Molecular characterization of different preproGnRHs in Astyanax altiparanae (Characiformes): Effects of GnRH on female reproduction

Abstract

Gonadotropin‐releasing hormone (GnRH) is a key molecule in the initiation of the hypothalamic–pituitary–gonadal axis. Thus, knowledge about GnRH may contribute to the effectiveness of species reproduction. Using a Neotropical tetra Astyanax altiparanae as a fish model species, the GnRH forms were characterized at the molecular level and the role of injected GnRHs in vivo was evaluated. The full‐length complementary DNA (cDNA) sequences of preproGnRH2 (612 bp) and preproGnRH3 (407 bp) of A. altiparanae were obtained, and the GnRH1 form was not detected. The cDNA sequences of preproGnRH2 and preproGnRH3 were found to be conserved, but a change in the amino acid at position 8 of the GnRH3 decapeptide of A. altiparanae was observed. All the injected GnRHs stimulated lhβ messenger RNA (mRNA) expression but not fshβ mRNA expression, and only GnRH2 was able to increase maturation‐inducing steroid (MIS) levels and possibly stimulate oocyte release. Furthermore, only GnRH2 was able to start the entire reproductive hormonal cascade and induce spawning.

Enhancer evolution as a driving force for lineage-specific paralog usage in the central nervous system

“…Gnrh1 KO piranha showed dense fibers of GnRH3 in the pituitary (Fig. 2C-1), which should be able to regulate gonadotropin release as in other Characiform species that lost gnrh1 [24] (e.g. all Characidae species examined in the present study), although some technical limitations prevented us from confirming the natural breeding ability of the gnrh1 KO piranha.…”

“…If we can find a species whose hypophysiotropic GnRH neurons co-express both gnrh1 and gnrh3, it should give strong supporting evidence for explaining the mechanism for this seeming switch of paralog usage among different species, e.g., co-expression of gnrh1 and gnrh3 in the hypophysiotropic GnRH neurons in the common ancestor may play a permissive role in each species to lose one of them. Interestingly, we found reports in two characiform species (order Characiformes); in pacu (Piaractus mesopotamicus, family Serrasalmidae) three different forms of GnRH peptides were identified by using HPLC analysis followed by mass spectrometry [23], whereas gnrh1 gene could not be identified in another Characiform family, Characidae species, including Astyanax altiparanae [24] and Mexican tetra, in which gnrh1 is not found in Ensembl genome database (Fig. S1).…”

Aspectos Econômico Da Piscicultura Na Amazônia Brasileira

“…No entanto, Buzollo et al (2018) registraram aumento do consumo diário da dieta, ganho de peso e taxa de crescimento específico, além de favorecimento da hipertrofia muscular, para tambaquis com peso inicial de 6,53 ± 0,43 g sob 29 % de proteína (Tabela 4). Para tambaquis com peso inicial de 36,91 a 37,15g e peso final de 196,41 a 240, 97 g, Vidal et al (1998) concluíram que a relação da eficiência proteica reduziu com aumento da proteína dietética nos níveis testados (18,21,24,27, 30% de proteína na dieta). Segundo os autores, para a faixa de peso estudada, 25,01% de proteína bruta na dieta atenderam à exigência dos tambaquis (Tabela 4).…”

GnRHa implants and temperature modulate Lambari‐do‐rabo‐amarelo, Astyanax altiparanae (Characiformes: Characidae) induced reproduction out of the reproductive season

“…A . altiparanae have been used as a model to study reproductive biology (Abreu et al, 2021; Cassel, Chehade, et al, 2017; Cassel, de Paiva Camargo, et al, 2017; Chehade et al, 2020; Costa et al, 2014; De Paiva Camargo et al, 2017; Gomes et al, 2013; Jesus et al, 2017); however, few studies focused on applying physiological tools to enhance the production of this fish species (Brambila‐Souza et al, 2019).…”