bluuebunny/crossref_metadata_2025 huggingface dataset:
Iron chelation and hydroxyl radical scavenging reduce the inflammatory response of endothelial cells after infection with Chlamydia pneumoniae or influenza A
Authors: Visseren F. L. J. , Verkerk M. S. A. , Van Der Bruggen T. , Marx J. J. M. , Van Asbeck B. S. , Diepersloot R. J. A.
Published: March 2003

Background Chronic low‐grade inflammation is associated with increased risk of vascular diseases. The source of inflammation is unknown but may well be chronic and/or repetitive infections with microorganisms. Direct infection of endothelial cells (ECs) may also be a starting point for atherogenesis by initiating endothelial procoagulant activity, increased monocyte adherence and increased cytokine production. We hypothesized that iron‐mediated intracellular hydroxyl radical formation after infection is a key event in triggering the production of interleukin‐6 (IL‐6) by ECs in vitro.

Methods Cultured ECs were incubated with Fe(II) and Fe(III) or infected with Chlamydia pneumoniae or influenza A/H1N1/Taiwan/1/81 for 48 and 24 h, respectively. To determine the role of iron and reactive oxygen species, cells were coincubated with the H2O2 scavenger N‐acetyl‐l‐cysteine, with the iron chelator deferoxamine (DFO) or with the intracellular hydroxyl radical scavenger dimethylthiourea (DMTU). After the incubation periods, supernatants were harvested for IL‐6 determination.

Results Incubating ECs with Fe(II) and Fe(III) resulted in increased IL‐6 production. Similarly, infection with C. pneumoniae and influenza A also induced an IL‐6 response. Coincubating ECs with DFO or DMTU blocked this response. Nuclear factor‐κB activity was increased after infection and blocked by coincubation with DFO or DMTU.

Conclusion Cultured ECs respond to infection and iron incubation with increased production of IL‐6. Iron, the generation of intracellular hydroxyl radical and NF‐κB activity are essential in cellular activation, suggesting that reactive oxygen species generated in the Haber–Weiss reaction are essential in invoking an immunological response to infection by ECs.
Mouse models for genetic dissection of polygenic gastrointestinal diseases
Authors: Hillebrandt S. , Matern S. , Lammert F.
Published: March 2003

Many diseases with a major public health impact are the result of complex interactions between environmental factors and multiple genes. In the past decade, methods for genome analysis, in particular quantitative trait locus (QTL) analysis in animal models, were developed to identify and localize the genes responsible for multifactorial (polygenic) diseases; QTL analysis is based on experimental crosses between inbred strains with high and low genetic susceptibility. Recently the genes underlying several QTLs could be cloned successfully. Here we describe the impact of these genomic approaches in mice on our understanding of the multifactorial genetics of three gastrointestinal diseases related to metabolism (cholesterol cholelithiasis), development (gastroschisis), and colorectal cancer. The examples demonstrate how mouse models continue to be an invaluable tool in unravelling complex pathomechanisms and unlocking our understanding of human diseases.
Low‐density‐lipoprotein peak particle size in a Mediterranean population
Authors: M. Rizzo , Barbagallo C. M. , Severino M. , Polizzi F. , Onorato F. , Noto D. , Cefalù A. B. , Pace A. , Marino G. , Notarbartolo A. , Averna R. M.
Published: March 2003

Background The predominance of small, dense low‐density lipoprotein (LDL) particles (‘LDL phenotype B’) has been associated with a three‐fold increased risk of myocardial infarction, but the feasibility of the identification of small, dense LDL as independent predictors of coronary artery disease risk in population studies remains questioned.

Design We evaluated the LDL peak particle size and its relation with other established risk factors for coronary heart disease in a group of 156 randomized subjects living on the Mediterranean island of Ustica (71 males and 85 women, range of age 20–69 years), representing approximately 30% of the total population.

Results The prevalence of LDL phenotype B subjects was low (approximately 15% in both men and women) and there was a clear trend for both genders in reducing the LDL peak particle size with age. Moreover, LDL phenotype B subjects had higher BMI values, prevalence of diabetes and plasma triglyceride (TG) levels and lower plasma HDL‐C concentrations in comparison with LDL phenotype A individuals; in a multivariate analysis, plasma TG levels were the only variable independently associated with LDL peak particle size.

Conclusions In this population, which appears to be somewhat protected by premature coronary artery disease, a low prevalence of the LDL pattern B was found in both men and women, and plasma TG could have a key role in regulating the LDL peak particle size. The follow up, still ongoing, will provide useful information on the predictive role of LDL peak particle size on cardiovascular risk, at least in a low‐risk population.
Molecular cloning and sequencing of feline stromal cell‐derived factor‐1α and β
Authors: Nishimura Y. , Miyazawa T. , Ikeda Y. , Izumiya Y. , Nakamura K. , Cai J.‐S. , Sato E. , Kohmoto M. , Mikami T.
Published: March 2003

The stromal cell‐derived factor‐1α and β (SDF‐1α/β) are the ligands of fusin/CXCR4, the co‐receptors of human immunodeficiency virus type 1 and the feline immunodeficiency virus. We cloned the cDNA of feline SDF‐1α/β. The open reading frames of feline SDF‐1α/β were 267/279 base pairs and encoded 89/93 amino acid residues.
Differential expression of MHC class II genes in lung tumour cell lines
Authors: Redondo M. , Ruiz‐Cabello F. , Concha A. , Hortas M. L. , Serrano A. , Morell M. , Garrido F.
Published: March 2003

