ISSN:
1432-072X
Keywords:
Chlorella fusca
;
Continuous turbidostatic culture
;
Orthophosphate
;
Influx and efflux rates
;
Inhibitors
;
Oscillations
;
Phosphate kinetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The main objective of the experiments with Chlorella fusca strain 211-8b was to measure, with adequate time resolution, the unidirectional influx rates of phosphate into non-phosphate-starved algae under different steady state conditions (light, temperature, 3-phosphoglycerate influence) or following the addition of several photosynthesis and phosphate transport inhibitors (phenylmercuric acetate, p-chloromercuribenzoate, arsenate). the algae were cultivated in a phosphate rich medium in a continuous turbidostat culture. The phosphate exchange experiments with carrier-free 32PO 4 3- were performed directly in the continuous culture. The sampling intervals after the tracer addition were 15 s. For a continuous steady state culture grown in the light (25° C) the unidirectional influx rate measured with 32P is 260 times higher than the net uptake rate (=influx minus efflux rate) calculated from the mass balance using the data of this culture. In all experiments, except the control experiment with trichloroacetic acid killed cells, the specific activity of the intracellular inorganic orthophosphate compartment oscillates around a constant mean value which never reaches the specific activity of the nutrient medium within the duration of the short-term experiments (7.5 min). The inhibitors strongly affect the characteristics of the oscillations. The unidirectional influx rates are constant. Oscillating flushing rates with unlabelled phosphate from a storage compartment have been postulates to explain the oscillations. Oscillating rates from the individual cells are apparently synchronized by an unknown mechanism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00446461
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