DOSAGE COMPENSATION IN DROSOPHILA MELANOGASTER TRIPLOIDS. II. GLUCOSE-6-PHOSPHATE DEHYDROGENASE ACTIVITY

[摘要] The level of activity of the enzyme glucose-6-phosphate dehydrogenase was determinel in flies having seven different chromosomic constitutions. All those having an integral number of chromosomes [ XAA, XXAA, XAAA, XXAAA, and XXXAAA (X=X chromosome, A =set of autosomes)] were found to have similar units of enzyme activity/mg live weight, while diploid females with a duplication and triploid females with a deficiency showed dosage effect. The amount of enzyme activity per cell , on the other hand, is also independent of the number of X' s present but appears roughly proportional to the number of sets of autosomes.—It is proposed that dosage-compensated sex-linked genes are controlled by a positively acting regulatory factor(s) of autosomal origin. With this hypothesis it is possible to explain dosage compensation as a consequence of general regulatory mechanisms without invoking a special device which applies only to the X chromosomes.

[学科分类] 医学（综合）