科学研究

Seminars

Spermatogenesis role on the evolution of new genes

2019-08-30

SPEAKER

Maria D. Vibranovski, Ph.D


Assistant Professor

Department of Genetics and Evolutionary Biology

University of São Paulo


Seminar Type

B-type


Preferred Location

Third Floor Lecture Hall, Jianzan Building (Phase I)

Chinese Institute for Brain Research, Beijing


Time

10:00-11:00  Friday,August 23th, 2019 


Host

Dr. Li Zhang


Topic

Spermatogenesis role on the evolution of new genes


Abstract

New genes can quickly assume critical roles in developmental pathways by producing essential structures. Several studies have pointed their important role in the formation of different novel traits related to sexual selection and cognitive behavior, among others. In different groups of species, new genes are majorly expressed in testis, more specifically in later phases of male gametogenesis. Our group study the role and impact of spermatogenesis - a system of great importance for survival and evolution of species that varies temporally with the development - to understand function and evolution of new genes. More specifically, we have discovered that their enhanced expression in testis is a consequence of haploid selection during the latter stages of male gametogenesis. Because emerging adaptive mutations will be fixed faster if their phenotypes are expressed by haploid rather than diploid genotypes, new genes with advantageous functions arising during this unique stage of development have a better chance to become fixed. In Drosophila, our group also investigate the impact of Meiotic Sex Chromosome Inactivation (MSCI) on the evolution and origin of new genes. The phenomenon, known as the transcriptional silencing of genes on the X chromosome in the male germline prior to meiosis, has long been hypothesized to occur in Drosophila testes. We have combined cytological data and single-cell expression profile to ask if and when MSCI occurs. In early germ cells, the ratio of sex-linked to autosomal (X:A) gene expression is balanced, and active RNA Polymerase II (Pol II) is present on the X and autosomes. As spermatocytes mature, the X:A ratio decreases and active Pol II is depleted from the X chromosome. Our results not only show that MSCI does occur in Drosophila spermatogenesis, but also elucidate the molecular mechanism responsible for the X chromosome regulation. Together, male germline development has important implications on the origin of new genes revealing their potential role in fertility and fecundity, as new gene meiotic and post-meiotic expression and fitness can be directly related to sperm morphogenesis and motility.


Speaker Biography

Maria D. Vibranovski is an assistant professor of Department of Genetics and Evolutionary Biology at University of São Paulo. She received trainings for genetics for her master’s degree and trainings for biochemistry and molecular biology for her Ph.D. degree in Brazil. Then She worked as a postdoctoral researcher in University of Chicago before she returned University of São Paulo. Maria’s major interest is centered on sexual selection especially the testes-biased expression of new genes. Her studies have elucidated the impact of Meiotic Sex Chromosome Inactivation on the evolution of new genes. More importantly, her recent work shows that haploid selection during the latter stages of spermatogenesis play an important role of new gene evolution. Maris’s research is fundamentally important to understand how sexual selection and sex chromosome work together to fix genetic novelties, which naturally is very closely connected to the creation of functional novelties related to sexual differences.