ISSN:
1572-8773
Keywords:
Hg2+ toxicity
;
Nostoc calcicola
;
Electrolyte leakage
;
NO3 − uptake
;
Nitrate reductase
;
Metal interactions
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary The effect of mercury (Hg2+) in the absence and presence of methylmercury (CH3Hg+), cadmium (Cd2+), copper (Cu2+), nickel (Ni2+) and calcium (Ca2+) on Nostoc calcicola Bréb. has been studied in terms of electrolyte leakage, NO3 − uptake and in vivo nitrate reductase (NR) activity to discover any possible correlation among such parameters under Hg2+ stress. Leakage of electrolytes from Hg2+-treated cyanobacterial cells was directly proportional to Hg2+ concentrations and exposure time. In comparison to NO3 − uptake, an about 60-fold slower rate of NR activity was observed in the untreated cultures, the former being five times more Hg2+-sensitive. A non-competitive synergistic interaction of Hg2+ with CH3Hg+ or Cd2+ and antagonistic with that of Ni2+ or Ca2+ has been observed for both the processes of NO3 − utilization. The antagonistic interaction of Cu2+ with Hg2+ in terms of NO3 − uptake and synergistic with respect to NR activity, has been attributed to the dual bonding preference of Cu2+ for cellular ligands. These findings suggest that (a) a statistically significant correlation exists among such parameters; (b) Hg2+ predominantly attacks the cyanobacterial cell membrane; (c) Hg2+ inhibits NO3 − utilization; (d) the presence of other cations increases or decreases the inhibitory actions of Hg2+.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01140581
