Lack of the alanine-serine-cysteine transporter 1 causes tremors, seizures, and early postnatal death in mice.

The Na(+)-independent alanine-serine-cysteine transporter 1 (Asc-1) is exclusively expressed in neuronal structures throughout the central nervous system (CNS). Asc-1 transports small neutral amino acids with high affinity especially for D-serine and glycine (K(i): 8-12 microM), two endogenous glutamate co-agonists that activate N-methyl-D-aspartate (NMDA) receptors through interacting with the strychnine-insensitive glycine binding-site. By regulating D-serine (and possibly glycine) levels in the synaptic cleft, Asc-1 may play an important role in controlling neuronal excitability. We generated asc-1 gene knockout (asc-1(-/-)) mice to test this hypothesis. Behavioral phenotyping combined with electroencephalogram (EEG) recordings revealed that asc-1(-/-) mice developed tremors, ataxia, and seizures that resulted in early postnatal death. Both tremors and seizures were reduced by the NMDA receptor antagonist MK-801. Extracellular recordings from asc-1(-/-) brain slices indicated that the spontaneous seizure activity did not originate in the hippocampus, although, in this region, a relative increase in evoked synaptic responses was observed under nominal Mg(2+)-free conditions. Taken together with the known neurochemistry and neuronal distribution of the Asc-1 transporter, these results indicate that the mechanism underlying the behavioral hyperexcitability in mutant mice is likely due to overactivation of NMDA receptors, presumably resulting from elevated extracellular D-serine. Our study provides the first evidence to support the notion that Asc-1 transporter plays a critical role in regulating neuronal excitability, and indicate that the transporter is vital for normal CNS function and essential to postnatal survival of mice.

Export of dissolved organic carbon, nitrogen and phosphorus following clear-cutting of three Norway spruce forest growing on drained peatlands in southern Finland

Abstract

Recent Advances in Valorization Methods of Inorganic/Organic Solid, Liquid, and Gas Wastes

The main goal of this special issue was to gather contributions dealing with the latest breakthrough methods for providing value compounds and energy/fuel from waste valorization. Valorization is a relatively new approach in the area of industrial wastes management, a key issue to promote sustainable development. In this field, the recovery of value-added substances, such as antioxidants, proteins, vitamins, and so forth, from the processing of agroindustrial byproducts, is worth mentioning. Another important valorization approach is the use of biogas from waste treatment plants for the production of energy. Several approaches involving physical and chemical processes, thermal and biological processes that ensure reduced emissions and energy consumptions were taken into account. The papers selected for this topical issue represent some of the mostly researched methods that currently promote the valorization of wastes to energy and useful materials ...

Inorganic and organic phosphorus fractions in peat from drained mires in northern Finland

Abstract

Geochemical evolution of active porphyry copper tailings impoundments : from alkaline deposition towards acidification

