article published yes Marwan N Elkrewi author 0B46FACA-A8E1-11E9-9BD3-79D1E56974250000-0002-5328-7231 Mikhail A. Moldovan author c8bb7f32-3315-11ec-b58b-e5950e6c14a00000-0002-8876-6494 Marion A L Picard author 2C921A7A-F248-11E8-B48F-1D18A9856A870000-0002-8101-2518 Beatriz Vicoso author 49E1C5C6-F248-11E8-B48F-1D18A9856A870000-0002-4579-8306 BeVi department Sex chromosome evolution under male- and female- heterogamety project Schistosomes, the human parasites responsible for snail fever, are female-heterogametic. Different parts of their ZW sex chromosomes have stopped recombining in distinct lineages, creating “evolutionary strata” of various ages. Although the Z-chromosome is well characterized at the genomic and molecular level, the W-chromosome has remained largely unstudied from an evolutionary perspective, as only a few W-linked genes have been detected outside of the model species Schistosoma mansoni. Here, we characterize the gene content and evolution of the W-chromosomes of S. mansoni and of the divergent species S. japonicum. We use a combined RNA/DNA k-mer based pipeline to assemble around 100 candidate W-specific transcripts in each of the species. About half of them map to known protein coding genes, the majority homologous to S. mansoni Z-linked genes. We perform an extended analysis of the evolutionary strata present in the two species (including characterizing a previously undetected young stratum in S. japonicum) to infer patterns of sequence and expression evolution of W-linked genes at different time points after recombination was lost. W-linked genes show evidence of degeneration, including high rates of protein evolution and reduced expression. Most are found in young lineage-specific strata, with only a few high expression ancestral W-genes remaining, consistent with the progressive erosion of nonrecombining regions. Among these, the splicing factor u2af2 stands out as a promising candidate for primary sex determination, opening new avenues for understanding the molecular basis of the reproductive biology of this group. https://research-explorer.ista.ac.at/download/10167/11352/2021_MolecularBiolEvolution_Elkrewi.pdf application/pdfno https://creativecommons.org/licenses/by/4.0/ Oxford University Press2021 eng sex chromosomesevolutionary strataW-linked genesex determining geneschistosome parasites 0737-4038 1537-1719 34146097 00074136860000910.1093/molbev/msab178 138125345-58 https://research-explorer.ista.ac.at/record/19386 Elkrewi MN, Moldovan MA, Picard MAL, Vicoso B. 2021. Schistosome W-linked genes inform temporal dynamics of sex chromosome evolution and suggest candidate for sex determination. Molecular Biology and Evolution. 138(12), 5345–58. M.N. Elkrewi, M.A. Moldovan, M.A.L. Picard, B. Vicoso, Molecular Biology and Evolution 138 (2021) 5345–58. Elkrewi, Marwan N., et al. “Schistosome W-Linked Genes Inform Temporal Dynamics of Sex Chromosome Evolution and Suggest Candidate for Sex Determination.” <i>Molecular Biology and Evolution</i>, vol. 138, no. 12, Oxford University Press, 2021, pp. 5345–58, doi:<a href="https://doi.org/10.1093/molbev/msab178">10.1093/molbev/msab178</a>. Elkrewi, Marwan N, Mikhail A. Moldovan, Marion A L Picard, and Beatriz Vicoso. “Schistosome W-Linked Genes Inform Temporal Dynamics of Sex Chromosome Evolution and Suggest Candidate for Sex Determination.” <i>Molecular Biology and Evolution</i>. Oxford University Press, 2021. <a href="https://doi.org/10.1093/molbev/msab178">https://doi.org/10.1093/molbev/msab178</a>. Elkrewi MN, Moldovan MA, Picard MAL, Vicoso B. Schistosome W-linked genes inform temporal dynamics of sex chromosome evolution and suggest candidate for sex determination. <i>Molecular Biology and Evolution</i>. 2021;138(12):5345-5358. doi:<a href="https://doi.org/10.1093/molbev/msab178">10.1093/molbev/msab178</a> M. N. Elkrewi, M. A. Moldovan, M. A. L. Picard, and B. Vicoso, “Schistosome W-linked genes inform temporal dynamics of sex chromosome evolution and suggest candidate for sex determination,” <i>Molecular Biology and Evolution</i>, vol. 138, no. 12. Oxford University Press, pp. 5345–58, 2021. Elkrewi, M. N., Moldovan, M. A., Picard, M. A. L., &#38; Vicoso, B. (2021). Schistosome W-linked genes inform temporal dynamics of sex chromosome evolution and suggest candidate for sex determination. <i>Molecular Biology and Evolution</i>. Oxford University Press. <a href="https://doi.org/10.1093/molbev/msab178">https://doi.org/10.1093/molbev/msab178</a> 101672021-10-21T07:49:12Z2026-10-12T22:31:18Z