The resorption of zinc from scales of sea trout (Salmo trutta) during the upstream spawning migration

SUMMARY. The concentration of zinc in the scales of unripe, prespawning, estuarine sea trout was compared to that in the scales of sea trout about to spawn in fresh water. Zinc concentrations in scales from estuarine sea trout were in agreement with a published concentration factor but those from fresh water were not — a 43–52% reduction in the zinc concentration of the scales was observed. This withdrawal of trace metals from scales was also likely for iron but these data were less conclusive. This reclamation of trace metals from scales may represent the withdrawal of stored nutrients from body reserves to be used in gonad development and maturation.     

Dietary and water-borne Zn exposures affect energy reserves and subsequent Zn tolerance of Daphnia magna

Enhanced tolerance of aquatic organisms to metal toxicity is one of the important issues of environmental monitoring programs. Determination of dominant uptake route(s) of metals may help to better predict the toxic effects posed by metals. This study aimed to investigate the importance of Zn uptake routes on tolerance and energy reserves of Daphnia magna. Neonates of D. magna were exposed to water-borne zinc, dietary zinc (algae Pseudokichneriella subcapitata loaded with Zn) or to combination of both for 4 days. LC50 (48 h) values of Zn were considerably different from different zinc pre-exposures. Four-day pre-exposure of D. magna neonates produced enhanced tolerance to Zn toxicity. The lowest LC50 values were found in controls (48.2 microM) (no Zn added to their exposure medium and food) and after water-borne Zn pre-exposures (46.2 microM). The level of tolerance increased when dietary Zn was included in pre-exposures, reaching the highest level of LC50 value (70.8 microM) in the highest pre-exposure concentration of diet and water-borne combination experiment. The energy reserves of D. magna also varied significantly under different pre-exposure routes of zinc. In all cases, control animals contained lowest levels of protein, sugar and lipid. Likewise, they represented the lowest energy reserves. Protein levels were highest in the highest dietary Zn exposure, and lowest in the water-borne exposures. Highest and lowest sugar levels were measured in the lowest and highest water-borne Zn exposures, respectively. In contrast, lipid levels were higher in the higher Zn exposure of all exposure routes, the combination exposure resulting in highest lipid levels. The highest total energy reserve was measured in animals that lived in the highest Zn exposure of diet and water-borne combination experiment, mainly due to greater lipid reserves in algae reared in Zn containing media. Results suggest that the dietary exposure route should be considered carefully in natural monitoring studies, and be considered in regulatory assessments of zinc and population dynamics of cladocerans.     

Asymmetric distribution of metals in the Xenopus laevis oocyte: a synchrotron X-ray fluorescence microprobe study.

The asymmetric distribution of many components of the Xenopus oocyte, including RNA, proteins, and pigment, provides a framework for cellular specialization during development. During maturation, Xenopus oocytes also acquire metals needed for development, but apart from zinc, little is known about their distribution. Synchrotron X-ray fluorescence microprobe was used to map iron, copper, and zinc and the metalloid selenium in a whole oocyte. Iron, zinc, and copper were asymmetrically distributed in the cytoplasm, while selenium and copper were more abundant in the nucleus. A zone of high copper and zinc was seen in the animal pole cytoplasm. Iron was also concentrated in the animal pole but did not colocalize with zinc, copper, or pigment accumulations. This asymmetry of metal deposition may be important for normal development. Synchrotron X-ray fluorescence microprobe will be a useful tool to examine how metals accumulate and redistribute during fertilization and embryonic development.     

A comparative view at comprehensive information resources on three-dimensional structures of biological macro-molecules.