J. Smuda: Geochemical evolution of active porphyry copper tailings impoundments Thesis abstract Mine waste is the largest volume of materials handled in the world. The oxidation of sulfidic mine waste may result in the release of acid mine drainage (AMD) rich in heavy metals and arsenic to the environment, one of the major problems the mining industry is facing today. To control and reduce this environmental impact, it is crucial to identify the main geochemical and hydrological processes influencing contaminant liberation, transport, and retention. This thesis presents the results of a geochemical, mineralogical and stable isotope study (δ2H, δ18O, δ34S) from two active porphyry copper tailings impoundments in Mediterranean (Carén tailings impoundment, El Teniente mine, Central Chile) and hyper-arid climate (Talabre tailings impoundment, Chuquicamata, Northern Chile) from the deposition in alkaline environment (pH 10.5) towards acidification after several years of exposure. The major hydrological results were the identification of vertical contaminant and water transport in the uppermost, not water-saturated zone, triggered by capillary rise due to evaporation, and infiltration downwards due to new tailings deposition, and of horizontal transport in the groundwater zone. At the surface of the sedimented tailings, evaporation of pore water led to the precipitation of Na-Ca-Mg sulfates (e.g., gypsum, tenorite), in hyper-arid climate also halite. At the Carén tailings impoundment, renewed deposition in a 4-week interval inhibited a pH decrease below neutral values and the formation of an efflorescent salt crust. At the Talabre tailings impoundment, deposition breaks of several years resulted in the formation of acidic oxidation zones in the timeframe of less than 4 years. This process enabled the transport of liberated Cu, Zn, and Fe via capillary rise to the surface, where these metals precipitated as heavy-metal sulfates (e.g., devilline, krohnkite) and chlorides (eriochalcite, atacamite). Renewed depositing may dissolve efflorescent salts and transport liberated elements towards the groundwater zone. This zone was found to be highly dynamic due to infiltration and mixing with water from different sources, like groundwater, catchment water, and infiltration from superficial waters. There, Cu was found to be partially mobile due to complexation with Cl (in Cl-rich groundwater, Talabre) and dissolved organic matter (in zones with infiltration of catchment water rich in dissolved organic matter, Carén). A laboratory study on the isotopic fractionation of sulfur and oxygen of sulfate in different minerals groups (water-soluble sulfates, low- and high-crystalline Fe(III) oxyhydroxides) contributed to the use of stable isotopes as tracer of geochemical and transport processes for environmental studies. The results highlight that a detailed geochemical, stable isotope and mineralogical study permits the identification of contamination processes and pathways already during the deposition of mine tailings. This knowledge allows the early planning of adequate actions to reduce and control the environmental impact during tailings deposition and after the closing of the impoundment. J. Smuda: Geochemical evolution of active porphyry copper tailings impoundments Résumé de these Les déchets miniers constituent les plus grands volumes de matériel gérés dans le monde. L'oxydation des déchets miniers sulfuriques peut conduire à la libération de drainages miniers acides (DMA) riches en métaux et arsenic dans l'environnement, ce qui est l'un des principaux problèmes de l'industrie minière aujourd'hui. Pour contrôler et réduire ces impacts sur l'environnement, il est crucial d'identifier les principaux processus géochimiques et hydrologiques influençant la libération, le transport et la rétention des contaminants. Cette thèse présente les résultats d'une étude géochimique, minéralogique et des isotopes stables (δ2H, δ18O, δ34S) sur des déchets miniers de 2 sites de dépôt actifs en climat méditerranéen (Dépôt de déchets de Carén, mine de El Teniente, Centre du Chili) et en climat hyper-aride (Dépôt de déchets de Talabre, mine de Chuquicamata, Nord du Chili). L'objectif était d'étudier l'évolution des déchets de la déposition en milieu alcalin (pH = 10.5) vers l'acidification après plusieurs années d'exposition. Le principal résultat hydrologique a été l'identification de 2 types de transport : un transport vertical de l'eau et des contaminants dans la zone non saturée en surface, induit par la montée capillaire due à l'évaporation et par l'infiltration subséquente de la déposition de sédiments frais ; et un transport horizontal dans la zone des eaux souterraines. À la surface des déchets, l'évaporation de l'eau interstitielle conduit à la précipitation de sulfates de Na-Ca-Mg (ex. gypse, ténorite) et halite en climat hyper-aride. Dans le site de Carén, une nouvelle déposition de déchets frais à 4 semaines intervalle a empêché la baise du pH en deçà des valeurs neutres et la formation d'une croûte de sels efflorescentes en surface. Dans le site de Talabre, les fentes de dessiccation des dépôts ont entraîné la formation d'une zone d'oxydation à pH acide en moins de 4 ans. Ce processus a permis la libération et le transport par capillarité de Cu, Zn, Fe vers la surface, où ces éléments précipitent sous forme de sulfates de métaux lourds (ex., dévilline, krohnkite) de chlorures (ex. ériochalcite, atacamite). Une nouvelle déposition de sédiments frais pourrait dissoudre ces sels et les transporter vers la zone des eaux souterraines. Cette dernière zone était très dynamique en raison du mélange d'eaux provenant de différentes sources, comme les eaux souterraines, l'eau de captage et l'infiltration des eaux superficielles. Egalement dans cette zone, le cuivre était partiellement mobile à cause de la formation de complexe avec le chlore (dans les zone riche en Cl, Talabre) et avec la matière organique dissoute (dans les zones où s'infiltre l'eau de captage riche en matière organique, Carén). Une étude en laboratoire sur le fractionnement des isotopes stables de sulfure et d'oxygène des sulfates dans différents groupes de minéraux (sulfates hydrosolubles, sulfures de oxy-hydroxyde de Fe(III) faiblement ou fortement cristallins) a permis d'apporter une contribution à leur utilisation comme traceurs dans l'étude des processus géochimiques et de transport lors d'études environnementales. Les résultats montrent qu'une étude détaillée de la géochimie, des isotopes stables et de la minéralogie permet d'identifier les processus et les voies de contamination déjà pendant la période de dépôt des déchets miniers. Cette connaissance permet de planifier, dès le début de l'exploitation, des mesures adéquates pour réduire et contrôler l'impact sur l'environnement pendant la période de dépôts de déchets miniers et après la fermeture du site.

