Identifying the mechanisms and resource use implications of acclimation to high-temperature in marine cyanobacteria.

自1880年以来，海洋表面温度上升了约0.8摄氏度，预计到2100年将再上升2摄氏度。这将使生活在热带水域的动植物暴露在比它们的祖先在过去100万年里经历的温度更高的温度中。这些生物包括光合作用的微生物，它们提供支持海洋食物网的有机物质，并促进二氧化碳从大气向海洋的转移。在温度高于25摄氏度的热带水域，浮游植物很可能会经历温度上升对其生理的直接负面影响，因为它们经常暴露在高于其生长最适温度的温度中。这种情况与温带和极地水域的情况形成了对比，在温带和极地水域，温度的升高可能会刺激本土浮游植物的生长，或者允许更多耐热的物种迁徙。我们的研究解决了这样的问题：“蓝藻如何适应超适宜生长的温度？”“这种适应对它们在气候变暖的海洋中的生产力有何影响？”以及“我们如何在蓝藻生长模型中解释对超最佳温度的适应？”不同于以前对蓝藻、藻类和维管植物对热休克的短期(几分钟到几小时)反应的研究，我们建议研究长期(几天到几周)适应热应激的机制以及这种适应对生长和生理的影响。据我们所知，这将是第一次对藻类或蓝藻长期适应超适宜(热)温度的调查，因此，通过提供与全球变暖特别相关的信息，这将补充更广泛的关于植物、藻类和蓝藻适应亚适宜(冷)温度的文献。我们将采用一种全面的方法，使用最先进的方法来获得这种理解。转录学将被用来产生数据，以构建涉及感知和响应高温的基因调控网络。对具有不同高温耐受性的物种之间的这些网络进行比较，将被用来确定可能解释观察到的热敏感性的共同性和差异。蛋白质组学和代谢组学将被用来评估由于适应高温而发生的细胞代谢重塑。生理速率、元素组成(C、N、P)和生化组成的测量将用于评估这种驯化在生物量和生产力方面的系统水平结果。拟议的热适应综合评估既及时又新颖，将有助于在英国研究人员在具有全球意义的主题中产生重大影响的领域继续保持卓越。我们的研究将帮助科学家了解人类活动导致的全球变暖如何改变地球生命维持系统的一个基本组成部分。海洋浮游植物产生的氧气约占我们呼吸的50%，并在数千年的时间尺度上发挥着调节大气二氧化碳水平的作用。我们获得的信息将用于进一步发展日益复杂的海洋生态模型，用于预测海洋如何应对气候变化。此外，正在调查蓝藻在生物技术中的潜在用途，以生产低价值产品，如动物饲料用蛋白质或用于生产生物柴油的脂肪，以及高价值产品，包括供人类消费的营养补充剂(胡萝卜素、脂肪酸、多糖、维生素、甾醇)和其他产品(染料、药品、粘合剂、表面活性剂)。

Sea surface temperature has increased by about 0.8 degrees Celcius since 1880 and is projected to increase by another 2 degrees by the year 2100. This will expose the plants and animals that live in tropical waters to temperatures that are warmer than their ancestors have experienced over the past million years. Included in these organisms are the photosynthetic microrganisms that provide the organic matter that supports marine food webs and facilitate transfer of carbon dioxide from the atmosphere to ocean. In tropical waters where temperatures are above about 25 degrees Celcius, phytoplankton are likely to experience direct negative effects of increased temperature on their physiology as they are often exposed to temperatures that are higher than the optimal temperature for their growth. This situation contrasts with that for temperate and polar waters where increased temperature may stimulate growth of the indigenous phytoplankton species or allow more thermally tolerant species to immigrate.Our research addresses the questions "How do cyanobacteria acclimate to temperatures that are supra-optimal for growth?" "What are the implications of this acclimation for their productivity in a warming ocean?" and "How can we account for acclimation to supra-optimal temperatures in models of cyanobacteria growth?" Unlike previous research on short-term (minutes to hours) responses of cyanobacteria, algae and vascular plants to heat shock, we propose to investigate the mechanisms of long-term (days to weeks) acclimation to heat stress and the implications of this acclimation for growth and physiology. As far as we are aware, this will be the first such investigation of long term acclimation to supra-optimal (heat) temperatures for an alga or a cyanobacterium, and as such will complement the more extensive literature on acclimation to sub-optimal (cold) temperatures in plants, algae and cyanobacteria by providing information that is particularly relevant in the face of global warming. We will employ a holistic approach using state-of-the-art methods to obtain this understanding. Transcriptomics will be used to generate the data to construct gene regulatory networks involved in sensing and responding to high temperature. Comparison of these networks amongst species with different tolerances to high temperature will be used to identify communalities and differences that may explain the observed thermal sensitivities. Proteomics and metabolomics will be used to assess the remodeling of cell metabolism that occurs as a consequence of acclimation to high temperature. Measurements of physiological rates, elemental composition (C, N, P) and biochemical composition will be used in an assessment of the system level outcomes of this acclimation in terms of biomass and productivity. The proposed comprehensive assessment of thermal acclimation is both timely and novel, and will contribute to continued excellence in a field where UK researchers make major impacts in a topic of global significance.Our research will help scientists to understand how global warming due to man's activities is changing a fundamental component of Earth's life support system. Marine phytoplankton produce about 50% of the oxygen that we breathe, and play a role over millennial times scales in regulating atmospheric carbon dioxide levels. The information that we obtain will be used in the further development of the increasingly sophisticated models of marine ecology that are used in making projections of how the ocean is responding to climate change. In addition, cyanobacteria are being investigated for their potential use in biotechnology for production of low value products such as protein for animal feed or lipids for production of bio-diesel, as well as high value products including nutritional supplements (carotenoids, fatty acids, polysaccharides, vitamins, sterols) for consumption by humans and other products (dyes, pharmaceuticals, adhesives, surfactants).