title: Identification of miRNAs associated with sexual maturity in chicken ovary by Illumina small RNA deep sequencing.
abstract: BACKGROUND
  MicroRNAs have been suggested to play important roles in the regulation of gene expression in various biological processes. To investigate the function of miRNAs in chicken ovarian development and folliculogenesis, two small RNA libraries constructed from sexually mature (162-day old) and immature (42-day old) ovary tissues of Single Comb White Leghorn chicken were sequenced using Illumina small RNA deep sequencing.
  
  
  RESULTS
  In the present study, 14,545,100 and 14,774,864 clean reads were obtained from sexually mature (162-d) and sexually immature (42-d) ovaries, respectively. In total, 202 known miRNAs were identified, and 93 of them were found to be significantly differentially expressed: 42 miRNAs were up-regulated and 51 miRNAs were down-regulated in the mature ovary compared to the immature ovary. Among the up-regulated miRNAs, gga-miR-1a has the largest fold-change (6.405-fold), while gga-miR-375 has the largest fold-change (11.345-fold) among the down-regulated miRNAs. The three most abundant miRNAs in the chicken ovary are gga-miR-10a, gga-let-7 and gga-miR-21. Five differentially expressed miRNAs (gga-miR-1a, 21, 26a, 137 and 375) were validated by real-time quantitative RT-PCR (qRT-PCR). Furthermore, the expression patterns of the five miRNAs were analyzed in different developmental stages of chicken ovary and follicles of various sizes.
  
  
  CONCLUSIONS
  The present study provides the first miRNA profile in sexually immature and mature chicken ovaries. Some miRNAs such as gga-miR-1a and gga-miR-21are expressed differentially in immature and mature chicken ovaries as well as among different sized follicles, suggesting an important role in the follicular growth or ovulation mechanism in the chicken.
authors.affiliation: Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Taian 271018 Shandong Province, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Kang
authors.forename: Xinxing
authors.initials: X
authors.lastname: Cui
authors.forename: Yujie
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chunhong
authors.initials: C
authors.lastname: Yang
authors.forename: Yunliang
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D000818:Animals; D002645:Chickens / Q000235:genetics* / Q000502:physiology*; D005260:Female; D059014:High-Throughput Nucleotide Sequencing; D035683:MicroRNAs / Q000235:genetics*; D058977:Molecular Sequence Annotation; D006080:Ovarian Follicle / Q000378:metabolism / Q000502:physiology; D010053:Ovary / Q000378:metabolism* / Q000502:physiology; D017423:Sequence Analysis, RNA; D012741:Sexual Maturation / Q000235:genetics*; D059467:Transcriptome
chemical_list: D035683:MicroRNAs