Localization of tRNA genes of Drosophila melanogaster by in situ hybridization.

Six purified tRNAs labeled with 125I by chemical or enzymatic methods were hybridized to polytene chromosomes of Drosophila melanogaster. The main chromosomal regions of hybridization wer: tRNAGly(GGA), 58A, 84C, and 90E; tRNALeu(2), 44E, 66B5-8, and 79F; tRNASer(2b), 86A, 88A9-12, and 94A6-8; tRNAThr(3), 47F and 87B; tRNAThr(4), 93A1-2; and tRNATyr(1 gamma), 19F, 22F-23A, 41, 50C1-4 and 85A. At 50C the hybridization of tRNATyr(1 gamma) was polymorphic in the giant strains. When the hybridization of three valine isoacceptors studied previously was re-investigated, it was found that only one hybridization site, 90BC, was shared between tRNAVal(3b) and tRNAVal(4). tRNAVal(3a) did not have any sites in common with the other two.