Nucleotide sequencing of a putatitve vasotocin cDNA from the frog, Xenopus laevis

Previously, Conway and Gainer (1987) postulated inversion of the third exons of vasotocin (AVT) and mesotocin (MT) genes in a frog, Xenopus laevis. Thus, sequencing analysis of a putative Xenopus AVT cDNA was conducted (clone J1). This clone had been previously obtained by screening a cDNA library with a synthetic probe based on published sequence data from a toad, Bufo japonicus. Screening and sequencing of the target cDNA was also repeated at much higher stringency. Also, amplification of the target DNA by polymerase chain reaction (PCR) was conducted. Clone J1 and one of the additional clones obtained were highly homologous to Xenopus 28S rRNA and to a Xenopus alpha-tubulin gene, respectively. Four other clones obtained had no apparent sequence homology to Bufo AVT or MT. Moreover, no specifically amplified fragments were obtained by the PCR study. This suggests that there might be significant variability in the AVT genes between Xenopus and Bufo species.