bluuebunny/crossref_metadata_2025 huggingface dataset:
mRNA expression patterns of insulin‐like growth factor system components in human neuroendocrine tumours
Authors: Wulbrand  , Remmert  , Zöfel  , Wied  , Arnold  , Fehmann
Published: March 2003

Background

Insulin‐like growth factors (IGF) and their corresponding receptors and binding proteins are important in carcinogenesis for several tumours, but their expression pattern in the functionally and biologically heterogeneous human neuroendocrine tumours of the gastroenteropancreatic tract is largely unknown.

Materials and methods

This study searched for the mRNA expression patterns of components of the IGF system: IGF‐1 and IGF‐2, IGF receptors 1 and 2 (IGF‐1R, IGF‐2R), IGF‐binding proteins 1–6 (IGFBP1–6)) in the most frequent human gastroenteropancreatic neuroendocrine tumours (gastrinomas, insulinomas, tumours associated with carcinoid syndrome and functionally inactive tumours) employing reverse transcriptase‐polymerase chain reaction (RT‐PCR).

Results

In the 37 tumour samples analysed (nine gastrinomas, 10 insulinomas, nine tumours associated with carcinoid syndrome and nine functionally inactive tumours) IGFBP‐2 was found in all tumour samples while the IGFBP‐1 was expressed only at low frequency (10–22%) among the four tumour types. The IGF‐2R was predominantly expressed in gastrinomas. Among the four tumour types the expression of IGF‐1R, IGF‐2R and IGFBP‐6 varied significantly. In addition, 12 pairs of significantly coexpressed IGF system components were detected (IGF‐1 ↔ IGF‐1R, IGF‐1 ↔ IGF‐2R, IGF‐1 ↔ IGFBP‐3, IGF‐1 ↔ IGFBP‐6, IGFBP‐3 ↔ IGF‐1R, IGFBP‐6 ↔ IGF‐1R, IGFBP‐1 ↔ IGF‐2R, IGFBP‐3 ↔ IGF‐2R, IGFBP‐5 ↔ IGF‐2R, IGFBP‐3 ↔ IGFBP‐5, IGFBP‐3 ↔ IGFBP‐6, IGFBP‐5 ↔ IGFBP‐6).

Conclusions

The described differences of the expression patterns of the IGF system components in neuroendocrine tumour subtypes suggest tumour type‐dependent different pathways in tumour growth control by IGF system components.
Investigation of bone changes in microgravity during long and short duration space flight: comparison of techniques
Authors: McCarthy I. , Goodship A. , Herzog R. , Oganov V. , Stussi E. , Vahlensieck M.
Published: March 2003

Loss of bone mass is a continuing problem in long‐term space flight. Although counter‐measure programmes have been developed, effective assessment of these programmes is hampered by a lack of monitoring techniques that can be used in‐flight.

Three techniques were used to evaluate changes in bone during two missions of 180 and 20 days to the MIR space station, involving three subjects. Dual energy X‐ray absorptiometry (DXA) was used before and after flight to measure whole body and regional bone mineral density (BMD). Ultrasonic measurements of velocity (SOS) and broadband attenuation (BUA) of the calcaneus were measured during the 180 day mission and before and after the 20 day mission. Phase velocity of flexural waves in the tibia was also measured on the same days as the ultrasonic measurements of the calcaneus.

DXA measurements demonstrated significant variation between different sites in the body for changes in BMD, with the greatest changes occurring in the lumbar spine and proximal femur. There was a trend for increasing phase velocity in the tibia during the 180 mission, but this was not significant. BUA and SOS measurements of the calcaneus showed consistent but divergent patterns of changes during the mission.

Although in‐flight measurements of bone using ultrasound or phase velocity may provide information on the kinetics of bone loss in space flight, the heterogeneity of response in the skeleton means that it is difficult to predict overall bone loss from measurements at one particular site.
Moderate exercise, postprandial lipaemia and triacylglycerol clearance
Authors: Gill J. M. R. , Mees G. P. , Frayn K. N. , Hardman A. E.
Published: March 2003

Moderate intensity exercise reduces postprandial triacylglycerol (TG) concentrations. We tested whether this reflects increased TG clearance.

Eight normotriglyceridaemic men, aged 48·3 ± 7·3 years (mean ± SD), performed two oral fat tolerance tests (blood samples taken in the fasted state and for six hours after a high‐fat meal containing 1·00 g fat, 0·97 g carbohydrate, 58 kJ energy kg−1 fat‐free body mass) and two intravenous fat tolerance tests (blood samples in the fasted state and after a bolus injection of Intralipid, 0·1 g fat kg−1 body mass). The afternoon before one oral and one intravenous test, subjects walked briskly for 90 min; no exercise was performed before the control tests.

Prior exercise reduced fasting TG concentration similarly in the oral (16 ± 7 %) (mean ± SEM) and intravenous (18 ± 7 %) tests, and reduced postprandial TG concentrations in the oral test by 18 ± 6 % (all P < 0·05). However, prior exercise did not increase Intralipid clearance (disappearance curve slopes: control, 4·69 ± 0·49 % min−1; exercise, 4·85 ± 0·40 % min−1).

