The silkworm W chromosome is a source of female-enriched piRNAs
- Shinpei Kawaoka1,7,
- Koji Kadota2,7,
- Yuji Arai1,
- Yutaka Suzuki3,
- Tsuguru Fujii1,
- Hiroaki Abe4,
- Yuji Yasukochi5,
- Kazuei Mita5,
- Sumio Sugano3,
- Kentaro Shimizu2,
- Yukihide Tomari6,
- Toru Shimada1,2 and
- Susumu Katsuma1,8
- 1Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
- 2Agricultural Bioinformatics Research Unit, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
- 3Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 108-8639, Japan
- 4Division of Agriscience and Bioscience, Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
- 5National Institute of Agrobiological Sciences, Tsukuba 305-8634, Japan
- 6Institute of Molecular and Cellular Biosciences, and Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 113-0032, Japan
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↵7 These authors contributed equally to this work.
Abstract
In the silkworm, Bombyx mori, the W chromosome plays a dominant role in female determination. However, neither protein-coding genes nor transcripts have so far been isolated from the W chromosome. Instead, a large amount of functional transposable elements and their remnants are accumulated on the W chromosome. PIWI-interacting RNAs (piRNAs) are 23–30-nt-long small RNAs that potentially act as sequence-specific guides for PIWI proteins to silence transposon activity in animal gonads. In this study, by comparing ovary- and testis-derived piRNAs, we identified numerous female-enriched piRNAs. Our data indicated that female-enriched piRNAs are derived from the W chromosome. Moreover, comparative analyses on piRNA profiles from a series of W chromosome mutant strains revealed a striking enrichment of a specific set of transposon-derived piRNAs in the putative sex-determining region. Collectively, we revealed the nature of the silkworm W chromosome as a source of piRNAs.
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Footnotes
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↵8 Corresponding author.
E-mail katsuma{at}ss.ab.a.u-tokyo.ac.jp.
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Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.027565.111.
- Received March 29, 2011.
- Accepted September 13, 2011.
- Copyright © 2011 RNA Society
