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- Title
POTENTIAL TOLERANCE MECHANISMS OF <em>PROROCENTRUM MICANS</em> (DINOPHYCEAE) TO SUBLETHAL LEVELS OF COPPER.
- Authors
Lage, Olga M.; Parente, M.; Teresn, M.; Vasconcelos, S. D.; Gomes, Carlos A. R.; Salema, Roberto
- Abstract
We investigated how Proprocentrum micans Ehrenberg, a planktonic dinoflagellate common in Portuguese coastal waters is able to tolerate and recover from sublethal concentrations of copper(II). The experimental design simulated events in inshore waters, where P. micans is subjected to high levels of pollutanmts, including copper Decrease in growth rate, induction of a growth lag phase, temporary loss of motility, and potassium leakage were the effects induced in P. micans cultures by 90 nM labile copper. A 10-20-fold increase in cellular copper concentration was observed in toxicity experiments. Copper efflux (representing a 50% decrease in cellular metal content) was a short-term tolerance mechanism. A 25-kDa protein was detected after only 3 h of exposure to copper, but there was no evidence of phytochelatin synthesis. Ultracytochemical labeling of metals with the sulfide-silver procedure showed that copper was associated with the thecal plates, starch grains, and, to a lesser extent, lipid droplets. High values of fixation capacities and average conditional stability constants for copper binding by starch, amyplopectin, and cellulose support the location of cooper in thecal plates and starch grains. We conclude that P. micans responds rapidly to copper toxicity and has two tolerance mechanisms for coppers copper efflux and sequestratin in polymeric substances.
- Subjects
SCIENTIFIC method; STATISTICAL hypothesis testing; GROWTH rate; COPPER; GRAIN
- Publication
Journal of Phycology, 1996, Vol 32, Issue 3, p416
- ISSN
0022-3646
- Publication type
Article
- DOI
10.1111/j.0022-3646.1996.00416.x