The non-protein amino acid β-N-methylamino-l-alanine in Portuguese cyanobacterial isolates

Abstract

The tailor made amino acid β-N-methyl-amino-L-alanine (BMAA) is a neurotoxin produced by cyanobacteria. It has been associated with certain forms of progressive neurodegenerative disease, including sporadic Amyotrophic Lateral Sclerosis and Alzheimer's disease. Some different reports of BMAA in cyanobacterial blooms from lakes, reservoirs, and other water resources have been made by different investigators. We here report the detection of BMAA of both free and protein-bound produced by cyanobacteria, belonging to the Chroococcales, Oscillatoriales and Nostocales ordered. We use a rapid and sensitive HPLC-FD method that utilizes methanol elution and the Waters AQC Tag chemistry. On other hand, we have used three different assay procedures for BMAA extraction from cyanobacteria: Trichloroacetic acid (TCA), Methanol/Acetone and hydrochloric acid (HCl). All assays let successfully detect BMAA in all cyanobacteria samples analyzed. Nevertheless, with TCA and HCl extraction procedures the highest BMAA values, for free as well as protein-bound BMAA were detected. BMAA content could not be related to the taxonomy of the isolates or to their geographical origin, and no correlation between free and protein-bound BMAA concentrations were observed within or between taxonomic groups. These data offer confirmation of the taxonomic and geographic ubiquity of BMAA from naturally occurring populations of cyanobacteria, for the first time reported for estuaries.

New Typical Vector of Neurotoxin β-N-Methylamino-l-Alanine (BMAA) in the Marine Benthic Ecosystem

“…A picture is developing of widespread occurrence of BMAA in aquatic organisms (Table S1) [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38]. Of particular interest is the presence of BMAA in marine animals collected from the coastal area of Florida, USA, and the southern coast of Stockholm, Sweden [22,23].…”

The neurotoxin BMAA in aquatic systems : analysis, occurrence and effects

“…Table 5.1). In the only studies where multiple AQC methods were quantitatively compared, there was a discrepancy in results between the AQC LC-FLD and the AQC LC-MS/MS method [93] and between two AQC LC-FLD methods [133].…”

“…[82,95,144,147,157,159,163]). Especially in studies in which optical detection was used as the primary analytical method and in which high BMAA concentrations were found using these methods [96,121,133,144]; no reference to the debate on concentrations and methods was made.…”

“…At present, the cause of these differences in BMAA concentrations in cyanobacteria has not been identified yet, although it is very probable that studies that have used the unselective HPLC-FLD (e.g. [33,35,133]) have misidentified BMAA and/or overestimated its concentrations [93].…”

“…[151,152]) -though this is not the case for the BMAA results reported. Indeed, there is a strong bimodality in the absence/presence of BMAA in cyanobacteria samples, and analysis of similar [93,133] or comparable samples [36,122] with different methods yields different results (Table 5.1). This strongly suggests that additional factors to those influencing cyanobacterial metabolite production play a role in the reported divergences in cyanobacterial BMAA concentrations.…”