Population Studies of a Lethal Mutant in Drosophila Melanogaster

OVE FRYDENBERGconsidered honiozygously lethal, persisted in the stocks even in the absence of artificial selection. Identification of the mutnntI n order to identify the mutant a linkage analysis was carried out employing a rucucci chromosome as reference.The analysis revealed that the mutant is located in the third chrornosonie between the czi locus (111: 50.0) and the e locus (111: 70.7) at a distance of some five to six centimorgans to the right of cu.This corresponds fairly well to the position of the Sb locus.It also became clear that the mutant was associated with a cro3sing-over inhibitor occurring to the right of the mutant in chromosome 111 since the recombination between the loci e and cci (111: 100.7) was reduced to less than two per cent of its L I S L M ~ value.A preliminary analysis of the chromosome in the salivary glands has shown that the mutant is linked to a short inversion extending from the proximal end of 93E to the distal part of 98F.It is in all probability identical with Zn(3R) M o .That the mutant actually is a n allele of the Sb locus was finally proved by crossing mutant flies to a stock of the constitution D Sbl Pciyne.If the mutant is allelic to S b , this mating should segregate