Mercury in mercury(II)-spiked soils is highly susceptible to plant bioaccumulation

Heavy metal phytotoxicity assessments usually use soluble metal compounds in spiked soils to evaluate metal bioaccumulation, growth inhibition and adverse effects on physiological parameters. However, exampling mercury phytotoxicity for barley (Hordeum vulgare) this paper highlights unsuitability of this experimental approach. Mercury(II) in spiked soils is extremely bioavailable, and there experimentally determined bioaccumulation is significantly higher compared to reported mercury bioaccumulation efficiency from soils collected from mercury-polluted areas. Our results indicate this is not affected by soil sorption capacity, thus soil ageing and formation of more stable mercuric complexes with soil fractions is necessary for reasonable metal phytotoxicity assessments.     

A stereological study of the effects of mercury inhalation on the cerebellum

Mercury in the environment that arises from organic and inorganic sources can cause irreversible damage to the nervous system. Toxicity may be direct or may arise from interactions with other metals in the environment. We evaluated the possible effects of mercury vapor on rat cerebellum. Twelve adult female rats were divided into control and experimental groups. The rats in the experimental group were exposed to mercury vapor for 9 h/day for 45 days. Cerebellar tissue samples were evaluated using stereology and for histopathology. The total number of Purkinje cells was estimated using a physical disector method. We found that in the experimental group, overall volume decreased and the number of Purkinje cells was reduced. We also found cellular damage including pycnotic nuclei, eosinophilic cytoplasm and vacuolization; these features were absent in the control group. We found that chronic exposure to inorganic mercury vapor is toxic to the cerebellum.     

Bioaccumulation of mercury,arsenic, cadmium,and lead in plants grown on coal mine soil

Mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb) are the major toxic metals released by coal mining activities in the surrounding environment. These metals get accumulated in the soils. The plants grown on the contaminated soil uptake these toxic metals in their roots and aerial parts. This study monitored the bioaccumulation of Hg and other three toxic metals in coal mine soil. The pot study of Hg accumulation in Brassica juncea showed that the extent of Hg uptake by roots and shoots of the plants grown on was high in the mature plant and Hg content in root was higher than the shoot. In the soil of unreclaimed overburden (OB) dump, the toxic metal content was higher than that of reclaimed OB dump which posed high ecological risk in the soil of unreclaimed OB dump. Bioaccumulation coefficient (BAC) value showed that Hg was not accumulated in the leaves of Dalbergia sissoo L., Gmelina arborea, Peltaphorum inerme L., Cassia seamea L, and Acacia mangium L grown on coal mine soil.     

A Survey of Heavy Metal Levels in Eels (Anguilla anguilla) from some Rivers in East Anglia,England: the Use of Eels as Pollution Indicators

A survey was made of mercury, cadmium and lead in the liver and flesh of 517 eels from eleven rivers in East Anglia. Eels from some sites showed high metal levels, indicating sources of metal contamination. Eel liver is a suitable indicator of inorganic pollution and the flesh is a suitable indicator of organic pollution.     

Ebselen Protects Ca2+ Influx Blockage But Does Not Protect Glutamate Uptake Inhibition Caused By Hg2+

The goal of this study was to investigate the isolated and combined effect of ebselen and Hg2+ on calcium influx and on glutamatergic system. We examined the in vitro effects of 2 phenyl-1,2-benzisoselenazol-3(2H)-ona), (Ebselen) on 45Ca2+ influx in synaptosomes of rat at rest and during depolarization and glutamate uptake into synaptosomes. Entry of 45Ca was measured during exposure to mercury in non-depolarizing and depolarizing solutions. Ebselen abolished the inhibition of 45Ca2+ influx on non-depolarizing conditions; however, ebselen did no modify inhibition uptake of 45Ca2+ caused by Hg2+ in high K+ depolarizing medium. Ebselen did not modify glutamate uptake inhibition caused by Hg2+ in synaptosomes. These results indicate that ebselen has an in vitro protective effect against Hg2+ induced inhibition of Ca2+ influx into synaptosomes, depending on the depolarizing conditions of the assay. The effects of Hg2+ on glutamate uptake were not modified by ebselen, suggesting that its protection is dependent on the target protein considered.     

Maternal and sibling factors induce dormancy in dimorphic seed pairs of Aegilops triuncialis

Germination and emergence are stimulated by environmental cues, but strongly influenced by maternal controls. However, traits related to seed dispersal may have important influences on germination as well. For example, the sibling rivalry hypothesis suggests that germination may be inhibited when sibling seeds remain within a single dispersal unit. These two influences on germination suggest different, and possibly conflicting, evolutionary strategies for optimizing individual fitness. Using an invasive annual grass that produces dispersal units with dimorphic seeds, I found significant reductions in seedling emergence that suggested the presence of both strong maternal and sibling influences on the germination of the smaller seed of dimorphic pairs. Both influences were capable of nearly complete germination suppression of the small seed, but there was no strong evidence for a hierarchy among the two factors. The maternal effect is consistent with a bet-hedging strategy for survival in variable environments where resource availability can be unpredictable, but the sibling effect likely represents a mechanism for reducing competition between closely related individuals, particularly under conditions of resource limitation.     

Differential mercury volatilization by tobacco organs expressing a modified bacterial merA gene

INTRODUCTIONEnvironmental pollution is an increasing prob-lem both fOr developing and developed countries.Mercury, both in organic and ionic fOrm, is one of themost hazardous pollutants among the heavy met-als[l]and its accumuIation in human body results ininactivation of metabolic enzymes and structuralproteins[2, 3] giving rise to serious health problems(Minamatasyndrome).Usually mercury pollution is caused by indus-trial and agricultural activities, releasing mercuryinto air, water an…     

Selectivity in heavy metal- binding to peptides and proteins

The metal-binding affinities and three-dimensional structures of three synthetic 18-residue peptides with sequences derived from that of the highly conserved metal-binding motif MXCXXC found in many heavy metal-binding proteins were determined. A change in register of the cysteines and alanines of the sequence from the periplasmic mercury-binding protein, MerP, i.e., CAAC, CACA, and CCAA, affects the specificity of metal binding, in particular, the peptide with vicinal cysteines binds only mercury. The three-dimensional structures of the mercury-bound forms of the three peptides determined in solution by NMR spectroscopy peptides differ considerably, even though they are all linear bicoordinate complexes. The three-dimensional structure of the peptide with CAAC bound to Cd(II) demonstrates that the metal-binding loop is malleable enough to accommodate modes of coordination other than linear bicoordinate.     

Occurrence of Cu-ATPase in Dictyostelium: possible role in resistance to copper

Dictyostelium discoideum amoebae showed an uncommon resistance to Cu(2+), as pointed out through cell growth rate (EC(50) = 469 +/- 30 microM) and the neutral red cytotoxicity assay (EC(50) = 334 +/- 45 microM). Although no evidence of Cu-inducible metallothionein was found, Cu-dependent ATPase activity was cytochemically detected on pelletted, resin-embedded amoebae. This activity required Cu(2+) in the incubation medium, was sensitive to TPEN, vanadate and temperature, and showed dose-dependent increase after exposure of amoebae to 10-500 microM Cu(2+) for 7 days. Accordingly, immunofluorescence and Western blotting revealed the occurrence of a Cu-inducible, putative homologue of human Menkes (MNK) Cu-P-type ATPase. To verify if Cu-ATPase is involved in copper resistance, amoebae were exposed to low concentrations of Cu(2+) and vanadate followed by the neutral red assay. Exposure to either treatment showed no effect, while a combination caused a dramatic increase of Cu toxicity, possibly depending on Cu-ATPase inhibition.