Activity and inactivity of moth sex chromosomes in somatic and meiotic cells

Chromosoma. 2019 Dec;128(4):533-545. doi: 10.1007/s00412-019-00722-8. Epub 2019 Aug 13.


Moths and butterflies (Lepidoptera) are the most species-rich group of animals with female heterogamety, females mostly having a WZ, males a ZZ sex chromosome constitution. We studied chromatin conformation, activity, and inactivity of the sex chromosomes in the flour moth Ephestia kuehniella and the silkworm Bombyx mori, using immunostaining with anti-H3K9me2/3, anti-RNA polymerase II, and fluoro-uridine (FU) labelling of nascent transcripts, with conventional widefield fluorescence microscopy and 'spatial structured illumination microscopy' (3D-SIM). The Z chromosome is euchromatic in somatic cells and throughout meiosis. It is transcriptionally active in somatic cells and in the postpachaytene stage of meiosis. The W chromosome in contrast is heterochromatic in somatic cells as well as in meiotic cells at pachytene, but euchromatic and transcriptionally active like all other chromosomes at postpachytene. As the W chromosomes are apparently devoid of protein-coding genes, their transcripts must be non-coding. We found no indication of 'meiotic sex chromosome inactivation' (MSCI) in the two species.

Keywords: Bombyx; Ephestia; Germline-limited activity; Heterochromatin; MSCI; Sex chromatin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bombyx / genetics
  • Bombyx / metabolism
  • Chromatin / metabolism*
  • Chromosomes, Insect / metabolism
  • Meiosis
  • Moths / genetics*
  • Moths / metabolism
  • Sex Chromosomes / metabolism*


  • Chromatin