Identification and Characterization of MicroRNAs from Phaeodactylum tricornutum by High-throughput Sequencing and Bioinformatics Analysis

Diatoms, which are important planktons widespread in various aquatic environments, are believed to play a vital role in primary production as well as silica cycling. The genomes of the pennate diatom Phaeodactylum tricornutum and the centric diatom Thalassiosira pseudonana have been sequenced, revealing some characteristics of the diatomsâ?? mosaic genome as well as some features of their fatty acid metabolism and urea cycle, and indicating their unusual properties. To identify microRNAs (miRNAs) from P. tricornutum and to study their probable roles in nitrogen and silicon metabolism, we constructed and sequenced small RNA (sRNA) libraries from P. tricornutum under normal (PT1), nitrogen-limited (PT2) and silicon-limited (PT3) conditions. A total of 13 miRNAs were identified. They were probable P. tricornutum-specific novel miRNAs. These miRNAs were differentially expressed in PT1, PT2 and PT3, and their potential targets were involved in various processes. Our results indicated that P. tricornutum contained novel miRNAs that differed from miRNAs of other organisms and that they might play important regulator roles in P. tricornutum metabolism. Overall design: Constructing and sequencing small RNA (sRNA) libraries from P. tricornutum under normal (PT1), nitrogen-limited (PT2) and silicon-limited (PT3) conditions