Abstract
The number of sequences represented in the polyadenylated RNA population of the
Xenopus oocyte and the degree to which these sequences are specific for early development have been determined by RNA-cDNA hybridization. Approximately 20,000 different sequences are found in the immature oocyte and the mature oocyte, and these sequences are the same in both types of cells. Approximately 5% of these sequences are present at a 15-fold higher concentration than the other 95%. The percentage of nonrepeated nuclear DNA homologous to the polyadenylated RNA was also determined and was in agreement with the number of sequences determined by the cDNA measurement. In addition, the number of sequences present in the
Xenopus laevis kidney tissue culture cell and in the swimming tadpole was measured; approximately 20,000 different sequences were present in both the tissue culture cell and in the tadpole. The majority of the sequences present in the oocyte are not specific for early development since they are shared with both the tissue culture cell and the swimming tadpole; however, some sequences appear to be greatly increased in relative abundance in the tissue culture cell and the tadpole as compared to the oocyte.