Growth and cytochrome c oxidase activity in larval stages of the minute (2) l 2 mutant of Drosophila

Total soluble protein present in 48-, 60-and 72-hour larval stages of Drosophik melanogaster was determined for controls and for heterozygotes of the following Minute mutants: M(2)1, M(2)173, M(2)z, M(2)S-10, M(3)w, M(3)124, M(3)B2, M(3)y and M ( 3 ) l . Cytochrome c oxidase activity was also assayed at these stages of development in mitochondria isolated from whole larvae of each genotype.The results indicate that all of these mutants possess a common retardation in the rate of growth throughout the larval period. The different Minutes, however, each had distinctive growth patterns, often characterized by particular lags occurring at specific stages. The concentration of cytochrome c oxidase was not necessarily lowered in conjunction with periods of especially retarded growth, but instead, activity higher than that of the control was frequently found. Only one mutant of those tested, M(2)z, showed a significantly lower concentration of this enzyme.

Growth and cytochrome c oxidase activity in minute mutants of Drosophila

Farnsworth

1965

Oxidative phosphorylation in the minute mutants of Drosophila

1965

Oxidative phosphorylation was studied in mitochondria isolated from whole 72-hour larvae heterozygous for nine different Minute mutants with loci on the second and third chromosomes, i.e: M(2)12, M(2)1, M(2)173, M(2)z, M(3)w, M(3)124, M(3)B2, M(3)y and M ( 3 ) l .In all Minutes, oxidative phosphorylation was found to be abnormal in that phosphorylation was uncoupled from oxygen uptake to a greater extent as compared to controls. Differences with respect to respiration and/or phosphorylation were also evident between the Minutes themselves. The results strengthen the hypothesis that lesions in oxidative phosphorylation are associated with the Minute phenotype and demonstrate genetic control over this basic cellular process. In addition, if it is assumed that the Minutes are heterochromatic, as believed by many investigators, then the present study indicates a physiological function for heterochromatin.

Studies on the terminal respiratory system in the minute(2)z mutant of Drosophila melanogaster

Goldin

1968

Individual sites of ATP synthesis were studied in the Minute(2)z mutant of Drosophzla me2anogaster by supplying appropriate substrates to isolated mitochondria and determining the ratio of phosphorus esterifield to oxygen consumed at each locus. In this manner it was determined that the terminal locus of phosphorylation in the Minute is comparable to control, but the first two sites of ATP synthesis and possibly the substrate level phosphorylation are aberrant.The significance of these data and their relation to the Minute effect are discussed.