Molecular characterization of HLA class II expression was investigated in five lung tumour cell lines at the protein and mRNA levels. The cell lines exhibited a differential expression of HLA‐DR, HLA‐DP and HLA‐DQ products and also showed differences in the inducibility of HLA class II genes by γ‐IFN. Gamma‐IFN stimulation induced only HLA‐DR expression to varying degrees in three cell lines, while only one cell line showed stimulation for HLA‐DP and none for HLA‐DQ antigens. These results suggest locus‐specific regulation for the three loci. The presence of DR protein on the cell‐surface membrane was always positively correlated with the presence of HLA‐DR mRNA in the cells. After treatment with 5‐azacytidine in the A549 cell line, which expressed the lowest values, there was no effect on HLA class II levels. This suggested that methylation does not play an important role in the lack of MHC class II antigen expression.

In addition to studying mRNA levels of HLA class II antigens, we analysed mRNA of the proto‐oncogene c‐myc and observed a positive correlation of two mRNA: the increments in HLA‐DR expression were associated with increments in c‐myc expression. This suggests a relationship between the regulatory mechanisms which control the expression of c‐myc and HLA‐DR antigens in lung tumour cell lines.
Rapid and simultaneous HLA class I (‐A, ‐B and ‐C loci) DNA typing using the microtitre plate–reverse hybridization assay (MRHA)
Authors: Moribe T. , Hirai H. , Kimura M. , Inagawa A. , Nakatani S. , Kaneshige T. , Inoko H.
Published: March 2003

We have established a precise, rapid, simple and practical HLA class I DNA typing method using the microtitre plate–reverse hybridization assay (MRHA), which enables us to perform simultaneous DNA typing of the HLA‐A, ‐B and ‐C loci using the same PCR parameters and hybridization conditions. PCR‐amplified products for the HLA‐A, ‐B and ‐C loci were hybridized, respectively, with sequence‐specific oligonucleotide (SSO) probes, which were immobilized covalently onto a microtitre plate, in hybridization buffer containing formamide at 37 °C. After washing at room temperature, the bound PCR products were detected by peroxidase‐conjugate streptavidine followed by colour development such as enzyme immunoassay (EIA). In addition to the simple thermoregulation for hybridization and postwashing, strong positive signals, low background and high reproducibility, this DNA typing method enabled simultaneous typing of the HLA‐A, ‐B and ‐C loci using a single microtitre plate as in HLA serotyping. The assignment of the HLA genotype was easily achieved by automated colorimetric reading and computer software, based on the cut‐off value (threshold) established for each probe. For routine HLA class I typing, it may be possible to replace serological typing with the HLA class I DNA typing system using our MRHA method.
Allele frequencies of polymorphisms of TNFA, IL‐6, IL‐10 and IFNG in an Italian Caucasian population
Authors: Poli F. , Nocco A. , Berra S. , Scalamogna M. , Taioli E. , Longhi E. , Sirchia G.
Published: March 2003

Polymorphisms in the regulatory and intronic regions of several cytokines have been associated with differential cytokine production. In this paper we genotyped, using the polymerase chain reaction–sequence‐specific primers (PCR‐SSP) method, a series of 363 healthy Italian Caucasians with the aim of obtaining a reference population for further studies on the role of cytokines in the inflammatory and immune responses. We also compared the results to those for other populations. The polymorphisms analysed were those of tumour necrosis factor alpha (TNFA), interleukin 6 (IL‐6), interleukin 10 (IL‐10) and interferon gamma (IFNG). We found that the frequency of allele TNFA*1 at position −380 was 87.7% and that of TNFA*2 was 12.4%, significantly different from those of the UK and Japanese populations but not different from that of a population in Gambia. For IL‐10 the frequencies of alleles −1082A and −1082G were 63.0% and 37.0% and those of alleles −819C, − 819T, −592C and −592A were 70.8, 29.2, 70.8 and 29.2%, respectively, significantly different from those observed in south‐east England, in Manchester and in an Oriental population from southern China. The frequencies of IL‐6 alleles − 174C and −174G were 29.0 and 71.0%, respectively; for IFNG polymorphisms at position −874, in the population under evaluation, the alleles −874T and −874A were present in 44.7 and 55.3% of the subjects, respectively. Genotype frequencies of IL‐6 were significantly different from those observed in populations from Germany and from the UK. The analysis carried out by our group indicates that there is heterogeneity in the frequencies of the cytokine polymorphisms among the different Caucasian populations, and this underlines the importance of a ‘local’ reference population when evaluating the clinical relevance of cytokine gene polymorphisms.
Effects of microorganisms on hydraulic conductivity decrease in infiltration
Authors: SEKI  , MIYAZAKI  , NAKANO
Published: March 2003

