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.

Mouse zinc transporter 1 gene provides an essential function during early embryonic development.

Abstract: The SLC30 family of cation diffusion transporters includes at least nine members in mammals, most of which have been documented to play a role in zinc transport. The founding member of this family, Znt1, was discovered by virtue of its ability to efflux zinc from cells and to protect them from zinc toxicity. However, its physiological functions remain unknown. To address this issue, mice with targeted knockout of the Znt1 gene were generated by homologous recombination in embryonic stem cells. Heterozygous Znt1 mice were viable. In contrast, homozygous Znt1 mice died in utero soon after implantation due to a catastrophic failure of embryonic development. Although extraembryonic membranes formed around these embryos, the embryo proper failed to undergo morphogenesis past the egg cylinder stage and was amorphous by d9 of pregnancy. Expression of the Znt1 gene was detected predominantly in trophoblasts and in the maternal deciduum during the postimplantation period (d5 to d8). The failure of homozygous Znt1 embryos to develop could not be rescued by manipulating maternal dietary zinc (either excess or deficiency) during pregnancy. However, embryos in Znt1 heterozygous females were ∼3 times more likely to develop abnormally when exposed to maternal dietary zinc deficiency during later pregnancy than were those in wildtype females. These studies suggest that Znt1 serves an essential function of transporting maternal zinc into the embryonic environment during the egg cylinder stage of development, and further suggest that Znt1 plays a role in zinc homeostasis in adult mice. genesis 40:74–81, 2004. © 2004 Wiley-Liss, Inc.

Accumulation, regulation and toxicity of copper, zinc, lead and mercury in Hyalella azteca

Abstract: Zinc, lead and mercury accumulation in the amphipod Hyalella azteca increases with increasing exposure to metals. During 10 week chronic toxicity tests, metal accumulated at the highest non-toxic/lowest toxic concentration was 126/136 µg Zn g−1, 7.1/16 µg Pb g−1 and 56/90 µg Hg g−1 dry weight. Concentrations of lead and mercyry in control animals were substantially lower (1.3 µg Pb g−1 and 0.4 µg Hg g−1), but concentrations of zinc in controls (74 µg g−1) were about one half those of the lowest toxic concentration. Copper was completely regulated. Accumulated copper concentrations after 10 weeks exposure to all waterborne copper concentrations resulting in less than 100% mortality were not significantly different from controls (79 µg g−1). Lead and mercury concentrations in wild H. azteca should be useful indicators of potential toxicity. Zinc accumulation may also be a useful indicator of zinc toxicity, but careful comparison with control or reference animals is necessary because of the small differences between toxic and control concentrations. Copper is not accumulated by H. azteca under chronic exposure conditions and body burdens of field animals cannot be used as an indicator of exposure or potential toxic effects. Short term exposures to copper, however, result in elevated copper concentrations in H. azteca, even at concentrations below those causing chronic toxicity. Short term bioaccumulation studies might, therefore, provide a useful indication of potential chronic copper toxicity.

Iv. the mechanism of ectomycorrhizal amelioration of zinc toxicity

Abstract: less zinc is taken up, and growth is better than in the non-mycorrhizal condition. The results also show that the metal may be adsorbed to electronegative sites in the hyphal cell walls and extra-hyphal, polysaccharide slime. The possible dual role of this slime in fungus/Betula compatibility and the amelioration mechanism is discussed.

Zinc tolerance in Betula spp. IV: The mechanism of ectomycorrhizal amelioration of zinc toxicity

Abstract: Aseptic cultures of Paxillus involutus Fr. and clones of Betula pendula Roth. and B. pubescens Ehrh. were used in experiments, involving X-ray microanalysis and split-plate culture, to investigate the mechanism of ectomycorrhizal amelioration of zinc toxicity to Betula. Results imply that as the fungal mycelium colonizes fresh soil, zinc is adsorbed to the surface of hyphae, thereby lowering the concentration of zinc in the soil solution surrounding roots. In consequence, less zinc is taken up, and growth is better than in the non-mycorrhizal condition. The results also show that the metal may be adsorbed to electronegative sites in the hyphal cell walls and extra-hyphal, polysaccharide slime. The possible dual role of this slime in fungus/Betula compatibility and the amelioration mechanism is discussed.