Low Temperature Spectra of the Cytochromes of Drosophila melanogaster

From the ¹ From the Department of Biology, State University of New York, Buffalo, New York 14214

Low temperature spectra of the cytochromes of Drosophila melanogaster were conducted on intact mitochondria isolated from whole larvae and on 0.85 % NaCl-washed particles obtained from these mitochondria. Sarcosomes of adult flight muscle were also studied. The strains of Drosophila used included Canton S wild type and three members of the Minute series of mutants, i.e. M(2)z, M(2)1, and M(2)1², and their control.

The cytochrome spectra of all strains revealed the presence of cytochromes a + a₃, b, and c. Although cytochrome c₁, as defined in mammalian systems, was absent from these preparations, two cytochromes with absorption maxima at 551 and 555 mµ, corresponding to those found in housefly sarcosomes, are described. It is postulated that the 551 and 555 mµ components are located between cytochromes b and c of the electron transport chain, the 551 mµ component in a position analogous to cytochrome c₁ of mammals and the 555 mµ component on a bifurcation of the main pathway.

No qualitative differences were present among the spectra of the mutants, their controls, or homozygous wild type, implying that at least the heme portions of the cytochromes are normal in these mutants. In addition, no differences between larval mitochondria and adult flight muscle sarcosomes were found, indicating that the electron transport chain is qualitatively similar in both stages of the life cycle.

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