Microorganisms can clog pores in soils and decrease hydraulic conductivity and infiltration. We did three column experiments to clarify the effects. In all three columns, glucose solution of 50 μg cm−3 was percolated for 120 days, and both the saturated hydraulic conductivity, Ks, and the volume ratio of the gas phase, a, were measured continuously. The Ks decreased rapidly for the initial 10 days, and it slowly decreased for the following 110 days. By adding chloramphenicol to the second column as bactericide and cycloheximide to the third column as fungicide, we observed clogging by bacteria and fungi, respectively, bacterial clogging proceeding more rapidly than the fungal clogging. The volume of the gas phase increased and reached the maximum value of 30.6% after 103 days from the beginning of percolation. This large amount of gas was retained in the soil pores as bubbles and occluded the pathways of water, resulting in the decrease in Ks. When the percolating solution was changed to sodium azide (a strong biocide), after 120 days the volume of the gas phase decreased rapidly, and Ks increased simultaneously.
Iron oxide mineralogy of Terre Rosse and Rendzinas in relation to their moisture and temperature regimes
Authors: SINGER A. , SCHWERTMANN U. , FRIEDL J.
Published: March 2003

Terre Rosse and Rendzinas occur on limestones close together under the same climatic conditions. Their differences in iron oxide mineralogy are believed to be due to differences in the pedoclimate. We monitored the soil moisture tension and the soil temperature over nearly 3 years in Terra Rossa‐Rendzina pairs on hard limestone and soft chalk in Israel. The Terre Rosse dried out more rapidly than the Rendzinas mainly because of their smaller water‐holding capacity. In summer, average soil temperatures in the Rendzinas were significantly lower than in the Terre Rosse.

Haematite dominates the red Terre Rosse and goethite the yellower Rendzinas. This difference appears to be related to the soil climate, specifically the moisture regime of the two soils, and supports the hypothesis that release of Fe and formation of ferrihydrite in Terre Rosse during the wet winter is followed by transformation to haematite during marked desiccation in the dry summer. By contrast, wetter soil conditions in the Rendzinas direct the formation of Fe oxides more towards goethite. either directly or by transformation of ferrihydrite via solution.
Sorption of organic acids in acid soils and its implications in the rhizosphere
Authors: JONES D. L. , BRASSINGTON D. S.
Published: March 2003

Organic acids have been implicated in many soil‐forming and rhizosphere processes, but their fate in soil is poorly understood. We examined the sorption of four simple short‐chain organic acids (citric, oxalic, malic and acetic) in five acid soils and on synthetic iron hydroxide (ferrihydrite). The results for both soils and ferrihydrite indicated that the sorption depended on concentration in the following order of strength: phosphate >> oxalate > citrate > malate >> acetate. The sorption reactions in soil were shown to be little influenced by pH, whereas for ferrihydrite, sorption of all ligands increased strongly with decreasing pH. The sorption of organic anions onto ferrihydrite was influenced to a lesser extent by the presence of metal cations in solution. From the results we calculated that when organic acids enter solution they rapidly become sorbed onto the soil's exchange complex (> 80% within 10 min), and we believe that this sorption will greatly diminish their effectiveness to mobilize nutrients from the rhizosphere.
Reduced CO2 release from decomposing wheat straw under N‐limiting conditions: simulation of carbon turnover
Authors: HADAS A. , PARKIN T. B. , STAHL P. D.
Published: March 2003

The turnover of residue carbon in soil containing little available N can affect the management of crop residues. The effects of N deficiency on CO2 release from decomposing wheat straw were measured in an incubation experiment and interpreted by computer simulation. Straw with a C:N ratio of 91, incubated for 460 days in sand that was inoculated with a soil suspension, released CO2 much more slowly than when inorganic N was added to obtain a C:N ratio of 5. The evolution of CO2 continued longer without added N, approaching the amount released in the high N treatment with time. The simulation model NCSOIL was modified to simulate reduced CO2 release from decomposing residue when N limits microbial growth by (i) including the decomposers' biomass in the rate of residue decomposition in the form of a Monod‐type equation, where the biomass reduced the rate when its concentration was small compared with a saturation constant, and (ii) including formation of a polysaccharide‐like pool that received the decomposed C that could not be assimilated by the biomass because of insufficient N. The modified model simulated the reduced CO2 production in the absence of sufficient N, as a result of a smaller microbial biomass that reduced the rate of residue decomposition, and the formation of polysaccharides as long as N limited synthesis of microbial biomass.
The nature and kinetics of organic matter release from soil by salt solutions
Authors: Reemtsma T. , Bredow A. , Gehring M.
Published: March 2003

Laboratory experiments in soil columns were performed to study the influence of dissolved salts on the amount and composition of organic matter (OM) released from soil. Samples of two surface soils from former wastewater infiltration sites were leached with solutions containing dissolved salts (NaH2PO4, NaNO3, CaCl2) and by deionized water. The NaH2PO4 solution induced strongest release with 0.6% of soil organic carbon (Corg) with 700 ml for 100 g of soil, while CaCl2 released the least, summing to 0.1–0.2% of Corg. The OM released was characterized by UV absorbance (aromaticity), ultrafiltration (molecular size distribution) and solid‐phase extraction (polarity). The results suggest that CaCl2 preferentially released readily soluble OM. For the other solutions we assume solubilization by enhanced electrostatic repulsion (water), sodium exchange (NaNO3), and sodium exchange and calcium decomplexation and displacement of sorbed organic anions (NaH2PO4) to be the major mechanisms of release. In all experiments a phase of spontaneous desorption was observed, followed by a phase of steady‐state desorption. Activation energies for steady‐state release were estimated from kinetic investigations and suggest that the release is controlled by diffusion towards the phase boundary. These investigations emphasize the influence of dissolved salts on the nature and quantity of organic matter released from soil. The method presented seems able to characterize soil organic matter with respect to its availability and its mode of association with the soil matrix.
Changes to water repellence of soil aggregates caused by substrate‐induced microbial activity
Authors: Hallett P. D. , Young I. M.
Published: March 2003

