Functional and evolutionary analysis of b chromosomes using the Astyanax paranae fish (Characiformes Characidae) as model

Abstract

Very recently, the power of next-generation sequencing (NGS) began to be applied to research on supernumerary chromosomes (B) of different organisms. However, this technology has not been applied to the B chromosomes in fish. Results of the Laboratory of Fish Biology and Genetics (IB/UNESP/Botucatu) show that a population of Astyanax paranae the Capivara river, Tietê River basin, has a large metacentric B chromosome. From the FISH technique the sequences of 18S rDNA and histone H1 were identified in this chromosome. It is considered, therefore, the possibility of the presence of ribosomal DNA and histone H1 being connected to the origin of the supernumerary chromosomes in this species. The identification of a symmetrical arrangement of these sequences in the arms of the B chromosome reinforces the hypothesis that their origin is due to the formation of an isochromosome. Thus, the aim of this project involves the investigation of the total genomic content of this B chromosome, and the identification of potentially functional regions, single copy genes, repetitive DNA and B-specific molecular markers through next-generation sequencing, aiming to study their origin, function and evolution from the chromosomes of the complement A. This project inserts into the overall program of cytogenetic studies of Neotropical fishes being developed in the Laboratory of Genetics and Biology of Fishes (IB/UNESP/Botucatu), aiming at a better understanding of chromosome structure of eukaryotic cells and in particular fish. (AU)