Spontaneous gain of susceptibility suggests a novel mechanism of resistance to hybrid dysgenesis in Drosophila virilis

PLoS Genet. 2018 May 29;14(5):e1007400. doi: 10.1371/journal.pgen.1007400. eCollection 2018 May.

Abstract

Syndromes of hybrid dysgenesis (HD) have been critical for our understanding of the transgenerational maintenance of genome stability by piRNA. HD in D. virilis represents a special case of HD since it includes simultaneous mobilization of a set of TEs that belong to different classes. The standard explanation for HD is that eggs of the responder strains lack an abundant pool of piRNAs corresponding to the asymmetric TE families transmitted solely by sperm. However, there are several strains of D. virilis that lack asymmetric TEs, but exhibit a "neutral" cytotype that confers resistance to HD. To characterize the mechanism of resistance to HD, we performed a comparative analysis of the landscape of ovarian small RNAs in strains that vary in their resistance to HD mediated sterility. We demonstrate that resistance to HD cannot be solely explained by a maternal piRNA pool that matches the assemblage of TEs that likely cause HD. In support of this, we have witnessed a cytotype shift from neutral (N) to susceptible (M) in a strain devoid of all major TEs implicated in HD. This shift occurred in the absence of significant change in TE copy number and expression of piRNAs homologous to asymmetric TEs. Instead, this shift is associated with a change in the chromatin profile of repeat sequences unlikely to be causative of paternal induction. Overall, our data suggest that resistance to TE-mediated sterility during HD may be achieved by mechanisms that are distinct from the canonical syndromes of HD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatin / genetics*
  • Computational Biology
  • DNA Copy Number Variations / genetics
  • DNA Transposable Elements / genetics*
  • Drosophila / genetics*
  • Female
  • Genomic Instability
  • High-Throughput Nucleotide Sequencing
  • Infertility / genetics*
  • Male
  • Ovary / metabolism
  • RNA, Small Interfering / genetics*
  • RNA, Small Interfering / metabolism
  • Real-Time Polymerase Chain Reaction
  • Sequence Analysis, RNA

Substances

  • Chromatin
  • DNA Transposable Elements
  • RNA, Small Interfering

Grants and funding

This work was supported by the Russian Science Foundation grant (No. 14-50-00060). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.