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Molecular Evolution of Genes Involved in Vertebrate Sex Determination

  1. Michihiko Ito,
  2. Shuuji Mawaribuchi

Published Online: 20 SEP 2013

DOI: 10.1002/9780470015902.a0024948

eLS

eLS

How to Cite

Ito, M. and Mawaribuchi, S. 2013. Molecular Evolution of Genes Involved in Vertebrate Sex Determination. eLS. .

Author Information

  1. Department of Biosciences, Kitasato University, Sagamihara, Japan

Publication History

  1. Published Online: 20 SEP 2013

Abstract

Four sex-determining genes (SDGs) had been reported in vertebrates until 2011: Y-linked Sry in eutherian mammals, Z-linked Dmrt1 in the chicken, W-linked Dm-W in the African clawed frog Xenopus laevis and Y-linked Dmy (also called as dmrt1bY) in the teleost fish medaka. These genes encode deoxyribonucleic acid (DNA)-binding proteins. Both Dm-W and Dmy emerged through duplication of Dmrt1, whereas Sry evolved from allelic Sox3. Interestingly, in 2012, four different types of SDGs, which might not encode DNA-binding proteins, were reported in teleost fish: Patagonian pejerrey amhy, Oryzias luzonensis GsdfY, Takifugu rubripes Amhr2, and rainbow trout sdY. Although these SDGs are all sex chromosome-linked, a variety of them may be involved in the evolution of sex chromosomes. A coevolution model of SDGs and sex chromosomes has been proposed: undifferentiated or specialised sex chromosomes could allow diversity of SDGs or tend to fix a certain SDG, respectively, during species diversity in vertebrates.

Key Concepts:

  • There are a variety of SDGs including transcription factor genes and TGF-β signal-related genes.

  • SDGs could be classified into two types: insertion and mutations after duplication, and mutations of an allelic gene.

  • SDGs Dmy/Dm-W and Sry, which evolved through duplication of Dmrt1 and an allelic mutation of Sox3, respectively, have a higher substitution rate than their prototype genes.

  • Cis-regulatory elements in most of the SDGs should have evolved for their mRNA expressions at a sex-determining stage, but only an amino acid change by SNP between Amhr2 alleles could determine the sex in fugu fish.

  • SDGs and sex chromosomes would have coevolved during vertebrate evolution: undifferentiated or specialised sex chromosomes could allow diversity of SDGs or tend to fix a certain sex-determining gene, respectively.

Keywords:

  • sex;
  • sex determination;
  • sex chromosome;
  • coevolution;
  • neofunctionalisation;
  • Dmrt1;
  • Sry;
  • TGF-β;
  • duplication;
  • molecular evolution