Abnormal salivary gland puff associated with meiotic drive in mosquitos (Diptera, Culicidae)

Sweeny, TLG, P.; Barr, A. R.,  Journal of Medical Entomology,  24:623-627. 1987.

A meiotic drive factor, distorter (d), has been described previously for Culex pipiens L. mosquitoes. Males homozygous for the gene (Md/md) produce few female offspring owing to breakage of the female-determining dyad of chromosome 1 (the sex chromosome) during the first meiotic division of spermatogenesis. Orcein squash preparations of polytene salivary gland chromosomes of the distorter strain revealed a chromosome break and other abnormalities at zone 10C3, the location of a large puff that has been reported to be associated with sex determination in C. pipiens. In the polytene chromosomes, d apparently disrupts normal expansion and contraction of the puff. Zone 10C3 probably is also the breakpoint of the female-determining dyad. Zone 10C3 on the male-determining dyad seems to be resistant to the action of d, whereas zone 10C3 on the female-determining dyad is vulnerable to the destructive action of d. Possibly the break in the female-determining dyad occurs directly at m, the gene locus for “femaleness” in C. pipiens, in which case d may be a mutated form of m.