Heavy Metals

Habitats Laden with Heavy Metals

Grass Membrane

High concentrations of some heavy metal ions, such as chromium, mercury, lead, and cadmium, poison most plants. Some geographic sites are naturally rich in heavy metals as a result of normal geological processes. In other places, acid rain leads to the release of toxic aluminum ions in the soil. Other human activities, notably the mining of metallic ores, leave localized areas known as tailings with substantial concentrations of heavy metals and low concentrations of nutrients. Such sites are hostile to most plants, and seeds falling on them generally do not produce adult plants. Mine tailings rich in heavy metals, however, generally are not completely barren (Figure 40.15). They may support 40.15 Life after Strip Mining Although high concentrations of heavy metals kill most plants, grass is colonizing this eroded strip mine in North Park, Colorado. 40.15 Life after Strip Mining Although high concentrations of heavy metals kill most plants, grass is colonizing this eroded strip mine...

Heavy metals

Under the term heavy metal fall all elements in the Earth's crust with a density of greater than 5 g cm2 in their metallic form. Thus defined, a large proportion of the periodic table of elements belongs to this category however, many heavy metals are very rare or extremely unavailable and are of no environmental concern. The toxicity of heavy metals is not due to the metal itself, but to ionic forms and other chemical species (e.g. Pb2 +, HgCHj, and Cr2O2 _). The active and toxic form of a metal usually constitutes only a small proportion of the total concentration in an environmental compartment, and depends on properties of the environment as well as the metal. One of the most important influences is due to environmental pH a low pH promotes dissociation of metal complexes and may increase the fraction of metal present in ionic form without changing the total concentration. The dynamic processes occurring at the interface of environmental ligands and biotic surfaces are studied...

Matter and Energy Cycles

These cycles also govern the transport of toxic substances within a system. It took many years before it was realized that persistent pesticides such as DDT would eventually be concentrated in top predators, such as raptors. The decline in populations of birds of prey because of reproductive failure caused by dDt was a consequence of the transport of the chemical through ecosystem food webs. Likewise, radionucleides from the 1986 explosion at the Chernobyl nuclear reactor have become concentrated in certain components of the ecosystems where they were deposited. This is particularly true of fungi, which take radionucleides and heavy metals from their food sources but do not shed the substances. Humans eating mushrooms from these forests can receive larger than expected doses of radiation, because the concentration in the fungi

Computerized Tomography

Micro-CT systems providing high-resolution images ( 50 im) and rapid data acquisition (typically 5 to 30 min) are emerging as a cost-effective means for detecting soft tissue structures, skeletal abnormalities, and tumors in live small animals 15-17 . Use of iodinated contrast agents enhances the weak endogenous contrast between different soft tissues. However, the difficulty in designing CT contrast agents limits the utility of the technique for molecular imaging applications. It is conceivable to generate probes using heavy metals and to improve image contrast by employing methods as K-edge subtraction and x-ray fluorescence imaging 18 , but at least in the near future, micro-CT will be rather used to supplement data from other molecular imaging techniques.

Preface to the Series

The assessment of safe to use starts with the harvested plant material, which has to comply with an official monograph. This may require absence of, or prescribed limits of, radioactive material, heavy metals, aflatoxin, pesticide residue, as well as the required level of active principle. This analytical control is costly and tends to exclude small batches of plant material. Large-scale, contracted, mechanized cultivation with designated seed or plantlets is now preferable.

Plants and Microorganisms

Nated by heavy metals such as lead, mercury, or selenium. Certain plants (Astragalus, for example) are able to accumulate high concentrations of metals such as selenium in their tissues. The plants can be harvested, the tissue burned, and the metal-contaminated ash (now small in volume) can be stored in a hazardous waste facility.

