Effects of active genes on B chromosomes of Astatotilapia latifasciata and contributions in understanding the interaction between B and sex chromosomes

• Grant number: 18/09127-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2018
• End date: May 31, 2019
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: César Martins
• Grantee: Amanda Alves Caetano Lima da Silva
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 15/16661-1 - Sex and B chromosome enigmas: model systems for the study of chromosome and genome evolution, AP.TEM

Abstract

B chromosomes are additional, but dispensable, elements identified in the karyotype of several eukaryote groups and have unclear effects. These chromosomes can be observed in the species Astatotilapia latifasciata, where they affect the expression of some types of DNA sequences. In some cases, just B chromosomes affect gene expression, while in other situations B chromosomes interact with sex chromosomes to promote this effect. Indeed, B chromosomes seem to have a close relationship with sex chromosomes when they are compared. Since they have anunivalent behavior in meiosis, repetitive DNA enrichment, plus other similar characteristics, which could indicate that they have a common origin and function. In fact, there are evidences that B chromosomes have important effects on female sex determination of several species of cichlid fish. Moreover, some gene copies with high levels of integrity and with function related to hormonal metabolism were found on B chromosomes of A. latifasciata. Taking into account that hormonal levels stand as the main differences between males and females it is possible that these gene copies on this extra chromosome are active and are accentuating the previously observed differences on the gene expression levels. Thus, the present proposal intends to analyze the possible functionality and effects of B-gene copies on the expression of several genes of A. latifasciata. (AU)