Soil microbes produce exudates which upon drying become water‐repellent, thus altering hydraulic properties. The influence of microbial activity caused by adding plant nutrients on the hydraulic characteristics of soil aggregates is reported. Soil aggregates were collected from a field that had been fertilized with different amounts of nitrogen. Aggregates were also incubated with different nutrient treatments in the laboratory. Their sorptivity, hydraulic conductivity and water repellency were measured with a new device. Adding nitrogen was found to decrease sorptivity and hydraulic conductivity because of increased water repellency in the field. In the laboratory studies, the addition of nutrients caused severe water repellency in the soil aggregates. Respiration studies identified a large increase in biological activity following nutrient amendment which produces water‐repellent materials.
Charred organic carbon in German chernozemic soils
Authors: Schmidt M. W. I. , Skjemstad J. O. , Gehrt E. , Kögel‐Knabner I.
Published: March 2003

Burning vegetation produces partly charred plant material which subsequently could contribute to the highly refractory proportion of soil organic matter. The presence of charred organic carbon (COC) was investigated in 17 horizons originating from nine soils from Germany and the Netherlands using a suite of complementary methods (high‐energy ultraviolet photo‐oxidation, scanning electron microscopy, solid‐state 13C nuclear magnetic resonance, lignin analysis by CuO oxidation). Charred organic carbon could not be detected in the A horizons of an Alisol and a Gleysol, but it contributed up to 45% of the organic carbon and up to about 8 g kg–1 of the soil in a range of grey to black soils (Cambisol, Luvisol, Phaeozem, Chernozem and Greyzem). All these soils have chernozemic soil properties (dark colour, A–C profile, high base saturation, bioturbation). A 10‐km colour sequence of four chernozemic soils, which were very similar in chemical and physical properties, showed a strong relation between colour and the content of COC. This suggests that the COC affects mainly soil colour in the sequence studied. Finely divided COC seems to be a major constituent of many chernozemic soils in Germany. These results suggest that besides climate, vegetation and bioturbation, fire has played an important role in the pedogenesis of chernozemic soils.
Using regression models in design‐based estimation of spatial means of soil properties
Authors: Brus D. J.
Published: March 2003

The precision of design‐based sampling strategies can be increased by using regression models at the estimation stage. A general regression estimator is given that can be used for a wide variety of models and any well‐defined sampling design. It equals the π estimator plus an adjustment term that accounts for the differences between the π estimators for the spatial means of the auxiliary variables and the true spatial means of these variables. The regression estimator and ratio estimator follow from certain assumptions on the model and the sampling design. These are compared with the π estimator in two case studies.

In one study a bivariate field of linearly related variables was simulated and repeatedly sampled by Simple Random Sampling without replacement and sample sizes 10, 25, 50, 100 and 200. For all sample sizes the ratio of the standard error of the simple regression estimator to that of the π estimator was approximately 55%. The bias of the simple regression estimator was negligibly small. The confidence interval estimators were valid for all sample sizes except for n = 10. Also the ratio estimator was approximately unbiased, and the confidence interval estimators were valid for all sample sizes, even for n = 10. This is remarkable because the ratio estimator assumes that the intercept of the regression line is 0 which was incorrect for the simulated field. On the other hand, only approximately 55% of the potential gain was achieved because the model was inappropriate.

In a second study the spatial means of the Mean Highest Watertable of map units were estimated by Stratified Simple Random Sampling and the combined (multiple) regression estimator. The NAP elevation, the local elevation, the Easting and the Northing were used as auxiliary variables. For all map units except one the combined (multiple) regression estimator was more precise than the π estimator. The ratio of the standard errors varied from 0.36 to 1.04. The domain for which the regression estimator was less precise than the π estimator showed strong variation between strata. For this domain it was more efficient to group the strata into two groups and to fit simple models for these groups separately.
An explanation of linear increases in gas concentration under closed chambers used to measure gas exchange between soil and the atmosphere
Authors: Conen F. , Smith K. A.
Published: March 2003

Earlier models describing the accumulation of gases under closed chambers are based on the assumption of a constant concentration source that does not change during the time of chamber deployment. A new model is proposed which is based on the assumption of a constant production source, and takes into account possible changes in gas concentrations at the source during chamber deployment. Using N2O as an example, simulations have been carried out for different source strength and depth, diffusivities and air porosities. The main finding was a chamber‐induced increase in gas concentrations in the upper part of the soil profile, including the depth where the N2O source is located. The increase started immediately after chamber closure. Nevertheless, fluxes calculated from increasing concentrations within the chamber's headspace were always less than those expected under undisturbed conditions, i.e. in the absence of a chamber. This was due to a proportion of the gas produced being stored within the soil profile while the chamber was in place. The discrepancy caused by this effect increased with increasing air‐filled porosity and decreasing height of the chamber, and a procedure for correcting chamber flux measurements accordingly is proposed. The increase in soil gas concentrations after chamber closure was confirmed in a laboratory experiment.
A prototype osmotic tensiometer with polymeric gel grains
Authors: Biesheuvel P. M. , Van Loon A. P. , Raangs R. , Verweij H. , Dirksen C.
Published: March 2003

