Molecular oxygen can act as a collisional quencher of the singlet excited state of chloro­ phyll a. This effect is well described for chlorophyll a in various solvents but not for chloro­ phyll a in the antenna complexes of photosynthetic organisms. We studied the chlorophyll fluorescence decay of Chlorella vulgaris cells under different oxygen concentrations but did not find any evidence for q...

This study aims to assess the effects of two pesticides, namely the insecticide carbofuran and the herbicide isoproturon, on monospecifically cultivated marine and freshwater phytoplankton according to standard methods. In the presence of pesticide, growth rates were lower in marine species Chaetoceros gracilis and Phaeodactylum tricornutum than in freshwater species Chlorella vulgaris and Sele...

ASSIMILATORY NITRATE REDUCTASE (NADH: nitrate oxidoreductase, EC 1.6.6.1) from Chlorella vulgaris has been purified to electrophoretic homogeneity with an overall yield of 60% by a procedure that utilizes blue dextran-agarose as an affinity column. Nitrate reductase binds to blue dextran and is not eluted in the presence of high ionic strength buffer but is rapidly eluted in the presence of mum...

Chlorella vulgaris was tested to assess their toxicities in freshwater contaminated by the metal compounds of copper (Cu) and cadmium (Cd), both singly and combined. Exposure to 0.5 and 1.5 M Cu or 1.0 and 2.0 M Cd alone significantly decreased algal growth and chlorophyll content and increased reactive oxygen species (ROS) content. Two-way ANOVA analysis shows that the combination of these two...

The oxygen consumption of a starved chlorophyll-free, yellow mutant of Chlorella vulgaris is enhanced by very small amounts of blue light (lambda 450 mmu); a saturation level is reached at about 500 ergs cm(-2) sec(-1). At that intensity the respiration is about 3 times greater than in the dark. An action spectrum for the enhancement of respiration shows 2 peaks around lambda 450 and 375 mmu. F...

The toxic effects of ethyl cinnamate on the photosynthetic and physiological characteristics of Chlorella vulgaris were studied based on chlorophyll fluorescence and flow cytometry analysis. Parameters, including biomass, F(v)/F(m) (maximal photochemical efficiency of PSII), Ф(PSII) (actual photochemical efficiency of PSII in the light), FDA, and PI staining fluorescence, were measured. The res...