Molecular and hormonal mechanisms underlying oocyte maturation and ovulation and its application to seed production in the lambari (Astyanax altiparanae)

• Grant number: 22/16230-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: May 01, 2023
• End date: October 31, 2026
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Sergio Ricardo Batlouni
• Grantee: Mariana Roza de Abreu
• Host Institution: Centro de Aquicultura (CAUNESP). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The consecutive decrease in the last five years of ~5% per year in aquaculture production of native tropical species (~30% of national aquaculture production) is associated, despite other reasons, with the unpredictability of the success of seed production. Lambari (Astyanax altiparanae) is an excellent Neotropical model for this topic because it is small and has a short production cycle, in addition to being on the rise and expansion of the market, mainly for live bait. Our aim is therefore to investigate and fill a historical gap about the molecular and hormonal mechanisms that control final maturation and ovulation with a focus on inducing hormone receptors. We also aimed to study the space-time expression of LH, progesterone, and prostaglandin receptors; and based on that, adjust and propose an even more efficient hormonal induction protocol for this and other migratory species. For this, consecutive experiments will be conducted with protocols adjusted for the species and recently published (Roza de Abreu et al., 2021 and 2022), now adding crude lambari pituitary extract for hormone induction (patent filed by us in 2021: BR10202101833). In these experiments, with different protocols, collections will be carried out at different times for blood collection for analysis of plasma hormone profile; gonads, for RT-qPCR, histology, immunohistochemistry and in situ hybridization (RNAscope); and pituitary, for analysis of lhb gene expression. We intend to advance in the understanding of the reasons for failures in spawning, now also launching a new perspective on the receptors of injected hormones.