Gut metatranscriptome of blue mussels (Mytilus edulis)

Metatranscriptomic methods involving RNA sequencing (RNA-seq) are powerful tools for evaluating the gene expression profiles of transcriptionally-active microbes that inhabit the tissues of animals. Bivalve molluscs, like all invertebrates, are holobionts and sites of interactions between host animals and both prokaryotic and eukaryotic symbionts. The present communication describes the metatranscriptomic profile of the resident microorganisms that inhabit the gut of blue mussels, Mytilus edulis, under standard laboratory conditions. Each of the eight mussels described herein were housed in isolated microcosms with routine husbandry for 14 days before their gut tissues were sampled and subjected to RNA-seq. Subsequent mRNA reads that aligned to the mussel genome were removed, and the non-host reads were annotated for function and pathway analyses. Under laboratory conditions, the resident gut microbiota expressed genes associated mostly with aerobic energy processes, with other notable contributions from metabolism and protein processing genes. At the pathway level, the most abundant complete pathways expressed in the resident gut microbial communities were related to aerobic cellular respiration, nucleotide biosynthesis, and catabolism. These data represent novel, baseline microbial gene expression information from the gut of mussels, which are crucial for future research examining the mussel holobiont and bivalve microbial ecology. Public retrieval and secondary analyses of these metatranscriptomic profiles are highly encouraged.

基于RNA测序（RNA-seq）的宏转录组学（Metatranscriptomics）方法，是评估栖息于动物组织内的转录活性微生物基因表达谱的有力工具。双壳类软体动物与所有无脊椎动物一样，属于共生联合体（holobiont），同时也是宿主动物与原核、真核共生菌相互作用的场所。本研究报道了标准实验室条件下，栖息于紫贻贝（Mytilus edulis）肠道内的常驻微生物的宏转录组学特征。本研究涉及的8只紫贻贝均被单独饲养于隔离微宇宙培养体系中，经过14天常规饲养后，采集其肠道组织并进行RNA测序。后续通过基因组比对去除匹配贻贝基因组的mRNA读段（mRNA reads），对非宿主读段开展功能注释与通路分析。在实验室培养条件下，常驻肠道菌群的表达基因主要与有氧能量代谢过程相关，其次为代谢相关基因与蛋白质加工相关基因。在通路层面，常驻肠道微生物群落中表达丰度最高的完整代谢通路主要涉及有氧细胞呼吸、核苷酸生物合成与分解代谢。本数据集提供了贻贝肠道微生物基因表达的全新基线信息，这对于后续开展贻贝共生联合体及双壳类微生物生态学相关研究具有关键支撑作用。本研究高度鼓励公众获取该宏转录组学数据集并开展二次分析。