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Ectomycorrhiza (EM) formation improves tree growth and nutrient acquisition, particularly that of nitrogen (N). Few studies have coupled the effects of naturally occurring EM morphotypes to the nutrition of host trees. To investigate this, pine seedlings were grown on raw humus substrates collected at two forest sites, R2 and R3. Ectomycorrhiza morphotypes were identified, and their respective N uptake rates from organic (2-13C, 15N-glycine) and inorganic (15NH4Cl, Na15NO3, 15NH4NO3, NH415NO3) sources as well as their phosphate uptake rates were determined. Subsequently, the growth and nutritional status of the seedlings were analyzed. Two dominant EM morphotypes displayed significantly different mycorrhization rates in the two substrates. Rhizopogon luteolus Fr. (RL) was dominant in R2 and Suillus bovinus (Pers.) Kuntze (SB) was dominant in R3. 15N uptake of RL EM was at all times higher than that of SB EM. Phosphate uptake rates by the EM morphotypes did not differ significantly. The number of RL EM correlated negatively and the number of SB EM correlated positively with pine growth rate. Increased arginine concentrations and critical P/N ratios in needles indicated nutrient imbalances of pine seedlings from humus R2, predominantly mycorrhizal with RL. We conclude that different N supply in raw humus under Scots pine stands can induce shifts in the EM frequency of pine seedlings, and this may lead to EM formation by fungal strains with different ability to support tree growth. [ABSTRACT FROM PUBLISHER]

Transfer functions describing the coprecipitation of various trace elements (TE; As, Cd, Co, Cu, Cr, Mo, Ni, Pb, Zn), precipitating with iron(oxihydr)oxides from an aqueous solution, were developed and implemented in the computer model ‘Seeper’. ‘Seeper’ was developed to predict the progression of the concentrations of inorganic pollutants in unsaturated soils underneath contaminated areas and to evaluate the prospective contamination of the groundwater. Transfer functions provide a straight and simple relation between the coprecipitation of TE and easy to obtain standard soil parameters, without excessive repercussions on the usability and computation time of the model. Laboratory experiments were conducted to quantify coprecipitation in solutions with pH values ranging from 5 to 12 and containing various iron and TE concentrations. For the examined TE, the transfer functions describe the coprecipitated fraction as a function of the pH value and the concentration ratio between precipitated iron and a TE. The transfer functions yielded a good prediction of cadmium, cobalt, copper, molybdenum, nickel, and zinc ( R2 from 0.73 to 0.83). As for arsenic, chromium, and lead the correlation was not as good albeit a significant influence of precipitating iron on the mobility of these elements was observed and represented in the corresponding transfer functions. [ABSTRACT FROM AUTHOR]

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The results presented in this paper provide evidence for the role of phytochelatins (PCs) in the detoxification of arsenic in six nonhyperaccumulating plant species, Agropyron repens, Glecoma hederacea, Leonurus marrubiastrum, Lolium perenne, Urtica dioica and Zea mays, in a pot experiment with high phosphate treatment. These plants differed in their arsenic sensitivities and were selected to investigate whether PCs with longer chains in roots of arsenic-tolerant species are synthesized. Raised concentrations of total PCs were measured in plant species with a range of sensitivities to arsenic at equivalent levels of arsenic exposure, determined as the inhibition of root biomass. In addition, the production of PCs as a function of accumulated arsenic was studied. Long-term PC synthesis (over a 5-week period) was positively, but non-linearly correlated with arsenic, suggesting that probably not all As is bound by PCs. Moreover, it could be shown that the synthesis of different chain lengths of PCs is associated with differences in As tolerance. In the more tolerant grasses A. repens and L. perenne it was chiefly the dithiol PC2 which was measured. In contrast, the dominant PC species in the less tolerant plants U. dioica, G. hederacea, L. marrubiastrum and Z. mays was PC3, while PC2 and PC3 were detected as well. [ABSTRACT FROM AUTHOR]

