Biomagnification of cyanobacterial neurotoxins and neurodegenerative disease among the Chamorro people of Guam
Biomagnification of cyanobacterial neurotoxins and neurodegenerative disease among the Chamorro people of Guam
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DOI：
10.1073/pnas.2235808100
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发表时间：
2003-11-11
影响因子：
11.1
通讯作者：
Murch, SJ
中科院分区：
文献类型：
--
作者：
Cox, PA;Banack, SA;Murch, SJ
我们在这里报告生物放大作用（生物活性的增加积累，往往是有害的分子，通过更高的营养水平的食物链）的神经毒性非蛋白质氨基酸β-甲氨基-L-丙氨酸（BMAA）在关岛生态系统。自由生活的蓝藻产生0.3 μ g/g的BMAA，但在苏铁树的珊瑚状根中作为共生体产生2-37 μ g/g。BMAA集中在小果苏铁的发育中的生殖组织中，在肉质种子肉种皮中平均为9 mug/g，在最外层种子层中平均为1，161 mug/g。以种子为食的狐蝠（Pteropus mariannus）平均积累了3,556 mug/g的BMAA。狐蝠是土著查莫罗人的珍贵食物，他们把狐蝠放在椰子奶油里煮，然后整个吃掉。死于肌萎缩侧索硬化症/帕金森痴呆综合症（ALSPDC）的查莫罗人，一种神经退行性疾病，症状类似于肌萎缩侧索硬化症，帕金森病和阿尔茨海默病，他们的脑组织中平均有6.6 mug/g BMAA。BMAA通过关岛生态系统的生物放大作用符合一个典型的三角形，即有毒化合物在食物链上游的浓度不断增加。这可以解释为什么查莫罗人ALS-PDC的发病率是其他地方肌萎缩侧索硬化症发病率的50-100倍。蓝藻BMAA的生物放大作用可能不是关岛独有的;我们在加拿大阿尔茨海默氏症患者脑组织中发现的BMAA表明，BMAA在水生或陆地生态系统中的生物积累存在其他生态途径。
We here report biomagnification (the increasing accumulation of bioactive, often deleterious molecules through higher trophic levels of a food chain) of the neurotoxic nonprotein amino acid beta-methylamino-L-alanine (BMAA) in the Guam ecosystem. Free-living cyanobacteria produce 0.3 mug/g BMAA, but produce 2-37 mug/g as symbionts in the coralloid roots of cycad trees. BMAA is concentrated in the developing reproductive tissues of the cycad Cycas micronesica, averaging 9 mug/g in the fleshy seed sarcotesta and a mean of 1,161 mug/g BMAA in the outermost seed layer. Flying foxes (Pteropus mariannus), which forage on the seeds, accumulate a mean of 3,556 mug/g BMAA. Flying foxes are a prized food item of the indigenous Chamorro people who boil them in coconut cream and eat them whole. Chamorros who die of amyo trophic lateral sclerosis/parkinsonism-dementia complex (ALSPDC), a neurodegenerative disease with symptoms similar to amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease, have an average of 6.6 mug/g BMAA in their brain tissues. The biomagnification of BMAA through the Guam ecosystem fits a classic triangle of increasing concentrations of toxic compounds up the food chain. This may explain why the incidence of ALS-PDC among the Chamorro was 50-100 times the incidence of amyotrophic lateral sclerosis elsewhere. Biomagnification of cyanobacterial BMAA may not be unique to Guam; our discovery of BMAA in the brain tissue from Alzheimer's patients from Canada suggests alternative ecological pathways for the bioaccumulation of BMAA in aquatic or terrestrial ecosystems.