Sex determination is a crucial process in developmental biology. Its accurate regulation is a prerequisite for reproductive success and, therefore, the continued survival of a species. Since reproduction is also the function that determines the categorization of specific populations in the same or different species, the analysis of the specific molecular patterns that this process may follow is crucial for the comprehension of the detailed biochemical background mediating and maintaining the phenotypical variety observed at a macroscopical level. This is also useful for the explanation of the mechanism of infertility, since in many cases the disorder is caused by a genetic default.
Contemplating the above mechanisms as a whole, it is clear that they exhibit many differences (e.g. environmental contribution, number of genes involved, known primary sex-determinant or simultaneous action of different genes), but intriguing similarities as well. Among the latter one may briefly point at: a) the central role of aromatase regulation for female vertebrates. This similarity could also be generalized to include all sex steroids and their regulators, such as SF1. One should not fail to detect the homology of SF1 encoding gene, FtzF1 to Drosophila's fushi tarazu, which has not yet been adequately explained in terms of either evolutionary origin or gene function.
b) the action of sox family proteins in all mammals and some other vertebrates, such as fish. This category includes the primary sex determinant of all mammals, namely SRY, which might justify its proposed evolutionary history from an original autosome homologue, namely sox3.
c) the conservation of genes bearing a DM or LIM domain. This is a relatively new finding, but the fact that these products spread from dipterans and nematodes to humans must imply some degree of coherence in their regulatory mechanisms.
Whether to establish inter-relating patterns of evolution or simply for the sake of the knowledge that can be gleaned from understanding these vastly diffident mechanisms, these differences and similarities will definitely continue to hold the interest of the scientific community for years to come.
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