These data suggest that mechanisms other than increased TG clearance mediate the lower postprandial TG concentrations seen after moderate exercise.
Extrasystolic beats affect transmural electrical dispersion during programmed electrical stimulation
Authors: Wolk R. , Stec S. , Kulakowski P.
Published: March 2003

Background Experimental studies suggest that the electrocardiographic Tpeak–Tend (TpTe) interval reflects transmural dispersion of repolarization (TDR). The genesis and role of the TpTe interval in a clinical setting have not been established. This study aimed to assess the clinical usefulness of the TpTe interval as an index of TDR and a pro‐arrhythmic marker.

Materials and methods Endocardial monophasic action potential (MAP) duration and electrocardiographic QTp, QTe and TpTe intervals were assessed in 13 patients undergoing an electrophysiological study. Surface electrocardiograms were recorded during right ventricular pacing (Basic Cycle Length = 600 ms) before and after single extrastimuli.

Results Ventricular arrhythmia was induced in six patients. During ventricular pacing, MAP duration and QTp intervals shortened in response to extrastimuli applied at progressively shorter coupling intervals. In contrast, QTe intervals increased in response to premature stimulation and QTe dispersion increased at short coupling intervals. During sinus rhythm, the TpTe interval was greater in the inducible group in leads V3‐V4. Premature stimulation increased the duration of TpTe intervals, suggesting an increase in TDR. The maximum TpTe interval was greater in the inducible than in the noninducible group, both during baseline ventricular drive pacing (163 ± 22 vs. 130 ± 27 ms, respectively, P < 0·03) and after application of shortly coupled extrastimuli (263 ± 66 vs. 200 ± 47 ms, respectively, P < 0·05).

Conclusions The TpTe interval of surface ECG is likely to represent TDR. TDR is increased by premature ventricular stimulation and the magnitude of the maximum TpTe interval (i.e. maximum TDR) during ventricular pacing is greater in patients with inducible arrhythmias.
Effect of homocysteine on arachidonic acid release in human platelets
Authors: Signorello M. G. , Pascale R. , Leoncini G.
Published: March 2003

BackgroundIt has been suggested that homocysteine is implicated in the risk of atherosclerosis and thrombosis. The pathogenic mechanism has not been clarified, but oxygen‐free species produced by the homocysteine metabolism and auto‐oxidation could have a role.

DesignWe have studied the effect of homocysteine on arachidonic acid release in human platelets. Two important products of arachidonic acid metabolism – thromboxane B2(TXB2) and reactive oxygen species (ROS) – have been assayed.

ResultsResults indicate that homocysteine induces arachidonic acid release that is partially inhibited by 5,8,11,14‐eicosatetraynoic acid (ETYA). Platelet incubation with homocysteine significantly increases basal levels of TXB2and ROS. The effect is time‐ and dose‐dependent. The TXB2formation is strictly correlated with the arachidonic acid release. Moreover, ROS accumulation is largely inhibited by ETYA and partially reduced by diphenyleneiodonium (DPI), suggesting the involvement both of enzymes metabolising arachidonic acid (cyclooxygenase, lipooxygenase, cytochrome P450 monooxygenase) and of NAD(P)H oxidase.

ConclusionHomocysteine induces oxidative stress in human plateletsin vitro. The unbalance in platelet redox‐state and the increased TXB2formation may generate hyperactivation, contributing to a thrombogenic state leading to cardiovascular diseases.
Role of calcitonin in the rapid minute‐to‐minute regulation of plasma Ca2+ homeostasis in the rat
Authors: Wang W. , Lewin E. , Olgaard K.
Published: March 2003

Background  Plasma ionized calcium (Ca2+) is maintained at a very stable concentration in mammals. The hormones or factors involved in the very rapid regulation of calcium homeostasis are still debated. Thus, previous results from our laboratory have clearly shown that parathyroid hormone (PTH) and 1,25(OH)2D3 are not responsible for the rapid up‐regulation of plasma Ca2+ after a brief induction of hypocalcaemia. The present investigation therefore examined in vivo the possible role of calcitonin (CT) in the very rapid, minute‐to‐minute regulation of plasma Ca2+ in rats.

Study design  The rapid calcaemic response to acute thyroparathyroidectomy (TPTX) and to acute selective thyroidectomy (TX) (n = 10), as well as the possible effect of CT on the very rapid recovery of plasma Ca2+ after termination of a brief induction of hypocalcaemia were studied. Hypocalcaemia was induced by a 30‐min EGTA infusion in rats in three different protocols: 1 h after TPTX (n = 9) compared with control TPTX rats not given EGTA (n = 13); 1 h after TX (n = 7); and 1 h after TPTX, but during supplementation with exogenous CT (n = 8) and compared with the response in TPTX rats infused with vehicle (n = 8).

Results  An immediate and significant increase of plasma Ca2+ was found after TPTX (P < 0·01) as well as after selective TX (P < 0·01) in the nonfasting rats. Significant hypercalcaemia (P < 0·05) was still present in rats fasting for 2 days before these procedures, but the increase in plasma Ca2+ was considerably less (P < 0·01). After induction of a brief period of hypocalcaemia by infusion of EGTA a significant (P < 0·01) and rapid recovery of plasma Ca2+ took place within 10 min and a further increase within the next 60 min (P < 0·01), whether or not the rats were normal, TPTX, TX or were supplemented by CT during the experiments. The plasma Ca2+ recovery curves after termination of a brief induction of hypocalcaemia all had similar appearances, indicating that presence or absence of CT had no influence on this very rapid Ca2+ recovery after induction of hypocalcaemia.

