Science for Life Laboratory, Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.
PLoS Negl Trop Dis. 2011 Aug;5(8):e1283. doi: 10.1371/journal.pntd.0001283. Epub 2011 Aug 30.
The pathway for RNA interference is widespread in metazoans and participates in numerous cellular tasks, from gene silencing to chromatin remodeling and protection against retrotransposition. The unicellular eukaryote Trypanosoma cruzi is missing the canonical RNAi pathway and is unable to induce RNAi-related processes. To further understand alternative RNA pathways operating in this organism, we have performed deep sequencing and genome-wide analyses of a size-fractioned cDNA library (16-61 nt) from the epimastigote life stage. Deep sequencing generated 582,243 short sequences of which 91% could be aligned with the genome sequence. About 95-98% of the aligned data (depending on the haplotype) corresponded to small RNAs derived from tRNAs, rRNAs, snRNAs and snoRNAs. The largest class consisted of tRNA-derived small RNAs which primarily originated from the 3' end of tRNAs, followed by small RNAs derived from rRNA. The remaining sequences revealed the presence of 92 novel transcribed loci, of which 79 did not show homology to known RNA classes.
RNA 干扰途径在后生动物中广泛存在，参与众多细胞任务，从基因沉默到染色质重塑和抵御逆转录转座。单细胞真核生物克氏锥虫缺失经典的 RNAi 途径，无法诱导 RNAi 相关过程。为了进一步了解该生物体中运行的替代 RNA 途径，我们对来自锥虫前鞭毛体生命阶段的大小分级 cDNA 文库（16-61nt）进行了深度测序和全基因组分析。深度测序生成了 582,243 条短序列，其中 91%可以与基因组序列对齐。约 95-98%的对齐数据（取决于单倍型）对应于来自 tRNA、rRNA、snRNA 和 snoRNA 的小 RNA。最大的一类是由 tRNA 衍生的小 RNA，主要来源于 tRNA 的 3' 端，其次是来自 rRNA 的小 RNA。其余序列显示存在 92 个新转录的基因座，其中 79 个与已知的 RNA 类别没有同源性。