An accurate field method that directly measures the entire range of relevant soil water potentials for periods of months to years is not yet available. The osmotic tensiometer (OT) has the potential to fulfil these demands but is still in an early stage of development. We have designed a novel OT that should overcome several drawbacks of former designs by the use of cross‐linked polymeric gel grains instead of an aqueous solution of linear chain polymers inside the porous ceramic cup. For this reason, the cup can have large pores without polymer leakage. This ensures that water exchanges rapidly with the soil, resulting in a negligible pressure lag with changing temperatures, which is the most important source of a systematic measurement error of an OT. A second reason for better performance might be the inherent elasticity of the grains which should inhibit formation of a polymer cake at the filter. To study several of the key variables of the new sensor, transient and stationary experiments were performed in an aqueous solution the temperature, salt type and salt concentration of which were varied. Under similar conditions the swelling of the polymer grains was studied in more detail. The OT that we developed responds rapidly to changes in water potential, but is very susceptible to the influence of salts. To study and minimize salt influence, swelling tests of unconfined grains are proposed in combination with tests of the OT itself.
Using time domain reflectometry for monitoring mineralization of nitrogen from soil organic matter
Authors: De Neve S. , Van de Steene J. , Hartmann R. , Hofman G.
Published: March 2003

The mineralization of nitrogen from soil organic matter is important when one tries to optimize nitrogen fertilization and assess risks of N losses to the environment, but its measurement is laborious and expensive. We have explored the possibilities for monitoring N mineralization directly using time domain reflectometry (TDR). Net N and S mineralization were monitored over a 101‐day period in two layers (0–30 and 30–60 cm) of a loamy sand soil during aerobic incubation in a laboratory experiment. At the same time electrical conductivity of the bulk soil, σa, was measured by TDR. A series of calibration measurements with different amounts of KNO3 at different soil moisture contents was made with the topsoil to calculate the electrical conductivity, σw, of the soil solution from σa and θ. The actual σw was determined from the conductivity of 1:2 soil:water extracts (σ1:2) with a mass balance approach using measured NO3– concentrations, after correction for ions present prior to the addition of KNO3. The average N mineralization rate in the topsoil was small (0.12 mg N kg−1 day−1), and, as expected, very small in the subsoil (0.023 mg N kg−1 day−1). In the top layer NO3– concentrations calculated from σa determined by TDR slightly underestimated measured concentrations in the first 4 weeks, and in the second half of the incubation there was a significant overestimation of measured NO3–. Using the sum of both measured NO3– and SO42– reduced the overestimation. In the subsoil calculated NO3– concentrations strongly and consistently overestimated measured concentrations, although both followed the same trend. As S mineralization in the subsoil was very small, and initial SO42– concentrations were largely taken into account in the calibration relations, SO42– concentrations could not explain the overestimation. The very small NO3– and SO42– concentrations in the B layer, at the lower limit of the concentrations used in the calibrations, are a possible explanation for the discrepancies. A separate calibration for the subsoil could also be required to improve estimates of NO3– concentrations.
Carbon sequestration in forest soils: effects of soil type, atmospheric CO2 enrichment, and N deposition
Authors: Hagedorn F. , Maurer S. , Egli P. , Blaser P. , Bucher J. B. , Siegwolf R.
Published: March 2003

Soil contains the major part of carbon in terrestrial ecosystems, but the response of this carbon to enriching the atmosphere in CO2 and to increased N deposition is not completely understood. We studied the effects of CO2 concentrations at 370 and 570 μmol CO2 mol−1 air and increased N deposition (7 against 0.7 g N m−2 year−1) on the dynamics of soil organic C in two types of forest soil in model ecosystems with spruce and beech established in large open‐top chambers containing an acidic loam and a calcareous sand. The added CO2 was depleted in 13C and thus the net input of new C into soil organic carbon and the mineralization of native C could be quantified.

Soil type was the greatest determining factor in carbon dynamics. After 4 years, the net input of new C in the acidic loam (670 ± 30 g C m−2) exceeded that in the calcareous sand (340 ± 40 g C m−2) although the soil produced less biomass. The mineralization of native organic C accounted for 700 ± 90 g C m−2 in the acidic loam and for 2800 ± 170 g C m−2 in the calcareous sand. Unfavourable conditions for mineralization and a greater physico‐chemical protection of C by clay and oxides in the acidic loam are probably the main reasons for these differences. The organic C content of the acidic loam was 230 g C m−2 more under the large than under the small N treatment. As suggested by a negligible impact of N inputs on the fraction of new C in the acidic loam, this increase resulted mainly from a suppressed mineralization of native C. In the calcareous sand, N deposition did not influence C concentrations. The impacts of CO2 enrichment on C concentrations were small. In the uppermost 10 cm of the acidic loam, larger CO2 concentrations increased C contents by 50–170 g C m−2. Below 10 cm depth in the acidic loam and at all soil depths in the calcareous sand, CO2 concentrations had no significant impact on soil C concentrations. Up to 40% of the ‘new’ carbon of the acidic loam was found in the coarse sand fraction, which accounted for only 7% of the total soil volume. This suggests that a large part of the CO2‐derived ‘new’ C was incorporated into the labile and easily mineralizable pool in the soil.
Determination of surface area of soil by adsorption methods
Authors: Ferreiro E. A. , DE Bussetti S. G. , Helmy A. K.
Published: March 2003

