Genomic structure and sex determination in Curimatidae (Characiformes): a comparative genomic analysis between Cyphocarax modestus and Steindachnerina insculpta

• Grant number: 25/04823-9
• Support Opportunities: Scholarships in Brazil - Master
• Start date: January 01, 2026
• End date: February 28, 2027
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Ricardo Utsunomia
• Grantee: Leticia Masiero Desajacomo
• Host Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil
• Associated research grant: 24/03891-8 - Sex chromosomes evolution in Characoidei fishes, AP.TEM

Abstract

Sex determination (SD) is a fundamental process in organisms, yet it remains to be fully elucidated in certain groups. Fish have become a model organism of interest for investigating sex determination mechanisms because of their high diversity, ranging from monofactorial to multifactorial systems. While sex determination is often genetically determined, there exist systems that cannot be detected through cytogenetics, due to the absence of heteromorphic chromosomes. Consequently, genomic tools for identifying sex-linked loci emerge as a compelling alternative for studying these groups that still lack information on sex determination, as evidenced by the Curimatidae family. Despite the chromosomal conservation and stability present in the family, the genomic structure can undergo variations, as well as other variability already observed in the nucleolar organizer regions and heterochromatin, indicating processes of evolution and diversification that are occurring in this family. In spite of its biological importance and the resulting interest in further study, there are still crucial questions in this field that require answers. These include the following: i) Given the cytogenetic stability present in the family, are the mechanisms of sex determination the same for different genera? ii) Is there a sex-determining locus or distinct loci in this family? iii) Is the genomic structure of the species in this family conserved? In light of these considerations, the present project has been initiated with the objective of investigating these questions in the species Cyphocharax modestus and Steindachnerina insculpta, both of which belong to the Curimatidae family but are classified into different clades, employing comparative genomics methods and tools to elucidate the process of sex determination in the group and to facilitate a more comprehensive understanding of the evolutionary aspects that integrate them. (AU)