| Abstract: | Analysis of cDNA clones synthesized from vitellogenin mRNA of X. tropicalis revealed three different types of cDNA clones, i.e. A, A* and B. A and A* clones have a sequence divergence of about 6% and are both related to X. laevis vitellogenin cDNAs of subgroup A1 as well as A2 with a sequence divergence of 6-9%. B clones however, are related to X. laevis cDNA clones of subgroup B1 and B2 with a sequence divergence of about 7%. While the A and B clones correspond to vitellogenin mRNAs of similar abundance, A* clone is complementary to a vitellogenin mRNA about 100 fold less abundant than A and B mRNAs although all three vitellogenin mRNAs are encoded by single copy genes. Furthermore, two forms of A* mRNA were found. One of the two is lacking an internal fragment of about 900 bp. Since this DNA fragment is highly repeated in the genome, we suggest that this A* clone was synthesized from a processing intermediate of the A* precursor vitellogenin mRNA. |