Conclusions  Acute removal of the tonus of CT results in an acute increase in plasma Ca2+ for up to 3 h. This effect of CT is probably mainly related to the postprandial maintenance of normocalcaemia, but is also seen in fasting rats, although to a lesser degree. The very rapid calcaemic recovery after discontinuation of a brief induction of hypocalcaemia is, however, not a result of suppressed plasma calcitonin levels.
Molecular cloning of the cDNAs encoding the feline B‐lymphocyte activation antigen B7–1 (CD80) and B7–2 (CD86) homologues which interact with human CTLA4‐Ig
Authors: Nishimura Y. , Shimojima M. , Miyazawa T. , Sato E. , Nakamura K. , Izumiya Y. , Ikeda Y. , Mikami T. , Takahashi E.
Published: March 2003

We cloned the cDNAs encoding the feline homologues of B‐lymphocyte activation antigens B7–1 (CD80) and B7–2 (CD86). We expressed recombinant feline CD80 and CD86 molecules by the baculovirus expression system, and demonstrated their binding ability to human CTLA4‐murine immunoglobulin fusion protein.
Cloning and analysis of the gene encoding the human neonatal Fc receptor
Authors: Mikulska J. E. , Pablo L. , Canel J. , Simister N. E.
Published: March 2003

The neonatal Fc receptor, FcRn, is expressed in human placental syncytiotrophoblast, capillary endothelium, intestinal epithelium, and other tissues. By analogy with its role in the mouse, human FcRn is expected to transport maternal IgG to the foetus, and protect circulating IgG from catabolism. The larger subunit of FcRn is homologous to the α chains of the major histocompatibility complex (MHC) class I proteins, but is encoded outside the MHC on chromosome 19. We report the isolation of clones encoding the α chain of human FcRn from chromosome 19‐specific libraries. The sequence revealed a similar organization to classical and non‐classical MHC, and MHC‐related genes. Compared with classical MHC class I genes, the human FcRn α chain gene has expanded by acquiring many repetitive sequences in its introns, including multiple Alu elements in the fourth intron. Primer extension analysis showed that there are two transcription initiation sites in the upstream flanking sequence.
Immobilization of cadmium and zinc in soil by Al‐montmorillonite and gravel sludge
Authors: Lothenbach B. , Krebs R. , Furrer G. , Gupta S. K. , Schulin R.
Published: March 2003

We investigated the potential of montmorillonite, Al‐montmorillonite and gravel sludge to immobilize polluting heavy metals in agricultural soil. Batch experiments showed that both Al‐montmorillonite and montmorillonite immobilized zinc and cadmium. Zinc was bound specifically on Al‐montmorillonite and became increasingly incorporated into the interlayer hydroxy‐Al polymer, whereas there was no specific sorption on montmorillonite. Cadmium was bound on montmorillonite and Al‐montmorillonite unspecifically by cation exchange, but there was no incorporation into the lattice.

In pot experiments montmorillonite, Al‐montmorillonite, or gravel sludge were added to a soil contaminated with zinc and cadmium. Increasing doses of these agents decreased the concentrations of NaNO3‐extractable zinc and cadmium. Aluminium‐montmorillonite and gravel sludge were more efficient than montmorillonite in immobilizing both zinc and cadmium. Remobilization tests at pH between 4 and 5.5 showed that cadmium and zinc desorbed more easily from montmorillonite than from Al‐montmorillonite. Gravel sludge application increased the buffer capacity of the contaminated soil substantially. The binding agents decreased zinc concentrations in red clover (Trifolium pratense), and gravel sludge also reduced the cadmium concentrations.
Chemical nature of soil organic matter under grassland and recently established forest
Authors: CONDRON L. M. , NEWMAN R. H.
Published: March 2003

Carbon‐13 (C‐13) solid‐state NMR spectroscopy was used to investigate the chemical nature of organic C in mineral topsoil sampled under grassland and adjacent recently established (10–17 years old) coniferous forest (Douglas fir, Pseudotsuga menziesii; Ponderosa pine, Pinus ponderosa; Corsican pine, Pinus nigra) at two sites (Craigieburn, Cave Stream) in the South Island of New Zealand. This involved using a Cross‐Polarized/Magic‐Angle Spinning (CP/MAS) technique to identify different chemical forms of soil organic C, whilst Proton Spin Relaxation Editing (PSRE) was used to determine different ‘pools’ of soil organic C. Results obtained from the Craigieburn soils (0–5 cm) were more promising than those obtained from the Cave Stream soils (0–10 cm) because the total Fe content was smaller, and indicated a shift towards more recalcitrant forms of organic C in soil under trees compared with grassland, which might reflect reduced inputs of fresh organic matter to the soil under trees.
An improved method for determining the specific surface areas of topsoils with varied organic matter content, texture and clay mineral composition
Authors: Theng B. K. G. , Ristori G. G. , Santi C. A. , Percival H. J.
Published: March 2003

