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Evolution of the meiotic X-chromosome inactivation in Drosophila

Grant number: 19/10559-1
Support type:Scholarships in Brazil - Master
Effective date (Start): September 01, 2019
Effective date (End): July 31, 2021
Field of knowledge:Biological Sciences - Genetics
Principal Investigator:Maria Dulcetti Vibranovski
Grantee:Henry Angel Bonilla Bruno
Home Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:15/20844-4 - The role of gametogenesis on the origin and evolution of new genes, AP.JP

Abstract

Although there is currently much knowledge about the evolution of sex chromosomes, the meiotic inactivation of the X chromosome (MSCI) in the genus Drosophila is one of the processes in which the origin and evolution are not fully understood and are in constant debate. One of the hypotheses proposed to explain the evolution of MSCI is the sexual antagonism hypothesis (SAXI), according to this, sexual antagonism is the mechanism which generates the redistribution of late spermatogenesis genes on the X chromosome. Thus, the hypothesis predicts that during the evolution of the X chromosome, it is demasculinized (or feminized) and after this process, it is eventually inactivated. Studying X chromosomes in different evolutionary stages is a relevant tool to test one of the predictions of the hypothesis SAXI, being Drosophila miranda an ideal model for this purpose because it has three X chromosomes with different evolutionary ages. Nowadays, the sequencing of the genome of D. miranda has allowed to know about the redistribution of genes in X chromosomes, however, it is not yet known about the activation state of X chromosomes and, therefore, it cannot be accept or discard the hypothesis SAXI as an explanation for the evolution of MSCI. In this way, the present project aims to understand the origin and evolution of the meiotic inactivation process of the X chromosome through the comparative study of the old-X, 2do-X and neo-X chromosomes of D. Miranda, analyzing their states of chromosomal activation through cytological tools that involve the bioinformatic development of Oligopaint probes for the detection of theses X chromosomes by fluorescence in situ hybridization, and finally relating the state of desmasculinization of old-X, 2do-X and neo-X chromosomes to the level of genetic expression during the MSCI. In the broadest sense, the project will contribute to the compression of the evolution of the meiotic inactivation of the X chromosome, a common event in species with sexual determination XY, which has not only been observed in insects but also in mammals and nematodes.