Abstract
Reproduction in teleost fish is regulated by the hypothalamus-pituitary-gonads axis (HPG). Under regulation of GnRH, the pituitary gland secrets two gonadotropins: follicle-estimulating (FSH) and luteinising hormones (LH), heterodimers formed by a common alpha subunit, and a beta subunit, which confers specific biological functions. The gonadotropins modulate the production of sex steroids in the gonads, which in turn, act in the maintenance and regulation of the whole reproductive process. The information available about the hormonal regulation of reproduction in the South American teleost exercised by different levels of the HPG are scarce, although they showed the greatest diversity of species on Earth and a range of reproductive strategies. In this project, we propose to investigate the hormonal aspects that regulate the reproductive axis in Astyanax altiparanae Garutti e Britski, 2000, a Characiform endemic species of the Paraná river basin, which shows ecological, economic and academic relevance. Specifically, we aimed to (1) carry out the molecular cloning and phylogenetic analysis of the genes encoding bFSH and bLH from A. altiparanae, (2) analyse the expression profile of these genes using Real-Time qPCR during ontogeny and during the annual reproductive cycle in captivity, (3) its possible expression in other organs beyond the pituitary gland and (4) quantify by ELISA the levels of the sexual steroids during the reproductive cycle, in order to correlate the levels of these hormones with the process of gonadal differentiation and the different stages of the reproductive cycle in males e females of this species. Thus, we intend to elucidate some of the endocrine control of reproduction in this representative Characiform species, and in an indirect way, contribute to the improvement of techniques of induced spawning of native species, a limiting process in fish farming. (AU)
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