Molecular evolution of Sry and Sox gene

Area of Science:

• Genetics
• Evolutionary Biology
• Molecular Biology

Background:

• The mammalian sex-determining gene Sry, located on the Y chromosome, encodes a high-mobility group (HMG) box protein.
• Sox genes share sequence similarity with Sry, but their functional relationship, particularly in sex determination, remains largely unclear.
• Understanding the evolutionary and functional links between Sry and Sox genes is vital for comprehending primary sex determination.

Purpose of the Study:

• To clarify the ancestry and molecular evolution of the mammalian Sry gene.
• To investigate the evolutionary relationships between Sry and the broader Sox gene family.
• To deepen the understanding of primary sex determination mechanisms.

Main Methods:

• Construction and analysis of a molecular phylogenetic tree for the HMG box superfamily.
• Comparative sequence analysis of Sry and Sox genes across different mammalian groups.

Main Results:

• Nuclear non-histone HMG proteins are ancient, predating animal-plant divergence, with subsequent diversification into various subgroups.
• Sox and Sry genes diverged after lymphoid transcription factors, with Sry likely evolving from the Sox gene cluster hundreds of millions of years ago.
• Marsupial Sry genes are distinct from eutherian Sry and closely related to Sox genes, while mammalian Sry exhibits significantly higher evolutionary rates than Sox genes.

Conclusions:

• The Sry gene evolved from the Sox gene cluster, with marsupial Sry showing a closer relationship to Sox than eutherian Sry.
• The rapid molecular evolutionary rate of Sry is potentially influenced by its non-recombining location on the Y chromosome's short arm.
• Further research into Sry and Sox gene evolution will enhance our understanding of primary sex determination.