Characterizing Molecular Markers of Gonadal Maturation in Trout Using Germ Cell Transplantation and Genetic Manipulation Techniques

• Grant number: 24/22586-1
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Inland Water Fishery Resources
• Principal Investigator: Rafael Henrique Nóbrega
• Grantee: Amanda Rodrigues Tanamachi
• Supervisor: Goro Yoshizaki
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Institution abroad: Tokyo University of Marine Science and Technology (TUMSAT), Japan
• Associated to the scholarship: 24/09600-5 - Validation and Morphofunctional Characterization of Genes Involved in Spermatogonial Differentiation and Sexual Maturation in Zebrafish (Danio rerio), BP.PD

Abstract

Considering that early or delayed maturation may impact aquaculture species' production, it is essential to understand how spermatogonial stem cell (SSC) activity is regulated in order to manage fish puberty onset. Endocrine and paracrine signals are essential in the SSC niche affecting the delicate balance between SSC self-renewal and differentiation. On the other hand, molecular processes that regulate the transition from undifferentiated into differentiating state remain poorly investigated among the fish species. Understanding the regulation of SSCactivity and transitions is essential for addressing key reproductive challenges in aquaculture, such as early puberty and the optimization of broodstock management. This study aims to uncover conserved and species-specific molecular markers and pathways involved in SSC self-renewal and differentiation by integrating single-cell RNA sequencing (scRNAseq) data from zebrafish (Danio rerio) and rainbow trout (Oncorhynchus mykiss). Through differential expression and pathway enrichment analyses, candidate genes and pathways will be explored. RNAscope in situ hybridization will validate the spatial expression of these markers in trout testes, while functional assays involving chemical inhibitors and cultured SSCs will elucidate their roles in self-renewal and differentiation. Finally, the significance of these treatments will be also evaluated in vivo through germ cell transplantation. This approach will confirm the capacity of identified markers and pathways to regulate SSC activity and contribute to spermatogenesis. The findings of this project will enhance our understanding of the molecular regulation of SSCs and provide tools for managing puberty and gonadal maturation in aquaculture species with extended reproductive cycles