Collaborative Research: Production and Dynamics of DMSP and Related Compounds in Response to Oxidative Stress in Marine Phytoplankton

合作研究：海洋浮游植物氧化应激反应中 DMSP 及相关化合物的产生和动态

• 批准号: 0221106
• 负责人: David Kieber
• 金额: $ 27.65万
• 依托单位: SUNY College of Environmental Science and Forestry
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0221106&HistoricalAwards=false
• 关键词: Collaborative; Research; Production; Dynamics; DMSP

Oxidative stress is a pervasive problem for oxygen-evolving plants, and is likely to be especially important for marine phytoplankton growing in nutrient-impoverished waters with high fluxes of visible and ultraviolet (UV) solar radiation. Very little is known about how marine algae cope with oxidative stress. In this study, a new hypothesis is presented that dimethylsulfoniopropionate (DMSP) is a unique and very important antioxidant in the ocean that serves as a primary defense in combatting and alleviating oxidative stress. Its role as an antioxidant is likely because DMSP is the dominant cellular sulfur compound in, and a major organic constituent of many marine algae worldwide. Furthermore, preliminary results indicate that DMSP and its enzymatic lysis product, DMS are highly effective scavengers of toxic reactive oxygen species (e.g., hydroxyl radicals) in cells, removing these species faster, in some cases, than the well documented antioxidants, ascorbic acid and glutathione. DMSP and DMS oxidation yield dimethylsulfoxide (DMSO), which is also an effective oxidant scavenger as is acrylate, the other product of DMSP lysis. Together, these related compounds should serve as a multifunctional, highly flexible antioxidant system in DMSP-containing algae. To investigate this DMSP antioxidant system, the following related hypotheses are being tested by this research team: 1) Intracellular DMSP concentrations in phytoplankton will increase in response to chronic oxidative stress, and will decrease in response to acute oxidative stress. 2) Turnover of cellular DMSP is induced by oxidative stress, resulting in increased production of putative antioxidants. 3) Phytoplankton with high DMSP content and high DMSP lyase activity will be more resistant to oxidative stress than phytoplankton with low DMSP or low lyase activity. To test these hypotheses, axenic cultures of ecologically-important phytoplankton species and natural seawater populations are being exposed to various forms of oxidative stress, including high photon fluxes of visible light (400-700 nm) and/or UV radiation (290-400 nm), nutrient limitation (Fe and N), and addition of paraquat or copper. During these exposures, changes in cellular DMSP and related compounds will be determined along with DMSP lyase activity. Complementary measurements of other antioxidant defense systems (e.g., ascorbate, reduced and oxidized glutathione, ascorbate peroxidase, superoxide dismutase) will provide information on how the DMSP system varies in relation to these well-established antioxidant defenses. This project will elucidate the mechanisms that control DMSP levels in the ocean and its rate of conversion to DMS, which is globally-significant because of the important role of DMS in atmospheric chemistry and, possibly, climate. If the DMSP antioxidant hypothesis is correct, then an important, hitherto unknown, cellular function of DMSP will have been identified. Understanding the cellular physiology of DMSP and its relationship to other poorly-understood algal antioxidant systems will increase our understanding of the factors that control the distribution of ecologically-important phytoplankton in the sea. This study will also result in the interdisciplinary training of advanced undergraduate and graduate students in algal physiological ecology and oceanography. The PIs and students will disseminate results of this study through scholarly and public presentations, scientific journals, popular articles and freely-accessible web pages.

氧化应激对于氧气发展的植物是一个普遍的问题，对于在养分膨胀的水域中生长的海洋浮游植物尤其重要的是，可见的和紫外线（UV）太阳辐射量高。 关于海洋藻类如何应对氧化应激，知之甚少。 在这项研究中，提出了一种新的假设，即二甲基磺胺丙酸二甲酸（DMSP）是海洋中一种独特且非常重要的抗氧化剂，是对抗和减轻氧化应激的主要防御。 它作为抗氧化剂的作用可能是因为DMSP是主要的细胞硫化合物，并且是全球许多海洋藻类的主要有机成分。 此外，初步结果表明，DMSP及其酶促裂解产物DMS是对细胞中有毒活性氧（例如，羟基自由基）的高效清除剂，在某些情况下，这些物种在某些情况下更快地去除了这些物种，而在某些情况下，这些物种更快地去除了这些物种。 DMSP和DMS氧化产生二甲基硫氧化物（DMSO），它也是一种有效的氧化剂清除剂，丙烯酸酯是DMSP裂解的另一种产物。 总之，这些相关化合物应作为含DMSP的藻类中多功能，高度柔性的抗氧化剂系统。 为了研究该DMSP抗氧化剂系统，该研究团队正在测试以下相关假设：1）浮游植物中细胞内DMSP浓度会随着慢性氧化应激的响应而增加，并且对急性氧化应激的响应将减少。 2）细胞DMSP的营业额是由氧化应激引起的，从而导致推定抗氧化剂的产生增加。 3）与具有低DMSP或低裂解酶活性的浮游植物相比，具有高DMSP含量和高DMSP裂解酶活性的浮游植物对氧化应激的抵抗力更大。 为了检验这些假设，正在暴露于各种形式的氧化应激，包括可见光的高光子通量（400-700 nm）和/或UV辐射（290-400 Nm），营养（290-400 nm），营养限制（Fe and n ana），以及paraa ana， 在这些暴露期间，将与DMSP裂解酶活性一起确定细胞DMSP和相关化合物的变化。 对其他抗氧化剂防御系统的互补测量（例如，抗坏血酸，还原和氧化的谷胱甘肽，抗坏血酸酯过氧化物酶，超氧化物歧化酶）将提供有关DMSP系统如何在与这些良好已建立的抗氧化剂防御的关系中变化的信息。 该项目将阐明控制海洋中DMSP水平的机制及其转换为DMS，由于DMS在大气化学和可能的气候中，DMS在全球范围内具有重要意义。 如果DMSP抗氧化假设是正确的，那么迄今未知的重要，DMSP的细胞功能将被鉴定出来。 了解DMSP的细胞生理及其与其他不良藻类抗氧化剂系统的关系将增加我们对控制海洋生态重要的浮游植物分布的因素的理解。这项研究还将导致对藻类生理生态学和海洋学的高级本科生和研究生进行跨学科培训。 PIS和学生将通过学术和公开演讲，科学期刊，流行文章以及自由访问的网页来传播这项研究的结果。