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

ANA MARÍA PAHÍ-ROSERO; PEREZ MR; MECHALY A; LOPEZ G; ORTI, C; VISSIO, PG; SOMOZA, GM

Taller; 11th ISRPF INTERNATIONAL SYMPOSIUM ON REPRODUCTIVE PHYSIOLOGY OF FISH. 3; 2018

CHARACTERIZATION OF THE PRECURSOR ENCODING FOR GNIH ANDIMMUNOHISTOCHEMICAL LOCATION OF THIS PEPTIDE IN THE BRAIN OFOdontesthes bonaeriensis (ATHERINIFORMES).Pahí-Rosero Ana M.(1), Pérez María R.(1), Mechaly Alejandro S.(2), López Gabriela C. (1), OrtíGuillermo (3), Vissio Paula G. (4), Somoza Gustavo M. (1)(1) IIB-INTECH (CONICET-UNSAM), Chascomús, Argentina. (2) INIDEP, Mar del Plata, Argentina.(3) The George Washington University, Washington DC, USA. (4) Departamento de Biodiversidad yBiología Experimental (CONICET-UBA), Ciudad Autónoma de Buenos Aires, Argentina. email:anamaria@intech.gov.arIntroductionGonadotropin-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 inthe inhibition of gonadotropin release from the pituitary of birds and mammals, however itsfunction in teleosts has not been clearly established. Pejerrey, Odontesthes bonaeriensis, is anative fish from continental waters of the Pampas region of Argentina and has been used as amodel for research on reproduction and sex differentiation. In view of the diverse mechanismsinvolved in the hypothalamic control of pituitary function in fish, and due to the scarceinformation of GnIH physiology in teleosts, we performed an in silico analysis of the GnIHprecursor sequence and its position in a GnIH phylogenetic tree, along with the study of itsbrain-pituitary distribution.MethodsGnIH putative sequences were sought from the pejerrey genome database, and an in silicoanalysis of the putative translated protein was blasted. A maximum likelihood tree wasobtained based on the Jones-Taylor-Thornton model with the MEGA5 software. Theneuroanatomical distribution of immunoreactive GnIH (ir-GnIH) was characterized insections of adult pejerrey brain and pituitary using an anti-bullfrog GnIH antiserum kindlyprovided by Dr. K. Tsutsui (Japan).Result and DiscussionA partial sequence of 538 bp of cDNA encoding for the GnIH precursor peptide wasidentified. The in silico translation of this sequence included three putative RFamide-relatedpeptides: two 12 amino-acids peptides: a MPMRFamide (PLHMHANMPMRF) and aMPQRFamide (VPKSSPNMPQRF) and a 11 amino-acid peptide LPQRFamide(EAPSPVLPQRF). The phylogenetic analysis showed that pejerrey precursor is grouped inthe same clade as Cyprinidontiformes and Beloniformes with the higher percentage of identitywith cyprinodontiform sequences (78-81%), and only 23% and 27% with lamprey and humansequences, respectively. On the other hand, similar to other fish species, ir-GnIH somata wereobserved in the olfactory bulbs, the Nucleus Olfacto Retinalis and the Nucleus PosteriorisPeriventricularis (NPPv) in the preoptic area. Immnuoreactive GnIH fibers were observed inalmost all brain areas examined, and also reaching the pituitary gland.Conclusion: In the present study, the GnIH precursor was analyzed and the neuroanatomicaldistribution of GnIH in pejerrey fish was described. Both analyses showed that thesecharacteristics are fairly conserved in teleosts. This knowledge can enable us to start workingon the effects of GnIH in the control of reproduction and other physiological process inpejerrey.