| 摘要: |
| 神经毒素β-N-甲氨基-L-丙氨酸(β-N-methylamino-L-alanine,BMAA)主要来自淡水或海洋环境中的蓝藻和硅藻,在海洋生态系统中具有明显的生物放大作用,被认为是诱发阿尔茨海默症(Alzheimer's Disease,AD)等多种神经退行性疾病的重要环境因子。近年,BMAA及其同分异构体2,4-二氨基丁酸(2,4-diaminobutyric acid,DAB)在我国及其他多个沿海国家和地区的贝类水产品中被普遍检出,潜在威胁消费者健康和海洋生态安全。但目前有关BMAA对海洋微藻的化学生态学作用尚不清楚。为此,通过向球等鞭金藻(Isochrysis galbana)培养基中分别添加不同浓度的BMAA及20种蛋白氨基酸,探究了BMAA单独及其与氨基酸联合作用96 h对球等鞭金藻比生长率和氨基酸含量的影响,并分析了微藻吸收外源BMAA的含量。结果表明,球等鞭金藻能吸收培养体系中的外源BMAA,吸收量与BMAA的添加浓度呈正相关,且进入细胞内的BMAA多半以溶解结合态形式存在;BMAA抑制批次培养的球等鞭金藻比生长率的96 h半效应浓度(96 h-EC50)约为2 μmol/L;与对照组相比,暴露于BMAA 96 h后球等鞭金藻细胞内酪氨酸、丙氨酸、丝氨酸等15种氨基酸的合成量明显降低;除脯氨酸、苏氨酸、甘氨酸外,其他17种氨基酸与BMAA联合暴露实验均增强了BMAA对球等鞭金藻比生长率的抑制效应,这可能与培养体系中的氨基酸促进了微藻吸收外源BMAA的能力有关。因此,海洋生态系统中BMAA毒素的化学生态学作用应引起人们的关注。有关BMAA抑制球等鞭金藻有丝分裂的分子机制有待进一步研究。 |
| 关键词: 球等鞭金藻 β-N-甲氨基-L-丙氨酸(BMAA) 神经毒素 氨基酸 抑制效应 比生长率 |
| DOI：10.11693/hyhz20211200341 |
| 分类号:S963.21+3,Q175 |
| 基金项目:国家自然科学基金面上项目,41676093号;NSFC-山东联合基金重点项目,U2106205号。 |
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| EFFECT OF NEUROTOXIN BMAA ON GROWTH OF MICROALGA ISOCHRYSIS GALBANA IN BATCH CULTURES |
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LI Ai-Feng1,2, LIU Jian-Wei1, HU Yang1, FU Yi-Lei1, QIU Jiang-Bing1,2
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1.College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China;2.Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
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| Abstract: |
| Neurotoxin β-N-methylamino-L-alanine (BMAA) is mainly produced by cyanobacteria and diatoms in the freshwater or marine environments, and it has obvious biomagnification behavior in food web in the marine ecosystem, which has been supposed as an important environmental factor inducing multiple neurodegenerative diseases such as Alzheimer’s Disease. In recent years, BMAA and its isomer, 2,4-diaminobutyric acid (DAB), have been widely detected in diverse shellfish aquatic products in China and many other coastal countries or regions, which potentially would threaten the health of consumers and marine ecosystem safety. However, the chemical ecology effect of BMAA on marine microalgae is still unknown. In this study, the effect of BMAA alone and its combination with different amino acids on the specific growth rate and amino acid content of Isochrysis galbana, as well as the accumulation of exogenous BMAA by microalgae were studied, through separately adding BMAA in different concentrations and twenty different protein amino acids to the media for batch cultures of microalga I. galbana. Results show that the microalga I. galbana could accumulate exogenous BMAA from the culture media depending on the concentration of BMAA. More than half of BMAA molecules were present in soluble protein-associate form in the microalgal cells. The 96 h-EC50 value of BMAA was inferred as 2 µmol/L to inhibit the specific growth rate of I. galbana in the batch cultures. Compared with the control groups, the synthesis amounts of fifteen amino acids such as tyrosine, alanine, and serine were significantly decreased in the microalgal cells after 96-h exposure to BMAA. Except for proline, threonine, and glycine, the other seventeen amino acids combined with BMAA enhanced the inhibitory effect of BMAA on the specific growth rate of I. galbana, by probably promoting the accumulation of exogenous BMAA by microalgae from the culture media. Therefore, the chemical ecology role of BMAA in marine ecosystems especially in the nearshore regions and the molecular mechanism of BMAA inhibiting the mitosis of I. galbana shall be revealed in the future. |
| Key words: Isochrysis galbana β-N-methylamino-L-alanine (BMAA) neurotoxin amino acids inhibitory effect specific growth rate |