The connection between the emission of atmospheric nitrogen (N) and the risk of groundwater pollution is significant for protection of the landscape with respect to the resources. The usually unknown amount of atmospheric nitrogen deposition has a high impact on N balances and on the leaching of nitrogen into the groundwater. Therefore, the present paper deals with the correlation between N emission and scenarios of potential risk assessment on N leaching into groundwater. The airborne N input into an agricultural landscape between the Saxon towns Taucha and Eilenburg (near Leipzig, Saxony) was measured by using the bulk N deposition method, the total atmospheric N deposition method with the ITNI system, and the bark sampling method, by focusing the results on the measurement of N input (punctual and regionalized) and on extrapolations to the risk of N leaching for planning purposes. On the forest measurement point the airborne N input is approximately twice as high as that on the 'open land' measurement point (about 15 kg N ha-1 yr-1). Two scenarios were calculated using different results of N deposition measurements; the measurement methods are described in the paper. For scenario 1, an annual potential N leaching of up to 11.5 kg/ha-1yr-1 could be modelled by using regionalized nitrate-N deposition and ammonium-N deposition data for open land. For scenario 2, because of the much higher measured inputs of 59.7 kg N ha-1yr-1 following the results of the ITNI system, the N discharge is excessively higher with up to 25 kg N ha-1yr-1. Both scenarios have been produced on the basis of a regional N balance with a surplus of 28.8 kg ha-1yr-1 (period 1998-2003) including original data from farms. The regionalization of the total atmospheric N deposition offers a new way to integrate the nowadays-unknown components of the N deposition into the estimation of potential risks of N leaching into the groundwater. The results are of high importance for groundwater protection. [ABSTRACT FROM AUTHOR]

Seafloor mapping of the Mauritania margin by multibeam bathymetry as well as shallow and high-resolution seismics in combination with core data has revealed a wide variety of seafloor features, which are primarily generated by turbidity currents and landslides. The largest observed features in the study area are two submarine slides, which both have affected over 30,000 km2 of seafloor. The Cap Blanc Slide is not considered to be a significant geohazard at the present day as it has a minimum age of 165 ka and shows no evidence of recent reactivation. In contrast, the complex Mauritania Slide Complex is characterized by a retrogressive failure style and has an age of only 10.5-10.9 cal. ka B.P.We found no indication for recent reactivation of this slide, but more data are needed to assess the present seafloor stability in this area. Turbidity current activity on the margin is evidenced by numerous gullies, canyons and channels. The largest of these is the >450 km-long meandering Cap Timiris Canyon.During the present Holocene sea-level highstand, however, terrigenous sediment supply to the modern outer shelf has been restricted and most of the conduits are therefore thought to be largely inactive, at least in terms of large sand-rich flows. [ABSTRACT FROM AUTHOR]

3-Hydroxyacyl-CoA dehydrogenase (HAD) functions in mitochondrial fatty acid β-oxidation by catalyzing the oxidation of straight chain 3-hydroxyacyl-CoAs. HAD has a preference for medium chain substrates, whereas short chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) acts on a wide spectrum of substrates, including steroids, cholic acids, and fatty acids, with a preference for short chain methyl-branched acyl-CoAs. Therefore, HAD should not be referred to as SCHAD. SCHAD is not a member of the HAD family, but instead, belongs to the short chain dehydrogenase/reductase superfamily. Previously reported cases of SCHAD deficiency are due to an inherited HAD deficiency. SCHAD, also known as 17β-hydroxysteroid dehydrogenase type 10, is important in brain development and aging. Abnormal levels of SCHAD in certain brain regions may contribute to the pathogenesis of some neural disorders. The human SCHAD gene and its protein product , SCHAD, are potential targets for intervention in conditions, such as Alzheimer's disease, Parkinson's disease, and an X-linked mental retardation, that may arise from the impaired degradation of branched chain fatty acid and isoleucine. [ABSTRACT FROM AUTHOR]

