title: Sexually biased transcripts at early embryonic stages of the silkworm depend on the sex chromosome constitution.
abstract: In the silkworm, Bombyx mori, females are heterogametic (WZ) whereas males have two Z chromosomes. Femaleness of B. mori is determined by the presence of the W chromosome, suggesting that there is a dominant feminizing gene on this chromosome. Recently, by transcriptome analysis of B. mori embryos, we discovered that a single W-chromosome-derived PIWI-interacting RNA (piRNA) is the long-sought primary determinant of femaleness in B. mori. However, sexual bias in the transcriptome of B. mori early embryos has not yet been well characterized. Using deep sequencing data from molecularly sexed RNA of B. mori embryos, we identified and characterized 157 transcripts that are statistically differentially expressed between male and female early embryos. Most of the female-biased transcripts were transposons or repeat sequences that are produced presumably from the W chromosome. Bioinformatic analysis revealed that these repetitive sequences are piRNA precursors. In contrast, male-biased genes were frequently transcribed from the Z chromosome, suggesting that dosage compensation in Z-linked genes does not occur or is incomplete at early embryonic stages. Our analysis has drawn a picture of a global landscape of sexually biased transcriptome during early B. mori embyogenesis and has suggested for the first time that most sexually biased embryonic transcripts depend on sex chromosomes.
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Munetaka
authors.initials: M
authors.lastname: Kawamoto
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Koga
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kiuchi
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Shoji
authors.affiliation: Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
authors.forename: Sumio
authors.initials: S
authors.lastname: Sugano
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Shimada
authors.affiliation: Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: katsuma@ss.ab.a.u-tokyo.ac.jp.
authors.forename: Susumu
authors.initials: S
authors.lastname: Katsuma
mesh_terms: D000818:Animals; D012831:Bombyx / Q000196:embryology* / Q000235:genetics*; D059006:Chromosomes, Insect; D004625:Embryo, Nonmammalian; D047108:Embryonic Development / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D019476:Insect Proteins / Q000235:genetics; D008297:Male; D046228:Microarray Analysis; D012333:RNA, Messenger / Q000235:genetics*; D012727:Sex Characteristics; D012730:Sex Chromosomes
chemical_list: D019476:Insect Proteins; D012333:RNA, Messenger
keywords: Dosage compensation; Sex determination; Silkworm; Transcriptome; W chromosome; piRNA