Molecular content, patterns of epigenetic changes and interference of supernumerary chromosomes in Drosophila melanogaster

Abstract

The essential set of chromosomes of individuals form the A complement, which include autosomes and sex chromosomes. However, in several species the presence of extra chromosomes or B chromosomes has been documented. These chromosomes are not an essential part of the genome, but it has already been noticed that their presence can cause changes in cell metabolism, altering the gene expression. The presence of B chromosome was described in the species Drosophila melanogaster six years ago and considering the amount of resources and information that has about this model organism, the B chromosomes may be deeper investigated. Initial studies with this species include general description of part of the composition of the B chromosome and its putative origin. The B chromosome is in most part heterochromatic and it was seen that carriers of this chromosome can be significantly affected by variegation effect, making it clears that the presence of B chromosome can affect the transcription of genetic loci sensitive to heterochromatin increase. In this project, we will advance aspects related to the composition, evolution and functionality of B chromosomes in D. melanogaster. For that, we will use sequenced genomes (0B and + B) to search for repetitive DNAs to be used in chromosome mapping to understand the evolution and composition of chromosome B. The pawns of epigenetic marks of B chromosomes will be studied by analyzes with antibodies against phosphorylation, acetylation, methylation and for RNA polymerase II that will allow the understanding of the functionality of these chromosomes in different tissues. Finally, the possible interference of B chromosomes in spermatogenesis will be tested by RNAseq experiments. These data will allow advances on the biology of B chromosomes in the species which, being a model in genetic studies, could be extrapolated to other organisms.