Genome Redundancy Gene Family Expansion in Legionella

Of proteins are transporters like in many genomes however, in Legionella multidrug efflux pumps for heavy metals and other toxic substances are highly represented. They could play an important role in adaptation to the environment and might also play a role in biocide resistance. Legionella also possess a prominent family of regulators with GGDEF-EAL domains (24 in strain Paris, 21 in strain Lens and 21 in strain Philadelphia 1), which are essential for virulence properties of many bacteria as they are involved in aggregation, biofilm formation or twitching motility. This protein family is also largely represented in many other bacteria however, C. burnetii, the most closely related prokaryote to Legionella, encodes only one.

Life in industrial barrens

Heavy metal tolerance of plants has been studied extensively and provides a well-documented example of rapid evolutionary adaptation (Bradshaw and McNeilly 1981 Macnair 1997). Several grass species, including Agrostis scabra Willd., Des-champsia caespitosa (L.) Beauv., Agrostis gigantea Roth. and Poa compressa L., colonising Sudbury's metal-contaminated soils, may have developed local metal-tolerant populations (Winterhalder 2000, and references therein). Although pollution tolerance in populations of long-lived trees has been detected less frequently than in populations of grasses and herbs, recently it had been demonstrated that long-lasting pollution impact increased pollution resistance of mountain birch in industrial barrens near both Monchegorsk and Nikel (Kozlov 2005 Eranen 2006), possibly by elimination of sensitive genotypes (survival selection) from the affected populations. Similarly, we discovered that resistance of non-specific esterases (enzymes degrading various...

Plant Responses to Environmental Challenges

Environmental challenges to plants are not limited to herbivores and pathogens. Some physical conditions pose substantial problems for plants and thus limit the places where plants can live. The most challenging physical environments include those that are very dry (deserts), that are water-saturated, that are dangerously salty, that contain high concentrations of toxic substances such as heavy metals, and that are very hot or very cold.

Results and open questions

Furthermore, this stress would be independent of the respiration process, but could be rather due to the high level of oxygen radicals in the environment or their formation in tissues due to metal oxidation. This enzymatic defense system still has to be studied in vivo for A. pompejana. Desbruyeeres et al. (1998) reported another potential molecular adaptation in response to the high heavy metal enrichment in the body of this species. The high concentration of metalothioneins-like proteins in digestive tracks, parapod and dorsal epidermis was suggested to reflect a response of the worm to potential metal toxicity. In fact, most remains to be done in the study of Alvinella pompejana response to chemical stress in this particularly harsh environment. Since the late nineties, no new data have been published on the adaptation of this species to hypercapnia, heavy metal toxicity or oxidative stress. Further developments in high-pressure technologies should provide access...

The Process of Natural Selection

The characteristics of a population can be changed by natural selection in several ways. If individuals in a population with an extreme value for a trait have the greatest fitness on average, then the mean value of the trait will change in a consistent direction, which is called directional selection. For example, the soil in the vicinity of mines contains heavy metals that are toxic to plants. Individuals with the greatest resistance to heavy metals have the highest survivorship. Evolution leads to an increase in resistance. If individuals in a population with intermediate values for a trait have the greatest fitness on average, then the variation in the trait will be reduced, which is called stabilizing selection. For example, in many species of birds, individuals with intermediate numbers of offspring have the greatest fitness. If an individual has a small number of offspring, that parent has reduced reproduction and a low fitness. If the number of offspring is large, the parent...

Source and Types of Pollution

In natural ecosystems is the single most important source of pollution. First, heavy dependence upon fossil fuels for energy, and on synthetic chemicals and materials helped to dump millions of metric tons of nonnatural compounds and chemicals into the environment. Among them are agrichemicals such as fertilizers, insecticides, fungicides, and herbicides, and home products. Application of excess chemical fertilizers to soil hampers natural cycling of nutrients, depletes the soil's own fertility, and destroys the habitat for thousands of small animals residing in the soil. Farm runoff carries priceless topsoil, expensive fertilizer, and animal manure into rivers and lakes, where these potential resources become pollutants. In the city, water pours from sidewalks, rooftops, and streets, picking up soot, silt, oil, heavy metals, and garbage. It races down gutters into storm sewers, and a weakly toxic soup gushes into the nearest stream or river. Many of these chemicals also seep through...

