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The avian W chromosome is a refugium for endogenous retroviruses with likely effects on female-biased mutational load and genetic incompatibilities
Link to bioRxiv paper:
http://biorxiv.org/cgi/content/short/2020.07.31.230854v1?rss=1
Authors: Peona, V., Palacios-Gimenez, O. M., Blommaert, J., Liu, J., Haryoko, T., Jonsson, K. A., Irestedt, M., Zhou, Q., Jern, P., Suh, A.
Abstract:
It is a broadly observed pattern that the non-recombining regions of sex-limited chromosomes (Y and W) accumulate more repeats than the rest of the genome, even in species like birds with a low genome-wide repeat content. Here we show that in birds with highly heteromorphic sex chromosomes, the W chromosome has a transposable element (TE) density of >55% compared to the genome-wide density of <10%, and contains over half of all full-length (thus potentially active) endogenous retroviruses (ERVs) of the entire genome. Using RNA-seq and protein mass spectrometry data, we were able to detect signatures of female-specific ERV expression. We hypothesise that the avian W chromosome acts as a refugium for active ERVs, likely leading to female-biased mutational load that may influence female physiology similar to the "toxic-Y" effect in Drosophila. Furthermore, Haldane's rule predicts that the heterogametic sex has reduced fertility in hybrids. We propose that the excess of W-linked active ERVs over the rest of the genome may be an additional explanatory variable for Haldane's rule, with consequences for genetic incompatibilities between species through TE/repressor mismatches in hybrids. Together, our results suggest that the sequence content of female-specific W chromosomes can have effects far beyond sex determination and gene dosage.
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Link to bioRxiv paper:
http://biorxiv.org/cgi/content/short/2020.07.31.230854v1?rss=1
Authors: Peona, V., Palacios-Gimenez, O. M., Blommaert, J., Liu, J., Haryoko, T., Jonsson, K. A., Irestedt, M., Zhou, Q., Jern, P., Suh, A.
Abstract:
It is a broadly observed pattern that the non-recombining regions of sex-limited chromosomes (Y and W) accumulate more repeats than the rest of the genome, even in species like birds with a low genome-wide repeat content. Here we show that in birds with highly heteromorphic sex chromosomes, the W chromosome has a transposable element (TE) density of >55% compared to the genome-wide density of <10%, and contains over half of all full-length (thus potentially active) endogenous retroviruses (ERVs) of the entire genome. Using RNA-seq and protein mass spectrometry data, we were able to detect signatures of female-specific ERV expression. We hypothesise that the avian W chromosome acts as a refugium for active ERVs, likely leading to female-biased mutational load that may influence female physiology similar to the "toxic-Y" effect in Drosophila. Furthermore, Haldane's rule predicts that the heterogametic sex has reduced fertility in hybrids. We propose that the excess of W-linked active ERVs over the rest of the genome may be an additional explanatory variable for Haldane's rule, with consequences for genetic incompatibilities between species through TE/repressor mismatches in hybrids. Together, our results suggest that the sequence content of female-specific W chromosomes can have effects far beyond sex determination and gene dosage.
Copy rights belong to original authors. Visit the link for more info