Measuring the specific surface area (SSA) of soils that contain much organic matter (OM) is problematic. The adsorption of p‐nitrophenol (pNP) from xylene at room temperature yielded realistic values for the SSA of a wide range of clays, oxides and subsoils. Here we have extended the same measurement to some topsoils with varied OM content, texture and clay mineral composition. Specifically, we have compared the surface areas measured by adsorption of N2, and, applying the BET equation, with the values obtained by adsorption of pNP, before and after treatment of the samples with hydrogen peroxide. In all instances, the removal by H2O2 of organic matter – albeit in part only – led to a marked increase in the SSAs measured by nitrogen because of the exposure of micropores previously blocked or covered by OM. The surface areas measured by pNP were appreciably larger than those obtained by the standard BET equation, and showed little change after removal of organic matter. However, the surface area of two smectite‐rich samples measured by pNP increased substantially after peroxidation, presumably because smectite crystals decomposed during treatment with H2O2.

The results suggest that, under the experimental conditions used, pNP could diffuse without hindrance into and through organic matter, enabling it to adsorb on to micropore surfaces within clay aggregates (domains). In keeping with this suggestion, the relation between the surface areas measured by pNP and the corresponding values calculated from the clay and OM contents, and clay mineral composition, of the soils was close to 1:1. An even stronger relation was observed between the measured and calculated values for cation exchange capacity.
Modelling long‐term phosphorus leaching and changes in phosphorus fertility in excessively fertilized acid sandy soils
Authors: Del Campillo M. C. , Van Der Zee S. E. A. T. M. , Torrent J.
Published: March 2003

The sound management of agricultural soils that are heavily loaded with phosphorus (P) involves minimizing the losses of P responsible for eutrophication of surface waters, while ensuring enough P for crops. This paper describes a simple model to examine the compatibility of these two objectives in acid sandy soils in a temperate humid climate. The model is based on several assumptions regarding reversible and irreversible P sorption by P‐reactive soil compounds (mainly poorly crystalline Fe and Al oxides) and release of P to water (water‐P test). Model inputs are amount of P leached, P uptake by crops, and contents of poorly crystalline Fe and Al oxides in soil. The model predicts that reducing the amount of leached P to what is environmentally acceptable (e.g. 0.44 kg P ha–1 year–1, equivalent to 1 kg P2O5 ha–1 year–1) results in the long run in available soil P test values below target concentrations for optimum crop growth. When the amount of leached P is set to a fixed value the model predicts that soils with large contents of Fe and Al oxides can maintain the initial soil P test values for longer periods than other soils. The content in available P decreases if fertilizer P is applied to the soil at a rate equal to P uptake by crops. These results stress the difficulties involved in trying to make agricultural and environmental needs compatible in acid sandy soils.
Nitrogen fertilizer leaching from cropped and irrigated sandy soil in Central Turkey
Authors: Ünlü K. , Özeni˙rler G. , Yurteri˙ C.
Published: March 2003

Pollution of ground water caused by excessive and uncontrolled use of nitrogen fertilizer is worrying. A recent example of such pollution has been observed in an agricultural basin in the province of Nevsehir, Turkey, where up to 900 kg ha−1 nitrogen fertilizer is used for growing potatoes in sandy soils under irrigation. Using nitrogen fertilizer in amounts that guarantee large yields without polluting ground water is essential. We present results of field experiments and numerical simulations involving 15N‐labelled nitrogen fertilizer leaching. In the field, we monitored the movement of water and the distributions of nitrogen species within the soil–water–plant continuum. The detailed dynamics of the nitrogen cycle within the system were simulated. Simulations included calibration and validation of the nitrogen version of the LEACHM model (LEACHN, version 3) and long‐term applications of the model. The model’s predictions of nitrogen fluxes under long‐term use of fertilizer and irrigation were analysed. Nearly half of the applied ammonium‐N was converted to nitrate‐N during the growing season. With increasing additions of N the rate of plant uptake declined, while leaching increased significantly, and the fraction of nitrogen remaining in the soil profile increased only moderately. In long‐term applications, a significant fraction of the applied fertilizer tended to accumulate after the first year in soil as the residual nitrogen not taken up by the crop. Accumulated residual nitrogen is converted to nitrate‐N and leached rapidly from the soil profile during the wet season following the harvest. To reduce leaching of the residual nitrate, the rates, frequencies and timings of fertilizer application and irrigation must be scheduled in accordance with the plant growth periods and the hydraulic regime of the soil.
A comparison of some robust estimators of the variogram for use in soil survey
Authors: Lark R. M.
Published: March 2003

The standard estimator of the variogram is sensitive to outlying data, a few of which can cause overestimation of the variogram. This will result in incorrect variances when estimating the value of a soil property by kriging or when designing a sampling grid to map the property to a required precision. Several robust estimators of the variogram, based on location and scale estimation, have been proposed as improvements. They seem to be suitable for analysis of soil data in circumstances where the standard estimator is likely to be affected by outliers. Robust estimators are based on assumptions about the distribution of the data which will not always hold and which need not be made in kriging or in estimating the variogram by the standard estimator.