The rapidly increasing amount of information on three-dimensional (3D) structures of biological macro-molecules has still an insufficient impact on genome analysis, functional genomics and proteomics as well as on many other fields in biomedicine including disease-related research. There are, however, attempts to make structural data more easily accessible to the bench biologist. As members of the world-wide Protein Data Bank (wwPDB), the RCSB Protein Data Bank (PDB), the Protein Data Bank Japan and the Macromolecular Structure Database are the primary information resources for 3D structures of proteins, nucleic acids, carbohydrates and complexes thereof. In addition, a number of secondary resources have been set up that also provide information on all currently known structures in a relatively comprehensive manner and not focusing on specific features only. They include PDBsum, the OCA browser-database for protein structure/function, the Molecular Modeling Database and the Jena Library of Biological Macromolecules--JenaLib. Both the primary and secondary resources often merge the information in the PDB files with data from other resources and offer additional analysis tools thereby adding value to the original PDB data. Here, we briefly describe these resources from a user's point of view and from a comparative perspective. It is our aim to guide researchers outside the structure biology field in getting the most out of the 3D structure resources.     

Multilevel Anthropogenic Cycles of Copper and Zinc: A Comparative Statistical Analysis

Contemporary cycles for copper and zinc are coanalyzed with the tools of exploratory data analysis. One-year analyses (circa 1994) are performed at three discrete spatial levels-country (52 countries that comprise essentially all anthropogenic stocks and flows of the two metals), eight world regions, and the planet as a whole-and are completed both in absolute magnitude and in per capita terms. This work constitutes, to our knowledge, the first multiscale, multilevel analysis of anthropogenic resources throughout their life cycles. The results demonstrate that (1) A high degree of correlation exists between country-level copper and country-level zinc rates of fabrication and manufacturing, entry into use, net addition to in-use stocks, discard, and landfilling; (2) Regional-level rates for copper and zinc cycle parameters show the same correlations as exist at country level; (3) On a per capita basis, countries add to in-use stock almost 50% more copper than zinc; (4) The predominant discard streams for copper and zinc at the global level are different for the two metals, and relative rates of different loss processes differ geographically, so that resource recovery policies must be designed from metalspecific and location-specific perspectives; (5)When absolute magnitudes of life-cycle flows are considered, the standard deviations of the data sets decrease from country level to regional level for both copper and zinc, which is not the case for the per capita data sets, where the statistical properties of the data sets for both metals approach being independent of spatial level, thus providing a basis for predicting unmeasured per capita metal flow behavior.     

Protective management of trees against debarking by deer negatively impacts bryophyte diversity

When wildlife populations become too large, they impact other flora and fauna within the ecosystems that they inhabit. For example, the recent rise in population numbers of sika deer in Japan has led to the stripping of bark from tree overstories in forested areas. This has led to protective management actions, such as wrapping the trunks of trees in wire mesh. The present study investigates the impact of this management action on epiphytic diversity at Mt. Ohdaigahara, which is one of the hotspots for bryophyte diversity in Japan. The correlation between the diversity of epiphytic bryophytes and environmental variables was examined, including the presence/absence of wire mesh protection. A generalized linear model showed that species richness and bryophyte cover was significantly correlated with both tree diameter (at 1.5 m height) and tree density (P < 0.01), but negatively correlated with wire mesh protection. Inductively coupled plasma-mass spectrometry analysis showed a significant 3- to 6-fold higher concentration of zinc in bryophytes occupying tree bark under wire mesh protection than for those without wire mesh. Hence, the high sensitivity of bryophytes to zinc accumulation, as a result of toxicity caused by galvanized iron mesh, has led to the loss of species richness and bryophyte cover on tree trunks. Furthermore, other heavy metals found in wire mesh may also contribute to the negative effect on bryophytes. Therefore, to establish best practices for biodiversity conservation that include bryophytes, materials that are free of heavy metals should be preferentially used for tree protection.     

