Partial cloning and polymorphism of the melatonin1a (Mel1a) receptor gene in two breeds of goat with different reproductive seasonality

The melatonin(1a) (Mel(1a)) receptor gene was cloned in two breeds of goat, one with marked seasonal ovarian activity (Alpine breed) and the other with low seasonal variations in ovulatory activity (Creole breed), to determine whether reproductive seasonality is related to the structure of the Mel(1a) gene. The main part of exon II was amplified by PCR using sheep sense and antisense primers in 17 Alpine and 13 Creole goats, and cDNAs were subcloned and sequenced in both directions. The results indicate the presence of an identical sequence in 12 of the 30 animals, that is, six Alpine and six Creole goats. The greatest similarity in the 784 nucleotides of exon II (primers excluded) that was obtained was found with ovine Mel(1a) receptor sequence (98.4%) and the differences consisted of 12 nucleotide and four amino acid changes. The presence of seven mutations compared with the previous reference sequence was observed and their combinations indicated the presence of at least five other alleles; one mutation resulted in a change in one amino acid in three Alpine goats. No difference in allelic distribution was observed between the two breeds. The results indicate that no relationship could be established between the Mel(1a) receptor gene structure and the expression of seasonality of reproduction in goats.