The estimators are reviewed. Simulation studies show that the robust estimators vary in their susceptibility to moderate skew in the underlying distribution, but that the effects of outliers are generally greater. The estimators are applied to some soil data, and the resulting variograms used for ordinary kriging at sites in a separate validation data set. In most cases the variograms derived from the standard estimator gave kriging variances which appeared to overestimate the mean squared error of prediction (MSEP). Kriging with variograms based on robust estimators sometimes gave kriging variances which underestimated the MSEP or did not differ significantly from it. Estimates of kriging variance and the MSEP derived from the validation data were generally close to estimates from cross‐validation on the prediction set used to derive the variograms. This indicates that variogram models derived from different estimators could be compared by cross‐validation.
Temperature dependence of thermal conductivity of soil over a wide range of temperature (5–75°C)
Authors: Hiraiwa Y. , Kasubuchi T.
Published: March 2003

The coupled heat and mass transfer in soil can be analysed by examining the temperature dependence of thermal conductivity. We have measured the thermal conductivity of two kinds of soil (Ando soil and Red Yellow soil) as a function of both temperature (5–75°C) and water content by the twin heat probe method. From our results we concluded that the thermal conductivity resulting from the latent heat transfer can be separated from the apparent thermal conductivity by subtracting the thermal conductivity at a temperature near 0°C from that at a higher temperature. The relation between the phenomenological enhancement factor (β) and the volumetric air‐filled porosity was divided into two parts: β increases linearly as the volumetric air‐filled porosity increases from zero (that is, water saturation), to the point at which soil water potential corresponds to −320 J kg−1; from that point to oven‐dry condition, β decreased logistically with the volumetric air‐filled porosity. From these results, we could generalize the behaviour of β.
Estimating variograms of soil properties by the method‐of‐moments and maximum likelihood
Authors: Lark R. M.
Published: March 2003

Variograms of soil properties are usually obtained by estimating the variogram for distinct lag classes by the method‐of‐moments and fitting an appropriate model to the estimates. An alternative is to fit a model by maximum likelihood to data on the assumption that they are a realization of a multivariate Gaussian process. This paper compares the two using both simulation and real data.

The method‐of‐moments and maximum likelihood were used to estimate the variograms of data simulated from stationary Gaussian processes. In one example, where the simulated field was sampled at different intensities, maximum likelihood estimation was consistently more efficient than the method‐of‐moments, but this result was not general and the relative performance of the methods depends on the form of the variogram. Where the nugget variance was relatively small and the correlation range of the data was large the method‐of‐moments was at an advantage and likewise in the presence of data from a contaminating distribution. When fields were simulated with positive skew this affected the results of both the method‐of‐moments and maximum likelihood.

The two methods were used to estimate variograms from actual metal concentrations in topsoil in the Swiss Jura, and the variograms were used for kriging. Both estimators were susceptible to sampling problems which resulted in over‐ or underestimation of the variance of three of the metals by kriging. For four other metals the results for kriging using the variogram obtained by maximum likelihood were consistently closer to the theoretical expectation than the results for kriging with the variogram obtained by the method‐of‐moments, although the differences between the results using the two approaches were not significantly different from each other or from expectation. Soil scientists should use both procedures in their analysis and compare the results.
Effects of rock fragment cover on soil infiltration, interrill runoff and erosion
Authors: Cerdà A.
Published: March 2003

Considerable attention has been paid recently to the influence of surface rock fragments on hydrological and erosional processes, although much of this research has been done on disturbed soils under laboratory conditions. I have studied the effects of rock fragments on soil infiltration, runoff and erosion under field conditions using simulated rainfall on bare areas of natural soils within typical Mediterranean scrubland characterized by patchily distributed vegetation. Sample areas were chosen where rock fragments cover more than half the surface within unvegetated patches. Twenty experiments were carried out by applying rain at an intensity of 55 mm h−1 for 60 minutes. This approach shows that rock fragments (i) retard ponding and surface runoff, and (ii) give greater steady‐state infiltration rates and smaller interrill runoff discharges, sediment concentrations and interrill erosion rates. A second set of six experiments was carried out by applying rainfall at an intensity of 55 mm h−1 for two runs of 60 minutes. The second run was initiated 10 minutes after the first. During this interval, surface rock fragments were removed in order to measure their effects on infiltration, interrill runoff and erosion rates. In this way, I showed that water and soil losses are reduced by the rock fragments. After the removal of rock fragments the steady‐state infiltration rate diminished from 44.5 to 27.5 mm h−1 and the runoff coefficient, sediment concentration and erosion rates were, respectively, 3, 33 and 39 times greater than they were before the rock fragments were removed.
Nitrate leaching loss under annual and perennial pastures with and without lime on a duplex (texture contrast) soil in humid southeastern Australia
Authors: Ridley A. M. , White R. E. , Helyar K. R. , Morrison G. R. , Heng L. K. , Fisher R.
Published: March 2003

Mineral N accumulates in autumn under pastures in southeastern Australia and is at risk of leaching as nitrate during winter. Nitrate leaching loss and soil mineral N concentrations were measured under pastures grazed by sheep on a duplex (texture contrast) soil in southern New South Wales from 1994 to 1996. Legume (Trifolium subterraneum)‐based pastures contained either annual grass (Lolium rigidum) or perennial grasses (Phalaris aquaticaandDactylis glomerata), and had a control (soil pH 4.1 in 0.01 mCaCl2) or lime treatment (pH 5.5). One of the four replicates was monitored for surface runoff and subsurface flow (the top of the B horizon), and solution NO3–concentrations.

