ISSN:
1439-0426
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Laboratory experiments were conducted to test interactive effects of calcium (Ca2+) content and the presence of humic substance (HS) on malachite green (MAG)-induced toxicity in fish embryos and larvae by means of a semistatic 144-h-embryo-larval-test with zebrafish (Danio rerio). Two kinds of reconstituted water samples were used to produce the test media by mixing salts into deionized water resulting in either hard water (↑Ca − HS), or soft water (↓Ca − HS). By adding HS two additional test media were produced (↑Ca + HS, ↓Ca + HS). MAG was tested in concentrations of 0.05, 0.10, 0.15, 0.20, 0.25 mg L−1. The toxicity ranking of MAG (mg L−1) to embryos based on 96-h-LC50 in the different test water samples is: ↑Ca − HS (0.061) 〉 ↑Ca + HS (0.123) = ↓Ca − HS (0.12) ≥ ↓Ca + HS (0.134) and on 144-h-LC50 to larvae is: ↑Ca − HS (0.038) 〉 ↑Ca + HS (0.06) 〉 ↓Ca − HS (0.077) = ↓Ca + HS (0.077). Mortality of all the groups was significantly different (P 〈 0.05). Increased Ca2+ concentrations did not protect zebrafish embryos and larvae from MAG-induced toxicity. At high Ca2+ conditions, the mortality of the embryos as well as of the larvae is reduced in the ↑Ca + HS group relative to the ↑Ca − HS group. Thus, at high Ca2+ conditions the HS does affect the MAG-induced mortality. The mechanism which causes the higher toxicity of MAG in the presence of higher Ca2+ concentrations is poorly understood. A probable explanation could be the stimulation of the calcium-binding protein calmodulin as well as the calmodulin kinase II in cell membranes in the presence of high Ca2+ concentrations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1439-0426.2003.00488.x
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