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Updated: May 22, 2026

Analysis of Transgenerational Epigenetic Inheritance in C. elegans Using a Fluorescent Reporter and Chromatin Immunoprecipitation (ChIP)
Published on: May 5, 2023
Retrogenes moved out of the z chromosome in the silkworm
Jun Wang1, Manyuan Long, Maria D Vibranovski
1Department of Ecology and Evolution, The University of Chicago, Chicago, IL 60637, USA. wangj@uchicago.edu
Abstract:
Previous studies on organisms with well-differentiated X and Y chromosomes, such as Drosophila and mammals, consistently detected an excess of genes moving out of the X chromosome and gaining testis-biased expression. Several selective evolutionary mechanisms were shown to be associated with this nonrandom gene traffic, which contributed to the evolution of the X chromosome and autosomes. If selection drives gene traffic, such traffic should also exist in species with Z and W chromosomes, where the females are the heterogametic sex. However, no previous studies on gene traffic in species with female heterogamety have found any nonrandom chromosomal gene movement. Here, we report an excess of retrogenes moving out of the Z chromosome in an organism with the ZW sex determination system, Bombyx mori. In addition, we showed that those "out of Z" retrogenes tended to have ovary-biased expression, which is consistent with the pattern of non-retrogene traffic recently reported in birds and symmetrical to the retrogene movement in mammals and fruit flies out of the X chromosome evolving testis functions. These properties of gene traffic in the ZW system suggest a general role for the heterogamety of sex chromosomes in determining the chromosomal locations and the evolution of sex-biased genes.
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