title: Cloning, characterization and expression analysis of porcine microRNAs.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are small ~22-nt regulatory RNAs that can silence target genes, by blocking their protein production or degrading the mRNAs. Pig is an important animal in the agriculture industry because of its utility in the meat production. Besides, pig has tremendous biomedical importance as a model organism because of its closer proximity to humans than the mouse model. Several hundreds of miRNAs have been identified from mammals, humans, mice and rats, but little is known about the miRNA component in the pig genome. Here, we adopted an experimental approach to identify conserved and unique miRNAs and characterize their expression patterns in diverse tissues of pig.
  
  
  RESULTS
  By sequencing a small RNA library generated using pooled RNA from the pig heart, liver and thymus; we identified a total of 120 conserved miRNA homologs in pig. Expression analysis of conserved miRNAs in 14 different tissue types revealed heart-specific expression of miR-499 and miR-208 and liver-specific expression of miR-122. Additionally, miR-1 and miR-133 in the heart, miR-181a and miR-142-3p in the thymus, miR-194 in the liver, and miR-143 in the stomach showed the highest levels of expression. miR-22, miR-26b, miR-29c and miR-30c showed ubiquitous expression in diverse tissues. The expression patterns of pig-specific miRNAs also varied among the tissues examined.
  
  
  CONCLUSIONS
  Identification of 120 miRNAs and determination of the spatial expression patterns of a sub-set of these in the pig is a valuable resource for molecular biologists, breeders, and biomedical investigators interested in post-transcriptional gene regulation in pig and in related mammals, including humans.
authors.affiliation: Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA. Reddy.alavala@okstate.edu
authors.forename: Alavala Matta
authors.initials: AM
authors.lastname: Reddy
authors.forename: Yun
authors.initials: Y
authors.lastname: Zheng
authors.forename: Guru
authors.initials: G
authors.lastname: Jagadeeswaran
authors.forename: Simone L
authors.initials: SL
authors.lastname: Macmil
authors.forename: Wiley B
authors.initials: WB
authors.lastname: Graham
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Roe
authors.forename: Udaya
authors.initials: U
authors.lastname: Desilva
authors.forename: Weixiong
authors.initials: W
authors.lastname: Zhang
authors.forename: Ramanjulu
authors.initials: R
authors.lastname: Sunkar
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015723:Gene Library; D016678:Genome; D035683:MicroRNAs / Q000235:genetics*; D017423:Sequence Analysis, RNA; D034421:Sus scrofa / Q000235:genetics*
chemical_list: D035683:MicroRNAs