Expression of prolactin receptor mRNA in the abdominal gland of the newt Cynops ensicauda

To further the understanding that the structural development of the Cynops ensicauda abdominal gland and the synthesis of the pheromone silefrin in the gland are under the control of prolactin and androgen, we sought to demonstrate the presence of prolactin receptor (PRLR) mRNA in the gland. Firstly, PRLR cDNA was isolated from an abdominal gland cDNA library. A cDNA consisting of a 415-bp 5′-untranslated region, 1878-bp open reading frame and 175-bp 3′-untranslated region was obtained. The deduced amino acid sequence consisted of 626 amino acids with signal peptide and single transmembrane domain. By Northern blot analysis using partial C. ensicauda PRLR cDNA, two transcripts, of 3 and 10 kb, were detected for PRLR in the brain, liver, kidney, abdominal gland, oviduct and skin. RT-PCR coupled with Southern blot analysis showed that the PRLR gene was transcribed broadly in newt organs and revealed that PRLR mRNA levels in the abdominal gland were much higher in sexually developed newts than in the sexually undeveloped ones. By in situ hybridization, specific signals were detected in the epithelial cells of the abdominal gland of sexually developed newts, but much less in those of the sexually undeveloped ones.