Abstract
Poly(A)-containing RNA was isolated from ovaries of
Xenopus laevis laevis
and
Triturus cristatus carnifex
and used as a template for the synthesis of radioactive complementary DNA with RNA-dependent DNA polymerase. When annealed with an excess of homologous DNA, the complementary DNA is rendered double-stranded with kinetics that suggest that the coding sequences are single-copy in both these organisms. In
Triturus
, these sequences are distinct from the majority of the genome, which consists of repeated sequences, and distinct from the ribosomal cistrons, which are present in proportion to the increase in C-value relative to the
Xenopus
genome. Moreover, the number of different poly(A)-containing molecules in the ovary (sequence complexity) is the same in
Xenopus
and in
Triturus
.