Pitfalls in aminoacid and organic acid analysis: 3-hydroxypropionic aciduria.

Pitfalls in organic acid analysis can originate from inadequate methodology, analytical interferences, in vivo interactions and from pre-analytical conditions which often are unknown to the specialized analytical laboratory. Among the latter, ingested food and additives, metabolites of food processing or medications have to be considered. Bacterial metabolites from the gastrointestinal or urogenital system or formed after sample collection can lead to pitfalls as well. An example of such a patient whose urinary metabolites mimic at first glance inherited propionic aciduria is described.

Linking supply to demand: the neuronal monocarboxylate transporter MCT2 and the alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid receptor GluR2/3 subunit are associated in a common trafficking process.

MCT2 is the major neuronal monocarboxylate transporter (MCT) that allows the supply of alternative energy substrates such as lactate to neurons. Recent evidence obtained by electron microscopy has demonstrated that MCT2, like alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid (AMPA) receptors, is localized in dendritic spines of glutamatergic synapses. Using immunofluorescence, we show in this study that MCT2 colocalizes extensively with GluR2/3 subunits of AMPA receptors in neurons from various mouse brain regions as well as in cultured neurons. It also colocalizes with GluR2/3-interacting proteins, such as C-kinase-interacting protein 1, glutamate receptor-interacting protein 1 and clathrin adaptor protein. Coimmunoprecipitation of MCT2 with GluR2/3 and C-kinase-interacting protein 1 suggests their close interaction within spines. Parallel changes in the localization of both MCT2 and GluR2/3 subunits at and beneath the plasma membrane upon various stimulation paradigms were unraveled using an original immunocytochemical and transfection approach combined with three-dimensional image reconstruction. Cell culture incubation with AMPA or insulin triggered a marked intracellular accumulation of both MCT2 and GluR2/3, whereas both tumor necrosis factor alpha and glycine (with glutamate) increased their cell surface immunolabeling. Similar results were obtained using Western blots performed on membrane or cytoplasm-enriched cell fractions. Finally, an enhanced lactate flux into neurons was demonstrated after MCT2 translocation on the cell surface. These observations provide unequivocal evidence that MCT2 is linked to AMPA receptor GluR2/3 subunits and undergoes a similar translocation process in neurons upon activation. MCT2 emerges as a novel component of the synaptic machinery putatively linking neuroenergetics to synaptic transmission.

An evaluation of the inorganic and organic geochemistry of the San Vicente Mississippi Valley-type zinc-lead district, central Peru: Implications for ore fluid composition, mixing processes, and sulfate reduction

Mississippi Tialley-type zinc-lead deposits and ore occurrences in the San Vicente belt are hosted in dolostones of the eastern Upper Triassic to Lower Jurassic Pucara basin, central Peru. Combined inorganic and organic geochemical data from 22 sites, including the main San Vicente deposit, minor ore occurrences, and barren localities, provide better understanding of fluid pathways and composition, ore precipitation mechanisms, Eh-pH changes during mineralization, and relationships between organic matter and ore formation. Ore-stage dark replacement dolomite and white sparry dolomite are Fe and rare earth element (REE) depleted, and Mn enriched, compared to the host dolomite. In the main deposit, they display significant negative Ce and probably Eu anomalies. Mixing of an incoming hot, slightly oxidizing, acidic brine (H2CO3 being the dominant dissolved carbon species), probably poor in REE and Fe, with local intraformational, alkaline, reducing waters explains the overall carbon and oxygen isotope variation and the distributions of REE and other trace elements in the different hydrothermal carbonate generations. The incoming ore fluid flowed through major aquifers, probably basal basin detrital units, with limited interaction with the carbonate host rocks. The hydrothermal carbonates show a strong regional chemical homogeneity, indicating access of the ore fluids by interconnected channelways near the ore occurrences. Negative Ce anomalies in the main deposit, that are absent at the district scale, indicate local ore-fluid chemical differences. Oxidation of both migrated and indigenous hydrocarbons by the incoming fluid provided the local reducing conditions necessary for sulfate reduction to H2S, pyrobitumen precipitation, and reduction of Eu3+ to Eu2+. Fe-Mn covariations, combined with the REE contents of the hydrothermal carbonates, are consistent with the mineralizing system shifting from reducing/rock-dominated to oxidizing/fluid-dominated conditions following ore deposition. Sulfate and sulfide sulfur isotopes support sulfide origin from evaporite-derived sulfate by thermochemical organic reduction; further evidence includes the presence of C-13-depleted calcite cements (similar to-12 parts per thousand delta(13)C) as sulfate pseudomorphs, elemental sulfur, altered organic matter in the host dolomite, and isotopically heavier, late, solid bitumen. Significant alteration of the indigenous and extrinsic hydrocarbons, with absent bacterial membrane biomarkers (hopanes) is observed. The light delta(34)S of sulfides from small mines and occurrences compared to the main deposit reflect a local contribution of isotopically light sulfur, evidence of local differences in the ore-fluid chemistry.

