引用

鱿鱼Euprymna scolopes与生物发光的海洋细菌颤音纤维纤维Fischeri形成了共生的共生关系。各种宿主和微生物因子调节共生关联和宿主免疫成分，并被认为在这些共生关联的建立和维持中起着至关重要的作用。E. scolopes是一种无脊椎动物，不包含经典抗体依赖性适应性免疫系统。因此，它仅依靠其先天免疫系统，该系统具有两种主要类型的组成部分：体液和细胞。在这些成分中，模式识别受体（PRR）是一大批一线传感器，可让宿主识别和区分外国药物与自分子与自我分子，并参与体液和细胞免疫反应。含有蛋白质（TEP）的硫酯是最古老的先天性免疫PRRS分子之一，并且在脊椎动物和VII无脊椎动物生物体中发现。然而，这些分子中的许多分子中的许多分子在动物纤维细菌关联中的免疫功能尚未得到很好的研究。这项研究的第一个目的是研究大肠杆菌中TEP分子的存在和多样性及其在共生中的可能作用。假设E. scolopes包含多种TEP分子，并且在共生细菌存在下调节这些分子，以允许在共生动力学中有效地定植和维持。在计算机中，方法用于识别并最初表征大肠杆菌中的TEP分子。 Transcriptome analysis resulted in the identification of eight different TEP molecules (A2M-1, A2M-2, C3-1, C3-2, TEP-1, TEP-2, TEP-3, and MCR-1) in E. scolopes that were categorized into four subfamilies. In this study, E. scolopes A2M and MCR molecules were identified for the first time. To verify the expression of TEP molecules, end point polymerase chain reaction (PCR) was used to amplify TEP transcripts in uncolonized and colonized juveniles, and in one adult tissue. Six out of the eight TEPs (A2M-1, A2M-2, C3-1, C3-2, TEP-1, TEP-2, and MCR-1) were successfully amplified in all three types of samples tested: whole body of uncolonized and colonized juveniles, and adult gill tissue. TEP-2 was not able to be amplified in any of the three samples, while TEP-3 was amplified only in 24 h-colonized juveniles and in adult gills. Real time-quantitative PCR (RT-qPCR) results showed that three genes (C3-1, C3-2, and MCR-1) were downregulated, with statistical significance, in 48 h-colonized juveniles, supporting the hypothesis that exposure to V. fischeri bacteria results in the modulation of the squid host’s immune genes to allow for the symbiont colonization and persistence. The next phase of this research study focused on investigating the effects of environmentally evolved symbiotic V. fischeri on the development, survival, and health of the squid. The highly viii specific squid-Vibrio symbiotic association provides an experimental model to investigate the role of symbionts on the development of animal host tissues. In nature, E. scolopes acquires its symbiont V. fischeri horizontally from the surrounding seawater within few hours of hatching. Then, the bacteria will colonize the crypt spaces, a specialized region in the squid’s light organ (LO). Following colonization by V. fischeri, the juvenile LO undergoes multiple developmental changes, including the regression and apoptosis of the ciliated epithelial appendages (CEA). It was hypothesized that environmentally evolved V. fischeri strains that respond to environmental stressors such as temperature changes will adapt and have a better ability to colonize the squid’s LO compared to the ancestral strains. To test this hypothesis, two objectives were formulated: (1) to examine the timeline progression of morphological changes in the juvenile squid LO following colonization with temperature-evolved V. fischeri strains, and compare to that of their ancestral strains; and (2) to assess squid’s health and survival upon exposure to temperature evolved strains and compare to that of their ancestral strains. Analysis of regression of the appendages surface epithelium indicated that the temperature evolved strains of V. fischeri ES114 and EM17 showed faster morphological changes in the LO, suggesting that these temperature evolved strains could be more efficient in initiating the developmental process in the squid than their corresponding ancestral strains. Survival and health of juvenile squid were not affected by the colonization by temperature evolved strains. Furthermore, these findings suggest that the squid-Vibrio symbiosis can be adapted and sustained despite abiotic changes in their environment and provide a framework for future studies on the symbiosis between animals and environmentally adapted bacteria.