Dependence of sulphate uptake by Anacystis nidulans on energy, on osmotic shock and on sulphate starvation

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Abstract
Sulphate uptake by Anacystic nidulans under aerobic conditions in the light was found to be sensitive to metabolic poisons, such as N, N′-dicyclohexyl-carbodiimide and carbonyl cyanide m-chlorophenyl hydrazone. It was also depressed by darkness. The sulphate absorption is an energy-dependent process. Sulphate uptake was also inhibited by chromate and selenate. Osmotic shock strongly affected sulphate uptake. This effect could be interpreted by a loss of a binding protein involved in the absorption of sulphate. Osmotic shock also depressed oxygen production in light and oxygen consumption in darkness; however, shocked cells were able to grow normally. Sulphate uptake was strongly enhanced by sulphate starvation, but this enhancement was partly prevented by chloramphenicol. Apparently sulphate starvation depressed the synthesis of a carrier involved in the transport of sulphate. During sulphate starvation the membrane potential, measured by the uptake of triphenylmethylphosphonium, increases. This may be due to changes in the membrane.