How do fish spermatogonial cells decide to shift from self-renewal to proliferation/differentiation on the onset of puberty?

• Grant number: 24/15270-8
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: January 25, 2025
• End date: January 24, 2026
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering
• Principal Investigator: Rafael Henrique Nóbrega
• Grantee: Amanda de Oliveira Ribeiro
• Supervisor: Jean-Jacques Lareyre
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Institution abroad: Institut National de la Recherche Agronomique, Rennes (INRA), France
• Associated to the scholarship: 22/10389-1 - New insights on gonadal growth factors of Lambari, Astyanax altiparanae: basic knowledge and development of biotechnological strategies to delay puberty, BP.PD

Abstract

The study of puberty in fish is specially relevant because either the premature or the late onset of the gonadal maturation are significant issues for many cultivated species. At the onset of fish puberty, signaling from the pituitary reaches the developing testis, inducing or inhibiting the expression of many factors in the spermatogonial stem cell niche, regulating the balance between germ stem cell self-renewal and differentiation. Although the modulation of this shift from quiescent undifferentiated spermatogonia to highly proliferative and differentiating spermatogonia has potential to control the initiation of gonadal maturation, information on how each cell population in a complex tissue such as the testis responds to the pubertal signaling cascade is still poorly understood. This knowledge, nevertheless, has a great potential to help delineate molecular-based strategies to control puberty onset, providing cell-specific targets for the implementation of biotechnological applications in aquaculture. Moreover, preliminary results from our group show that genes involved in the establishment of epigenetic marks are overexpressed in a specific spermatogonial population during the onset of spermatogenesis in zebrafish. Based on this background, we propose here to understand the genetic and epigenetic control of the shift between self-renewing and proliferative/differentiating spermatogonial populations during puberty onset in fish, at the single cell-level. To achieve this aim, we have planned to unravel gene expression alterations in different germ cell populations in the zebrafish and rainbow trout using single cell RNA sequencing and 3D spatial transcription analysis (RNAscope), finding i) species-specific and evolutionary conserved gene markers and enriched regulatory pathways for each of these testicular cell populations, ii) possible hidden cell subpopulations in the testis through spermatogenesis, iii) evolution of the expression pattern for genes involved in the remodeling of epigenetic marks, and iiii) evidence of the control of symmetrical vs. asymmetrical divisions in undifferentiated spermatogonia.