Investigating the presence of heteromorphic sex chromosomes in Psalidodon paranae (Characiformes, Characidae): a revisitation after the genomics era

• Grant number: 24/04969-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2024
• End date: May 31, 2025
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Ricardo Utsunomia
• Grantee: Mariana Canova de Oliveira
• Host Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil

Abstract

B chromosomes are supernumerary genomic elements found in eukaryotes, whose biology remains poorly understood. Previous studies have hinted at an association between these chromosomes and the sex of individuals in Psalidodon paranae, a fish species commonly known as "lambari," showing a significant difference in B chromosome frequency between sexes. Preliminary genomic analyses in this species have revealed a highly differentiated XX/XY sex determination system, unprecedented at the cytogenetic level, possibly due to the association between B chromosomes and sex. Using classical and molecular cytogenetic methods, our study aims to confirm the presence of a differentiated sex chromosome system in P. paranae, potentially the first description of an XX/XY system in Characidae fishes. Analysis will focus on a specific population collected in Botucatu, São Paulo, Brazil, characterized by metacentric B chromosomes. This investigation seeks to elucidate whether B chromosomes influence sexual differentiation and their association with the sexual ratio in the population, providing insights into their function and contributing to the understanding of sexual determination evolution and genomic variability in this Neotropical fish species.