A technique for onsite application of X-ray fluorescence (XRF) spectrometry to samples from sediment cores aboard a research vessel was developed and tested. The method is sufficiently simple, precise, and fast to be used routinely for high-resolution analyses of depth profiles as well as surface samples. Analyses were performed with the compact high-performance energy-dispersive polarisation X-ray fluorescence (EDPXRF) analyser Spectro Xepos. Contents of the elements Si, Ti, Al, Fe, Mn, Mg, Ca, K, Sr, Ba, Rb, Cu, Ni, Zn, P, S, Cl and Br were simultaneously determined on 200–225 samples of each core within 24 h of recovery. This study presents a description of the employed shipboard preparation and analysis technique, along with some example data. We show land-based datasets that support our decisions to use powder samples and to reduce the original measuring time for onboard analyses. We demonstrate how well the results from shipboard measurements for the various elements compare with the land-based findings. The onboard geochemical data enabled us to establish an element stratigraphy already during the cruise. Correlation of iron, calcium and silicon enrichment trends with an older reference core provided an age model for the newly retrieved cores. The Spectro Xepos instrument performed without any analytical and technical difficulties which could have been caused by rougher weather conditions or continuous movement and vibration of the research vessel. By now, this XRF technique has been applied during three RV Meteor cruises to approximately 5,000 Late Quaternary sediment samples from altogether 23 gravity cores, 25 multicorer cores and two box cores from the eastern South Atlantic off South Africa/Namibia and the eastern Atlantic off NW Africa. [ABSTRACT FROM AUTHOR]

High-resolution records of Ca and Sr were obtained from shipboard XRF analyses of bulk sediments in five gravity cores from the southern Cape Basin, South Atlantic Ocean. Sr/Ca ratios display regular glacial/interglacial variations of 14–40% and reveal a close correlation with the SPECMAP record, minimum Sr/Ca ratios appearing during glacial (δ18 O) maxima, distinct increases during periods of deglaciation, and highest ratios in interstadials. Shifts in carbonate-producing phytoplankton and/or zooplankton assemblages over glacial/interglacial cycles are suggested to be the main cause for the observed variations in Sr/Ca patterns. Quick assessment of the relationship between Sr/Ca ratios and the SPECMAP record made it possible to easily transfer an age model to the newly collected cores already during the cruise. [ABSTRACT FROM AUTHOR]

Different methods to determine the source strength of two harbour sediment fractions were applied and are discussed with a focus on As, Cd, Cr, Co, Cu, Mo, Ni, Pb, and Zn. Four different batch experiments were performed with both the sandy and the silty fractions of harbour sediments sampled at the disposal site for dredged material in Bremen Seehausen, north Germany. In addition to the batch experiments a modified centrifugation tube was used in order to obtain pore water from the unsaturated silty fraction. Column experiments were run with the sandy fraction of the material under saturated and unsaturated conditions, irrigated with artificial acid rain water. The results show that the legal threshold value applying to Mo and Pb is not exceeded in any of the methods applied to the sandy or the silty fractions. As for the sandy fraction, Cr and Co were also below this limit. Cd, Ni, Cu and Zn exceeded the threshold values in some of the batch experiments applied to both fractions, depending on the pH value and the elution agent used in the experiment. All results obtained from saturated column leaching were below the respective threshold values; however, it should be noted that the pH was between 7 and 8 throughout the entire experiment. This pH also applied to the unsaturated column, with the exception of the ‘first flush’. This first sample had a pH value of 3.8, which was due to sulphide oxidation at the beginning of the experiment and led to strong leaching of all the elements under study. As a consequence, arsenic, Cu and Ni values exceeded their respective threshold values. [ABSTRACT FROM AUTHOR]

Two monofunctional Δ3, Δ2-enoyl-CoA isomerases, one in mitochondria (mECI) and the other in both mitochondria and peroxisomes (pECI), belong to the low-similarity isomerase/hydratase superfamily. Both enzymes catalyze the movement of a double bond from C3 to C2 of an unsaturated acyl-CoA substrate for re-entry into the β-oxidation pathway. Mutagenesis has shown that Glu165 of rat mECI is involved in catalysis; however, the putative catalytic residue in yeast pECI, Glu158, is not conserved in mECI. To elucidate whether Glu165 of mECI is correctly positioned for catalysis, the crystal structure of rat mECI has been solved. Crystal packing suggests the enzyme is trimeric, in contrast to other members of the superfamily, which appear crystallographically to be dimers of trimers. The polypeptide fold of mECI, like pECI, belongs to a subset of this superfamily in which the C-terminal domain of a given monomer interacts with its own N-terminal domain. This differs from that of crotonase and 1,4-dihydroxy-2-naphtoyl-CoA synthase, whose C-terminal domains are involved in domain swapping with an adjacent monomer. The structure confirms Glu165 as the putative catalytic acid/base, positioned to abstract the pro-R proton from C2 and reprotonate at C4 of the acyl chain. The large tunnel-shaped active site cavity observed in the mECI structure explains the relative substrate promiscuity in acyl-chain length and stereochemistry. Comparison with the crystal structure of pECI suggests the catalytic residues from both enzymes are spatially conserved but not in their primary structures, providing a powerful reminder of how catalytic residues cannot be determined solely by sequence alignments. [ABSTRACT FROM AUTHOR]

