Cross-reaction of snRNA and an Alu I-like sequence from rat with DNAs from different eucaryotic species.

Sequence homologies to rat U1-snRNA and U2-snRNA were investigated in DNA from 23 eucaryotic species (3 lower eucaryotes, 4 plants, and 16 animals) using dot hybridization at various stringency conditions. Cross-hybridization among very distantly related species in e.g. plants-insects or mold-vertebrates is not the rule; there are, however, examples for stronger homologies like Rattus-Dictyostelium. Furthermore, DNA from all 23 species was analysed for sequence homologies with the repetitive DNA sequence B1 (an Alu I family equivalent) from rat. We observed a wide range of homologies covering some plants and insects, up to vertebrates. Hybridization at increasing stringency conditions revealed species with higher degree of homology to the rat B1 sequence: maize, chicken, and hamster.