Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
Mikimoto Pharmaceutical CO., LTD., Kurose 1425, Ise, Mie, 516-8581, Japan.
Sci Rep. 2019 Jan 22;9(1):247. doi: 10.1038/s41598-018-36726-0.
Piwi-interacting RNAs (piRNAs) belong to a recently discovered class of small non-coding RNAs whose best-understood function is repressing transposable element activity. Most piRNA studies have been conducted on model organisms and little is known about piRNA expression and function in mollusks. We performed high-throughput sequencing of small RNAs extracted from the mantle, adductor muscle, gill, and ovary tissues of the pearl oyster, Pinctada fucata. RNA species with sequences of approximately 30 nt were widely expressed in all tissues. Uridine at the 5' terminal and protection from β-elimination at the 3' terminal suggested that these were putative piRNAs. A total of 18.0 million putative piRNAs were assigned to 2.8 million unique piRNAs, and 35,848 piRNA clusters were identified. Mapping to the reference genome showed that 25% of the unique piRNAs mapped to multiple tandem loci on the scaffold. Expression patterns of the piRNA clusters were similar within the somatic tissues, but differed significantly between the somatic and gonadal tissues. These findings suggest that in pearl oysters piRNAs have important and novel functions beyond those in the germ line.
Piwi 相互作用 RNA（piRNA）属于一类新发现的小非编码 RNA，其最被理解的功能是抑制转座元件的活性。大多数 piRNA 的研究都是在模式生物中进行的，而关于软体动物中 piRNA 的表达和功能知之甚少。我们对珍珠贝（Pinctada fucata）的套膜、闭壳肌、鳃和卵巢组织中提取的小 RNA 进行了高通量测序。约 30nt 序列的 RNA 种类在所有组织中广泛表达。5'端的尿嘧啶和 3'端的 β-消除保护表明这些是推定的 piRNA。总共鉴定出 1800 万个推定 piRNA，它们被分配到 280 万个独特的 piRNA 中，并且鉴定出 35848 个 piRNA 簇。与参考基因组的映射表明，25%的独特 piRNA 映射到支架上的多个串联基因座上。piRNA 簇的表达模式在体组织内相似，但在体组织和性腺组织之间差异显著。这些发现表明，在珍珠贝中，piRNA 具有超越生殖系的重要和新的功能。