Metallothioneins in redblooded and hemoglobinless notothenioids

Further studies unraveled the presence in the icefish liver of a second cDNA encoding a second MT isoform. According to the nomenclature adopted for mammal MT isoforms, the proteins obtained by translation of the two cDNAs were termed MT-I and MT-II. Although Northern blot analyses confirmed the presence in liver tissue of significant endogenous levels of MT mRNA, without a concomitant accumulation of MT protein, high levels of both MT mRNA and MT protein were detected in specimens of C. hamatus treated with CdCl2 solution (Carginale et al. 1998). Quantification of the MT-I and MT-II transcripts from control and Cd-treated icefish showed an alteration in the ratio of the two MT isoform transcripts. Constitutively expressed transcripts consisted mostly of MT-II, whereas the MT-I transcript was preferentially expressed after cadmium induction (Carginale et al. 1998). These results, while confirming the existence of a discrepancy between MT mRNA and MT protein levels, showed that...

Regulation of MT expression in notothenioids

Heavy metals are the most general and powerful of these inducers their action is mediated by short cis-acting elements present in the MT gene promoter, termed metal responsive elements (MREs) (Culotta and Hamer 1989 Searle et al. 1987 Varshney et al. 1986). MREs have been shown to mediate transcriptional response of MT genes to zinc and cadmium through trans-acting binding proteins (MTF) (Auf der Maur et al. 1999 Brugnera et al. 1994 Dalton et al. 2000 Koizumi et al. 1999 Seguin and Prevost 1988). Recent evidence indicate that MTF1 functions as mediator of MT induction in conditions of physiological stress (Murphy et al. 2005). Several additional cis-acting elements have been identified in human MT genes, which are involved in the regulation of basal and induced expression of MT genes (Andrews 2000 Friedman and Stark 1985 Samson and Gedamu 1998). In conclusion, there is a striking difference between promoter sequences of MT isoforms in notothenioids,...

Kearns Sayre Syndrome

Perirolandic Cerebral Cortex

Generally accumulate preferentially in myelin. Organic solvents such as are used by painters lead to irregular, patchy demyelination and can cause so-called house-painter's dementia or an organic psychiatric syndrome. Demyelination, loss of gray-white matter distinction, and signal changes in the basal ganglia have been described in toluene sniffers. Heavy metal poisoning also shows selective affinity for certain brain regions, as seen for example in Wilson disease (neostria-tum, mesencephalon, dentatorubral tracts, nucleus dentatus), lead encephalopathy (cerebellar white matter in adults, cortical neurons in infants and children),and mercury poisoning in Minamata disease (occipital and parietal cortex).

Immobilization of Microalgae

Adhesive Flow Polymerisation Vesel

Several microalgae synthesize metabolites of great commercial interest. Microalgae also act as filters for wastewater N and P, heavy metals, and xenobiotic compounds. However, the cost-effective harvesting of microalgae is one of the major bottlenecks limiting the microalgal biomass applications. In this context, immobilization of algal cells has been proposed for circumventing the harvest problem as well as retaining the high-value algal biomass for further processing. In recent years, innovative approaches have been employed in the field of coimmobilization and microencapsulation, which have proved the superiority of immobilized cells over the free cells. Further, the development in the field of biosensor technology with immobilized microalgae presents an early warning device to monitor pollutants in natural waters. This chapter reviews the various applications of immobilized microalgae and addresses the specific methods concerning the production of coimmobilized beads and the...

Laboratory Aids to Diagnosis

This ratio should be calculated on at least two 24-hour urine collections, as day-to-day variability may occur. A ratio above 6 in adults is elevated. Urinary studies for heavy metals may be useful if a peripheral neuropathy is suspected. Myoglobinuria occurs in several diseases of muscle. Both hemoglobin and myoglobin give positive reactions to orthotolidine and benzidine. Immunoassay and electrophoresis techniques can measure myoglobin. The ammonium sulfate test has often proved unreliable or difficult to interpret. Excretion of acid maltase is decreased in acid maltase deficiency.

