Institute for Advanced Study, Shenzhen University, Shenzhen, China.
Guangdong Provincial Key Laboratory of Marine Biotechnology & Marine Biology Institute, Shantou University, Shantou, China.
Dev Comp Immunol. 2020 Jan;102:103470. doi: 10.1016/j.dci.2019.103470. Epub 2019 Aug 17.
Special innate immune mechanisms against pathogens are developed in marine invertebrates such as mud crab, which is also an economically important aquaculture species in many coastal countries. Hemolymph is a critical site in host immune response, but its source of microorganisms is less known. In this study, we provided a detailed investigation of the microorganisms inhabiting various body sites of healthy mud crabs, including hemolymph, midgut, gill, subcuticular epidermis and hepatopancreas. By using fluorescence microscopy and high-throughput sequencing of the bacterial 16S rRNA genes, various abundances and kinds of microorganisms were observed in the healthy mud crabs, of which some are potential pathogens to mud crab and human. The SourceTracker analysis and oral injection experiment confirm the hypothesis that hemolymph microorganisms are derived from the digestive systems of invertebrates with open circulatory systems, indicating that these microorganisms play vital roles in crab immune response. Moreover, physiological differences (gut length), behavioral characteristics (foraging behavior), diet preferences (herbivory), and/or sex hormones (testosterone) possibly determine the unique features of the crab-associated microbiota for both sexes. These findings also contribute to the development of appropriate microbial immunoenhancers, which has potential applications for improving quality and yield during crab aquaculture.
海洋无脊椎动物（如泥蟹）发展出了特殊的先天免疫机制来抵御病原体，泥蟹也是许多沿海国家具有重要经济价值的水产养殖物种。血淋巴是宿主免疫反应的关键部位，但人们对其微生物来源知之甚少。在这项研究中，我们详细调查了健康泥蟹的各种身体部位（包括血淋巴、中肠、鳃、皮下表皮和肝胰腺）中栖息的微生物。通过荧光显微镜观察和细菌 16S rRNA 基因高通量测序，我们观察到健康泥蟹中存在各种数量和种类的微生物，其中一些是泥蟹和人类的潜在病原体。SourceTracker 分析和口服注射实验证实了血淋巴微生物来源于具有开放式循环系统的无脊椎动物消化系统的假设，表明这些微生物在螃蟹免疫反应中发挥着重要作用。此外，生理差异（肠道长度）、行为特征（觅食行为）、饮食偏好（草食性）和/或性激素（睾酮）可能决定了两性螃蟹相关微生物组的独特特征。这些发现也有助于开发适当的微生物免疫增强剂，这对于提高螃蟹养殖的质量和产量具有潜在的应用价值。
