Diatom Sensory Mechanisms: Drivers of Global Marine Productivity

硅藻感觉机制：全球海洋生产力的驱动因素

• 批准号: NE/R015449/2
• 负责人: Katherine Helliwell
• 金额: $ 55.91万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FR015449%2F2
• 关键词: Diatom; Sensory; Mechanisms; Drivers; Global

The oceans support a large proportion of global biodiversity. Sustaining life at the base of marine food chains are photosynthetic microbes, known collectively as phytoplankton. These organisms are vital in regulating our climate, absorbing carbon dioxide from the atmosphere. They also generate almost half the oxygen we breathe. Phytoplankton are probably best known for their formation of massive 'algal blooms' in the ocean, due to rapid population growth triggered by a combination of physical and biological factors. Due to the release of harmful toxins, some phytoplankton blooms can have a negative impact on marine ecosystems, fisheries and human health. Effects of climate change and nutrient pollution have led to more severe and frequent blooms. However, many blooms are not caused by harmful species, and are vital for sustaining marine ecosystems including fish populations. To better understand factors that control bloom dynamics and toxicity, we need to learn more about the molecular processes that trigger their sudden proliferation, and subsequent demise.In many parts of the ocean, nutrients such as nitrogen and phosphorus are in scarce supply. This can limit phytoplankton growth, and cause competition between microbes for survival. In the marine environment a combination of physical factors can lead to sporadic increases in nutrients. This is one of the factors that can stimulate rapid proliferation of phytoplankton cells and lead to algal bloom formation. One of the most successful phytoplankton groups in modern oceans is the diatoms. Diatoms are particularly good at detecting favourable conditions and are often the first to dominate the early stages of bloom formation. Moreover, their success in regions of pulsed nutrient supply suggests that they possess sophisticated mechanisms for sensing and responding to fluctuations in nutrients. However, the sensory mechanisms that mediate the cellular responses of diatom cells to key environmental stimuli remain poorly understood. This represents a major knowledge gap, especially since it is the signalling mechanisms that coordinate acclimation to the environment that likely underpin the ecological success and global impact of the diatoms.I have generated a cutting-edge toolkit to study how diatoms are able to sense changes in their environment using the signalling molecule calcium, which functions as a messenger within the cell. This has led to the remarkable discovery that diatoms use calcium for detecting pulses of the nutrient phosphorus. This novel nutrient signalling mechanism is distinct from plants and animals and points to fundamental differences in nutrient perception between these organisms, which need to be elucidated. I will dissect specific components of this signalling pathway to identify how it helps diatoms respond rapidly to changing nutrient conditions and contribute towards bloom formation. Using my innovative tools, I will also examine other unknown aspects of the diatom sensory system. Alongside physical factors, biological interactions of diatoms with other microbes such as competitors, parasites and predators can critically regulate their growth and bloom development. In the second part of my proposal I will examine how diatoms are able to sense, and alter their behaviour to interact with, their microbial neighbours. Since both nutrient supply and bacteria can govern toxin production by harmful diatoms, a key objective will be to expand my molecular tool kit to the toxic bloom-forming diatom Pseudo-nitzschia multiseries.This research will identify mechanisms that govern dynamics of a globally important phytoplankton group that supports some of our major marine resources. The work will moreover provide insight of regulatory processes and 'master-regulators' that coordinate cellular responses to key environmental drivers that impact diatom growth and toxicity of harmful diatom species, allowing us to better predict bloom formation and toxicity.

海洋支撑着全球生物多样性的很大一部分。在海洋食物链的基础上维持生命的是光合微生物，统称为浮游植物。这些生物在调节我们的气候，吸收大气中的二氧化碳方面至关重要。它们还产生了我们呼吸的几乎一半的氧气。浮游植物可能最出名的是它们在海洋中形成大规模的“藻华”，这是由于物理和生物因素共同引发的人口快速增长。由于释放有害毒素，一些浮游植物大量繁殖可能对海洋生态系统、渔业和人类健康产生负面影响。气候变化和营养污染的影响导致了更严重和更频繁的水华。然而，许多水华不是由有害物种引起的，对维持包括鱼类种群在内的海洋生态系统至关重要。为了更好地了解控制水华动态和毒性的因素，我们需要更多地了解触发它们突然增殖和随后消亡的分子过程。在海洋的许多地方，氮和磷等营养物质供应不足。这会限制浮游植物的生长，并导致微生物之间的生存竞争。在海洋环境中，各种物理因素的结合可导致营养物的零星增加。这是其中一个因素，可以刺激浮游植物细胞的快速增殖，并导致藻类水华的形成。现代海洋中最成功的浮游植物群体之一是硅藻。硅藻特别善于探测有利的条件，往往是第一个在水华形成的早期阶段占主导地位。此外，它们在脉冲养分供应区域的成功表明，它们拥有感知和响应养分波动的复杂机制。然而，介导硅藻细胞对关键环境刺激的细胞反应的感觉机制仍然知之甚少。这代表了一个重大的知识差距，特别是因为它是协调适应环境的信号机制，可能是支撑硅藻的生态成功和全球影响力。我已经产生了一个尖端的工具包，研究硅藻如何能够使用信号分子钙来感知环境的变化，钙在细胞内起着信使的作用。这导致了一个引人注目的发现，硅藻使用钙来检测营养磷的脉冲。这种新的营养信号传导机制与植物和动物不同，并指出这些生物体之间营养感知的根本差异，需要加以阐明。我将剖析这一信号通路的具体组成部分，以确定它如何帮助硅藻迅速应对不断变化的营养条件，并有助于水华的形成。利用我的创新工具，我还将研究硅藻感觉系统的其他未知方面。除了物理因素外，硅藻与其他微生物（如竞争对手，寄生虫和捕食者）的生物相互作用可以关键地调节它们的生长和开花发育。在我的建议的第二部分，我将研究硅藻是如何能够感觉到，并改变他们的行为与他们的微生物邻居互动。由于营养供应和细菌都可以控制有害硅藻的毒素生产，一个关键的目标将是将我的分子工具箱扩展到有毒水华形成硅藻Pseudo-nitzschia multiseries.This研究将确定一个全球重要的浮游植物群体，支持我们的一些主要海洋资源的动态管理机制。这项工作还将提供监管过程和“主调节器”的见解，这些调节器协调细胞对影响硅藻生长和有害硅藻物种毒性的关键环境驱动因素的反应，使我们能够更好地预测水华形成和毒性。

项目成果

The Molecular Life of Diatoms

硅藻的分子生命

• DOI: 10.1007/978-3-030-92499-7_2
• 发表时间: 2022
• 作者: Rynearson T

Cold-induced [Ca2+]cyt elevations function to support osmoregulation in marine diatoms.

• DOI: 10.1093/plphys/kiac324
• 发表时间: 2022-09-28
• 期刊: PLANT PHYSIOLOGY
• 影响因子: 7.4
• 作者: Kleiner, Friedrich H.;Helliwell, Katherine E.;Chrachri, Abdul;Hopes, Amanda;Parry-Wilson, Hannah;Gaikwad, Trupti;Mieszkowska, Nova;Mock, Thomas;Wheeler, Glen L.;Brownlee, Colin
• 通讯作者: Brownlee, Colin

Cryptic bacterial pathogens of diatoms peak during senescence of a winter diatom bloom.

硅藻的隐性细菌病原体在冬季硅藻花的衰老过程中达到顶峰。

• DOI: 10.1111/nph.19441
• 发表时间: 2023
• 期刊: The New phytologist
• 作者: Branscombe L