The tissue distribution, subcellular localization, and metabolic functions of human 17β-hydroxysteroid dehydrogenase type 10/short chain l-3-hydroxyacyl-CoA dehydrogenase have been investigated. Human liver and gonads are abundant in this enzyme, but it is present in only negligible amounts in skeletal muscle. Its N-terminal sequence is a mitochondrial targeting sequence, but is not required for directing this protein to mitochondria. Immunocytochemical studies demonstrate that this protein, which has been referred to as ER-associated amyloid β-binding protein (ERAB), is not detectable in the ER of normal tissues. We have established that protocols employed to investigate the subcellular distribution of ERAB yield ER fractions rich in mitochondria. Mitochondria-associated membrane fractions believed to be ER fractions were employed in ERAB/Aβ-binding alcohol dehydrogenase studies. The present studies establish that in normal tissues this protein is located in mitochondria. This feature distinguishes it from all known 17β-hydroxysteroid dehydrogenases, and endows mitochondria with the capability of modulating intracellular levels of the active forms of sex steroids. [ABSTRACT FROM AUTHOR]

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EH pH diagrams have been calculated using the PHREEQC programme in order to establish the predominance fields of Mn, Fe, Co, Ni, Cu and As in bottom waters from the Angola Basin. Predominance fields are presented separately for both aquatic species and solid mineral phases in order to simplify interpretation of the data. The diagrams show significant differences from standard EH pH diagrams for these elements calculated for freshwater at 25 °C and 1 bar which assume an element concentration of 10-6 M. In particular, our diagrams show that Mn2+ and NiCO are the predominant aquatic species for Mn and Ni in bottom seawater and FeOOH, Fe2O3, Fe3O4, CoFe2O4, CuFe2O4, CuFeO2, and Ba3 (AsO4)2 the predominant solid phases for Fe, Co, Cu and As, respectively. Mn and Ni are therefore undersaturated and Fe, Co, Cu and As supersaturated in bottom seawater from the Angola Basin. Neither rhodochrosite (MnCO3) nor siderite (FeCO3) can form in this marine environment in equilibrium with seawater. A mixed Mn-Ca carbonate is therefore formed within the pore waters of reducing sediments. The high Ni/Cu ratios in cobalt-rich manganese crusts formed adjacent to the oxygen minimum zone may be explained by the change from Cu2+ to CuCl as the dominant aquatic species of Cu in seawater at an EH of +0.48 V. [ABSTRACT FROM AUTHOR]

Copyright of Grundwasser is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Behavioural and electrophysiological changes caused by inorganic lead treatment at different phases of the ontogenesis were investigated in Wistar rats. They were treated by gavage with 80.0, 160.0, and 320.0 mg/ kg lead during the 5th-15th days of pregnancy, or the 5th-15th days of pregnancy + 4 weeks of lactation (females of P generation), or the 5th-15th days of pregnancy + 4 weeks of lactation (females of P generation) + 8 weeks after weaning (males of F1 generation). The behavioural (open field) and electrophysiological (electrocorticogram, cortical evoked potentials, etc.) parameters of F1 male rats in the above groups were investigated at the age of 12 weeks. Only rats exposed to lead during pregnancy exhibited a significant hyperactivity in the OF test expressed as a higher ambulation rate in the first minute in the OF and as longer running distances. Grooming was also increased. The spontaneous and evoked electrophysiological functions showed dose- and treatment-dependent changes (e.g. decreased mean amplitude and increased frequency of the electrocorticogram, lengthened latency and duration of the evoked potentials, etc.). The results indicate that the low-level pre- and postnatal inorganic lead exposure considerably affects both the behaviour and the function of the nervous system. [ABSTRACT FROM AUTHOR]

Discusses the control of fatty acid oxidation in the heart with emphasis on the energy-linked regulation of this process. Relationship between the energy-dependent rate of fatty acid oxidation and the intramitochondrial ratio of [acetyl-CoA]:[free CoA]; Effects of coenzymes and fatty acid metabolites on the activities of enzymes of fatty acid oxidation.

