Meeting Abstract

P1.40  Wednesday, Jan. 4  Isolation and expression patterns of two V1a-type arginine vasotocin receptor mRNAs in the protogynous bluehead wrasse LEMA, SC*; SALVESEN, KE; SLANE, MA; GODWIN, J; California Polytechnic State University; Pennsylvania State University; North Carolina State University; North Carolina State University slema@calpoly.edu

Arginine vasotocin has been implicated as a key regulator of behavioral and reproductive plasticity in teleost fishes. Several studies have now demonstrated changes in vasotocin circuits in the hypothalamic preoptic area during sex change in fish, but the role of vasotocin receptors in this process remains unknown. Here, we isolated and sequenced two full-length cDNAs encoding V1a-type receptors (V1a1 and V1a2) from the protogynous bluehead wrasse (Thalassoma bifasciatum) using degenerate primer PCR and 5’- and 3’-rapid amplification of cDNA ends (RACE). RT-PCR revealed that the relative abundance of these two receptor transcripts varied among wrasse tissues with V1a1 receptor mRNAs at greatest levels in the telencephalon, hypothalamus, optic tectum, cerebellum and testis, but V1a2-type transcripts most abundant in the hypothalamus, cerebellum and gills. Quantitative real-time RT-PCR further demonstrated that these transcripts varied in relative abundance with sexual phase. Relative levels of the V1a2 transcript were greater in both the whole brain and isolated hypothalamus of terminal phase (TP) male wrasse compared to initial phase (IP) males or females. Meanwhile in the gonads, V1a1 mRNAs were at levels 2.5 fold greater in the testes of IP males – and 4 to 5 fold greater in the testes of TP males – than levels of this same transcript in the ovarian tissues of females. These results provide evidence that vasotocin receptor transcript abundance in the hypothalamus and gonads of bluehead wrasse varies in distinct patterns linked to sexual phase, and bestow a foundation for future studies investigating how expression patterns of these receptor paralogs are influenced by gonadal and social status.