Satellite DNAs and the differentiation of sex chromosomes in vertebrates. Part II. The nascent XX/XY sex chromosome system of Hoplias malabaricus (Characiformes, Erythrinidae) as a model

Abstract

Fish offer excellent conditions for analyzing the evolution of sex chromosomes, providing important subsidies for understanding this process among vertebrates as a whole. In particular, Erythrinidae fishes exhibit a broad spectrum of sex chromosome system mechanisms, ranging from nascent to highly differentiated, as well as single and multiple sex chromosome systems. Such variability in sex chromosome morphology and composition not only exists within closely related species but often within populations of the same species, as is the case with the species Hoplias malabaricus. In this species, distinct nascent and highly differentiated sex chromosome systems occur among different karyomorphs. This project aims to analyze the differentiation of the nascent XX/XY sex system present in the karyomorph F of Hoplias malabaricus. The isolation and characterization of the satellite DNA library (satellitome) of males and females will be carried out. Comparative analyzes of the chromosomal distribution pattern of these satDNAs between males and females will allow us to investigate the processes of chromosomal differentiation occurring in the initial stages of differentiation of the nascent Y chromosome (Molecular cytogenetic analysis). Additionally, satDNA families differentially distributed among sex chromosomes will be selected to investigate the homogenization and recombination rate of different haplotypes (genomic analysis). At the same time, the project will facilitate the integration of a network of national and international researchers, equally interested in the subject to be investigated, making its execution feasible and the obtaining of promising results for cytogenetics and evolutionary genetics.