Dosage compensation of genes on the left and right arms of the X chromosome of Drosophila pseudoobscura and Drosophila willistoni

Abstract

The authors investigated the occurrence of dosage compensation in D. willistoni and D. pseudoobscura, two species whose X chromosome is metacentric with one arm homologous to the X and the other homologous to the left arm of chromosome 3 of D. melanogaster. Crude extracts were assayed for isocitrate dehydrogenase (XR), glucose 6 phosphate dehydrogenase (XL?), 6 phosphogluconate dehydrogenase (XL?), and α glycerophosphate dehydrogenase (chromosome 2) in D. willistoni, and for esterase 5 (XR), glucose 6 phosphate dehydrogenase (XL?), 6 phosphogluconate dehydrogenase (XL?) and amylase (chromosome 3) in D. pseudoobscura. Results obtained indicate that a mechanism for dosage compensation is operative in both arms of the X chromosome of these two species.