Effects of Testosterone on Sequence Complexity of Polyadenylated RNA from Rat Seminal Vesicle

Abstract

The sequence complexity of mRNA from seminal vesicles has been examined in rats of different androgen status. Total cellular poly(A)-rich RNA was isolated from normal rats, rats castrated seven days previously and castrated rats induced with testosterone in vivo for three days. Radioactive DNA complementary to each RNA preparation was synthesised with reverse transcriptase from avian myeloblastosis virus and then hybridised to its own RNA in vast RNA excess. Computer analysis of the results suggests that in each case the data are best explained by assuming the RNA to be composed of three classes distinguished by their relative abundance. In normal and induced rats, approximately 40 % of the mRNA is accounted for by about one species represented up to 240000 times per cell. Castration has little effect on the proportion of total mRNA occupied by the highly abundant mRNA but greatly decreases the cellular concentration (3 1 100 copies per cell). In normal rats the remainder of the mRNA of the seminal vesicle comprises about 17 middle abundant sequences (15800 copies per cell) and at least 6000 scarce sequences (10 copies per cell). Heterologous hybridisations are virtually indistinguishable over their entire rot range. This suggests that androgen manipulation has little effect on the total sequence complexity of seminal vesicle mRNA and is accompanied by no gross differences in the relative abundance of the majority of mRNA species. In this respect, testosterone action in the seminal vesicle differs substantially from those of other steroid hormones in other steroid-responsive systems and even from that of testosterone itself in another accessory sexual tissue of the male rat, the ventral prostate.