C and 7DE which is esse