UV-C suppression on hazardous metabolites in Microcystis aeruginosa: Unsynchronized production of microcystins and odorous compounds at population and single-cell level.

The effectiveness of UV-C towards the toxin and odor of M. aeruginosa at population and single cell levels were investigated in three ways. In the absence of UV-C, MC-LR and ß-cyclocitral production show similar pattern of incremental rate with growth rate on population level shown as intracellular concentrations of MC-LR (CMC) and ß-cyclocitral (CBCC), but the cellular quota of MC-LR (QMC) and ß-cyclocitral (QBCC) at single-cell level reached the maximum values, 37.5 ± 1.2 fg cell-1 and 4.3 ± 0.1 fg cell-1, just after the early exponential phase. Second, upon UV-C irradiation, the CMC consistently decreased by 10-41% with increase of UV-C dosage (50-200 mJ cm-2) while CBCC increased by 2-14%. Third, during the 14 days' post-UV incubation, UV-C at 75-200 mJ cm-2 induced remarkable suppressing effects on both CMC and CBCC for 3-14 days. The suppressing effects on QMC and QBCC were induced by UV-C at 100 mJ cm-2 and above, with shorter suppressing periods by 1-4 days and lower decremental rates by 21%-30% than that of CMC and CBCC, indicating interruptions on biosynthesis processes partially contribute to suppression effects of CMC and CBCC. The suppression effect on either CBCC or QBCC, with higher decrement rates while lower recovery rates, was more severe than CMC and QMC.

The influence of ultraviolet radiation on the content of pharmacologically active taxoids in yew tissues.

The aim of the work was the investigation of the influence of UV radiation on the taxoids contents in yew tissues. The experiment was performed using Taxus baccata var. Aurea Corr. twigs irradiated with UV C (lambda = 254 nm) and UV A (lambda = 366 nm) in comparison to control samples. Multistep procedure of sample preparation was applied before the analysis of paclitaxel and 10-DAB III: SPE using alumina - for purification from the chlorophylles, waxes and polar balasts as well as zonal micropreparative TLC on silica - for isolation of partially separated fractions. The quantitation of some taxoids in the isolated fractions was performed using RP-HPLC procedure in system C18/acetonitrile + water. The experiments with UV-A and especially UV-C radiation showed changes in concentrations of paclitaxel and its precursor-10-deacetylbaccatin III. The results can be utilized to increase the yield of the taxoids isolated for medicinal and practical purposes.