Food Chain Magnification of Marine Toxins

在这项研究中，夏威夷大学马诺阿分校的研究人员将研究夏威夷珊瑚礁动植物群中两种神经毒素的生物放大倍数。这两种毒素，β - n -甲氨基- l -丙氨酸（BMAA）是一种低分子量（约120amu）氨基酸，而雪卡毒素（CTX）是一种大分子（约1200 amu）聚醚，因为它们的化学性质不同，因此可能有非常不同的生物放大模式。这项工作将利用研究和解释特定氨基酸中氮分异的最新进展来确定生物体在食物网中相对于第一营养水平的位置。来源氨基酸（甘氨酸、赖氨酸、苯丙氨酸、丝氨酸、苏氨酸和酪氨酸）记录了食物网底部氮源的d15N值，营养氨基酸（丙氨酸、天冬氨酸、谷氨酸、异亮氨酸、亮氨酸、脯氨酸和缬氨酸）反映了消费者的营养水平。将在(1)简单的线性食物链和(2)非结构化食物网的框架内分析鱼类和贝类组织中营养氨基酸和来源氨基酸的d15N值差异与毒素浓度之间的关系，以确定哪种理论结构与实验结果最一致。进一步的研究将集中于对CTX和BMAA生产的环境控制程度，以及这些毒素在鱼类和贝类体内的浓度差异在多大程度上反映了消费生物的摄食/生理差异或生产者一级物种之间的差异。拟议的工作反映了实验观察和理论理解的整合，以深入了解通过海洋食物网调节毒素运动的过程。实验使用化合物特异性15N分析来源和营养氨基酸来确定生物体？非结构化食物网理论或其变体的应用可能证明有必要解释具有珊瑚礁生物群落特征的复杂食物网中的生物放大模式。由于这些食物网的复杂性绝不是异常的，因此从本研究中获得的见解可能对食物网偏离严格线性的海洋系统具有广泛的适用性。拟议工作的更广泛影响包括(1)资助夏威夷大学（UH）全球环境科学专业的学生参与他们的高级研究项目，(2)包括NSF REU学生（C-MORE微生物海洋学研究经验-提案待定），(3)由UH副校长承诺投入20万美元用于购买一台四极杆质谱仪，并配备适当的APCI/ESI探针硬件，以方便确定珊瑚礁动植物提取物中的雪卡毒素和相关毒素的结构；(4)出版针对本科生和研究生的教育材料；并将这些材料纳入夏威夷大学海洋系的课程中。

In this study, researchers at the University of Hawaii at Manoa will examine the biological magnification of two neurotoxins in the flora and fauna of Hawaiian coral reefs. The toxins, beta-N-methylamino-L-alanine (BMAA), a low molecular weight (ca. 120amu) amino acid, and ciguatoxin (CTX), a large molecular weight (ca. 1,200 amu) polyether, were selected for study because of their different chemical natures and hence potentially very different biological magnification patterns. The work will take advantage of recent advances in the study and interpretation of nitrogen fractionation within specific amino acids to identify an organism's position in the food web relative to the first trophic level. Source amino acids (glycine, lysine, phenylalanine, serine, threonine and tyrosine) record the d15N value of the source of nitrogen at the base of the food web, and trophic amino acids (alanine, aspartic acid, glutamic acid, isoleucine, leucine, proline and valine) reflect the trophic level of the consumer. The relationship between the difference between the d15N values of trophic and source amino acids and toxin concentrations in the tissues of fish and shellfish will be analyzed within the framework of (1) a simple linear food chain and (2) an unstructured food web to determine which theoretical construct is most consistent with experimental results. Additional studies will focus on the degree of environmental control of CTX and BMAA production and the extent to which differences in the concentrations of these toxins in fish and shellfish reflect differences in the feeding/physiology of consumer organisms or variability between species at the producer level.The proposed work reflects the integration of experimental observations and theoretical understanding to gain insight into the processes that regulate the movement of toxins through marine food webs. Experimentally the use of compound-specific 15N analyses of source and trophic amino acids to determine an organism?s position in a food web is an important recent advancement, and application of unstructured food web theory or variations thereof will likely prove necessary to explain the patterns of biological magnification in the complex food webs that characterize coral reef biological communities. Since the complexity of these food webs is by no means anomalous, insights gained from this study may have broad applicability to marine systems where food webs depart from strict linearity. The broader impacts of the proposed work include (1) funding for the participation of University of Hawaii (UH) Global Environmental Science majors working on their senior research projects, (2) the inclusion of NSF REU students (C-MORE Research Experiences in Microbial Oceanography - proposal pending), (3) a $200,000 commitment by the UH vice chancellor for research to purchase a quadrupole mass spectrometer with the appropriate APCI/ESI probe hardware to facilitate the determination of the structures of ciguatoxins and related toxins in extracts from coral reef flora and fauna, and (4) the publication of educational materials that target both undergraduate and graduate students, and the inclusion of these material into courses offered by the Department of Oceanography at the University of Hawaii.