Cyanobacteria ~ blue-green algae Ancient, ubiquitous Created world’s oxygen atmosphere Ancestors of green plants Produce ~ 50% of the oxygen in the atmosphere today BUT: Develop excessive blooms, scums, mats due to human pressures on water resources Present economic, aesthetic, and health problems Many produce potent TOXINS Risk management needs

Freshwater cyanobacterial blooms, a global phenomenon

Cyanotoxins occur annually in water resources, including those used for drinking, fisheries, recreation and tourism present substantial risks to human and animal health are produced globally require to be detected and quantified to meet guidelines and regulations

Classes of Cyanotoxins (1) Hepatotoxins: microcystins, nodularins cylindrospermopsins (2) Neurotoxins: anatoxin-a, homoanatoxin anatoxin-a(s), saxitoxins (3) Irritants and allergenic toxins: aplysiatoxins, lipopolysaccharide endotoxins

Microcystins Group of >80 structurally related cyclic heptapeptides In acute cases death occurs by hypovolaemic shock Able to inhibit protein phosphatases and may affect cell cycle Tumour promoters

Cylindrospermopsin A guanidine alkaloid hepatotoxin andgenotoxin Affects multiple organs Inhibits eukaryotic protein translation Causes DNA strand breaks Mostly found in tropical

Saxitoxins A group of ~20 structurally related alkaloids Bind to voltage gated Na+ channels Paralysis and death LD50 10μg kg-1 (i.p. mouse)

Anatoxin-a Small molecular weight alkaloid that mimics acetylcholine 7 structural variants known to exist Structural analogue of cocaine Death by paralysis and asphyxiation

LPS endotoxins Characteristic of Gram negative bacteria (including cyanobacteria) Found in the outer layer of the cell wall The lipid A component responsible for human health effects Fever, vomiting, diarrhoea and inflammation

BMAA- a new cyanobacterial toxin? Non-protein amino acid Binds to glutamic acid receptors Acutely neurotoxic to primates in high doses Associated with an incidence of Motor Neuron Disease

GenusToxins produced AnabaenaAnatoxinsAnatoxins, Microcystins, SaxitoxinsMicrocystinsSaxitoxins AnabaenopsisMicrocystins AphanizomenonSaxitoxinsSaxitoxins, CylindrospermopsinsCylindrospermopsins CylindrospermopsisCylindrospermopsinsCylindrospermopsins, SaxitoxinsSaxitoxins HapalosiphonMicrocystins LyngbyaAplysiatoxinsAplysiatoxins, Lyngbyatoxin aLyngbyatoxin a MicrocystisMicrocystins NodulariaNodularin NostocMicrocystins Phormidium (Oscillatoria)Anatoxin Planktothrix (Oscillatoria) AnatoxinsAnatoxins, Aplysiatoxins, Microcystins, SaxitoxinsAplysiatoxins MicrocystinsSaxitoxins SchizothrixAplysiatoxins Trichodesmiumyet to be identified UmezakiaCylindrospermopsin

* Not all species within a genus produce the same toxins. In addition to these toxins, many other bioactive compounds have been isolated from cyanobacteria. Some have been determined to be toxic to specific organisms and are potentially toxic to humans.

Impacts on Human Health Gastrointestinal upsets (USA, Zimbabwe, UK, Australia, Sweden) Contact dermatitis, mucosal irritation (Pacific Islands,UK, USA, Norway, Australia) Liver damage (Brazil, Australia) Kidney damage (Australia) Neurological damage (Brazil) Pulmonary consolidation (atypical pneumonia, UK)

Potential Long-Term Health Effects Microcystins – Tumour promotion Nodularin – Tumour promotion and possible carcinogenicity Cylindrospermopsin – Carcinogenicity through effects on DNA BMAA – Possible association with human neurodegeneration

Exposure routes Drinking water Diet Dermal Pulmonary Haemodialysis

Human health incidents Itaparica Dam – Gastrointestinal upset (2000 cases) – 88 deaths over a 42 day period – Microcystis and Anabaena present in water – Cyanotoxins thought to be the cause Primary liver cancer in China – “Hot spots” related to drinking water supply – Surface vs. well water

CLIMATE CHANGE internationally agreed that cyanobacterial Blooms will increase in geographical spread, population density and seasonal duration

Examination of the evolutionary history of cyanobacteria, studies of their ecophysiology, and recent investigations of phytoplankton dynamics and community structure in response to global climate change all suggest that cyanobacteria will probably thrive under environmental conditions associated with global warming.

The Team