Molecular and Biochemical Basis for Stable Carbon Isotope Ratios in Hydrothermal Vent Ecosystems

热液喷口生态系统中稳定碳同位素比的分子和生化基础

• 批准号: 9504257
• 负责人: Colleen Cavanaugh
• 金额: $ 25.5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-06-15 至 1998-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9504257&HistoricalAwards=false
• 关键词: Molecular; Biochemical; Basis; Stable; Carbon

9504257 Cavanaugh Studies of stable isotopes allow valuable insight into various aspects of carbon cycling. For example, such stable carbon isotope data have been used to lend support to the putative dependence of several hydrothermal vent animals on organic matter produced by chemosynthetic endosymbionts. Unfortunately the observed isotope fractionations in various ecosystems have not always been readily understood, leading to equivocal conclusions regarding tropic relations between species in a given ecosystem. Again, the hydrothermal vent ecosystems provide an example of this. del13C values measured for symbiotic bivalves (del13C = -27% to -35%) mimic those of free-living chemoautotrophs, indicating the symbionts' nutritional role. In contrast, the food sources are less clear for tubeworm-chemoautotroph symbioses since these tissues exhibit surprisingly heavy stable isotope values (del13Cs = -9 to -35%). While a number of theories have been presented, the heavier isotope values for the symbioses have never been adequately explained. The recognition of different Rubisco forms being expressed may have far reaching implications, beyond interpretations of carbon cycling at hydrothermal vent ecosystems. The recent discovery of a form II Rubisco in a dinoflagellate indicates that this enzyme is not confined to the bacterial autotrophs, and may well explain the isotopically heavy del13C values of organic matter recovered from the open ocean. Accurately resolving the effects of various forms of the carbon fixation enzyme, Rubisco, may have a tremendous impact on interpretation of del13C data in ecological and paleontological studies. ***

小行星9504257 对稳定同位素的研究使人们对碳循环的各个方面有了有价值的了解。 例如，这种稳定的碳同位素数据已被用来支持若干热液喷口动物对化学合成内共生体产生的有机物的依赖性。 不幸的是，在各种生态系统中观察到的同位素分馏并不总是容易理解，导致在给定的生态系统中物种之间的热带关系的模棱两可的结论。 热液喷口生态系统再次提供了这方面的一个例子。 共生双壳类的del 13 C值（del 13 C = -27%至-35%）与自由生活的化能自养生物的del 13 C值相似，表明共生体的营养作用。 相比之下，食物来源不太清楚管虫化能自养共生体，因为这些组织表现出令人惊讶的重稳定同位素值（del 13 Cs = -9至-35%）。 虽然已经提出了许多理论，但共生体的较重同位素值从未得到充分解释。 对不同Rubisco形式的认识可能具有深远的影响，超出了对热液喷口生态系统碳循环的解释。 最近发现的一种甲藻中的II型Rubisco表明，这种酶并不局限于细菌的自养生物，并可能很好地解释了从公海回收的有机物的同位素重del 13 C值。 准确地解决各种形式的碳固定酶，Rubisco的影响，可能会产生巨大的影响，在生态和古生物学研究的del 13 C数据的解释。 ***