Quality Control Mouse Bioassay

Found that media prepared with tap water could support adequate development of both 1-cell and 2-cell mouse embryos to the blastocyst stage respectively, compared to media prepared with ultrapure water. The apparent contradiction of these studies can be resolved by taking into account the different stages of development used at the start of culture, the types of media used, and the supplementation of medium with protein. Fukada et al. (312) used BWW, a simple-type medium, whereas Silverman et al. (314) used Ham's F-10. The latter medium contains amino acids, which may chelate any possible toxins present in the tap water, e.g., heavy metals. George et al. (313), included high levels of BSA in their zygote cultures to the blastocyst. Albumins can chelate potential embryotoxins and thereby mask the effect of any present in the culture medium (154,201). Furthermore, all studies used blastocyst development as the sole criterion for assessing embryo development. Blastocyst development is a...

Development of industrial barrens

Although acute damage by sulphur dioxide, the main phytotoxic component of smelter fumes, definitely contributed to vegetation decline (e.g. Haywood 1910 Euler 1939 Makhnev et al. 1990), the importance of this damage for the development of industrial barrens remains unclear. Extreme levels of sulphur dioxide, especially near the roastbeds, killed adjacent forests during relatively short time (Hedgcock 1912 Dean and Swain 1944 Gordon and Gorham 1963 Kryuch-kov 1993 Hutchinson and Symington 1997). However, absence of industrial barrens around power plants and aluminium smelters hints that development of this kind of landscape is impossible without severe soil contamination by heavy metals (see Sect. 5.1). In particular, near Anaconda smelter, percent bare ground positively correlated with both concentrations of hazardous substances in soil and soil phytotoxicity revealed by laboratory experiments, thus suggesting the leading role of soil contamination in loss of vegetation in the field...

Metallothionein and associated systems

Metallothionein

When metallothionein was first described, the function attributed to it was to regulate the cellular concentrations of essential metals. This was assumed to involve donating metals to specific metal-requiring ligands (enzymes, zinc fingers, structural proteins), while preventing aspecific binding to macromolecules by keeping the free concentrations of metals very low. In addition some metallothioneins turned out to be highly inducible by non-essential heavy metals (e.g. Cd) and this suggested a detoxification role. This classical, dual role of metallothionein has come under fire recently. The following issues describe the more complicated situation today. Induction of metallothionein by exposure to heavy metals has been studied extensively, but the mechanism is not yet clear. As in the case of antioxidant enzymes, inducibility is due to the presence of specific sequences in the promoter of the gene, which bind a transcription factor activated by metals. In the case of metallothionein...

Theyre trying to poison me

High levels of heavy metals and some other elements (such as lead, copper, arsenic and antimony) are toxic to most organisms. There are microorganisms which can tolerate these elements and may even use them in their metabolism. These can be useful for cleaning up polluted areas. There are also microorganisms that can utilise any form of naturally occurring organic compounds which derive from biological activity. Microbes which degrade petroleum, and other types of hydrocarbon deposits, may be a nuisance under some circumstances, but are useful for cleaning up spills. Not all organic compounds are metabolised by microorganisms. Some of human origin (such as plastics, detergents and pesticides) are not degraded and thus accumulate in the environment, often with harmful effects.

Hazardous Metallic Coatings

Enameled ware, galvanized metal, copper, cadmium, antimony, zinc or tin utensils will not be used for food contact surfaces. The soluble salts and or oxides of such heavy metals can cause abrupt and severe gastrointestinal symptoms, typically in a setting where foods or beverages of high acid content have reacted chemically with the metal containers in which they were prepared or stored.