The soil contained more mineral N in autumn (64–133 kg N ha−1to 120 cm) than in spring (51–96 kg N ha−1), with NO3–comprising 70–77%. No NO3–leached in 1994 (475 mm rainfall). In 1995 (697 mm rainfall) and 1996 (666 mm rainfall), the solution at 20 cm depth and subsurface flow contained 20–50 mg N l−1as NO3–initially but < 1 mg N l−1by spring. Nitrate‐N concentrations at 120 cm ranged between 2 and 22 mg N l−1during winter. Losses of NO3–were small in surface runoff (0–2 kg N ha−1year−1). In 1995, 9–19 kg N ha−1was lost in subsurface flow. Deep drainage losses were 3–12 kg N ha−1in 1995 and 4–10 kg N ha−1in 1996, with the most loss occurring under limed annual pasture. Averaged over 3 years, N losses were 9 and 15 kg N ha−1year−1under control and limed annual pastures, respectively, and 6 and 8 kg N ha−1year−1under control and limed perennial pastures. Nitrate losses in the wet year of 1995 were 22, 33, 13 and 19 kg N ha−1under the four respective pastures. The increased loss of N caused by liming was of a similar amount to the decreased N loss by maintaining perennial pasture as distinct from an annual pasture.
Measurement of the wettability of organic materials in relation to water content by the capillary rise method
Authors: Michel J. ‐C. , Rivière L. ‐M. , Bellon‐Fontaine M. ‐N.
Published: March 2003

A new measuring technique based on a capillary rise method has been developed to quantify the wettability of more or less decomposed peats (the main materials used as horticultural growing media) in relation to their water content. A preliminary study of their physico‐chemical and biochemical characteristics enabled us to study the variation of their physical properties (particularly their rewetting capacity) in relation to their degree of decomposition. Analysis of these physical properties during two drying and rewetting cycles showed that the greater their degree of decomposition, the greater and more irreversible was their shrinkage. The change from hydrophilicity to hydrophobicity was measured by the increase of the water contact angle during desiccation and by the progressive change from bipolar to apolar surfaces. A strong correlation between the water retention of peats (related to their degree of decomposition) and their free energy (also called hydration energy) at the interface between solid and water ΔGSW is also shown.
Physical fractionation of soil and structural and functional complexity in organic matter turnover
Authors: Christensen B. T.
Published: March 2003

Physical fractionation is used increasingly to study the turnover of organic matter in soil. This essay links the methods of fractionation to concepts of turnover by defining levels of structural and functional complexity that refer to experimentally verifiable pools of organic matter in the soil.

Physical fractionation according to size and density of soil particles emphasizes the importance of interactions between organic and inorganic soil components in the turnover of organic matter. It allows the separation of free and occluded uncomplexed organic matter and of primary and secondary organomineral complexes. This methodological approach recognizes that the overall regulation of decomposer activity is through the structure of soil, which determines gas exchange, the availability of substrates and water, and the transport of solutes.

Results from physical fractionations suggest three levels of structural and functional complexity in the turnover of organic matter in soil. Primary organomineral complexes isolated from fully dispersed soil account for the primary level of complexity. The clay‐, silt‐ and sand‐sized complexes are seen as the basic units in soil, surface reactions between substrates, organisms and minerals being the main regulatory mechanisms. Secondary complexes reflect the degree of aggregation of primary organomineral complexes and refer to the second level of complexity. Physical protection of uncomplexed organic matter and soil organisms and the creation of gas and moisture gradients are emergent features regulating the turnover at this level of complexity. The structurally intact soil (the soil in situ) constitutes the third level of complexity. This integrates the effects of primary and secondary complexes. Emergent structural features associated with this level are resource islands, macropores, roots, mesofauna, tillage and soil compaction, the corresponding functional features being related to the transport and exchange of solutes and gases, and the spatial distribution and comminution of litter and uncomplexed organic matter. Thus, a thorough understanding of the turnover and storage of organic matter in soil can be acquired only by considering all levels of complexity in the decomposition subsystem.
Soil solution concentration of Cd and Zn canbe predicted with a CaCl2 soil extract
Authors: Degryse F. , Broos K. , Smolders E. , Merckx R.
Published: March 2003