Social influence of larvae on ovarian maturation in primary and secondary reproductives of the dampwood termite Zootermopsis angusticollis

We tested the effect of larvae on the reproductive maturation and fecundity of female primary and secondary reproductives of the termite Zootermopsis angusticollis Hagen (Isoptera; Termopsidae) by varying the number of third‐ to fourth‐instar larvae nesting with heterosexually paired reproductives. Primary females had higher fecundities and oviposited sooner when nesting with larvae than females lacking larvae, but gained less body mass and had fewer functional ovarioles per ovary. Secondary reproductives nesting with larvae also had higher fecundities and oviposited sooner, but unlike primaries, they gained more body mass and had more functional ovarioles when larvae were present. The specific response of both primary and secondary females varied according to the number of larvae present. These results suggest that larvae can enhance the fecundity of primary and secondary females. Larvae may increase the energetic reserves of reproductives by performing colony labour, reducing pathogen load and providing trophallactic secretions. Trophallaxis with larvae may significantly enhance endogenous nitrogen, which is a limiting nutrient for termites. Primary females, which normally need to produce a first brood quickly to initiate a new colony, may expend limited nutritional resources on oogenesis rather than producing additional ovarioles. Primaries may also store fewer energetic reserves for long‐term brood care, and therefore gained less mass when larvae were present to attend to non‐reproductive tasks. Secondary females may exhibit a greater positive response to larvae than primaries because they begin reproductive life with fewer stored resources and thus their development and fecundity are more dependent on assistance from larvae. Both primary and secondary reproductives may become more dependent on the contributions of larvae as their rate of egg production increases with subsequent bouts of oviposition.     

Zinc and copper uptake by silver beet grown in secondary treated effluent

The study was conducted in a hydroponics set-up to determine the suitability of zinc (Zn) and copper (Cu) contaminated wastewater as a growth medium for edible crops; to identify accumulation of Zn and Cu in different parts of the plants and to understand their effects on plant growth. Silver beet was found to produce adequate yields in the Zn (1.7 mg/L and 2.0mg/L) and Cu (0.35 mg/L and 1.1mg/L) spiked medium but not in the secondary treated domestic effluent. The plants grown in secondary treated effluent showed stunted growth and accumulated Zn and Cu to a high level in their shoots. In all other mediums Zn and Cu accumulated more in the roots. The stunted growth of silver beet in secondary treated wastewater and uptake of Zn in particular was considered to be due to the deficiency of nitrogen and other plant nutrients rather than the effect of heavy metals. The study also revealed that if there was adequate amount of macronutrients available for growth, silver beet could be grown in domestic effluent without the risk of Zn or Cu contamination to the undesired level through hydroponics.     

The Multilevel Cycle of Anthropogenic Zinc

A comprehensive annual cycle for stocks and flows of zinc, based on data from circa 1994 and incorporating information on extraction, processing, fabrication, use, discard, recycling, and landfilling, was carried out at three discrete governmental unit levels—54 countries and 1 country group (which together comprise essentially all global anthropogenic zinc stocks and flows), nine world regions, and the planet as a whole. All of these cycles are available in an electronic supplement to this article, which thus provides a metadata set on zinc flows for the use of industrial ecology researchers. A "best estimate" global zinc cycle was constructed to resolve aggregation discrepancies. Among the most interesting results are the following: (1) The accumulation ratio, that is, addition to in-use stock as a function of zinc entering use, is positive and large (2/3 of zinc entering use is added to stock) (country, regional, and global levels); (2) secondary input ratios (fractions of input to fabrication that are from recycled zinc) and domestic recycling percentages (fractions of discarded zinc that are recycled) differ among regions by as much as a factor of six (regional level); (3) worldwide, about 40% of the zinc that was discarded in various forms was recovered and reused or recycled (global level); (4) zinc cycles can usefully be characterized by a set of ratios, including, notably, the utilization efficiency (the ratio of manufacturing waste to manufacturing output: 0.090) and the prompt scrap ratio (new scrap as a fraction of manufacturing input: 0.070) (global level). Because capturable discards are a significant fraction of primary zinc inputs, if a larger proportion of discards were recaptured, extraction requirements would decrease significantly (global level). The results provide a framework for complementary studies in resource stocks, industrial resource utilization, energy consumption, waste management, industrial economics, and environmental impacts.     

