Louise F. Morrison

Co-occurrence of β-N-methylamino-l-alanine, a neurotoxic amino acid with other cyanobacterial toxins in British waterbodies, 1990–2004

The neurotoxic amino acid, beta-N-methylamino-L-alanine, was found to be present in all of 12 analysed samples of cyanobacterial blooms, scums and mats, which had been collected in seven years between 1990 and 2004 inclusive and stored at -20 degrees C. BMAA identification was by high performance liquid chromatography with fluorescence detection and by triple quadrapole mass spectrometry after derivatization. The samples originated from 11 freshwater lakes and 1 brackish waterbody, used either for drinking water, recreation, or both. BMAA was present at between 8 and 287 microg g(-1) cyanobacterial dry weight and was present as both the free amino acid and associated with precipitated proteins. Ten of the samples contained additional cyanotoxins (including microcystins, anatoxin-a, nodularin and saxitoxin) at the time of sample collection. Five of the samples were associated with animal deaths, attributable at the time of sample collection, to microcystins, nodularin or anatoxin-a. The data demonstrate the presence of BMAA by high performance liquid chromatography and mass spectrometry in a diverse range of cyanobacterial bloom samples from high resource waterbodies. Furthermore, samples collected over several years shows that BMAA can co-occur with other known cyanotoxins in such waterbodies. Health risk assessment of cyanobacterial BMAA in waterbodies is suggested.

Investigations into the taxonomy, toxicity and ecology of benthic cyanobacterial accumulations in Myall Lake, Australia

Large benthic accumulations of cyanobacteria occur in sheltered embayments within Myall Lake, New South Wales, Australia. The lake is shallow, with the entire bottom within the euphotic zone, and it is generally considered pristine, having low nutrient concentrations. The accumulations are highly organic and contain a mix of species mainly from the order Chroococcales, with two forms of Aphanothece being dominant. However polymerase chain reaction (PCR) analysis indicates a close similarity to Microcystis flos-aquae. The cells appear to lack aerotopes and form sticky mucilaginous amalgamations, which may enhance their benthic habit. Although Chroococcales also dominate the planktonic cyanobacterial community, the benthic species are seldom, if ever, found entrained within the water column. Some hepatotoxicity was indicated by mouse bioassay, protein phosphatase inhibition assay, enzyme-linked immuno-sorbent assay (ELISA) for microcystins, PCR and by chromatographic evidence for a microcystin. Ecological aspects of the distribution, gross morphology of the organisms and management implications for recreational water-users are discussed.

Analysis of the cyanotoxins anatoxin-a and microcystins in Lesser Flamingo feathers

Feathers from carcasses of the Lesser Flamingo (Phoeniconaias minor), which had died after ingesting cyanobacterial toxins (cyanotoxins) contained between 0.02 and 30.0 µg microcystin-LR equivalents per gram of feather according to HPLC and ELISA analysis of feather extracts. Anatoxin-a was detected less frequently in the Lesser Flamingo feathers, up to 0.8 µg anatoxin-a per gram of feather being recorded. When feathers from different body regions were analysed and compared for microcystins and anatoxin-a, wing feathers were found to contain the highest concentrations of these cyanotoxins, the order of concentration and frequency of analytical detection being wing > breast > head. Consistent with the presence of the microcystins and anatoxin-a in gut contents and the livers of the dead birds and negligible in vitro adsorption to feathers, the cyanotoxins associated with the feathers of the dead wild flamingos are inferred to be primarily of dietary origin. †Dedicated to the memory of Ekkehard and Angelika Vareschi.

Quantification and localization of microcystins in colonies of a laboratory strain of Microcystis (Cyanobacteria) using immunological methods

Microcystins (MCs) are cyanobacterial hepatotoxins responsible for animal poisonings and human health incidents. Whilst the colony-forming Microcystis spp. are among the most commonly encountered MC-producers, quantitative data are lacking on MC concentrations per colony and on the localization of MCs within Microcystis colonies. We have quantified and localized MCs in colonies of a laboratory strain of Microcystis aeruginosa using antibodies against microcystin-LR. MCs were quantified in 70 colonies of Microcystis EBRO. The MC quota per colony (n = 70) ranged from 0.36 to 15.23 ng colony−1 and showed a positive relationship with colony size. MC distribution within the colonies was determined using cryosectioning and immunogold localization. MCs were specifically localized in the nucleoplasmic region of the cells and were also associated with major inclusion bodies, with a preferential association with the thylakoids (the most abundantly labelled subcellular site) and around polyphosphate bodies. All of the cells in the MC-containing colonies were specifically labelled for MCs with no gradients in MC antibody labelling across colony transects being apparent. The toxins were also found to be associated with colony mucilage. MC antisera are useful for the investigation of MC distribution within cyanobacterial populations by ELISA, and may be used in the future to localize the toxins within cyanobacterial colonies, filaments and gyres from natural environments.

A Novel Biosurfactant, 2-Acyloxyethylphosphonate, Isolated from Waterblooms of Aphanizomenon flos-aquae

A novel biosurfactant, 2-acyloxyethylphosphonate, was isolated from waterblooms of Aphanizomenon flos-aquae. Its structure was elucidated by chemical degradation and HRFABMS, GC/EI-MS and 1D- and 2D-NMR spectral analyses. The surfactant contained one mole of 2-hydroxyethylphosphonate and one mole of fatty acid, with hexadecanoic acid accounting for 84.1% of the total fatty acid content. The structure was confirmed by synthesis of 2-oleoyloxyethylphosphonate from ethylene oxide, phosphorus acid and oleic acid chloride. Considering the isolated surfactant molecule as hexadecanoyloxyethylphosphonic acid (mw. 364), the critical micelle concentration (CMC) was about 22 mM.