Next Generation Sequencing analysis of Astyanax paranae (Characiformes, Characidae) genomes presenting 0 and 2 B-chromosomes.

Abstract

Very recently the power of next-generation sequencing (NGS) analysis began to be applied to research on supernumerary or B chromosomes of different organisms. However, this technology has not been yet applied to the B chromosomes found in fish species. Results obtained in the Laboratory of Fish Biology and Genetics (IB/UNESP/Botucatu) show that in the population of Astyanax paranae from the Capivara stream, a component of the Tietê River basin, a large metacentric B chromosome can be found, and sites for sequences of 18S rDNA and histone H1 were identified in this particular chromosome by using the FISH technique. It is known that B chromosomes are generally poor in active gene sequences. It is considered, therefore, the possibility that the presence of ribosomal DNA and histone H1sequences 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 its origin is probably due to the formation of an isochromosome. Thus, the present project involves the investigation of the total genomic content of the B chromosome in this species, and the identification of potentially functional regions of single copy genes, repetitive DNA and specific molecular markers through next-generation sequencing, aiming to study its origin, function and evolution when compared with the chromosomes of the A complement. This project can be inserted 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 to better understand the chromosome structure of eukaryotic cells, and in particular, of fish. The bioinformatic analysis will be performed at the Genetics Department of the University of Granada, under the supervision of Dr. Juan Pedro Martinez Camacho. That institute has five researchers with high capacity for genomic assembly analysis.