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忍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。活跃的火山土代表着具有独特特征的极端环境：金属离子浓度升高，大范围内持续的脱气，以及高温。土壤温度升高，以及低O2、高二氧化碳和酸化的土壤，对栖息的生物群来说是不适宜居住的挑战。本提案将从机械上理解与生态有关的、生态系统工程、土栖入侵蚯蚓物种(Amynthas Gracilis)对自然来源的物理化学应激源的鸡尾酒的适应。此外，对这种具有极端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、农业和蚯蚓堆肥)、医学(缺氧和高二氧化碳模型)和环境管理(生态毒理学、风险评估、土地开垦)中得到应用。弗纳斯是亚速尔群岛上S·米格尔的一个乡村教区，位于一座活火山的破火山口内。FurNas持续的火山活动造成了三个威胁生命的土壤：当地低O2(10%)和高二氧化碳水平(54%)，高温(37oC)，以及由于土壤酸化而使金属浓度升高(PH5.8)。令人震惊的是，这种极端的土壤养活了一批有生存能力的纤细线虫。[值得注意的是，接触二氧化碳的人中，二氧化碳浓度超过17%会在1分钟内导致死亡。]本项目的目的是研究这种生活在土壤中的多细胞动物如何耐受活跃的火山土的不适宜居住条件的特定功能方面。我们将调查三种不同情景下纤细线虫种群的分子和生理反应：i)直接从不活跃的和活跃的火山土壤中采集的蚯蚓；ii)从火山活跃的土壤中移植到微宇宙中的蚯蚓，反之亦然；以及iii)一系列代表在野外遇到的三个化学/物理挑战的组合(即单一或组合)的实验室‘暴露’。我们的观察将包括以下内容：-全面的土壤分析，以允许对蚯蚓吸收的金属有效性进行建模。-分析基因表达，以揭示蚯蚓如何调节其转录组，使其能够耐受活火山活动带来的严重挑战。-对遗传数据进行计算机查询，以确定与金属应激、耐热性、二氧化碳新陈代谢和低氧有关的具有重要功能的目标基因的突变。-测量一种被称为“低氧诱导因子”(HIF)的保守基因的表达水平，以前的研究表明，HIF在调节脊椎动物对低氧、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‘热休克’应激反应伴侣超家族的基因的表达。-进行生化和生理测量，以确定O2穿过体壁的效率，以及血红蛋白的数量和亲氧特性。-测量Amynthas的耗氧量和ATP产生率的日变化，以确定在活跃的火山土壤中行为和生理是否发生改变。同时，我们建议支持一名博士生确定亚速尔群岛和(通过合作)亚洲(老挝、韩国、泰国、中国南部)的细毛虫种群的遗传结构，亚洲是世界性物种的发源地。学生还将研究这种生物的繁殖，据报道主要是无性繁殖(孤雌生殖)，以及这对一个在广泛的环热带范围内成功入侵殖民者的物种的影响。

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.