Organic acids in the rhizosphere and phytoavailability of sewage sludge-borne trace elements

The aim of this work was to quantify low molecular weight organic acids in the rhizosphere of plants grown in a sewage sludge-treated media, and to assess the correlation between the release of the acids and the concentrations of trace-elements in the shoots of the plants. The species utilized in the experiment were cultivated in sand and sewage sludge-treated sand. The acetic, citric, lactic, and oxalic acids, were identified and quantified by high performance liquid chromatography in samples collected from a hydroponics system. Averages obtained from each treatment, concentration of trace elements in shoots and concentration of organic acids in the rhizosphere, were compared by Tukey test, at 5% of probability. Linear correlation analysis was applied to verify an association between the concentrations of organic acids and of trace elements. The average composition of organic acids for all plants was: 43.2, 31.1, 20.4 and 5.3% for acetic, citric, lactic, and oxalic acids, respectively. All organic acids evaluated, except for the citric acid, showed a close statistical agreement with the concentrations of Cd, Cu, Ni, and Zn found in the shoots. There is a positive relationship between organic acids present in the rhizosphere and trace element phytoavailability.

Reconstruction of the recent history of a large deep prealpine lake (Lake Bourget, France) using subfossil chironomids, diatoms, and organic matter analysis: towards the definition of a lake-specific reference state

This paper presents the recent history of a large prealpine lake (Lake Bourget) using chironomids, diatoms and organic matter analysis, and deals with the ability of paleolimnological approach to define an ecological reference state for the lake in the sense of the European Framework Directive. The study at low resolution of subfossil chironomids in a 4-m-long core shows the remarkable stability over the last 2.5 kyrs of the profundal community dominated by a Micropsectra-association until the beginning of the twentieth century, when oxyphilous taxa disappeared. Focusing on this key recent period, a high resolution and multiproxy study of two short cores reveals a progressive evolution of the lake's ecological state. Until AD 1880, Lake Bourget showed low organic matter content in the deep sediments (TOC less than 1%) and a well-oxygenated hypolimnion that allowed the development of a profundal oxyphilous chironomid fauna (Micropsectra-association). Diatom communities were characteristic of oligotrophic conditions. Around AD 1880, a slight increase in the TOC was the first sign of changes in lake conditions. This was followed by a first limited decline in oligotrophic diatom taxa and the disappearance of two oxyphilous chironomid taxa at the beginning of the twentieth century. The 1940s were a major turning point in recent lake history. Diatom assemblages and accumulation of well preserved planktonic organic matter in the sediment provide evidence of strong eutrophication. The absence of profundal chironomid communities reveals permanent hypolimnetic anoxia. From AD 1995 to 2006, the diatom assemblages suggest a reduction in nutrients, and a return to mesotrophic conditions, a result of improved wastewater management. However, no change in hypolimnion benthic conditions has been shown by either the organic matter or the subfossil chironomid profundal community. Our results emphasize the relevance of the paleolimnological approach for the assessment of reference conditions for modern lakes. Before AD 1900, the profundal Micropsectra-association and the Cyclotella dominated diatom community can be considered as the Lake Bourget reference community, which reflects the reference ecological state of the lake.

