title: Zygotic amplification of secondary piRNAs during silkworm embryogenesis.
abstract: PIWI-interacting RNAs (piRNAs) are 23-30-nucleotide-long small RNAs that act as sequence-specific silencers of transposable elements in animal gonads. In flies, genetics and deep sequencing data have led to a hypothesis for piRNA biogenesis called the ping-pong cycle, where antisense primary piRNAs initiate an amplification loop to generate sense secondary piRNAs. However, to date, the process of the ping-pong cycle has never been monitored at work. Here, by large-scale profiling of piRNAs from silkworm ovary and embryos of different developmental stages, we demonstrate that maternally inherited antisense-biased piRNAs trigger acute amplification of secondary sense piRNA production in zygotes, at a time coinciding with zygotic transcription of sense transposon mRNAs. These results provide on-site evidence for the ping-pong cycle.
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: Shinpei
authors.initials: S
authors.lastname: Kawaoka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
authors.forename: Koji
authors.initials: K
authors.lastname: Kadota
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Kahori
authors.initials: K
authors.lastname: Hara
authors.forename: Sumio
authors.initials: S
authors.lastname: Sugano
authors.forename: Kentaro
authors.initials: K
authors.lastname: Shimizu
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Tomari
authors.forename: Toru
authors.initials: T
authors.lastname: Shimada
authors.forename: Susumu
authors.initials: S
authors.lastname: Katsuma
mesh_terms: D000818:Animals; D012831:Bombyx / Q000196:embryology* / Q000235:genetics*; D016000:Cluster Analysis; D004625:Embryo, Nonmammalian; D047108:Embryonic Development / Q000235:genetics / Q000502:physiology; D005260:Female; D005784:Gene Amplification / Q000502:physiology*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D046228:Microarray Analysis; D008954:Models, Biological; D008969:Molecular Sequence Data; D023121:RNA, Messenger, Stored / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism; D015053:Zygote / Q000378:metabolism*
chemical_list: D023121:RNA, Messenger, Stored; D034741:RNA, Small Interfering