How significant are estimates of surface areas of soils obtained by adsorption methods? To answer this we tested the applicability of an equation that relates monolayer coverage (N) of an adsorbent with the area (A) of adsorbate, NAz = k, for six soil samples using six adsorbates of different sizes. The data obtained confirm the validity of the equation with the z parameter ranging between 1.25 and 1.41. Hence each soil sample showed preferences towards small‐sized adsorbates for which the product NA (calculated surface area) is inversely related to the size of adsorbate. We also demonstrated that the equation has roots in the Langmuir adsorption equation.
Spin accounting and RESTORE – two new methods to improve quantitation in solid‐state 13C NMR analysis of soil organic matter
Authors: Smernik R. J. , Oades J. M.
Published: March 2003

Rapid T1ρH relaxation and inefficient cross‐polarization have long been known to affect quantitation in solid‐state 13C cross‐polarization (CP) NMR spectra of soil organic matter. We have developed two new techniques to overcome these problems. The first, spin accounting, enables accurate gauging of how quantitative a spectrum is likely to be. The result is expressed as the percentage of potential NMR signal that can be accounted for (Cobs). Spin accounting improves on the established spin counting technique by correcting for rapid T1ρH relaxation and inefficient cross‐polarization. Spin accounting identifies three components: one that is well represented in CP spectra, one that is under‐represented in CP spectra due to rapid T1ρH relaxation, and one that is under‐represented in CP spectra due to inefficient cross‐polarization. For a range of eight de‐ashed soils, Cobs was in the range 83–106%, indicating that virtually all potential signal could be accounted for after correcting for rapid T1ρH relaxation and inefficient cross‐polarization. The second new technique, RESTORE (REstoration of Spectra via TCH and T One Rho (T1ρH) Editing), generates subspectra for the three components identified in spin accounting. The sum of the three RESTORE subspectra is essentially a corrected CP spectrum. The RESTORE spectra of all eight soils more closely resembled the corresponding, and presumably quantitative, Bloch decay spectra than did the CP spectra. RESTORE identifies the types of structures underestimated by CP, and the cause of their underestimation. Rapid T1ρH relaxation most affected carbonyl and carbohydrate carbons, whereas inefficient cross‐polarization most affected aromatic carbons.
Genesis of the terrae rossae of the Sierra Gádor (Andalusia, Spain)
Authors: Delgado R. , Martín‐ García J. M. , Oyonarte C. , Delgado G.
Published: March 2003

Some aspects of the genesis of terrae rossae are still subject to controversy while others related to the genesis of the mineral fraction have been studied very little. We have studied four terrae rossae over limestone (two Chromic‐Leptic Luvisols, a Rhodi‐Leptic Luvisol and a Chromi‐Leptic Cambisol) in Sierra Gádor (Almería, southern Spain), in particular the various formation processes by (i) examination of their morphological, analytical and mineralogical characteristics (including crystallochemical parameters of the mica), (ii) examination of the insoluble residue of the gravel and rock, (iii) scanning electron microscopy (SEM) of sand and silt grains, and (iv) examination of the geochemistry of the soil solution. We have investigated the autochthonous or allochthonous nature of the soil material (fine earth and gravel) in relation to the rocky substrate, concluding that both origins are possible. Our SEM study of the morphology of the quartz grains shows that some are insoluble residue and some are probably wind blown from desert and coastal sources. The micas in the fine earth fractions are inherited from the insoluble residue. Comparison of the crystallochemical parameters of micas in the insoluble residue and the soil clay shows that the clay has more SiIV and (Fe, Mg)VI, and less AlIV, AlVI and x (layer charge) than the insoluble residue. It also has fewer polytypes 2M1 and more 1M and has a smaller crystal size, especially in B horizons. The kaolinite is of varied origins including neoformation and inheritance from underlying rock. Some of the kaolinite and some mica has been blown in from elsewhere, probably from desert and coastal sources. The soils have undergone other typical processes of terrae rossae including dissolution of carbonate, illuviation of clay and iron oxides, and rubifaction.
Temperature effects on N mineralization: changes in soil solution composition and determination of temperature coefficients by TDR
Authors: De Neve S. , Hartmann R. , Hofman G.
Published: March 2003