Organic matter processing and soil evolution in a braided river system

Traditionally, braided river research has considered flow, sediment transport processes and, recently, vegetation dynamics in relation to river morphodynamics. However, if considering the development of woody vegetated patches over a time scale of decades, we must consider the extent to which soil forming processes, particularly related to soil organic matter, impact the alluvial geomorphic-vegetation system. Here we quantify the soil organic matter processing (humification) that occurs on young alluvial landforms. We sampled different geomorphic units, ranging from the active river channel to established river terraces in a braided river system. For each geomorphic unit, soil pits were used to sample sediment/soil layers that were analysed in terms of grain size (<2mm) and organic matter quantity and quality (RockEval method). A principal components analysis was used to identify patterns in the dataset. Results suggest that during the succession from bare river gravels to a terrace soil, there is a transition from small amounts of external organic matter supply provided by sedimentation processes (e.g. organic matter transported in suspension and deposited on bars), to large amounts of autogenic in situ organic matter production due to plant colonisation. This appears to change the time scale and pathways of alluvial succession (bio-geomorphic succession). However, this process is complicated by: the ongoing possibility of local sedimentation, which can serve to isolate surface layers via aggradation from the exogenic supply; and erosion which tends to create fresh deposits upon which organic matter processing must re-start. The result is a complex pattern of organic matter states as well as a general lack of any clear chronosequence within the active river corridor. This state reflects the continual battle between deposition events that can isolate organic matter from the surface, erosion events that can destroy accumulating organic matter and the early ecosystem processes necessary to assist the co-evolution of soil and vegetation. A key question emerges over the extent to which the fresh organic matter deposited in the active zone is capable of significantly transforming the local geochemical environment sufficiently to accelerate soil development.

Why do they separate it or not? Attitudes and behaviors towards organic waste separation

This article shows the results of an exploratory study related to the separation of organic waste in order to offer suggestions for the improvement of waste disposal communication campaigns. The overall objective is to analyze attitude and behavior of those who do and those who do not separate organic waste, related to a specific promotional campaign carried out in two neighborhoods, in the municipality of Badalona (Spain), within the framework of the study of proenvironmental attitudes and behaviors and based on the Psychosocial Four Spheres Model. 1,010 interviews were conducted and data was analyzed using Chi-Squared Automatic Interaction Detector (CHAID). Waste separation behavior was used as a dependent variable. The reasons given to explain why people do or do not separate organic waste and sociodemographic variables, have been introduced as independent variables. In accordance with the Four Spheres Model, results show significant differences in waste separation. Based on the profiles obtained, we find some predictive variables that facilitate the development of communication campaigns according to the requirements of each community.

Why do they separate it or not? Attitudes and behaviors towards organic waste separation

This article shows the results of an exploratory study related to the separation of organic waste in order to offer suggestions for the improvement of waste disposal communication campaigns. The overall objective is to analyze attitude and behavior of those who do and those who do not separate organic waste, related to a specific promotional campaign carried out in two neighborhoods, in the municipality of Badalona (Spain), within the framework of the study of proenvironmental attitudes and behaviors and based on the Psychosocial Four Spheres Model. 1,010 interviews were conducted and data was analyzed using Chi-Squared Automatic Interaction Detector (CHAID). Waste separation behavior was used as a dependent variable. The reasons given to explain why people do or do not separate organic waste and sociodemographic variables, have been introduced as independent variables. In accordance with the Four Spheres Model, results show significant differences in waste separation. Based on the profiles obtained, we find some predictive variables that facilitate the development of communication campaigns according to the requirements of each community.

Yield and fruit quality of apple from conventional and organic production systems

The objective of this study was to assess the yield and fruit quality of apple produced with a conventional and an organic production systems in Southern Brazil. The orchards consisted of alternate rows from 10 to 12-year old 'Royal Gala' and 'Fuji' apple trees on M.7 rootstocks, grown as slender spindles, on 4x6 m spacing. Eighteen apple trees of each cultivar and management system were randomly selected and assessed for nutrition, flowering, fruit set, yield, and fruit quality during two growing seasons (2002/2003 and 2003/2004). The organic management system resulted in lower concentrations of K, Mg, and N in leaves and fruits, and in smaller fruits for both cultivars, and lower fruit yield for 'Fuji' than from the conventional production system. For both cultivars, fruits from the organic orchard harvested at commercial maturity had a more yellowish skin background color, higher percentage of blush in the fruit skin, higher soluble solids content, higher density, higher flesh firmness, and higher severity of russet than fruits from the conventional orchard. Fruit from the organic orchard had lower titratable acidity in 'Royal Gala', and higher incidence of moldy core and lower incidence of watercore in 'Fuji', than fruit from the conventional orchard. A non-trained sensory panel detected no significant differences for fruit attributes of taste, flavor and texture between fruit from the production systems for either cultivar.