Risk assessment of heavy metals in soil requires an estimate of the concentrations in the soil solution. In spite of the numerous studies on the distribution of Cd and Zn in soil, few measurements of the distribution coefficient in situ, Kd, have been reported. We determined the Kd of soils contaminated with Cd and Zn by measuring metal concentrations in the soil and in the soil solution and attempted to predict them from other soil variables by regression. Soil pH explained most of the variation in logKd (R2 = 0.55 for Cd and 0.70 for Zn). Introducing organic carbon content or cation exchange capacity (CEC) as second explanatory variable improved the prediction (R2 = 0.67 for Cd and 0.72 for Zn), but these regression models, however, left more than a factor of 10 of uncertainty in the predicted Kd. This large degree of uncertainty may partly be due to the variable degree of metal fixation in contaminated soils. The labile metal content was measured by isotopic dilution (E value). The E value ranged from 18 to 92% of the total metal content for Cd and from 5 to 68% for Zn. The prediction of Kd improved when metals in solution were assumed to be in equilibrium with the labile metal pool instead of the total metal pool. It seems necessary therefore to discriminate between ‘labile’ and ‘fixed’ pools to predict Kd for Cd and Zn in field contaminated soils accurately. Dilute salt extracts (e.g. 0.01 m CaCl2) can mimic soil solution and are unlikely to extract metals from the fixed pool. Concentrations of Cd and Zn in the soil solution were predicted from the concentrations of Cd and Zn in a 0.01 m CaCl2 extract. These predictions were better correlated with the observations for field contaminated soils than the predictions based on the regression equations relating logKd to soil properties (pH, CEC and organic C).
Two robust estimators of the cross‐variogram for multivariate geostatistical analysis of soil properties
Authors: Lark R. M.
Published: March 2003

If we wish to describe the coregionalization of two or more soil properties for estimation by cokriging then we must estimate and model their auto‐ and cross‐variogram(s). The conventional estimates of these variograms, obtained by the method‐of‐moments, are unduly affected by outlying data which inflate the variograms and so also the estimates of the error variance of cokriging predictions. Robust estimators are less affected. Robust estimators of the auto‐variogram and the pseudo cross‐variogram have previously been proposed and used successfully, but the multivariate problem of estimating the cross‐variogram robustly has not yet been tackled.

 Two robust estimators of the cross‐variogram are proposed. These use covariance estimators with good robustness properties. The robust estimators of the cross‐variogram proved more resistant to outliers than did the method‐of‐moments estimator when applied to simulated fields which were then contaminated.

Organic carbon and water content of the soil was measured at 256 sites on a transect and the method‐of‐moments estimator, and the two robust estimators, were used to estimate the auto‐variograms and cross‐variogram from a prediction subset of 156 sites. The data on organic carbon included a few outliers. The method‐of‐moments estimator returned larger values of the auto‐ and cross‐variograms than did either robust estimator. The organic carbon content at the 100 validation sites on the transect was estimated by cokriging from the prediction data plus a set of variograms fitted to the method‐of‐moments estimates and two sets of variograms fitted to the robust estimates. The ratio of the actual squared prediction error to the cokriging estimate of the error variance was computed at each validation site. These results showed that cokriging using variograms obtained by the method‐of‐moments estimator overestimated the error variance of the predictions. By contrast, cokriging with the robustly estimated variograms gave reliable estimates of the error variance of the predictions.
Incidence of escaped farmed salmon, Salmo salar L., in commercial salmon catches and fresh water in Northern Ireland
Authors: CROZIER
Published: March 2003

External morphological characteristics were used to identify escaped farmed Atlantic salmon, Salmo salar L., in a coastal salmon fishery in County Antrim, Northern Ireland during four fishing seasons and at an adjacent freshwater location (R. Bush) during a 5‐year period. Out of a total of 36 326 adult salmon examined in the fishery, 883 (2.4%) were identified as having escaped from sea cages. Annual average values ranged from 0.26% to 4.04% of the fish caught. Occurrence of escapees entering an adult trap in fresh water averaged 0.88%, with a range of 0.13–2.62%, depending on year. No correlation between presence in the marine fishery and in fresh water was evident, the latter year‐round figures probably being more indicative of presence of escapees in spawning stocks. Entry to fresh water was significantly later on average for escaped farmed salmon, compared with wild salmon.
Revealing trends in densities of juvenile Atlantic salmon,Salmo salarL., in the subarctic River Teno using cluster analysis on long‐term sampling data
Authors: Niemelø E. , Julkunen M. , Erkinaro J.
Published: March 2003

The density of juvenile Atlantic salmon,Salmo salarL., was monitored at 57 sites representing different habitats in the River Teno and two of its major tributaries from 1979 to 1995. Cluster analyses were used to combine sites with similar densities and to study trends in densities within clusters. It was found that management measures have played an important role in maintaining salmon stocks and there was some evidence of increasing juvenile salmon densities. Parr densities decreased significantly in one cluster containing 45% of the sites studied in the River Utsjoki, whereas densities increased significantly in one cluster in the River Teno and in one cluster in the River Inarijoki containing 38% of the sites in these rivers. Fry densities increased significantly in two clusters containing 16% of all the sites studied in the three rivers. In general, the mean densities in successive years in the clusters were independent. The results demonstrate the value of long‐term monitoring in ecological investigations.
A system for automatic recording of fish tagged with coded acoustic transmitters
Authors: Thorstad E. B. , Økland F. , Rowsell D. , Mckinley R. S.
Published: March 2003

A telemetry system designed to automatically record the presence and swimming direction of fish tagged with coded acoustic transmitters is described. The present paper presents results from an extensive mapping of signal strengths and the proportion of correctly identified codes from a transmitter at various positions outside automatic listening stations (ALS). The system is evaluated on the basis of two field seasons, during which 107 Atlantic salmon, Salmo salar L., were tagged with acoustic transmitters in a fjord system in south‐western Norway. By installing one ALS (two at high water discharges) in the mouth of the River Suldalslågen and two ALSs in the Hylsfjord, the presence and swimming direction of all tagged salmon entering the river and the inner part of the 750‐m‐wide Hylsfjord were recorded.
A comparative study of the species composition of discards from five fisheries from the Algarve (southern Portugal)
Authors: ERZINI K. , COSTA M. E. , BENTES L. , BORGES T. C.
Published: March 2003

