title: Identification and characterization of novel microRNAs from Schistosoma japonicum.
abstract: BACKGROUND
  Schistosomiasis japonica remains a major public health problem in China. Its pathogen, Schistosoma japonicum has a complex life cycle and a unique repertoire of genes expressed at different life cycle stages. Exploring schistosome gene regulation will yield the best prospects for new drug targets and vaccine candidates. MicroRNAs (miRNAs) are a highly conserved class of noncoding RNA that control many biological processes by sequence-specific inhibition of gene expression. Although a large number of miRNAs have been identified from plants to mammals, it remains no experimental proof whether schistosome exist miRNAs.
  
  
  RESULTS
  We have identified novel miRNAs from Schistosoma japonicum by cloning and sequencing a small (18-26 nt) RNA cDNA library from the adult worms. Five novel miRNAs were identified from 227 cloned RNA sequences and verified by Northern blot. Alignments of the miRNAs with corresponding family members indicated that four of them belong to a metazoan miRNA family: let-7, miR-71, bantam and miR-125. The fifth potentially new (non conserved) miRNA appears to belong to a previously undescribed family in the genus Schistosome. The novel miRNAs were designated as sja-let-7, sja-miR-71, sja-bantam, sja-miR-125 and sja-miR-new1, respectively. Expression of sja-let-7, sja-miR-71 and sja-bantam were analyzed in six stages of the life cycle, i.e. egg, miracidium, sporocyst, cercaria, schistosomulum, and adult worm, by a modified stem-loop reverse transcribed polymerase chain reaction (RT-PCR) method developed in our laboratory. The expression patterns of these miRNAs were highly stage-specific. In particular, sja-miR-71 and sja-bantam expression reach their peaks in the cercaria stage and then drop quickly to the nadirs in the schistosomulum stage, following penetration of cercaria into a mammalian host.
  
  
  CONCLUSIONS
  Authentic miRNAs were identified for the first time in S. japonicum, including a new schistosome family member. The different expression patterns of the novel miRNAs over the life stages of S. japonicum suggest that they may mediate important roles in Schistosome growth and development.
authors.affiliation: Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, Shanghai, China.
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Xue
authors.forename: Jun
authors.initials: J
authors.lastname: Sun
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Zhang
authors.forename: Zhangxun
authors.initials: Z
authors.lastname: Wang
authors.forename: Yufu
authors.initials: Y
authors.lastname: Huang
authors.forename: Weiqing
authors.initials: W
authors.lastname: Pan
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005260:Female; D015723:Gene Library; D008018:Life Cycle Stages / Q000235:genetics; D008297:Male; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D018510:RNA, Helminth / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012549:Schistosoma japonicum / Q000235:genetics* / Q000254:growth & development; D012554:Schistosomiasis japonica / Q000469:parasitology / Q000662:veterinary; D017423:Sequence Analysis, RNA / Q000379:methods; D012689:Sequence Homology, Nucleic Acid
chemical_list: D035683:MicroRNAs; D018510:RNA, Helminth