Temporal variabilities of the concentrations of intra- and extracellular microcystin and toxicMicrocystis species in a hypertrophic lake, Lake Suwa, Japan (1991-1994)

Abstract

Temporal variability in the concentration of toxic heptapeptide microcystin was studied ( ) ( ) during the warm season of four years 1991 -1994 in a hypertrophic lake Lake Suwa in central ( ) ( Honshu, Japan. Lake water samples ca. 5 L were filtered to separate intracellular microcystin cell ) ( ) fraction from extracellular microcystin filtered lake water fraction . These fractions were analyzed to measure the total quantity of microcystin in lake water. Total amounts of extra-and intracellular microcystin were measured with high performance liquid chromatography. Concentrations of intracellu-( ) lar microcystin usually exceeded concentrations of extracellular microcystin 24 out of 26 times . High concentrations of intracellular microcystin were found during the exponential growth phase of the blooms, whereas concentrations of extracellular microcystin were highest at the end of the blooms.( ) However, concentrations of extracellular microcystin remained very small -4 g / L compared to the levels of intracellular microcystin. The relatively higher percentages of microcystin in filtered lake water ( ) )20% at the end of blooms suggests that release of microcystin from cells occurs during senescence and the decomposition period of Microcystis cells.

Hepatic Histopathological Characteristics and Antioxidant Response of Phytoplanktivorous Silver Carp Intraperitoneally Injected with Extracted Microcystins

“…MCs were prepared and measured as previously described [14] with some improvements. Briefly, the materials were extracted three times with 10 mL of 75% methanol (v/v) for 3 h at 4 .…”

The first study on the effects of microcystin-RR on gene expression profiles of antioxidant enzymes and heat shock protein-70 in Synechocystis sp. PCC6803

“…The samples were centrifuged at 12 000g for 10 min, and the supernatant was used to determine the concentration of MC-RR. MCs samples were prepared according to the method of Park and Lwami (1998) with minor modifications. 1-ml supernatant of the samples was applied to a C18 reversed phase cartridge (0.5 g), which had been preconditioned by washing with 10-ml 100% methanol and 10-ml distilled water.…”

“…Recovery experiments were performed in sixplicate spiked water as described previously (Park and Lwami, 1998): 1 ml 1 mg/ml of purified MC-RR was applied to 0.5 g C18 reversed phase cartridge, and the column was washed and eluted according to the above method of MC-RR samples preparation. The recovery of the analytical method was calculated.…”

Effects of Nitrogen Forms on the Production of Cyanobacterial Toxin Microcystin-LR by an Isolated Microcystis aeruginosa

“…It was reported that the content of MC-RR in the isolated strains of M. viridis and M. aeruginosa from Dianchi Lake were higher than that of MC-LR. [16,17] Park et al [18] observed that the content of MC-RR in collected cyanobacterial cells from Lake Suwa in Japan was much higher than that of MC-LR. Here a MC-LR rather than MC-RR producing strain M. aeruginosa DC-1 was isolated from the Dianchi Lake of China.…”