β-N-methylamino-l-alanine (BMAA), a non-protein amino acid with neurodegenerative features, is known to be produced by cyanobacteria, diatoms and a dinoflagellate. BMAA research has intensified over the last decade, and knowledge has been gained about its bioaccumulation in aquatic and terrestrial ecosystems, toxic effects in model organisms and neurotoxicity in vivo and in vitro. Nevertheless, knowledge of the actual physiological role of BMAA in the producing species or of the ecological factors that regulate BMAA production is still lacking. A few studies propose that BMAA functions to signal nitrogen depletion in cyanobacteria. To investigate whether BMAA might have a similar role in diatoms, two diatom species – Phaeodactylum tricornutum and Thalassiosira weissflogii – were exposed to exogenous BMAA at environmental relevant concentrations, i.e. 0.005, 0.05 and 0.5 μM. BMAA was taken up in a concentration dependent manner in both species in the BMAA free fraction and in the protein fraction of T. weissflogii. As a result of the treatments, the diatom cells at some of the time points and at some of the BMAA concentrations exhibited lower concentrations of chlorophyll a and protein, in comparison to controls. At the highest (0.5 μM) concentration of BMAA, extracellular ammonia was found in the media of both species at all time points. These results suggest that BMAA interferes with nitrogen metabolism in diatoms, possibly by inhibiting ammonium assimilation via the GS/GOGAT pathway.

β-N-甲基氨基-1-丙氨酸（BMAA）是一种具有神经变性特征的非蛋白质氨基酸，已知是由蓝细菌，硅藻和鞭毛鞭毛藻产生的。BMAA研究在过去十年中得到了加强，并且已经获得了有关其在水生和陆地生态系统中的生物蓄积性，对模型生物的毒性作用以及体内和体外神经毒性的知识。但是，仍然缺乏关于BMAA在生产物种中实际生理作用或调节BMAA生产的生态因素的知识。一些研究表明，BMAA的功能是指示蓝细菌中的氮耗竭。为了研究BMAA是否可能在硅藻中具有相似的作用，我们研究了两种硅藻物种–角皮氏菌（Phaeodactylum tricornutum）和Welasflogii-和Thalassiosira weissflogii –以环境相关浓度（即0.005、0.05和0.5μM）暴露于外源BMAA。BMAA在T. weissflogii的BMAA游离组分和蛋白组分中都以浓度依赖性的方式吸收。处理的结果是，与对照相比，硅藻细胞在某些时间点和某些BMAA浓度下显示出较低的叶绿素a和蛋白质浓度。在BMAA的最高浓度（0.5μM）下，两种物种在所有时间点的介质中均发现了细胞外氨。这些结果表明，BMAA可能通过抑制经由GS / GOGAT途径的铵同化作用来干扰硅藻中的氮代谢。