Structure and origin of the B chromosomes of curimbatá Prochilodus lineatus (Teleostei, Characiformes)

• Grant number: 21/12722-7
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2022
• End date: July 31, 2024
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Fábio Porto-Foresti
• Grantee: Fábio Porto-Foresti
• Host Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil
• Associated researchers: Diogo Teruo Hashimoto ; Fausto Foresti ; Ricardo Utsunomia

Abstract

B or supernumerary chromosomes are extra elements to the A chromosomes complement and can be found in a wide diversity of organisms. These elements are not essential to the life cycle of organisms and are known as parasite chromosomes, once they do not benefit their hosts, but uses their cellular machinery for replication. These chromosomes were described in the fish species Prochilodus lineatus more than 35 years ago and recent analyses evidenced the occurrence of, at least, 3 distinct variants. However, their repetitive content is very similar and suggest a common origin of these supernumerary elements, with subsequent diversification. Despite being one of the main model organisms for B chromosomes studies, nothing is known about its gene content, which could reveal indications about its evolutionary history and origin, as well as helping to understand how these elements were fixed in the ancestral populations, since, currently, it is known that the gene content of these chromosomes may represent one of the causes of their fixation. In this sense, the present project aims to fully characterize the B chromosomes of Prochilodus lineatus through the generation of a chromosome-level genome of an individual bearing the 3 described variants, as well as testing the hypothesis of common origin of these chromosomes in other congeneric species. We believe that the assembly of B chromosomes will address important questions about the origin and evolution of these elements, as well as serve as a basis for future genomic and functional studies that will allow a more complete understanding of the biology of these enigmatic elements. (AU)