Comparative studies of cytochrome c oxidase activity and mutability in two strains of Drosophila.

Abstract

OMPARATIVE studies of spontaneous and X-ray-induced mutation rates for a number of strains of Drosophila melanogaster show strain differences (DEMEREC 1937; DEMEREC, KAUFMANN and HOOVER 1938). The more recent investigations by STRBMNBS (1959) on the Oslo and Iso-Amherst strains of this species demonstrate strain differences in the mutation patterns as determined by sequential broods for dominant lethals, sex-linked recessive mutations and 2-3 translocations. STRBMNB also compared the differences in rate of induction of mutations in sperm of young males with sperm of older males. The differences in mutation rates and patterns of sensitivity were correlated with the developmental rates of the two strains. Since the purpose of our investigation is the delineation of genetically determined physiological differences that are related to spontaneous and induced mutability, these strains were ideal material for the study. The experiments of KING, SCHNEIDERMAN and SAX (1952) show an increase in the induced mutation rate when Tradescantia is irradiated in the presence of carbon monoxide. HAAS, DUDGEON, CLAYTON and STONE (1954) demonstrated the effect of carbon monoxide on the induction of mutations by irradiation in Drosophila. STONE (1956) and DEBUSK, using the poky strain of Neurospora which lacks cytochrome oxidase and uses the alternate terminal oxidase, reported the comparative effects of carbon monoxide during irradiation of poky and the normal strain. These experiments indicate that the cytochrome oxidase system plays a role in protection against the mutagenic effects of irradiation. For this reason we chose to do a comparative study of cytochrome c oxidase levels throughout the life cycles of strains exhibiting different mutation rates.