Characterization of the precursor encoding for GnIH and immunohistochemical location of this peptide in the brain of Odontesthes bonaeriensis (Atheriniformes)

PAHÍ-ROSERO ANA M.; LÓPEZ GABRIELA C.; SOMOZA GUSTAVO M.; MECHALY ALEJANDRO S.; VISSIO PAULA G.; PÉREZ MARÍA R.; ORTÍ GUILLERMO

Manaus

Simposio; 11th International Symposium on Reproductive Physiology of Fish (ISRPF); 2018

INTRODUCTIONGonadotropin-inhibitory hormone (GnIH) is a member of the RFamide neuropeptide family, originally discovered and characterized in birds. It is known that this peptide is involved in the inhibition of gonadotropin release from the pituitary of birds and mammals, however its function in teleosts has not been clearly established. Pejerrey, Odontesthes bonaeriensis, is a native fish from continental waters of the Pampas region of Argentina and has been used as a model for research on reproduction and sex differentiation. In view of the diverse mechanisms involved in the hypothalamic control of pituitary function in fish, and due to the scarce information of GnIH physiology in teleosts, we performed an in silico analysis of the GnIH precursor sequence and its position in a GnIH phylogenetic tree, along with the study of its brain-pituitary distribution.METHODSGnIH putative sequences were sought from the pejerrey genome database, and an in silico analysis of the putative translated protein was blasted. A maximum likelihood tree was obtained based on the Jones-Taylor-Thornton model with the MEGA5 software. The neuroanatomical distribution of immunoreactive GnIH (ir-GnIH) was characterized in sections of adult pejerrey brain and pituitary using an anti-bullfrog GnIH antiserum kindly provided by Dr. K. Tsutsui (Japan).RESULT AND DISCUSSIONA partial sequence of 538 bp of cDNA encoding for the GnIH precursor peptide was identified. The in silico translation of this sequence included three putative RFamide-related peptides: two 12 amino-acids peptides: a MPMRFamide (PLHMHANMPMRF) and a MPQRFamide (VPKSSPNMPQRF) and a 11 amino-acid peptide LPQRFamide (EAPSPVLPQRF). The phylogenetic analysis showed that pejerrey precursor is grouped in the same clade as Cyprinidontiformes and Beloniformes with the higher percentage of identity with cyprinodontiform sequences (78-81%), and only 23% and 27% with lamprey and human sequences, respectively. On the other hand, similar to other fish species, ir-GnIH somata were observed in the olfactory bulbs, the Nucleus Olfacto Retinalis and the Nucleus Posterioris Periventricularis (NPPv) in the preoptic area. Immnuoreactive GnIH fibers were observed in almost all brain areas examined, and also reaching the pituitary gland.CONCLUSIONIn the present study, the GnIH precursor was analyzed and the neuroanatomical distribution of GnIH in pejerrey fish was described. Both analyses showed that these characteristics are fairly conserved in teleosts. This knowledge can enable us to start working on the effects of GnIH in the control of reproduction and other physiological process in pejerrey.