Influence of Biotic and Abiotic Stressors on the Coevolution of the Tapeworm Schistocephalus Solidus with Its Specific Host, the Three-Spined Stickleback CLUSTER: "Evolutionary Genetics of Three-Spined Stickleback - Parasite Interactions"

在第二个资助期，我们建议将重点放在寄生虫上，特别是模型寄生虫（S. solidus）干扰（操纵）棘鱼宿主免疫系统的能力。从以前的实验中，我们知道来自不同地点的固体葡萄球菌寄生虫在感染和利用它们的棘鱼宿主方面有很大的不同。因此，预计来自不同地区的寄生虫的免疫调节能力存在差异。作为主要的读本，我们计划与M. Stoll， TBH Reusch和E. Bornberg-Bauer的项目合作使用转录组测序。Samonte-Padilla等人建立的两个S. solidus cDNA文库将作为转录组序列注释的主干。如果可能的话，转录组学数据将与计划中的S. solidus基因组计划相关联（由James Cotton， Sanger Institute和Klaus Brehm， University of w<s:1> rzburg）发起)。除了寄生虫转录组外，还将分析相应宿主棘鱼的转录组，从而能够在RNA水平上研究整个宿主-寄生虫相互作用组。尽管比较了不同适应的固溶体，我们计划使用环境压力作为额外的实验变量。(1)与其他同域和异域寄生虫共同感染，因为先前的实验表明，S. solidus能够诱导不同种类的眼吸虫产生不同水平的伴随免疫，并且可以作为宿主免疫操作时机的高度敏感指标（实验将在Plön进行，一个博士职位）；(2)基于先前实验的温度变化表明，在高温（24°C）下，对固态葡萄球菌的免疫操作开始得更早，但在低温（13°C）下，在较晚的时间点上更为突出，即使寄生虫仍然相对较小（实验将在m<s:1> nster进行，一个博士职位）。被侵染的棘鱼宿主与固体葡萄球菌以外的其他寄生虫的感染，以及温度的变化都会干扰宿主免疫系统的活动，并对固体葡萄球菌造成强烈的选择压力。因此，solidus可能会根据异源感染和温度变化等环境因素调整其在棘鱼宿主中的免疫调节活性，以减少其适应度损失。该项目的主要目标是研究固态葡萄诱导的宿主操作的转录组学背景，并揭示宿主操作与环境应激源的潜在相互作用。

For the second funding period, we propose to have a stronger focus on the parasite, in particular the ability of the model parasite (S. solidus) to interfere with (manipulate) the immune system of its stickleback hosts. From previous experiments it is known that S. solidus parasites from different locations differ substantially in their potential to infect and exploit their stickleback hosts. Consequently differences in immune-modulatory capabilities of parasites from different locations are expected. As a major read out we are planning to use transcriptome sequencing in cooperation with the project of M. Stoll, TBH Reusch and E. Bornberg-Bauer. Two cDNA libraries of S. solidus established by Samonte-Padilla et al. will be used as a backbone for the annotation of the transcriptome sequences. If possible, the transcriptomic data will be linked to a planned S. solidus genome project (initiated by James Cotton, Sanger Institute, and Klaus Brehm, University of Würzburg). In addition to the parasite transcriptomes, transcriptomes of the corresponding host sticklebacks will be analysed, enabling to investigate the whole host-parasite interactome on the RNA level. Despite the comparison of differentially adapted S. solidus, we are planning to use environmental stressors as additional experimental variables. (1) Co-infections with other sympatric and allopatric parasite species, since previous experiments showed that S. solidus is capable to induce different levels of concomitant immunity against different species of eye flukes, which, furthermore, serve as highly sensitive indicators for the timing of host immune manipulation (experiments to be conducted in Plön, one PhD position); and (2) temperature variation based on previous experiments indicating that at high temperatures (24°C), immune manipulation of S. solidus starts earlier, but is more prominent at low temperatures (13°C) at later time points, even if the parasites are still relatively small (experiments to be conducted in Münster, one PhD position). Both, infections of the infested stickleback host with other parasites than S. solidus, as well as temperature variation interfere with the activity of the host’s immune system and cause strong selective pressure on S. solidus. Consequently it is likely, that S. solidus is adapted to adjust its immune modulatory activity in the stickleback host in response to environmental factors such as heterologous infections and temperature variation to minimize its fitness loss. Main goals of the projects are to investigate the transcriptomics background of host manipulation induced by S. solidus and to unravel potential interaction(s) of host manipulation with environmental stressors.