Title

Rapid Evolution and Sequence Divergence at Tsga8 in Rodents

Presentation Type

Poster

Abstract

A central goal in molecular biology is to understand the contribution of individual genes to organismal form and function. Increasingly, biologists are using evolutionary comparisons of DNA sequences across multiple species to gain general insights into the functional importance of genes. For example, the rapid accumulation of mutations that alter the protein sequence of a gene may indicate that it has been a target of positive natural selection and thus plays an important role in the survival or reproduction of an organism. Testes specific gene a8 (Tsga8) is a gene on the X chromosome in mice that is thought to be involved in chromatin condensation during a crucial stage of sperm development, and thus likely plays an important role in male fertility. It has been previously demonstrated that Tsga8 is one of the most rapidly evolving genes known, varying widely in the length and number of amino acid repeats among a few closely related species of mice. Though Tsga8 was initially only known in mice, a highly divergent form of Tsga8 has now been identified in rats. In this experiment I demonstrate through PCR amplification, sequencing and gene alignment that Tsga8 is also very rapidly evolving across several species of rats. Specifically, I expanded the genetic sampling of this gene to seven additional species of rat. It appears that the rat version of this gene demonstrates similar patterns of divergence, with some exceptions, as found in mice. This suggests that similar forces are driving the rapid evolution of this gene in diverse species of rodents. Though the exact function of Tsga8 awaits further experimentation, my data indicate that this gene has played a recurrent role in the evolution of male reproduction across mice and rats.

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Apr 12th, 3:00 PM Apr 12th, 4:00 PM

Rapid Evolution and Sequence Divergence at Tsga8 in Rodents

UC Ballroom

A central goal in molecular biology is to understand the contribution of individual genes to organismal form and function. Increasingly, biologists are using evolutionary comparisons of DNA sequences across multiple species to gain general insights into the functional importance of genes. For example, the rapid accumulation of mutations that alter the protein sequence of a gene may indicate that it has been a target of positive natural selection and thus plays an important role in the survival or reproduction of an organism. Testes specific gene a8 (Tsga8) is a gene on the X chromosome in mice that is thought to be involved in chromatin condensation during a crucial stage of sperm development, and thus likely plays an important role in male fertility. It has been previously demonstrated that Tsga8 is one of the most rapidly evolving genes known, varying widely in the length and number of amino acid repeats among a few closely related species of mice. Though Tsga8 was initially only known in mice, a highly divergent form of Tsga8 has now been identified in rats. In this experiment I demonstrate through PCR amplification, sequencing and gene alignment that Tsga8 is also very rapidly evolving across several species of rats. Specifically, I expanded the genetic sampling of this gene to seven additional species of rat. It appears that the rat version of this gene demonstrates similar patterns of divergence, with some exceptions, as found in mice. This suggests that similar forces are driving the rapid evolution of this gene in diverse species of rodents. Though the exact function of Tsga8 awaits further experimentation, my data indicate that this gene has played a recurrent role in the evolution of male reproduction across mice and rats.