Discards from five of the most important fisheries (crustacean trawling, fish trawling, demersal purse seining, pelagic purse seining and trammel netting) in southern Portugal were studied and compared. A total of 236 species of all taxa were discarded, with fish and cephalopods accounting for more than 90% of the discarded biomass, except trammel nets (81%). Although there was some overlapping of species, multivariate analysis using cluster analysis for classification and multidimensional scaling (MDS) for ordination, showed that there were significant differences between the five gears in terms of species composition and biomasses discarded, with the least similarity between crustacean trawling and all other fishing operations. The differences between fisheries were probably as a result of a combination of gear selectivity and depth fished. The results suggest that discarding practices are likely to have different, yet significant impacts on the marine ecosystem, warranting further studies on the fate of discards, the factors influencing discarding and mitigation.
The fallacy of the missing middle: physics →…→ fisheries
Authors: BAUMANN MICHAEL
Published: March 2003

In this paper I discuss some of the shortcomings of today's marine science in response to a recently published paper by Ann Gargett (1997). Three problem areas have been identified in the field linking climate forcing and fish production: First, the yet‐to‐be established observational proof for a relationship between the two; Second, the strongly neglected biology of organisms at evolutionary and ecological time scales; and thrird, the disregard for spatial and temporal scales in the discussion of mechanisms and supporting data.
Relationships between anchovy (Engraulis encrasicolus) recruitment and environment in the Bay of Biscay (1967–1996)
Authors: BORJA ANGEL , URIARTE ANDRE´S , EGAÑA JOSEBA , MOTOS LORENZO , VALENCIA VICTOR
Published: March 2003

Various hypotheses have been put forward to explain the mechanisms leading to recruitment variability in fish populations. These have been based on either physical (wind stress, upwelling) or biological (food and predation) processes. In the Bay of Biscay, the hypothesis of a physical influence on anchovy recruitment has been confirmed. Oceanographic conditions in the Bay of Biscay in the spring and summer, influenced by north‐easterly winds of medium and low intensity, seem to induce good levels of recruitment to the anchovy (Engraulis encrasicolus) population. An index of upwelling was significantly correlated with annual recruitment of anchovy (P < 0.0001) for the period 1967–1996. This physical parameter explains about 59% of the variability in the recruitment of the Bay of Biscay anchovy. Two factors affecting productivity in the Bay of Biscay may be linked to north‐easterly winds, namely weak upwelling and an extension of the area influenced by river outflows. Both of these factors, together with low turbulence and stability, may act to enhance survival of the early life‐history stages of anchovy by increasing food availability. The potential use of this upwelling index to forecast the recruitment of the Bay of Biscay anchovy offers possibilities for improving the management of this population.
Modelling annual cycles of primary production in different regions of the Bohai Sea
Authors: GAO HUIWANG , FENG SHIZUO , GUAN YUPING
Published: March 2003

The Bohai Sea is a typical shallow sea in which the average depth of water is about 18 m, and which has a rich biodiversity and abundance of marine life. The values of primary production differ among the four different regions of the Bohai Sea. A biological model consisting of nutrients, phytoplankton, zooplankton and detritus is used to simulate the annual cycles of plankton and primary production in these four regions. The simulation is forced by monthly observational data. Water transparency, nutrient concentrations, temperature and incident irradiance influence the amount and variation of plankton and primary production. The model simulations indicate that transparency and nutrient concentration are the principal causes of the differences in primary production among the four regions of the Bohai Sea.
Springtime abundance of chaetognaths in the shelf region of the northern Gulf of Alaska, with observations on the vertical distribution and feeding of Sagitta elegans
Authors: BRODEUR RICHARD D. , TERAZAKI MAKOTO
Published: March 2003

Chaetognatha were among the most dominant macrozooplankton taxa collected in 6 years of springtime collections, both throughout the water column and near‐bottom on the continental shelf in the northern Gulf of Alaska. Three species (Sagitta elegans, S. scrippsae, and Eukrohnia hamata) were collected in 248 collections, although S. elegans was the numerically dominant species overall during most cruises. Collections taken in epibenthic sleds generally contained about two orders of magnitude more chaetognaths than those that sampled throughout the water column. Two size modes were apparent in the S. elegans size‐frequency distributions which were believed to belong to different cohorts. Growth rate was on the order of 2–3 mm per month. The two cohorts showed asynchronous diel vertical distribution patterns, with the smaller individuals found near the surface during the day whereas the larger individuals were near the surface at night. About 7.5% of the S. elegans examined contained food. Copepods made up the majority (∼89% by number) of the diet of both large and small individuals. Euphausiid juveniles and cirripede larvae were also observed, as well as several incidences of cannibalism by large chaetognaths on smaller individuals. Based on the results of two diel series, this species was observed to feed mainly during the night‐time.