title: Characterization of genes encoding prolactin and prolactin receptors in starry flounder Platichthys stellatus and their expression upon acclimation to freshwater.
abstract: This study aims to investigate the genes encoding prolactin (PRL) and prolactin receptors (PRLR) and their tissue-specific expression in starry flounder Platichthys stellatus. Starry flounder PRL gene consisting of five exons encodes an ORF of 212 amino acid residue comprised of a putative signal peptide of 24 amino acids and a mature protein of 188 amino acids. It showed amino acid identities of 73 % with tuna Thunnus thynnus, 71 % with black porgy Acanthopagrus schlegelii, 69 % with Nile tilapia Oreochromis niloticus, 64 % with pufferfish Takifugu rubripes, 63 % with rainbow trout Oncorhynchus mykiss, and 60 % with mangrove rivulus Kryptolebias marmoratus. Phylogenetic analysis of piscine PRLs also demonstrated a similarity between starry flounder and other teleosts but with a broad distinction from non-teleost PRLs. PRLR gene consists of eight exons encoding a protein of 528 amino acid residues. It showed a similarity to the PRLR2 subtype as reflected by amino acid identities of 54 % with A. schlegelii, 48.1 % with K. marmoratus, 46.3 % with tilapia O. mossambicus, and 46.1 % with O. niloticus PRLR2 as compared to PRLR1 isoform having less than 30 % identities. While mRNA transcript corresponding to PRL was detected only from the pituitary, most of PRLR mRNA was detected in the gill, kidney, and intestine, with a small amount in the ovary. The level of PRL transcript progressively increased during 6 days of acclimation to freshwater and then decreased but stayed higher than that of seawater at 60 days of acclimation. An opposite pattern of changes including a decrease at the beginning of the acclimation but a slight increase in the level osmolality was found as adaptation continued. The results support the osmoregulatory role of PRL signaling in starry flounder.
authors: Department of Fishery Biology, Pukyong National University, Busan 608-737, Republic of Korea.
authors: Gyeong Eon
authors: GE
authors: Noh
authors: Han Kyu
authors: HK
authors: Lim
authors: Jong-Myoung
authors: JM
authors: Kim
mesh_terms: D000064:Acclimatization / Q000235:genetics / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D005432:Flounder / Q000235:genetics*; D005618:Fresh Water; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology*; D005880:Gills / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D010902:Pituitary Gland / Q000378:metabolism; D011388:Prolactin / Q000235:genetics* / Q000378:metabolism; D011981:Receptors, Prolactin / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D017422:Sequence Analysis, DNA / Q000662:veterinary; D017385:Sequence Homology; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D011981:Receptors, Prolactin; D011388:Prolactin