Overview Of  Toxic Cyanobacteria And Dinoflagellates And mcy Gene Clusters Responsible For Cyanotoxin Production

Lande, Vijay Wasudeorao

Abstract

Overview of toxic cyanobacteria  is related to cyanotoxin in this research article. Cyanobacterial bloom occur  in oligotrophic to mesotrophic conditions in waterbodies and related with environmental factors and nutrient concentrations. Analysis of microcystins, and health hazard  due to cyanotoxin of Microcystis aeurignosa and Anabaena sp., Planktothrix agardhii, were highlighted here. It is observed that cyanobacteria, dinoflagellate toxins are of hepatotoxic and neurotoxic nature and protect cells against planktivores. Toxin from Aphanizomenonflos-aquae, marine dinoflagellate Gonyaulax sp., Alexandrium sp., Gymnodinium sp., and Pyrodinium sp., (saxitoxins-STX) were causing  paralytic shell fish  poisoning (in human being). Microcystins oligopeptide structure have several congeners in cyanobacteria as biotoxin  were observed several species of cyanobacteria except cylindrospermopsin,  (a guanidine alkaloid-cytotoxin). During recent years, molecular biologist’s identified  mcyA to mcyE gene clusters that synthesize microcystins in toxic cyanobacteria. Studies of degenerate primers directed to conserved functional motifs (exons – open reading frames) of mcyABC to mcyDE gene clusters. Mutational studies were conducted to locate microcystin synthetase coding gene  sequences of in mcyB and mcyD genes. Presence mcyE gene sequences in multiple numbers for proportionate  toxic factor of microcystins production in toxic Microcystis and Anabaena strains in lakes were reported. Microcystins inhibits eukaryotic serine/threonine protein phosphatase 1 and 2A functions and result in hepatotxic tumor promoter. Earlier researchers have studied various aspects of toxic cyanobacteria i.e. genetic markers based polymerase chain reaction (QRT-PCR), production of nonribosomally synthesis of cyclic heptapeptide of microcystins (ribosomes involve in translation process of protein synthesis) Picomolar concentration microcystin congeners can be detected using Mass M/Z (i.e. mass to charge ratio)  in Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry analysis (MALDI-TOF-MS). Microsystis toxin  can be destroyed in chlorine under pH dependent condition such that chlorine residual at least 0.5mg/l should be present after  contact time of 30 minute. Ozone is also preferred disinfectant for water supplies where microcystin and anatoxin may affect water quality. Microcystins causes chronic toxicity. Symptoms of  hepatotoxin toxicity are weakness, loss of appetite (anorexia), pallor of intestine mucous membranes, vomiting, cold extremities and diarrhoea. Anatoxin an irreversible inhibitor of cholinesterase.is  also known for acute toxicity e.i. staggering, muscle fasciculation gasping and convulsion.


Keyword(s)

Cyanobacteria; Dinoflagellate; Microcystin; mcyABC and mcyDE Gene Clusters; QRT-PCR Technique; MALDI-TOF-MS Analysis


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