title: A survey of small RNAs in human sperm.
abstract: BACKGROUND
  There has been substantial interest in assessing whether RNAs (mRNAs and sncRNAs, i.e. small non-coding) delivered from mammalian spermatozoa play a functional role in early embryo development. While the cadre of spermatozoal mRNAs has been characterized, comparatively little is known about the distribution or function of the estimated 24,000 sncRNAs within each normal human spermatozoon.
  
  
  METHODS
  RNAs of <200 bases in length were isolated from the ejaculates from three donors of proved fertility. RNAs of 18-30 nucleotides in length were then used to construct small RNA Digital Gene Expression libraries for Next Generation Sequencing. Known sncRNAs that uniquely mapped to a single location in the human genome were identified.
  
  
  RESULTS
  Bioinformatic analysis revealed the presence of multiple classes of small RNAs in human spermatozoa. The primary classes resolved included microRNA (miRNAs) (≈ 7%), Piwi-interacting piRNAs (≈ 17%), repeat-associated small RNAs (≈ 65%). A minor subset of short RNAs within the transcription start site/promoter fraction (≈ 11%) frames the histone promoter-associated regions enriched in genes of early embryonic development. These have been termed quiescent RNAs.
  
  
  CONCLUSIONS
  A complex population of male derived sncRNAs that are available for delivery upon fertilization was revealed. Sperm miRNA-targeted enrichment in the human oocyte is consistent with their role as modifiers of early post-fertilization. The relative abundance of piRNAs and repeat-associated RNAs suggests that they may assume a role in confrontation and consolidation. This may ensure the compatibility of the genomes at fertilization.
authors: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA. steve@compbio.med.wayne.edu
authors: Stephen A
authors: SA
authors: Krawetz
authors: Adele
authors: A
authors: Kruger
authors: Claudia
authors: C
authors: Lalancette
authors: Rebecca
authors: R
authors: Tagett
authors: Ester
authors: E
authors: Anton
authors: Sorin
authors: S
authors: Draghici
authors: Michael P
authors: MP
authors: Diamond
mesh_terms: D019295:Computational Biology; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D058727:RNA, Small Untranslated / Q000378:metabolism*; D017423:Sequence Analysis, RNA; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D035683:MicroRNAs; D034741:RNA, Small Interfering; D058727:RNA, Small Untranslated