Genetic mapping of the Adh locus in the repleta group of Drosophila by in situ hybridization.

A biotinylated probe of the Adh (alcohol dehydrogenase) gene of Drosophila melanogaster was used for in situ hybridization on polytene chromosomes of D. mojavensis and D. buzzatii, two species of the repleta group of the genus Drosophila. Hybridization showed that the Adh gene maps at the G1a band of the third chromosome. This is in accordance with a previous result obtained through the use of interspecific hybrid asynapsis as a cytological marker and establishes the limits of the precision of this method.