Zinc toxicity

About: Zinc toxicity is a research topic. Over the lifetime, 727 publications have been published within this topic receiving 34583 citations. The topic is also known as: zinc poisoning.

Influence of Dissolved Organic Carbon on the Acute Toxicity of Copper and Zinc to White Sturgeon (Acipenser transmontanus) and a Cladoceran (Ceriodaphnia dubia)

Abstract: We conducted acute lethality tests with white sturgeon (Acipenser transmontanus) and Ceriodaphnia dubia exposed to copper and zinc at dissolved organic carbon concentrations ranging from 0.5 to 5.5 mg/L. Dissolved organic carbon had minimal effects on zinc toxicity but did have a protective effect on acute copper toxicity, which was equal to that predicted by the copper biotic ligand model (BLM). The BLM-adjusted copper median effect concentrations for A. transmontanus ranged from 2.4 to 8.2 mg/L. Environ Toxicol Chem 2019;38:2682-2687. Published 2019 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work, and as such, is in the public domain in the United States of America.

Zinc tolerance of freshwater diatoms isolated from sites with zinc pollution; and pH effect on zinc toxicity

Abstract: The aim with this study was to observe the zinc (Zn), tolerance for different strains isolated from sites with Zn pollution and to observe if lower pH decreases the Zn toxicity. Another aim was to see if malformations could be an indicator for Zn pollution. Zn is found naturally in the bedrock, sediment and waterbodies. Mining is one activity which had led to high values of Zn > 60 mg Zn l⁻¹ in some areas in Sweden. Today diatoms are used as indicators for organic pollution, the amount of nutrients and also for the pH condition. Due to problem with high values of metals, the diatom indicator has been developed further to also involve detection of metal pollution. Zn can affect diatoms growth rate, photosynthesis, cell division as well as their silica transport and thereby leading to malformed diatoms. In this study Zn toxicity was observed as decrease in number of cells, degree of malformations and as a decrease in the photosystem II efficiency. The hypotheses for the study are the following: the tested strains isolated from polluted sites would have higher tolerance to Zn than diatoms isolated from non- polluted sites, Zn would be less toxic in pH 5 compared to pH 7 and malformations could indicate Zn pollution. The observed results confirmed the hypothesis regarding the tested strains having higher tolerance towards Zn than diatoms from non- polluted sites, by the approximated EC ₅₀ values of 0,91; 1,35 and 2,27 mg Zn l⁻¹ respectively. However, the observed results for the hypothesis regarding the lower pH decreasing the Zn toxicity, were contradictory. The hypothesis was verified by higher EC ₅₀ values for the cell growth and fluorescence in pH 5 than in pH 7 for the short term experiments. Whereas the hypothesis was rejected by a higher degree of malformation in pH 5 than in pH 7 and by a higher cell growth in pH 7 than in pH 5 in the long term experiment. The different results regarding the pH effect on Zn toxicity might be explained by the different exposure times, probably the low pH is causing more stress to the cells pre-grown in pH 7 than it relieves the Zn toxicity. The long term experiment displayed significant more malformations in the higher Zn concentrations in comparison to the controls under both pH 5 and 7, and verified that malformations could detect high Zn concentrations and indicate Zn pollution.

Metallothionein Synthesis and mRNA Levels in Cultured Hepatocytes from Lethal Milk Mutant Mice

Abstract: Primary hepatocyte cultures from adult lethal milk (1m) mutant mice displayed approximately a 2.5-fold increased metallothionein (MT) synthesis compared to wild-type cells in uninduced as well as zinc-treated cells, over a 0- to 160- JIMzinc dose-response range. Mutant hepatocytes also exhibited a greater level of MT-1 mRNA in both untreated and zinc-treated cultures compared to wild-type. Despite these measures of MT synthesis, untreated Im/lm hepatocytes exhibited twofold-reduced 6-h uptake of 65Zn compared to wild-type, zinc and copper levels in soluble fractions of Im/lm hepatocytes were equivalent to wild- type levels and Im/lm hepatocytes showed increased susceptibility to zinc toxicity as measured by zinc-induced detachment of cells from the culture dishes. These results suggest that the elevated MT synthesis observed in lethal milk mice does not, as previously reported in wild-type hepatocytes (1â€"3), increase zinc uptake or protect against heavy-metal toxicity (4, 5). Taken together with studies in vivo, our results suggest that an alteration in MT synthesis is probably a secondary affect of the lethal milk mutation. J. Nutr. 117: 183-188, 1987.

Effect of heavy metals on the growth of tissue cultures (II).

Abstract: The effect of toxic concentrations of three heavy metal compounds on the growth of the secondary callus tissue of Nicotiana tabacum L. and Ruta graveolens L. was studied. The metal compounds examined were ZnSO4, NiSO4, CuSO4. The metal compounds used were placed in Murashige, Skoog (1962) and White (1943) culture medium at 10(-6) and 10(-4) M concentration, respectively, before autoclaving. The culture media containing macro- and microelements and vitamins were completed with carbon source and regulators (IAA, GA, kinetin for Nicotiana and IAA, 2, 4-D for Ruta). The cultures were kept for 4 weeks at 25 (+2) degrees C under 16/8 n light/dark conditions. The value of pH was 5.6 before the autoclave treatment. The increase in fresh weight of the secondary callus tissue was inhibited by the metal compounds applied with both plant species (to 75-87% by zinc, 7-97% by nickel, 5-98% by copper with tobacco; to 47-69% by zinc, 5-88% by nickel, 57-90% by copper with rue). The cell number and dry weight per g of callus tissue partly increased, partly decreased compared to the control in response to the heavy metal treatment. The growth values obtained with various concentrations of the heavy metals were different in the two plant species due to differences in metabolism and organization potential between them.