Urban Mining's Potential to Relieve China's Coming Resource Crisis

China's mineral resource consumption has gone through multiple increases since 1980, resulting in the inadequacy of important strategic resources and a high level of external dependence. Some developed countries have already reduced primary resources consumption through urban mining. Can China also break through the bottleneck of the resource shortage and continue its economic and social development through strengthening of urban mining? This article selected copper (Cu), aluminum (Al), lead (Pb), and iron (Fe) as case studies and established predictive models for metal demand, recycling, and stock, based on stock analysis, material flow analysis, and a life distribution model, and then analyzed the metabolism of the four resources and compared the environmental effects of three scenarios. The study indicates that the urban mining potential of Cu, Fe, Al, and Pb will attain 8.1, 711.6, 37.0, and 12.1 million tonnes, respectively, in 2040. Compared with 2010, the substitution rate (secondary metals substituting primary metals) of Cu and Fe increase by 25.4% and 59.9%, whereas external dependence decreases by 30.8% and 25.7%. However, substitution is not obvious regarding Al and Pb. The low resource scenario decreases resources use, which will reduce external dependence in the short term, whereas the strengthened recovery scenario increases resource recovery and has a larger effect in reducing external dependence in the long term. So, in line with urban mining in the future, China should change its environment and resource strategy, further strengthen layout and construction of urban mining demonstration bases, and encourage the use of recyclable resources to provide a better foundation for urban mining.     

Aspects of trace element interactions during development

The origins of nutritional trace element deficiencies are summarized. Inadequate intake results in primary deficiency, whereas secondary or conditioned deficiencies can arise in several ways including trace element interactions. Evidence is presented and discussed for interactions of essential trace elements during prenatal and early postnatal development. Diets of widely different zinc and copper concentrations and ratios were fed to pregnant rats. Analysis of fetal outcome and copper and zinc concentrations of maternal and fetal livers showed that although there is an interaction between these metals it occurs only at levels of dietary copper deficiency. Iron and manganese interact so that high levels of one depress absorption of the other. Mice fed iron-supplemented diets had liver manganese concentrations lower than those of unsupplemented mice. Iron supplements at high but not low levels also depressed absorption of zinc. Conversely, zinc deficiency in pregnant rats caused higher than normal concentrations of iron in maternal and fetal liver. Trace element analyses of proprietary infant formulas indicate that in some, concentrations and ratios of these trace elements may be incorrect. The effects of essential trace element interactions during development should be further investigated. Caution is urged in considering levels of trace element supplements during pregnancy, lactation, or early childhood.     

Rainbow trout metallothionein

Two forms of hepatic metallothionein were isolated and purified from rainbow trout injected intraperitoneally with cadmium chloride. Both forms showed similarities with mammalian metallothioneins, had a high cystein content (30 mol%), and were void of aromatic amino acids and histidine. The molecular weight was estimated to be about 6000 dalton for the apothioneins, and the thiol groups of the cysteine residues complexed with the heavy metals (Cd, Cu, Zn) in a SH/Me⁺⁺ ratio of about 2.4. The amount of copper in metallothionein from rainbow trout was very high, greater than the amount of cadmium and zinc after injections of 3 mg cadmium/kg body weight. The total metal content of cadmium, copper and zinc in metallothionein 1 and 2 were about 7 and 8 atoms per molecule respectively.     

Zinc coordination sphere in biochemical zinc sites

Zinc is known to be indispensable to growth and development and transmission of the genetic message. It does this through a remarkable mosaic of zinc binding motifs that orchestrate all aspects of metabolism. There are now nearly 200 three dimensional structures for zinc proteins, representing all six classes of enzymes and covering a wide range of phyla and species. These structures provide standards of reference for the identity and nature of zinc ligands in other proteins for which only the primary structure is known. Three primary types of zinc sites are apparent from examination of these structures: structural, catalytic and cocatalytic. The most common amino acids that supply ligands to these sites are His, Glu, Asp and Cys. In catalytic sites zinc generally forms complexes with water and any three nitrogen, oxygen and sulfur donors with His being the predominant amino acid chosen. Water is always a ligand to such sites. Structural zinc sites have four protein ligands and no bound water molecule. Cys is the preferred ligand in such sites. Cocatalytic sites contain two or three metals in close proximity with two of the metals bridged by a side chain moiety of a single amino acid residue, such as Asp, Glu or His and sometimes a water molecule. Asp and His are the preferred amino acids for these sites. No Cys ligands are found in such sites. The scaffolding of the zinc sites is also important to the function and reactivity of the bound metal. The influence of zinc on quaternary protein structure has led to the identification of a fourth type of zinc binding site, protein inteface. In this case zinc sites are formed from ligands supplied from amino acid residues residing in the binding surface of two proteins. The resulting zinc site usually has the coordination properties of a catalytic or structural zinc binding site.     

