The hyperactive X chromosome is not early replicating in mitotically active somatic cells of Drosophila nasuta males.
The temporal order of replication of the X chromosome(s) in mitotically dividing male and female cells in early embryos and in brain ganglia of Drosophila nasuta larvae was examined using [3H]thymidine pulse labelling and autoradiography. Both the X chromosomes in female cells and the single X chromosome in male cells replicated in complete synchrony with the autosome set in the nucleus. Thus, unlike the well-known early completion of replication by the hemizygous X chromosome in polytene nuclei in the salivary glands of male Drosophila larvae, the single X chromosome in mitotically dividing cells does not replicate earlier than the autosomes. We conclude that transcriptional hyperactivity of the single X chromosome required for dosage compensation in somatic cells of male Drosophila is not dependent upon its early replication.
Lakhotia
S C
SC
Department of Zoology, Banaras Hindu University, Varanasi, Republic of India.
Roy
J K
JK
D000818:Animals; D004261:DNA Replication / Q000235:genetics; D004303:Dosage Compensation, Genetic; D004330:Drosophila / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D005260:Female; D008297:Male; D008938:Mitosis / Q000235:genetics; D013936:Thymidine / Q000378:metabolism; D014960:X Chromosome
D013936:Thymidine