Conclusion

Comparative analysis of the existing data demonstrated that industrial barrens have developed due to combined impact of different stressors, among which soil contamination by heavy metals, clearcutting and fires played the leading role. The combined effects are critical, as either stress alone would have caused much less damage (Jordan 1975). Pollution, accompanied by other human-induced disturbances (primarily clearcutting), damages and gradually kills the vegetation this process is usually concluded by a fire, facilitated by unusually large amount of woody debris accumulated in severely damaged communities. Since vegetation recovery is hampered by soil toxicity due to extreme contamination by heavy metals, soils remain bare for a long time and suffer from extensive wind and water erosion exacerbated by the intense frost-heaving. The destructive processes are enhanced by both disturbance of negative feedbacks regulating e.g. relationships between plants, herbivores, and their natural...

Capacitance

There are reports on very high sensitivity in assays of DNA, interleu-kins, and heavy metals. In these cases different affinity groups, including antibodies (Berggren and Johansson 1997), nucleic acids (Berggren et al. 1999), repressor proteins (Bontidean et al. 2001), and proteins with high selectivity for heavy metal ions (Bontidean et al. 1998), were immobilized on the sensor surface. It has furthermore been shown possible to use the sensor system for continuous monitoring as long as the capacity on the electrode surface is sufficient (Hedstrom and Mattiasson, unpublished results). After saturation, cleaning of the surface is required in order to release the bound material.

Pesticides

In contrast to heavy metals, pesticides are designed to affect a specific biochemical target, such as a single photosynthesis protein, a specific ion channel in the nervous system, or a key enzyme in a biosynthetic pathway. The biochemical damage caused by reacting with such a specific target is called the primary lesion. An example is the reaction of organophosphate insecticides with the enzyme acetylcholinesterase, which when inhibited will cause accumulation of acetylcholine, a neurotransmitter, in the synaptic cleft, leading to uncoordinated behaviour, spasms, and mortality in insects. From this fundamental toxicological principle one would expect that gene-expression profiles induced by pesticides would be limited to a small fraction of the genome. This appears not to be the case. Most pesticides, when administered to organisms outside of the context of agriculture, are less selective than expected. We discuss a few examples to illustrate this point.

Imaging Findings

Fungus Ball Maxillary Sinus

Both CT and MR findings of fungus ball are conditioned by the high content of heavy metals (iron and manganese) and calcium within fungal hyphae. As a result, CT density of the fungus ball is spontaneously hyperdense microcalcifications can be observed, scattered within the lesion (Fig. 6.18). Though extremely specific, these signs lack sensitivity (Dhong et al. 2000). The MR pattern may often be misleading actually, the paramagnetic properties of iron and manganese combined with the low number of freely moving protons provoke both T1 and T2 shortening. Consequently, on both sequences, MR demonstrates

Metallothioneins

Metallothionein (MT) is a low-molecular weight protein rich in thiol groups and heavy metals (Kagi 1993 Karin 1985). Since its discovery, MT was identified as a cadmium-binding protein and, for this very reason, has been considered an important factor involved in the protection of organisms from the harmful effects of toxic heavy metals such as cadmium and mercury. The improvement of analytical techniques and the increased understanding of the mechanisms of MT induction has strongly encouraged the use of MT as an environmental marker for metal pollution (Dallinger et al. 2000, 2004). On the other hand, a number of evidence indicate that MT can act as scavenger of free hydroxyl and superoxide radicals (Kumari et al. 2000 Wright et al. 2000 You et al. 2002) and that MT synthesis can be induced by oxidative stress in a fashion similar to heavy metals (Cai et al. 1999 Kondoh et al. 2001). In spite of several decades of studies, the exact function of MT is still matter of debate. The...

Mechanisms of Action

Most chemical agents (alcohols, phenols, aldehydes, heavy metals, oxidants) denature proteins irreversibly. Surfactant compounds (amphoteric and cationic) attack the cytoplasmic membrane. Acridine derivatives bind to DNA to prevent its replication and function (transcription).