title: A comparative study of small RNAs in Toxoplasma gondii of distinct genotypes.
abstract: BACKGROUND
  Toxoplasma gondii is an intracellular parasite with a significant impact on human health. Inside the mammalian and avian hosts, the parasite can undergo rapid development or remain inactive in the cysts. The mechanism that regulates parasite proliferation has not been fully understood. Small noncoding RNAs (sncRNA) such as microRNAs (miRNAs) are endogenous regulatory factors that can modulate cell differentiation and development. It is anticipated that hundreds of miRNAs regulate the expression of thousands of genes in a single organism. SncRNAs have been identified in T. gondii, however the profiles of sncRNAs expression and their potential regulatory function in parasites of distinct genotypes has largely been unknown.
  
  
  METHODS
  The transcription profiles of miRNAs in the two genetically distinct strains, RH and ME49, of T. gondii were investigated and compared by a high-through-put RNA sequencing technique and systematic bioinformatics analysis. The expression of some of the miRNAs was confirmed by Northern blot analysis.
  
  
  RESULTS
  1,083,320 unique sequences were obtained. Of which, 17 conserved miRNAs related to 2 metazoan miRNA families and 339 novel miRNAs were identified. A total of 175 miRNAs showed strain-specific expression, of which 155 miRNAs were up-regulated in RH strain and 20 miRNAs were up-regulated in ME49 strain. Strain-specific expression of miRNAs in T. gondii could be due to activation of specific genes at different genomic loci or due to arm-switching of the same pre-miRNA duplex.
  
  
  CONCLUSIONS
  Evidence for the differential expression of miRNAs in the two genetically distinct strains of T. gondii has been identified and defined. MiRNAs of T. gondii are more species-specific as compared to other organisms, which can be developed as diagnostic biomarkers for toxoplasmosis. The data also provide a framework for future studies on RNAi-dependent regulatory mechanisms in the zoonotic parasite.
authors.affiliation: Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, China.
authors.forename: Jielin
authors.initials: J
authors.lastname: Wang
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Liu
authors.forename: Boyin
authors.initials: B
authors.lastname: Jia
authors.forename: Huijun
authors.initials: H
authors.lastname: Lu
authors.forename: Shuai
authors.initials: S
authors.lastname: Peng
authors.forename: Xianyu
authors.initials: X
authors.lastname: Piao
authors.forename: Nan
authors.initials: N
authors.lastname: Hou
authors.forename: Pengfei
authors.initials: P
authors.lastname: Cai
authors.forename: Jigang
authors.initials: J
authors.lastname: Yin
authors.forename: Ning
authors.initials: N
authors.lastname: Jiang
authors.forename: Qijun
authors.initials: Q
authors.lastname: Chen
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D019295:Computational Biology; D020869:Gene Expression Profiling; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D051379:Mice; D016053:RNA, Protozoan / Q000235:genetics*; D058727:RNA, Small Untranslated / Q000235:genetics*; D014122:Toxoplasma / Q000145:classification* / Q000235:genetics* / Q000254:growth & development
chemical_list: D016053:RNA, Protozoan; D058727:RNA, Small Untranslated