Diversity of sequences of polyadenylated cytoplasmic RNA from rainbow trout (Salmo gairdnerii) testis and liver

We have compared the sequence complexity and diversity of polyadenylated cytoplasmic RNA derived from two differentiated trout tissues: liver and testis. The kinetics of hybridization of polyadenylated RNA from each of these tissues with complementary DNA synthesized by reverse transcriptase revealed three abundance classes for liver RNA, the first comprising 4 sequences, the second 120, and the third, 20 000; in contrast, testis RNA showed only two abundance classes containing 6 and 6100 different RNA sequences, respectively and of average length 6 x 10(5) daltons. The extent of overlapping among those two RNA populations was further studied by performing heterologous annealing reactions between cDNA and a vast excess of mRNA. Liver mRNA was complementary to 80% of the testis cDNA. Conversely, testis mRNA reacted with only 25% of the liver cDNA. Experiments with fractionated cDNA probes indicated that the unshared sequences belonged mainly to the less frequent, most complex, class of mRNAs.