Effect of hexachlorobenzene (HCB) on the activity of some enzymes from Tetrahymena pyriformis.

Tetrahymena pyriformis Wh 14 was grown in Erlenmeyer flasks under continuous stirring at 30 degrees C for three days . After the culture had produced dry matter of about 100 mg HCB was added in acetone at a dose level of 0, 0.001, 0.1 and 1.0 ppm to the culture and incubated for another 7 days. At a dose level of 0.001 ppm the activity of delta-aminolevulinate dehydratase, hexokinase, and pyruvate kinase remained unaffected but was increased for glutamic-oxaloacetic transaminase, glutamic dehydrogenase, isocitrate dehydrogenase, and malate dehydrogenase while 0.1 ppm HCB increased the activity of all enzymes studied, the only exception being glutamic-pyruvic transaminase, the activity of which was depressed by HCB exposure. A concentration of 1.0 ppm HCB depressed the activity of most of the enzymes below control values with the exception of the two mitochondrial enzymes, MDH and ICDH, studied here.

Effect of hexachlorobenzene (HCB) on photosynthetic oxygen evolution and respiration of Chlorella pyrenoidosa.

In experiments with Chlorella pyrenoidosa it was shown that an exposure of these cells to HCB at a dose level of 0.1, 1.0, and 5.0 ppm caused an inhibition of photosynthetic oxygen evolution of 33.3, 42, and 51%, respectively. Respiration, however, was inhibited only slightly, if at all.

Effect of hexachlorobenzene and acetone on algal growth: physiology and ultrastructure.

The effect of hexachlorobenzene (HCB) and acetone on growth and ultrastructure of the freshwater alga Chlorella pyrenoidosa was studied. The algal cells were grown for 76 h under continuous light in 10 ppm HCB with 0.33% acetone or in 0.33% acetone alone; the control cells were grown in nutrient solution only. As was deduced from determinations of dry matter, carbohydrates, chlorophyll content and total nitrogen, 0.33% acetone in nutrient solution slightly decreased the growth of the cells without having any influence on their ultrastructure while 3.33% acetone affected the ultrastructure of the cells severely. An incubation of Chlorella with 10 ppm HCB in nutrient sultion containing 0.33% acetone led to a drastic decrease of all growth parameters studied, total nitrogen and chlorophyll content being affected most strongly. These latter observations were in accord with the changes in ultrastructure showing damage to the cell membranes, disintegrated cytoplasm and sometimes even break down of cell organells leaving only starch grains, the pyrenoid and some endomembranes. In addition to these cells with severe lesions, quite normal cells were found.

Effect of hexachlorobenzene (HCB) on growth of Tetrahymena pyriformis.

Tetrahymena pyriformis Wh 14 was incubated with HCB (0.001 - 0.5 ppm) in Erlenmeyer flasks under continuous stirring at 30degreesC for 10 days in an incubator. HCB decreased growth as deduced from measurements of dry weight, carbohydrates, and total nitrogen. Total nitrogen and carbohydrates are decreased drastically while dry matter is reduced only by a factor of two. The excretion of a compound into the nutrient solution which yields a colour with modified Ehrlich reagent like porphobilinogen is very strongly increased by HCB. All effects observed were very well correlated with the concentration of this compound applied.

Effect of hexachlorobenzene on some growth parameters of Chlorella pyrenoidosa.

Chlorella pyrenoidosa was incubated with HCB (0.001-10.0 ppm) in a "light-thermostat" at 30 degrees C for 46 h with continuous light (4000 Lux) and aeration. HCB decreased growth as deduced from measurements of chlorophyll content, dry matter, carbohydrate content, and total nitrogen. Incubation with HCB for three months in Erlenmeyer-flasks resulted in an increase of chlorophyll over control value in cultures receiving 0.1 and 1.0 ppm HCB. After transfer of the cultures from Erlenmeyer-flasks to growth conditions of a "light-thermostat", growth of the algae was greatly enhanced by all HCB concentrations studied; a concentration of 0.1 ppm being most effective.