Evolution of gene dosage on the sex chromosome of schistosome parasites
XY systems usually have chromosome-wide dosage compensation of X-linked genes (such as the mammalian X-inactivation), whereas in many ZW systems, equalization of expression between the sexes is restricted to a minority of dosage-sensitive genes. Why such differences arose is still unclear. Using comparative genomics, transcriptomics and proteomics, we obtained a complete overview of the evolution of gene dosage on the Z-chromosome of Schistosoma parasites. We first detected genes on the Z-chromosomes of African (Schistosoma mansoni and S. haematobium) and Asian (S. japonicum) schistosomes and found many lineage-specific sex-linked genes. We use these to assess gene expression evolution following sex-linkage. The results suggest a reduction in expression of Z-linked genes in females after loss of the W-linked homolog, combined with upregulation of the Z in both sexes, likely representing an intermediate step in the acquisition of a chromosome-wide mechanism of compensation. Quantitative proteomics suggest that post-transcriptional mechanisms do not play a major role in balancing the expression of Z-linked genes.
Institute of Science and Technology Austria (IST Austria)
Domain 2 - UMR 3664 - Nuclear Dynamics