RESUMEN
A clonal isolate, termed L575, of the filamentous brackish-water cyanobacterium Nodularia spumigena Mertens emend. was found to produce a potent hepatotoxic peptide (50% lethal intraperitoneal dose for the mouse, 60 micrograms/kg) with chemical and toxicological properties similar to those of the hepatotoxic heptapeptides produced by other freshwater planktonic cyanobacteria. The isolate was made from a water sample collected in Lake Ellesmere, New Zealand, in 1980. The toxin, isolated and purified by high-performance liquid chromatography (HPLC) and analyzed by HPLC amino acid analysis, contained glutamic acid, beta-methyla-spartic acid, and arginine units in equivalent amounts. The fast-atom-bombardment mass spectrum of the toxin indicated the molecular weight to be 824. Batch cultures of strain L575 showed that the toxin content varied between 1.96 and 2.99 mg/g of cells and that a positive correlation between toxin content and chlorophyll a, but not biomass, was present.
Asunto(s)
Cianobacterias/metabolismo , Hígado/efectos de los fármacos , Péptidos/aislamiento & purificación , Toxinas Biológicas/aislamiento & purificación , Microbiología del Agua , Animales , Cromatografía en Gel , Cromatografía Líquida de Alta Presión , Cianobacterias/crecimiento & desarrollo , Cianobacterias/ultraestructura , Agua Dulce , Masculino , Espectrometría de Masas , Ratones , Microscopía Electrónica de Rastreo , Nueva Zelanda , Péptidos/análisis , Péptidos/toxicidad , Toxinas Biológicas/análisis , Toxinas Biológicas/toxicidadRESUMEN
Waterbloom samples of the colonial cyanobacterium Microcystis aeruginosa, collected in fish ponds at the Hydrobiological Institute, Wuhan, People's Republic of China, were hepatotoxic to mice. Lyophilized cells had an LD50 (i.p. mouse; 40 mg/kg) and signs of poisoning similar to that reported for other cyanobacterial hepatotoxic peptides. Two toxins, with an LD50 (i.p. mouse) of 40 and 150 micrograms/kg, were isolated using gel filtration and high performance liquid chromatography. The amino acid composition and mol. wt (994) of the 40 micrograms/kg toxin was the same as that for microcystin-LR, while the 150 micrograms/kg toxin had an amino acid composition and mol. wt (1048) different from any of the reported cyanobacteria heptapeptide toxins reported to date.