ISSN:
1572-8773
Keywords:
Anabaena flos-aquae
;
chlorophyll a
;
fluorescence emission
;
heavy metals
;
Hill activity
;
photosystem II
;
phycobilisomes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The effect of equimolar concentrations of Hg2+ and Cd2+ on the whole cell absorption spectra, absorption spectra of the extracted phycocyanin (PC) and fluorescence emission spectra of phycobilisomes (PBS) was investigated in the cells of Anabaena flos-aquae. The PC component of the PBS was found to be extremely sensitive to the Hg2+ rather than the Cd2+ ions. Further, the results showed that Hg2+ and Cd2+ induced decrease in the rate of Hill activity (H2O - DCPIP) was partially restored by the electron donor NH2OH, not by the diphenyl carbazide. Similarly, chlorophyll a fluorescence emission in the presence of metals showed that addition of NH2OH could effectively reverse the metal induced alterations in the fluorescence emission intensity. These results, together, suggested that Hg2+ and Cd2+ caused damage to the photosystems (PS) II reaction center. However, a relatively higher stimulation of the chlorophyll a emission at 695 nm with a red shift of 4.0 nm in the presence of Hg2+, and Cd2+ induced preferential decrease in the emission intensity at 676 nm as compared with the peak at 695 nm were indicative of the differential action of Hg2+ and Cd2+ on the PS II.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00140114
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