Induction Of Metal-binding Proteins Research Articles

Biomarkers in earthworms.

Earthworms are believed to be so-called key species within ecosystems and are often exposed to a wide range of anthropogenic compounds released to the terrestrial environment. As a consequence, they may suffer from the toxicity of these compounds. For these and other reasons, earthworms have been used extensively in ecotoxicological studies. In recent years the use of other biological responses (biomarkers) to estimate either exposure or resultant effects of chemicals has received increased attention. Biomarkers address the question of bioavailability by only responding to the bioactive fraction. They may incorporate effects following exposure to a mixture of chemicals. Biomarkers may also reduce extrapolation of results from the laboratory to the field, as they may be applicable under both conditions. The present review has drawn together current knowledge on potential biomarkers in earthworms and appraised them in relation to basic requirements needed for supplying information relevant to devising satisfactory risk assessment. A wide range of potential biomarkers have been measured in earthworms, including DNA alteration, induction of metal-binding proteins (MTs and MBP), depression of ChE activity and other enzymatic responses, energy reserve responses, responses in neural impulse conductivity, lysosomal membrane stability, immunological responses, changes in sperm numbers, histopathological changes, and behavioral changes. Both organic and inorganic compounds have been included; however, for each biomarker the main emphasis historically has been placed on only a few chemicals. Dose-response relationships were in some cases observed. Little information is available on the linkage of the biomarker response to effects at population or community levels. The influence of other factors, biotic and abiotic, on the biomarker responses and their temporal duration have been only sporadically reported.

Calibration of the estuarine amphipods, Gammarus zaddachi Sexton (1912), as biomonitors: toxicokinetics of cadmium and possible role of inducible metal-binding proteins in Cd detoxification

Collectives of gammarid amphipods ( Gammarus zaddachi and G. salinus) from four localities of the Ems- and Weser-estuary and from the freshwater tidal region of the River Hunte (NW-Germany) were exposed to constant Cd concentrations (51.5 ± 1.3 μg l −1) in artificial sea-water (5 ‰ salinity) for 15 days to investigate bioaccumulation and possible induction of metal-binding proteins in these amphipods. Toxicokinetic parameters (BCFs, rate constants) were calculated, to calibrate these amphipods as biomonitors for Cd. Our toxicokinetic study and additional literature data provide further support to utilize these organisms for biomonitoring, indicating BCFs for Cd within the same dimension (409–576) independent of the Cd exposure conditions, of the species and of the habitats considered. Results of gel and ion exchange chromatography indicate that metallothioneins or metallothionein-like proteins are not likely to play an important role in possible Cd detoxification in G. zaddachi, despite substantial Cd uptake up to 30 mg kg −1 (d.w.). Only a small amount of Cd appeared to be eventually bound to cytosolic components.

Depuration effects on trace metals in Anomalocardia brasiliana (Gmelin, 1791)

Bivalves have been regarded as suitable bioindicators of metal pollution in the marine and estuarine environments. However, the metal concentrations of the soft parts of individual bivalves can vary considerably depending on size variations, geographic and genetic differences, individual variability in metal uptake, ingestion of sediment particles and induction of metal-binding proteins. Metal-containing particulate matter in the gut can also be significant. These authors showed that if deputation is not carried out, then large variations in metal concentrations are more likely to occur. In the Todos os Santos Bay on the northeastern coast of Brazil, the cockle A. brasiliana is the most abundant bivalve and is well adapted to area conditions. An important source of food for many local communities, this species has been frequently used as an indicator for heavy metals pollution; however, no data have been published on metal concentrations of A. brasiliana of different size classes and on the effects of deputation on overall concentration. It is therefore important to determine the metal concentrations in A. brasiliana both from the point of view of how the concentrations relate to metal loading of the area. The effect of size upon metal concentration of shellfish has been examined bymore » Boyden, who found that zinc in Mytilus edulis was greater in smaller individuals while cadmium was independent of size. The objective of this study was to determine concentrations of copper, zinc, cadmium and lead in A. brasiliana collected from a site with a relatively low impact of heavy metal contamination, to examine metals in different size classes and to assess the effect of depuration on tissue concentration of the metals. These elements were selected due to their toxicity to marine organisms, when their excess as free metal may interact with cell structures and/or enzymes affecting metabolic activities. 22 refs., 2 figs., 2 tabs.« less

Induction of metal binding proteins in striped bass, Morone saxatilis, following cadmium treatment

1. 1. The time course of induction of cytosolic metal binding proteins (MBP) was observed following up to three daily intramuscular injections of cadmium chloride (0.2 mg cadmium/injection). 2. 2. Low molecular weight binding proteins were resolved by gel permeation chromatography on Sephadex G-75. Based on total metal binding capacity, the concentration of crude MBP increased 2.6 fold. This level of induction of MBP was confirmed by polarographic analysis. 3. 3. Initial binding of cadmium to MBP resulted in displacement of zinc, while at later times, zinc associated with MBP increased above control levels. 4. 4. Using 35S-cysteine incorporation, it was shown that the rate of hepatic MBP synthesis was significantly greater than controls and sham injected fish 18 hr after the third cadmium injection. 5. 5. Due to interfering proteins of molecular weights similar to the metal binding proteins one dimensional PAGE was not capable of verifying induction. However, the metal binding proteins were resolved using two dimensional gel electrophoresis.

Induction of metal-binding proteins by zinc is accompanied by reduction of other proteins including antibodies

1. Exposure of carp lymphoid cells to zinc causes formation of metal-binding proteins (metallothioneins). 2. Metallothionein induction is accompanied by a suppression of the production of other proteins. 3. Antibodies are among the proteins which are decreased by zinc exposure. 4. Similar results from in vitro experiments indicate that zinc might affect even fish living in water still regarded as unpolluted.

Interaction of Metals (Panel Discussion) (Proceedings of the 10th Symposium on Environmental Pollutants and Toxicology)

In the recent two decades, interest has been rising in metal-metal interaction in body. And at present the interactions to find its phenomenon is now being investigated. Therefore in the mechanism of interaction between metals, the hypothesis to explain this mechanism draw only out from these results reported. From these results, the following mechanism should be able to be indicated. (1) Competition in active site. There are competitions between metals against the activated substance or active site in body and those against absorption from a digestive tract, for example, the competition of lead and zinc to ALAD or the suppression by cadmium to the absorption of copper. (2) Formation of complex by metals. When two metals are administered simultaneously, the complex containing these metals is formed in body, and consequently metal toxicity is alleviated. This exsample is investigated in detail in Hg-Se interaction. (3) Induction of metal binding protein. This example can be seen in the induction of metallothionein. A metal which has the ability to induce Zn-thionein is used as pretreatment, and a metal which can replace Zn in Zn-thionein is used as challenge, and the toxicity of challenge metal may be mitigated.