Physiological responses of Dunaliella salina and Dunaliella tertiolecta to copper toxicity.
ABSTRACT Species differences in heavy metal tolerance were investigated by comparing the responses of Dunaliella tertiolecta and Dunaliella salina to elevated concentrations of CuCl2. Although both species showed reduced cell number ml(-1) of algal culture, D. salina was more affected by increase in CuCl2. This reflects higher sensitivity of D. salina to CuCl2 compared to D. tertiolecta. Total chlorophyll in terms of microg ml(-1) was higher in D. tertiolecta at all tested CuCl2 levels, but in terms of microg cell(-1) no significant difference was observed between the two species. Total carotenoids in microg cell(-1) increased with increase in CuCl2 in both species and it was about five times higher in D. salina at all CuCl2 concentrations. While both species showed significant increase in lipid peroxidation at elevated CuCl2, the malondialdehyde content of D. salina cells was about three times higher at most CuCl2 concentrations. Although ascorbate peroxidase (APX) activity increased with increase in CuCl2 levels in both species, higher activity was observed in D. tertiolecta at all tested CuCl2 concentrations. Cu content of D. salina cells was higher than D. tertiolecta which may be due to larger volume of D. salina cells. In conclusion, since hydroxyl radical (HO*) produced from H2O2 by Cu2+ (Haber-Weiss cycle) is involved in lipid peroxidation, higher ascorbate peroxidase activity in D. tertiolecta may partly account for lower sensitivity of this species to CuCl2 compared to D. salina.
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ABSTRACT: Although oxidative stress response, which protects organisms from the deleterious effects of reactive oxygen species, has been extensively studied in prokaryotes and eukaryotes, the information about entomopathogenic fungi is fragmentary. We investigated the relationship between copper stress and oxidative stress in entomopathogenic fungus, Isaria fumosorosea (isolate IF28.2). Our results promoted oxidative stress, as evidenced by remarkable inhibition of spore germination and biomass production, stimulation of cyanide-resistant respiration, and accumulation of oxidative modified proteins. Cell responses against both superoxide and peroxide stresses include expression of superoxide dismutase (SOD) and catalase; however, the extent of response was different: treatment with copper increased mainly Cu/Zn-SOD in a dose-dependent manner, whereas catalase production reached to a maximum value at 50 μg/ml Cu(2+) ion concentration. We also found that glucose 6-phosphate dehydrogenase has a role in the mechanism of protection against superoxide and peroxide stresses, and a remarkable increase in its production was observed when higher concentrations of copper were used. The observed hyperoxidative status and increased oxidative damage suggest a relationship between acute metal treatment and oxidative stress in fungal cells.Biological trace element research 01/2011; 143(1):600. · 1.92 Impact Factor
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ABSTRACT: This study investigates the pro-oxidant behavior of the antiepileptic drug carbamazepine (CBZ) on the marine algal species Dunaliella tertiolecta and the immune defense-related hemocytes of mussel Mytilus galloprovincialis. A phytotoxicity test, performed in a first step, showed a significant inhibition of the growth rate and the chlorophyll alpha (Chl-α) content in algae after exposure for 24 h to different concentrations of CBZ (1-200 mg L(-1)). On the other hand, the increased levels of lipid peroxidation products, such as MDA, measured in 24 h CBZ-treated cells were attenuated with time (48-96 h), followed by a significant recovery of both the algal growth rate and the Chl-α content in all cases. The latter could be related to the concomitant enhancement of total carotenoids in CBZ-treated algae with time, which in turn could protect algal growth and survival against CBZ-induced oxidative stress. On the other hand, the increased levels of cell death, superoxide anions ((·)O2 (-)), nitric oxides (NO, in terms of nitrites, NO2 (-)) and MDA content observed in mussel hemocytes exposed to environmentally relevant (0.01-1 μg L(-1)) and/or higher (10 and 100 μg L(-1)) concentrations of the drug, clearly indicate the ability of CBZ to induce oxidative effects on cells of non-target species, such as mussels, affecting thus their overall health status. The significant relationships occurred among the tested biological parameters in both bioassays, further reinforce CBZ-mediated pro-oxidant effects on species, widely used in ecotoxicological and toxicological studies and provide a more comprehensive view on its environmental fate and ecotoxicological risk evaluation.Ecotoxicology 08/2013; · 2.77 Impact Factor
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ABSTRACT: Heavy metals in air, soil, and water are great threat to the environment. Effluents from paint, tannery, electroplating industries contaminate irrigation water, which in turn exhibit toxic response to many crops and microorganisms including cyanobacterial biofertilizers. In aquatic system Cr exist in many forms, whereas, Cr(VI) is most toxic. In the present study metabolic alteration were studied in a cyanobacterial biofertilizer (Hapalosiphon fontinalis) in response to chromium (VI) with special reference to oxidative stress. Maximum growth inhibition was observed at 0.5 mM Cr at 20th day. Lipid peroxidation as TBARS increased with the increase in chromium concentration and suggested free radical mediated toxicity. Elevated levels of β- carotene, astaxanthin, superoxide dismutase, catalase and ascorbate peroxidase indicated their role in survival strategy of the test organism.MIRCEN Journal of Applied Microbiology and Biotechnology 07/2012; 28(7):2505-11. · 1.08 Impact Factor