TRANSCRIPTION OF REPETITIVE DNA-SEQUENCES IN THE LAMPBRUSH LOOP PAIR NOOSES FORMED BY STERILE ALLELES OF FERTILITY GENE-Q ON THE Y-CHROMOSOME OF DROSOPHILA-HYDEI

The Y chromosomal lampbrush loop-forming male fertility genes of Droso phila consist mainly of repetitive DNA sequences that do not code for proteins. We investigated whether differences in the transcription of these sequences can be detected in male-sterile alleles of male fertil ity gene Q, which forms the loop pair Nooses. The loop consists, for a pproximately two-thirds, of repeats of the Y-specific ayl family of re petitive DNA sequences. Of the remaining one-third, at least one-half is represented by defective retrotransposons of the gypsy family. Both sequence types are interspersed throughout the loop. Using both ayl a nd gypsy sequences as probes for transcript in situ hybridization, we show that, at the level of the light microscope, transcription of neit her sequence is detectably affected in the loops formed by a male-ster ile allele of gene Q. We conclude that the transcription of ayl and gy psy is required, but not sufficient for the function of gene Q.