ISSN:
1432-072X
Keywords:
Cadmium
;
Euglena
;
Mercury
;
Photochemical activities
;
Photosynthesis
;
Respiration
;
Zinc
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Results on the effect of sub-lethal concentrations of zinc chloride (ZnCl2), cadmium chloride (CdCl2), and mercuric chloride (HgCl2) on Euglena are presented. During the growth cycle respiratory oxygen uptake and photosynthetic oxygen evolution in the light are initially strongly inhibited by Zn, Cd and Hg. The effects of the three metals on photosynthesis, using oxygen evolution as a criterion was confirmed by carbon fixation techniques. Photosystem I (PSI) associated electron transport 2,6-dichlorophenol indophenol (DCPIP)red. → methyl viologen (MV) → O2, in contrast to total photosynthetic capacity, was only slightly inhibited by Zn, Cd and Hg, whereas the levels of activity of NADP-oxidoreductase in cells untreated or treated with heavy metals showed development like total photosynthesis. Metals strongly inhibited this enzyme which means that the supply of NADPH is lowered due to the action of Zn, Cd and Hg. Photosystem II (PSII) associated electron transport (H2O → dibromothymoquinone/2,3-dimethyl-5,6-methylenedioxy-D-benzoquinone → O2), however, was severely inhibited in a way similar to total photosynthesis. Effects on the cooperation of PSI + II showed patterns similar to PSII alone, i.e., heavy metals strongly reduced PSI + II dependent activities.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00405922
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