We studied the changes in composition of the soil solution following mineralization of N at different temperatures, with a view to using TDR to calculate temperature coefficients for the mineralization of N. Mineralization from soil organic nitrogen was measured during aerobic incubation under controlled conditions at six temperatures ranging from 5.5 to 30°C, and at constant water content in a loamy sand soil. We also monitored during the incubation the concentrations of SO42–, Cl–, HCO3–, Ca2+, K+, Mg2+ and Na+, and the pH and the electrical conductivity in 1:2 soil:water extracts. Zero‐order N mineralization rates ranged between 0.164 at 5.5°C and 0.865 mg N kg−1 soil day−1 at 30°C. There was a significant decrease in soil pH during incubation, of up to 0.6 pH units at the end of the incubation at 30°C. The electrical conductivity of the soil extracts increased significantly at all temperatures (the increase between the start and the end of the incubation was 4‐fold at 30°C) and was strongly correlated with N mineralization. The ratio of bivalent to monovalent cations increased markedly during mineralization (from 2.2 to 5.9 at 30°C), and this increase influenced the evolution of the electrical conductivity of the soil solution through the differences in molar‐limiting ion conductivity between mainly Ca2+ and K+. Zero‐order mineralization rate constants, k, for NO3– concentrations calculated from TDR varied between 0.070 (at 5.5°C) and 0.734 mg N kg−1 soil day−1 (at 30°C), which were slightly smaller, but in the same range, as the measured rates. Underestimation of the measured N mineralization rates was due, at least in part, to differences in cation composition of the soil solution between calibration and mineralization experiments. A temperature‐dependence model for N mineralization from soil organic matter was fitted to both the measured and the TDR‐calculated mineralization rates, k and kTDR, respectively. There were no significant differences between the model parameters from the two. Our results are promising for further use of TDR to monitor soil organic N mineralization. However, the influence of changing cation ratios will also have to be taken into account when trying to predict N mineralization from measured electrical conductivities.
Participation of local fishermen in scientific fisheries data collection: a case study from the Bangweulu Swamps, Zambia
Authors: TICHELER  , KOLDING  , CHANDA
Published: March 2003

The feasibility of participation by local fishermen in scientific fisheries data collection for stock assessment is described. Artisanal fishermen from the Bangweulu Swamps, Zambia, collected length‐frequency data for 1 year from their catch using the main fishing methods employed in the swamps as well as experimental gears. It is shown that with this method, it is possible to obtain large quantities of reliable and relatively cheap length‐frequency data that allow for a full length‐based stock assessment, including cohort analysis. There are also indications that with a proper feedback of the findings by the research institutions to the fishing communities, this sampling method might enhance the awareness of exploitation patterns and the management consequences. This may be seen as a first step in preparing the communities to take up their role in a community‐based approach in the management of the fish resources.
Growth and mortality of the narrowbarred Spanish Mackerel, Scomberomorus commerson (Lacepède), in Omani waters
Authors: Al‐Hosni A. H. S. , Siddeek S. M.
Published: March 2003

Length composition data from quarterly catches of Omani narrowband Spanish mackerel, Scomberomorus commerson (Lacepède), landed between 1987 and 1995 were used to estimate the growth, mortality and exploitation parameters of the stock. Non‐linear least square fitting provided a complete set of von Bertalanffy growth estimates: L∞ = 173.6 cm fork length; K = 0.28; and t0 = −0.86 years. There were no seasonal differences among the growth estimates. The instantaneous natural mortalities determined by three independent methods based on life‐history parameters were 0.35, 0.64 and 0.77. Seasonal total mortalities were calculated by the length converted catch curve method for evaluating seasonal exploitation ratios (E). The E‐values exceeded 0.4, indicating overexploitation during almost all the seasons studied. This was supported by the large reduction in the total landings of S. commerson from 27 762 t in 1988 to 3265 t in 1993.
Allozyme variation and stock structure in the black bream, Acanthopagrus butcheri (Munro) (Sparidae) in southern Australia: implications for fisheries management, aquaculture and taxonomic relationship with Acanthopagrus australis (Günther)
Authors: Farrington L. W. , Austin C. M. , Coutin P. C.
Published: March 2003

An investigation of allozyme variation at 32 loci in the black bream, Acanthopagrus butcheri (Munro), and the yellowfin bream, Acanthopagrus australis (Günther), revealed heterozygosities (H) equal to 0.035 and 0.065, respectively, and polymorphism (P0.95) equal to 0.067 and 0.200, respectively. The genetic data confirm the very high level of genetic similarity previously found between the two species, but nevertheless also support their recognition as separate species. The finding of only limited allozyme differentiation at three polymorphic loci amongst six black bream samples from south‐eastern Australia is consistent with the existence of a single panmictic population in this region. This would require that adult black bream have a greater capacity to survive in near‐shore marine environments than previously realised and that dispersal between estuaries is more extensive than was shown by tagging studies. In contrast, significant differences were found at two loci between black bream from south‐eastern Australia and a sample from south‐western Australia. The degree of genetic divergence between stocks in south‐eastern and south‐western Australia suggests that only local brood stock should be used for aquaculture or re‐stocking as a precaution until further investigations with DNA‐based techniques are conducted. The genetic divergence detected supports separate management for populations in Western Australia and Victoria.
Balances of phosphorus and nitrogen in carp ponds
Authors: Knösche R. , Schreckenbach K. , Pfeifer M. , Weissenbach H.
Published: March 2003

The impact of carp pond effluents on natural waters was investigated in the German federal states of Brandenburg, Saxony and Bavaria, and in Hungary. Data from 38 ponds (size = 0.25–122 ha) were available for the calculation of inlet–outlet differences. An average difference of 0.51 kg phosphorus (P) ha−1 year−1 was obtained. This means that every hectare of pond surface releases 510 g P less than it receives from the incoming water. This result was independent of the amount of fish harvested (≤ 1500 ha−1 year−1). The average retention of P (P‐balance) was 5.71 kg P ha−1 year−1. Phosphorus retention increased with increasing intensity of production. Nitrogen (N) retention increased with production intensity from 78.5 kg ha−1 year−1 in German standard ponds to > 290 kg N ha−1 year−1in pig‐cum‐fish ponds in Hungary. A predominantly mineralized sludge suspension is released during harvesting at loads below 1% of the retention capacity of the pond. Under usual pond management regimes, the sludge load during harvesting ranged from 50 to 200 L ha−1, equivalent to 0.3–9.3 g dry matter ha−1. The present study suggests that ponds are not a burden on the environment. By contrast, these water bodies improve water quality. Therefore, pressures to reduce the intensity of pond production cannot be justified on the basis of supposed impacts on water quality. However, even if loads during harvesting are low compared with the retention capacity of the pond, more effort should be carried out to reduce the pollution of streams by pond outlets downstream. This can be done by limiting pond drainage to periods when the suspended material has settled or by short‐term sedimentation of the sludge in a settling pond downstream of the rearing facility.
Long‐term effects of human influence on fish community structure and fisheries in Berlin waters: an urban water system
Authors: Wolter C. , Minow J. , Vilcinskas A. , Grosch U. A.
Published: March 2003