Copper and zinc level in biological samples from healthy subjects of vegetarian food habit in reference to community environment

Many epidemiologists have found a correlation between copper and zinc in the community environment and diseases, such as myocardial and vascular pathologies, and diabetes. The purpose of this study was to investigate the total daily intake of these two metals in cooked food, drinking water and air and their respective levels in blood and urine. A chronobiological methodology has been adopted to establish the reference values of these two metals in biological samples. It has been observed that the daily intake of copper is within the recommended value, whereas its urinary excretion is high. The daily intake of zinc is below the recommended value and its urinary excretion is also high. Both the metals showed a temporal oscillation pattern in blood and urine. A possible chronic zinc deficiency has been anticipated in this particular ethnic group of vegetarian food habit.     

Dynamic Substance Flow Analysis of Neodymium and Dysprosium Associated with Neodymium Magnets in Japan

Recycling of neodymium and dysprosium is of great interest because of the rapid growth in their demand and limited supply of new resources. To promote recovery from end‐of‐life (EoL) products, it is desirable to quantify the recycling potentials of neodymium and dysprosium by their end use. This study characterized the substance flows of neodymium and dysprosium associated with neodymium magnets in Japan by conducting a dynamic substance flow analysis. A bottom‐up approach was employed in the analysis to estimate annual consumption by end use. Factors used in the analysis were the amounts of rare earth contents, weight of a magnet used for each product, adoption ratios of neodymium magnet usage in each product, and lifetime of products. It was found that the amount of neodymium entering use was approximately half of the domestic consumption; the balance existing in final products that were exported from Japan. The economic feasibility of recycling neodymium magnets was evaluated for their largest two end uses: driving motors in hybrid electric vehicles (HEVs) and compressors in air conditioners. It was found that recycling the neodymium magnets used in the driving motors has the potential for economic feasibility in Japan. The result showed that lower transportation costs for recovered magnets can make the recycling economically feasible regardless of the content rate and the price of metals. The future increase of EoL HEVs contributes to the feasibility of recycling with a profit in the upcoming years. Strategies for more profitable recycling are concentrating scrap motors or magnets among recycling factories or selecting specific factories that deal with EoL HEVs.     

A conceptual framework for the revision of the ICD-10 classification of mental and behavioural disorders

The World Health Organization (WHO) is revising the ICD-10 classification of mental and behavioural disorders, under the leadership of the Department of Mental Health and Substance Abuse and within the framework of the overall revision framework as directed by the World Health Assembly. This article describes WHO’s perspective and priorities for mental and behavioural disorders classification in ICD-11, based on the recommendations of the International Advisory Group for the Revision of ICD-10 Mental and Behavioural Disorders. The WHO considers that the classification should be developed in consultation with stakeholders, which include WHO member countries, multidisciplinary health professionals, and users of mental health services and their families. Attention to the cultural framework must be a key element in defining future classification concepts. Uses of the ICD that must be considered include clinical applications, research, teaching and training, health statistics, and public health. The Advisory Group has determined that the current revision represents a particular opportunity to improve the classification’s clinical utility, particularly in global primary care settings where there is the greatest opportunity to identify people who need mental health treatment. Based on WHO’s mission and constitution, the usefulness of the classification in helping WHO member countries, particularly low- and middle-income countries, to reduce the disease burden associated with mental disorders is among the highest priorities for the revision. This article describes the foundation provided by the recommendations of the Advisory Group for the current phase of work.     

