Behavior of individual maternal pA+ RNAs during embryogenesis of Xenopus laevis

Of the 10 Xenopus oocyte cDNA clones previously examined in this laboratory (L. Golden, U. Schafer, and M. Rosbash, 1980, Cell22, 835–844), 5 are complementary to RNAs which which decrease in abundance during early development. We have further examined the behavior during embryogenesis of these 5 sets of clone-complementary RNAs. The results indicate that for 3 of these 5 sets of RNAs there is an increase in the per embryo levels of RNA. Thus, 8 of the 10 clones originally examined are complementary to RNAs which increase in amount during early embryogenesis. One of the remaining two clones is complementary to (at least) 4 RNAs which vary somewhat in their levels during embryogenesis. The last clone (XOC 2–7) is complementary to an RNA species which is largely destroyed at late blastula or early gastrula. This RNA is therefore the only maternal sequence, of the ten clones examined, which unambiguously decreases in amount during embryogenesis. The data also show that XOC 2–7 RNA is largely adenylated at oocyte maturation and then deadenylated during subsequent embryogenesis while another clone, XOC 1–2, is largely dead-enylated at oocyte maturation. The results also suggest that a large fraction of oocyte RNAs are present in early embryos (and in liver) and are largely the same size as in oocytes.