Commercial catch and fisheries monitoring data were compared with hydrological and water course characteristics conditions to identify the cause of changes in fisheries production in Berlin water courses since the 1950s. The urban parts of Berlin are densely populated, and the waters are under pressure from shipping, hydraulic engineering, pollution and recreation use. Most Berlin waters are polytrophic or hypertrophic, with an annual nutrient input of 595 t of total phosphorous and 8640 t of total nitrogen. A total of 34 fish species were recorded, eight of which were introduced. According to historical records, seven native fish species are extinct or missing. At present, the fish community is dominated by a few eurytopic species, i.e. roach, Rutilus rutilus (L.), common bream, Abramis brama (L.), silver bream, Blicca bjoerkna (L.), and perch, Perca fluviatilis L., which contribute 85% of all individuals caught. Two ‘faunal breaks’ were identified. The first was the changing of river character from a barbel to bream zone caused by damming and river regulation. This started in the thirteenth century and ended at the beginning of the twentieth century with the extinction of anadromous fishes. The second break was during the 1960s and 1970s, with the eutrophication of Berlin waters and the near total loss of submerged macrophytes. All phytophilic fish species declined greatly and a mass development of eurytopic species started. The catch of pike, Esox lucius L., common carp, Cyprinus carpio L., and tench, Tinca tinca (L.), became negligible, and at present, eel, Anguilla anguilla (L.), and pikeperch, Stizostedion lucioperca (L.), are the main commercial fish species. Concomitantly, the profitability of the fisheries declined and was linked to a decrease in the number of people employed in fisheries by more than 75% compared with 1950.
Growth and mortality of the catfish, Hemisynodontis membranaceus (Geoffroy St. Hilaire), in the northern arm of Lake Volta, Ghana
Authors: Ofori‐Danson P. K. , Vanderpuye C. J. , De Graaf G. J.
Published: March 2003

Estimates of growth and mortality of the catfish, Hemisynodontis membranaceus (Geoffroy St. Hilaire), in Lake Volta were obtained from length composition data compiled in 1995 and 1996. The von Bertalanffy growth function (VBGF) estimates were: L∞=44.5 cm standard length; K=0.62 year−1; and t0=−0.23 years. Natural mortality rate, M, was 1.20 year−1. Total mortality rate, Z, was computed as 4.39 year−1 and the exploitation ratio (E=F/Z) was 0.72. Although the fish is estimated to have longevity of about 5 years, those exploited are normally less than 2 years of age, which is indicative of growth over‐fishing. In order to arrest over‐exploitation of the species, there is a need to establish ‘lake reserves’. In addition, the fisheries management should be devolved from the state to the local level to compel fishermen to take greater responsibility for the sustainability and conservation of the fisheries.
Ontogenetic diet shifts in a neotropical catfish, Sorubim lima (Schneider) from the River Paraná System
Authors: Rossi L. M.
Published: March 2003

This study examines the diet of Sorubim lima (Schneider) during its early life stages and compares it with available food resources. Prey species preference was estimated by computing the Strauss index. The diet was diverse, and rotifers and cladocerans were the most important items. Pre‐flexion larvae ate rotifers and cladocerans. Around flexion, cladocerans were dominant and the ingestion of fish also began. As larvae grew, the percentage of rotifers diminished. In post‐flexion larvae, cladocerans were also dominant, and the ingestion of insects and fish was more frequent. The Strauss index showed negative selection for rotifers, positive values for cladocerans and neutral for copepods. The role of the lotic habitats as nursery areas for fish larvae was discussed.
The role of Lake IJsselmeer, a closed‐off estuary of the River Rhine, in rehabilitation of salmonid populations
Authors: HARTGERS E. M. , BUIJSE A. D.
Published: March 2003

After many technical measures and restocking activities in the River Rhine, there are now signs of salmonids being able to complete their anadromous life cycle. In Lake IJsselmeer, a former estuary of the River Rhine, the large effort associated with professional fisheries has been used to collect bycatch data on rare, migratory fish. To clarify the function of the lake for salmonids, catch data collected throughout the year between 1995 and 1999 were related to various possible migratory strategies known for these species. Species‐specific differences were found in timing, length–frequency distribution and maturity stage reflecting different behaviour of Atlantic salmon,Salmo salarL. (n=249) and sea trout,S. truttaL. (n=3962). There was evidence that salmon exhibited traditional anadromous behaviour and use the lake only as a corridor. By contrast, sea trout appears to use the lake both as a corridor and as feeding habitat.