The fadH gene coding for an NADPH-dependent 2,4-dienoyl-CoA reductase from Escherichia coli has been cloned by the polymerase chain reaction. This gene is located at 67.65 min on the E. coli chromosome. The complete open reading frame contains 2019 bp coding for the processed protein of 671 amino acid residues, with a calculated molecular mass of 72.55 kDa, which lacks the N-terminal methionine. Construction and expression of the plasmid pNDH, which contained the fadH gene under the control of the T7 promoter, resulted in a 110-fold increase in the reductase activity above the level detected in E. coli cells containing the control vector. The kinetic parameters of the purified reductase were determined to be 50 µM and 2.3 µM for the Km values of NADPH and 2-trans, 4-trans-decadienoyl-CoA, respectively, and 16 s-1 for the km value. Analysis of the kinetic data revealed that the reaction catalyzed by this enzyme proceeds via a ping-pong mechanism. The observed dissimilarity between the E. coli and mammalian 2.4-dienoyl-CoA reductase sequences suggests that they have evolved from distinct ancestral genes. Sequence analysis also suggests that the N-terminal part of the E. coli reductase contains the FAD-binding domain whereas the NADPH-binding domain is located in the C-terminal region of the protein. [ABSTRACT FROM AUTHOR]

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The spectrophotometric assay of 2,4-dienoyl coenzyme A (CoA) reductase (EC 1.1.1.34) was modified to improve the linearity and sensitivity of this method. 5-Phenyl-2,4-pentadienoyl-CoA, which has an absorbance maximum at 340 nm with an extinction coefficient of 44,300 M cm, was synthesized and used as substrate. This compound is reduced by nicotinamide adenine dinucleotide phosphate (NADPH)-dependent 2,4-dienoyl-CoA reductase to 5-phenyl-3-pentenoyl-CoA. When a tissue homogenate serves as an enzyme source, the product is further metabolized by ΔΔ-enoyl-CoA isomerase (EC 5.3.3.8) to 5-phenyl-2-pentenoyl-CoA, which is hydrated to 5-phenyl-3-hydroxypentanoyl-CoA by enoyl-CoA hydratase (EC 4.2.1.17). The modified assay method, which measures the decrease in absorbance at 340 nm due to the reduction of 5-phenyl-2,4-pentadienoyl-CoA and the oxidation of NADPH, is linear for a longer period of time and is twice as sensitive as the conventional assay with 2,4-decadienoyl-CoA as substrate. [ABSTRACT FROM AUTHOR]

Antibodies to pig heart 3-ketoacyl-CoA thiolase inhibited almost completely and in a parallel fashion thiolase and the acetyl-CoA-dependent fatty acid elongation system present in an acetone powder extract of pig heart mitochondria. This finding leads to the conclusion that mitochondrial fatty acid elongation occurs by reversal of fatty acid oxidation. Several lines of evidence point to the thiolase-catalyzed condensation reaction as the rate-limiting step in the formation of elongated products. However, the accumulation of hydroxy acids suggests the enoyl-CoA reductase activity is limiting in the synthesis of saturated fatty acids. [ABSTRACT FROM AUTHOR]

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The influence of the extraordinary climate in 1959 on the width of annual rings, distribution of cell types, fibre length and width of vessels was investigated on samples taken from oak, beech, spruce and pine. The origin of the specimens, the preparation and the measuring methods are described in detail. The fibres were prepared with the help of so-called Tesa-film. For evaluating the width of the vessels, a Zeiss particle-size analysator TGZ was used for the first time. The extremely warm and dry climate caused some structural changes of the following nature. The widths of annual rings were evidently smaller during the vegetation period of 1959, as became visible in the respective diagrams. In the cross-section of oak, a remarkably higher percentage of springwood- and a lower one of summerwood-vessels and fibres could be observed. Beech, on the other hand, showed no differences in this respect. All the species investigated had shorter fibres than in former years. In beechwood the vessel of the 1959 annual ring differed from others, particularly in the width of summerwood-vessels. In oakwood, the width of the vessels was affected in all zones of the ring. Springwood showed a smaller percentage of mediumsized vessels, and in summerwood a clear contraction of the vessels, in the middle as well as towards the end of the annual ring, could be stated. [ABSTRACT FROM AUTHOR]

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