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H-Y typing of karyotypically abnormal mice
E Simpson1, P Chandler, L L Washburn
1Clinical Research Centre, England, U.K.
Differentiation; Research in Biological Diversity
|January 1, 1983
Summary
Ohno's hypothesis proposed H-Y antigen triggers testis formation. While some evidence supports this, XY females positive for H-Y antigen challenge the idea, suggesting multiple genes are involved in male sex determination.
Area of Science:
- Genetics
- Developmental Biology
- Immunology
Background:
- Ohno's hypothesis posits the H-Y antigen as the primary trigger for mammalian testis formation.
- The H-Y antigen is a male-specific transplantation antigen encoded by the Y chromosome.
Purpose of the Study:
- To test Ohno's hypothesis regarding the H-Y antigen's role in testis determination.
- To investigate the genetic basis of gonad development in mice with aberrant karyotypes.
Main Methods:
- Analysis of H-Y antigen status in mice with abnormal karyotypes (XX Sxr males, XO females, XY females with YPOS/YORB or Thp mutations, X-Y recombinant mice).
- Comparison of H-Y antigen presence with gonad development (testes or ovaries).
Main Results:
- XX Sxr males and XO females align with Ohno's hypothesis (testes/H-Y positive, ovaries/H-Y negative).
- XY females with specific Y chromosome variants (YPOS, YORB) or Thp mutations were H-Y positive but developed ovaries, contradicting the hypothesis.
- Genetic analysis suggests testis determination involves multiple genes, not solely a Y-linked product.
Conclusions:
- The H-Y antigen is not the sole Y-linked gene responsible for testis determination.
- Normal testis differentiation likely involves the interaction of two or three genes.
- Ohno's hypothesis requires revision to account for complex genetic interactions in sex determination.