Barros Inês, Froufe Hugo, Marnellos George, Egas Conceição, Delaney Jennifer, Clamp Michele, Santos Ricardo Serrão, Bettencourt Raul
Department of Oceanography and Fisheries, University of the Azores, 9901-862 Horta, Portugal.
MARE-Marine and Environmental Sciences Centre, 9901-862 Horta, Portugal.
AIMS Microbiol. 2018 Mar 20;4(2):240-260. doi: 10.3934/microbiol.2018.2.240. eCollection 2018.
The deep-sea mussels (Bivalvia: Mytilidae) are the dominant macrofauna subsisting at the hydrothermal vents site Menez Gwen in the Mid-Atlantic Ridge (MAR). Their adaptive success in such challenging environments is largely due to their gill symbiotic association with chemosynthetic bacteria. We examined the response of vent mussels as they adapt to sea-level environmental conditions, through an assessment of the relative abundance of host-symbiont related RNA transcripts to better understand how the gill microbiome may drive host-symbiont interactions in vent mussels during hypothetical venting inactivity.
The metatranscriptome of was sequenced from gill tissues sampled at different time-points during a five-week acclimatization experiment, using Next-Generation-Sequencing. After Illumina sequencing, a total of 181,985,262 paired-end reads of 150 bp were generated with an average of 16,544,115 read per sample. Metatranscriptome analysis confirmed that experimental acclimatization in aquaria accounted for global gill transcript variation. Additionally, the analysis of 16S and 18S rRNA sequences data allowed for a comprehensive characterization of host-symbiont interactions, which included the gradual loss of gill endosymbionts and signaling pathways, associated with stress responses and energy metabolism, under experimental acclimatization. Dominant active transcripts were assigned to the following KEGG categories: "Ribosome", "Oxidative phosphorylation" and "Chaperones and folding catalysts" suggesting specific metabolic responses to physiological adaptations in aquarium environment.
Gill metagenomics analyses highlighted microbial diversity shifts and a clear pattern of varying mRNA transcript abundancies and expression during acclimatization to aquarium conditions which indicate change in bacterial community activity. This approach holds potential for the discovery of new host-symbiont associations, evidencing new functional transcripts and a clearer picture of methane metabolism during loss of endosymbionts. Towards the end of acclimatization, we observed trends in three major functional subsystems, as evidenced by an increment of transcripts related to genetic information processes; the decrease of chaperone and folding catalysts and oxidative phosphorylation transcripts; but no change in transcripts of gluconeogenesis and co-factors-vitamins.
深海贻贝（双壳纲：贻贝科）是大西洋中脊（MAR）梅内兹格温热液喷口处的主要大型动物。它们在如此具有挑战性的环境中取得适应性成功，很大程度上归功于其鳃与化学合成细菌的共生关系。我们通过评估宿主 - 共生体相关RNA转录本的相对丰度，研究了喷口贻贝适应海平面环境条件时的反应，以更好地了解在假设的喷口不活动期间，鳃微生物群如何驱动喷口贻贝中的宿主 - 共生体相互作用。
在为期五周的驯化实验中，从不同时间点采集的鳃组织中对[具体名称未给出]的宏转录组进行了测序，采用新一代测序技术。经过Illumina测序，共产生了181,985,262条150 bp的双端读数，每个样本平均有16,544,115条读数。宏转录组分析证实，水族箱中的实验驯化导致了鳃转录本的整体变化。此外，对16S和18S rRNA序列数据的分析能够全面表征宿主 - 共生体相互作用，其中包括在实验驯化过程中，与应激反应和能量代谢相关的鳃内共生体和信号通路逐渐丧失。主要的活跃转录本被归类到以下KEGG类别：“核糖体”、“氧化磷酸化”和“伴侣蛋白与折叠催化剂”，这表明在水族箱环境中对生理适应有特定的代谢反应。
鳃宏基因组学分析突出了微生物多样性的变化以及在适应水族箱条件过程中mRNA转录本丰度和表达的明显变化模式，这表明细菌群落活动发生了改变。这种方法具有发现新的宿主 - 共生体关联的潜力，能够证明新的功能转录本，并更清晰地描绘内共生体丧失过程中的甲烷代谢情况。在驯化接近尾声时，我们观察到三个主要功能子系统的趋势，这表现为与遗传信息过程相关的转录本增加；伴侣蛋白与折叠催化剂以及氧化磷酸化转录本减少；但糖异生和辅因子 - 维生素的转录本没有变化。
