Collaborative Research: Nitrogen Limitation and Ultraviolet Stress in Marine Macroalgae

合作研究：海洋大型藻类的氮限制和紫外线胁迫

• 批准号: 9906886
• 负责人: Carl Grobe
• 金额: $ 10.99万
• 依托单位: Westfield State College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9906886&HistoricalAwards=false
• 关键词: Collaborative; Research; Nitrogen; Limitation; Ultraviolet

Grobe 9906886Physical factors such as light, temperature and nutrient availability are known to limit marine productivity and play an important role in determining species distribution and community structure. Most understanding of the role of physical factors is based on studies with a single variable with other conditions being optimized for growth. Consequently, little information is available on physiological responses to the natural environment where several physical factors may be suboptimal. The ability to understand the constraints on marine productivity requires not only an understanding of potential synergistic or antagonistic interactions but also an analysis of their effects on algae with different ecological strategies. This investigation will examine the response of marine red macroalgae to simultaneous nitrogen limitation and ultraviolet radiation stress. Both factors are known to be important determinants of marine primary productivity and they frequently co-occur. This is true not only of the tropics, but also in cold- temperate oceans such as the Gulf of Maine. Red macroalgae were selected for this research because they provide the opportunity to study interactions between UV and nitrogen limitation in a group of algae with similar physiological and morphological characteristics but with well-defined differences in UV-tolerance and well-characterized contents of mycosporine-like amino acids. Furthermore, in contrast to phytoplankton, benthic macroalgae experience a more predictable light climate and are relatively long-lived, exposing individuals to a wider range of environmental conditions. The red algae studied from the Gulf of Maine will include Porphyra umbilicalis, Chondrus crispus, Membranoptera alata and Phycodry rubens. These species range from UV-tolerant intertidal and shallow sublittoral species to UV-susceptible species from the deeper sublittoral. The investigators anticipate that the costs and benefits of UV-tolerance and the impact of nitrogen limitation will vary between UV-tolerant and UV-susceptible species. The research will focus on the effect of nitrogen metabolism (limited or replete) on (a) short and long-term effects of UV-stress (e.g., short-tem inhibition of photosynthesis, lipid peroxidation, and growth), (b) UV-photoprotection including contents of sunscreens such as mycosporine-like amino acids (MAAs), antioxidants such as ascorbate, gluathione and tocopherols, and enzymes of reactive oxygen metabolism such as catalase, superoxide dismutase and ascorbate peroxidase, and (c) ability to recover from UV-stress (e.g., the role of protein synthesis in recovery). The research will also examine the effect of UV-stress on nitrogen metabolism (e.g., nitrogen content and rates of uptake and assimilation). The research will involve measurements on field-collected material, laboratory experiments under controlled conditions and outdoor experiments in flowing seawater and natural radiation manipulated by a variety of UV and photosynthetically active radiation (PAR)-filters. The research will substantially contribute to an understanding of the effect of UV and inorganic nitrogen availability on marine productivity and, in particular, elucidate the importance of interactions between these factors. The research involves collaboration between faculty at an undergraduate teaching institution (Westfield State College, MA) and a Land and Sea Grant research University (University of Maine). In addition to graduate education, the project has a substantial research experience for undergraduate component, providing undergraduates from Westfield State College with the opportunity to become involved in research.

物理因素，如光，温度和营养物质的可用性是众所周知的限制海洋生产力，并在确定物种分布和群落结构中发挥重要作用。大多数对物理因素作用的理解是基于对单一变量的研究，其他条件对生长进行了优化。因此，很少有关于对自然环境的生理反应的信息，其中几个物理因素可能是次优的。理解海洋生产力的限制的能力，不仅需要了解潜在的协同或拮抗作用，而且还需要分析它们对不同生态策略的藻类的影响。本研究将探讨海洋红藻对氮限制和紫外线胁迫的反应。众所周知，这两个因素都是海洋初级生产力的重要决定因素，而且经常同时出现。不仅热带地区如此，像缅因州这样的冷温带海洋也是如此。红色的大型藻类被选中进行这项研究，因为它们提供了机会，以研究在一组藻类具有相似的生理和形态特征，但具有明确的差异，在紫外线耐受性和良好的特点内容的类菌孢素氨基酸的紫外线和氮限制之间的相互作用。此外，与浮游植物相比，底栖大型藻类经历的光照气候更可预测，寿命相对较长，使个体暴露于更广泛的环境条件。从缅因州海湾研究的红藻将包括紫菜脐，角叉菜，膜翅目阿拉塔和藻红。 这些物种从耐紫外线的潮间带和浅亚沿岸物种到深亚沿岸的易受紫外线影响的物种。研究人员预计，耐紫外线的成本和收益以及氮限制的影响将在耐紫外线和易受紫外线影响的物种之间有所不同。该研究将集中在氮代谢（有限或充分）对（a）紫外线胁迫的短期和长期影响（例如，光合作用、脂质过氧化和生长的短期抑制），（B）UV-光保护，包括防晒剂如类菌孢菌素氨基酸（MAA），抗氧化剂如抗坏血酸、谷胱甘肽和生育酚，以及活性氧代谢酶如过氧化氢酶、超氧化物歧化酶和抗坏血酸过氧化物酶的含量，和（c）从UV-胁迫中恢复的能力（例如，蛋白质合成在恢复中的作用）。该研究还将研究紫外线胁迫对氮代谢的影响（例如，氮含量和吸收和同化速率）。这项研究将涉及对实地收集的材料进行测量，在受控条件下进行实验室实验，以及在流动的海水中进行室外实验，并通过各种紫外线和光合有效辐射过滤器控制自然辐射。这项研究将大大有助于了解紫外线和无机氮供应对海洋生产力的影响，特别是阐明这些因素之间相互作用的重要性。这项研究涉及本科教学机构（韦斯特菲尔德州立学院，马萨诸塞州）和陆地和海洋赠款研究大学（缅因州大学）的教师之间的合作。除了研究生教育外，该项目还为本科生提供了大量的研究经验，为韦斯特菲尔德州立学院的本科生提供了参与研究的机会。