The effect of inbreeding on aggregation of complex diseases in genetic isolates

We have studied the effect of genetic processes in ethnically and demographically diverse isolates on the epidemiology of complex diseases. Our long-term studies of five indigenous Dagestan ethnic groups have revealed ten genetic isolates with aggregation of schizophrenia-related diseases. According to Neel’s classification (1992), these isolates belong to primary and secondary depending on the duration of demographic process. We have found that the average demographic ages of the examined primary and secondary isolates were about 4000 and 700 years, respectively. The inbreeding level F was studied using two methods: analysis of marriage structure in three generations, which is traditional in population-genetic studies, and analysis of the same structure in extensive pedigrees (up to 11–13 generations). We have shown that with the second method, the F value increases two- to threefold in various isolates. The accumulated inbreeding in the primary isolates proved to be twofold higher than that in the secondary ones. Primary isolates have revealed relatively higher genetic and clinical homogeneity in combination with higher aggregation of population-specific complex disease pathology compared to secondary isolates. A decrease in observed recombinations and the number of genomic loci linked with the disease in primary isolates have been also demonstrated. Thus, our studies showed that complex diseases can be less expensive and mapping of genes for time-consuming if conducted in primary rather than in secondary isolates, in particular when dealing with genetically heterogeneous outbred human populations.     

A systems approach to plant bioprocess optimization

A dynamic model for plant cell metabolism was used as a basis for a rational analysis of plant production potential in in vitro cultures. The model was calibrated with data from 3-L bioreactor cultures. A dynamic sensitivity analysis framework was developed to analyse the response curves of secondary metabolite production to metabolic and medium perturbations. Simulation results suggest that a straightforward engineering of cell metabolism or medium composition might only have a limited effect on productivity. To circumvent the problem of the dynamic allocation of resources between growth and production pathways, the sensitivity analysis framework was used to assess the effect of stabilizing intracellular nutrient concentrations. Simulations showed that a stabilization of intracellular glucose and nitrogen reserves could lead to a 116% increase in the specific production of secondary metabolites compared with standard culture protocol. This culture strategy was implemented experimentally using a perfusion bioreactor. To stabilize intracellular concentrations, adaptive medium feeding was performed using model mass balances and estimations. This allowed for a completely automated culture, with controlled conditions and pre-defined decision making algorithm. The proposed culture strategy leads to a 73% increase in specific production and a 129% increase in total production, as compared with a standard batch culture protocol. The sensitivity analysis on a mathematical model of plant metabolism thus allowed producing new insights on the links between intracellular nutritional management and cell productivity. The experimental implementation was also a significant improvement on current plant bioprocess strategies.     

Analysis of zinc binding sites in protein crystal structures

The geometrical properties of zinc binding sites in a dataset of high quality protein crystal structures deposited in the Protein Data Bank have been examined to identify important differences between zinc sites that are directly involved in catalysis and those that play a structural role. Coordination angles in the zinc primary coordination sphere are compared with ideal values for each coordination geometry, and zinc coordination distances are compared with those in small zinc complexes from the Cambridge Structural Database as a guide of expected trends. We find that distances and angles in the primary coordination sphere are in general close to the expected (or ideal) values. Deviations occur primarily for oxygen coordinating atoms and are found to be mainly due to H-bonding of the oxygen coordinating ligand to protein residues, bidentate binding arrangements, and multi-zinc sites. We find that H-bonding of oxygen containing residues (or water) to zinc bound histidines is almost universal in our dataset and defines the elec-His-Zn motif. Analysis of the stereochemistry shows that carboxyl elec-His-Zn motifs are geometrically rigid, while water elec-His-Zn motifs show the most geometrical variation. As catalytic motifs have a higher proportion of carboxyl elec atoms than structural motifs, they provide a more rigid framework for zinc binding. This is understood biologically, as a small distortion in the zinc position in an enzyme can have serious consequences on the enzymatic reaction. We also analyze the sequence pattern of the zinc ligands and residues that provide elecs, and identify conserved hydrophobic residues in the endopeptidases that also appear to contribute to stabilizing the catalytic zinc site. A zinc binding template in protein crystal structures is derived from these observations.