Stress in a hot place: Ecogenomics and phylogeography in a pantropical sentinel inhabiting multi-stressor volcanic soils

了解任何后生动物如何耐受由多种应激源组成的极端环境，可能有助于预测当前和未来多方面的全球变化对生物多样性和生态功能的影响。活跃的火山土壤代表了具有独特特征的极端环境：金属离子浓度升高，在大范围内不断脱气，温度高。升高的土壤温度，以及低氧、高二氧化碳和酸化的土壤是不适合居住的生物群的挑战。本提案将从机制上理解与生态相关的、生态系统工程的、居住在土壤中的入侵蚯蚓物种（Amynthas gracilis）对自然起源的物理化学压力源的混合适应。此外，对这种具有极端微生物特征的后生动物生命形式的观察将在生物经济（生物技术、农业和蠕虫堆肥）、医学（缺氧和高碳酸血症模型）和环境管理（生态毒理学、风险评估、土地复垦）中得到应用。富纳斯是亚速尔群岛<s:1>米格尔岛的一个乡村教区，位于一座活火山的火山口内。弗纳斯持续的火山活动给土壤带来了三个可怕的威胁生命的挑战：当地低氧（10%）和高二氧化碳（54%），高温（37℃），以及由于土壤酸化（pH值5.8）而导致生物可利用的金属浓度升高。令人震惊的是，这种极端的土壤居然能养活一个存活的草属植物种群。[值得注意的是，二氧化碳浓度超过17%会导致暴露的人在1分钟内死亡。这个项目的目的是研究这种居住在土壤中的多细胞动物如何适应活跃火山土壤的恶劣条件的具体功能方面。本研究将研究三种不同情景下薄叶蚯蚓种群的分子和生理反应：i)直接从活跃和不活跃的火山土壤中取样蚯蚓；Ii)从火山活跃的土壤中移植到位于非活跃土壤中的蚯蚓，反之亦然；iii)一系列实验室“暴露”，代表该领域遇到的三种化学/物理挑战的每种组合（即单一或组合）。我们的观察将包括以下内容：-全面的土壤分析，以模拟蚯蚓吸收金属的有效性。-分析基因表达，揭示蚯蚓如何调节其转录组，使其能够承受活火山活动带来的严峻挑战。-对基因数据进行计算分析，以确定与金属胁迫、耐热性、二氧化碳代谢和缺氧有关的功能重要靶基因的突变。-测量被称为“缺氧诱导因子”（HIF）的保守基因的表达水平，先前的研究表明，HIF在调节脊椎动物对缺氧、热应激和金属毒性的反应中起着至关重要的作用。-测量属于应激反应伴侣的“热休克”超家族的基因表达。-生化和生理测量，以确定通过体壁的氧运输效率，以及血红蛋白的量和氧亲和力。-测量无足动物的氧气消耗和ATP生产速率的日变化，以确定在活跃的火山土壤中行为和生理是否被改变。同时，我们建议支持一名博士生确定亚速尔群岛和亚洲（老挝，韩国，泰国，华南）的a . gracilis种群的遗传结构，这是世界性物种的起源地区。该学生还将研究这种生物的繁殖，据报道，这种生物主要是无性繁殖的（孤雌繁殖），以及这种物种在广泛的热带地区成功的入侵殖民者的影响。

Understanding of how any metazoan organism tolerates an extreme environment comprised of multiple stressors may help to predict the impacts of current and future multifaceted global change on biodiversity and ecological function. Active volcanic soils represent extreme environments with unique features: elevated metal-ion concentrations, constant degassing over a wide area, and high temperature. Elevated soil temperature, as well as low O2, high CO2, and acidified soil are inhospitable challenges to the resident biota. The present proposal will derive a mechanistic understanding of the adaptation of an ecologically-relevant, ecosytem engineering, soil-dwelling invasive earthworm species (Amynthas gracilis) to cocktails of physico-chemical stressors of natural origin. Furthermore, the observations on this metazoan life-form with extremophile traits will have applications in the bioeconomy (biotechnology, agriculture and vermicomposting), medicine (models for anoxia & hypercapnia), and environmental management (ecotoxicology, risk assessment, land reclamation). Furnas, a rural parish on São Miguel in the Azores, is situated inside a caldera of an active volcano. Persistent volcanic activity at Furnas creates a soil presenting three formidable life-threatening challenges: locally low O2 (10%) and high CO2 levels (54%), high temperatures (37oC), and elevated metal concentrations rendered bioavailable due to soil acidification (pH 5.8). It is astounding that this extreme soil supports a viable population of A. gracilis. [It is noteworthy that CO2 concentrations greater than 17% leads death within 1 minute in exposed humans.] The aim of this project is to investigate specific functional aspects of how this soil-dwelling multi-cellular animal tolerates the inhospitable conditions of active volcanic soils.We will investigate the molecular and physiological responses of populations of A. gracilis under three discrete scenarios:i) earthworms sampled directly from inactive and actively volcanic soils;ii) earthworms transplanted from volcanically active to microcosms located in non-active soils, and vice versa; and iii) a series of laboratory 'exposures' representing every combination of the three chemical/physical challenges encountered in the field (i.e. singular or combinatorial). Our observations will encompass the following: - Comprehensive soil analyses to allow modeling of metal availability for uptake by the earthworms. - Profiling gene expression to reveal how the earthworm regulates its transcriptome enabling it to tolerate the severe challenges presented by active volcanism. - Computational interrogation of genetic data to identify mutations in functionally significant target genes involved in metal stress, thermo-tolerance, CO2 metabolism, and hypoxia.- Measuring the expression level of a conserved gene known as "Hypoxia-Induced Factor" (HIF) which previous studies indicate is paramount in regulating responses to hypoxia, thermal stress, and metal toxicity in vertebrates.- Measuring the expression of genes belonging to the 'heat-shock' superfamily of stress-response chaperones.- Biochemical and physiological measurements to determine the efficiency of O2 transport across the body wall, and the amount and O2-affinity properties of the haemoglobin. - Measuring diurnal changes in the O2 consumption and ATP production rates of Amynthas to establish whether behavior and physiology are modified in active volcanic soils.In parallel, we propose to support a PhD student to determine the genetic structure of A. gracilis populations in the Azores, and (through collaboration) in Asia (Laos, Korea, Thailand, South China), the region of origin of the cosmopolitan species. The studentship will also study the organism's reproduction, reported to be predominately asexual (parthenogenetic), and the implications of this for a species that is a successful invasive colonizer across a wide circum-tropical range.