bluuebunny/crossref_metadata_2025_split huggingface dataset:
Partitioning of river metabolism identifies phytoplankton as a major contributor in the regulated Murray River (Australia)
Authors: OLIVER RODERICK L. , MERRICK CHESTER J. 
Published: May 2006

Summary1. River metabolism was measured over an annual cycle at three sites distributed along a 1000 km length of the lowland Murray River, Australia.2. Whole system metabolism was measured using water column changes in dissolved oxygen concentrations while planktonic and benthic metabolism were partitioned using light‐dark bottles and benthic chambers.3. Annual gross primary production (GPP) ranged from 775 to 1126 g O2 m−2 year−1 which in comparison with rivers of similar physical characteristics is moderately productive.4. Community respiration (CR) ranged from 872 to 1284 g O2 m−2 year−1 so that annual net ecosystem production (NEP) was near zero, suggesting photosynthesis and respiration were balanced and that allochthonous organic carbon played a minor role in fuelling metabolism.5. Planktonic rates of gross photosynthesis and respiration were similar to those of the total channel, indicating that plankton were responsible for much of the observed metabolism.6. Respiration rates correlated with phytoplankton standing crop (estimated as the sum of GPP plus the chlorophyll concentration in carbon units), yielding a specific respiration rate of −1.1 g O2 g C−1 day−1. The respiration rate was equivalent to 19% of the maximum rate of phytoplankton photosynthesis, which is typical of diatoms.7. The daily GPP per unit phytoplankton biomass correlated with the mean irradiance of the water column giving a constant carbon specific photon fixation rate of 0.35 gO2 g Chl a−1 day−1 per μmole photons m−2 s−1 (ca. 0.08 per mole photons m−2 on a carbon basis) indicating that light availability determined daily primary production.8. Annual phytoplankton net production (NP) estimates at two sites indicated 25 and 36 g C m−2 year−1 were available to support riverine food webs, equivalent to 6% and 11% of annual GPP.9. Metabolised organic carbon was predominantly derived from phytoplankton and was fully utilised, suggesting that food‐web production was restricted by the energy supply.
Potential long‐term impacts of livestock introduction on carbon and nitrogen cycling in grasslands of Southern South America
Authors: PIÑEIRO GERVASIO , PARUELO JOSÉ MARIA , OESTERHELD MARTIN 
Published: May 2006

AbstractEmpirical evidence based on grazing exclusion at the scale of years to decades shows that grazing modifies carbon (C) and nitrogen (N) cycling. However, long‐term effects at the scale of centuries are less known, yet highly relevant to understand local and global impacts of grazing. Additionally, most studies have focused on the isolated response of C and N, with little understanding of their interactions. Using CENTURY, a process‐based biogeochemical model, we analyzed the impacts of 370 years of livestock grazing (i.e. long term, from early European colonization to present) in 11 sites across the Río de la Plata grasslands and compared them with those resulting from two decades of grazing (i.e. mid‐term, typical exclosure experiment). In the long term, livestock grazing primarily altered the N cycle through faster N returns to the soil via urine and dung, which were offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic N decreased by −880 kg ha−1 or −19%. Higher N outputs (mainly as NH3) opened the N cycle, potentially decreasing N2O and NOx emissions and increasing N depositions over the region. These greater outputs of N constrained C accumulation in soils, reducing soil organic C by −21 200 kg ha−1 (−22%, a reduction of −1.5 Pg of C for the whole region) and net primary production by −2192 kg ha−1 yr−1 (−24%). Mid‐term simulations showed that the effects of livestock introduction in a decadal time scale were substantially different both in magnitude and direction from long‐term responses. Long‐term results were not substantially affected when atmospheric CO2 content, species composition and fire regime were changed within plausible ranges, but highlighted fire‐grazing interactions as a major constraint of long‐term C and N dynamics in these grasslands.
Effect of oestradiol on PAMP‐mediated CCL20/MIP‐3α production by mouse uterine epithelial cells in culture
Authors: Soboll Gisela , Crane‐Godreau Mardi A. , Lyimo Magdalena A. , Wira Charles R. 
Published: May 2006

SummaryThe present study was undertaken to establish whether mouse uterine epithelial cells produce CCL20/macrophage inflammatory protein 3α (CCL20/MIP‐3α) and to determine whether secretion is under hormonal control and influenced by pathogen‐associated molecular patterns (PAMPs). In the absence of PAMPs, polarized uterine epithelial cells grown to confluence on cell culture inserts constitutively secreted CCL20/MIP‐3α with preferential accumulation into the apical compartment. When epithelial cells were treated with the Toll‐like receptor (TLR) agonists Pam3Cys (TLR2/1), peptidoglycan (TLR2/6) or lipopolysaccharide (LPS; TLR4), CCL20/MIP‐3α increased rapidly (4 hr) in both apical and basolateral secretions. Time–course studies indicated that responses to PAMPs added to the apical surface persisted for 12–72 hr. Stimulation with loxoribin (TLR7) and DNA CpG motif (TLR9) increased basolateral but not apical secretion of CCL20/MIP‐3α. In contrast, the viral agonist Poly(I:C) (TLR3) had no effect on either apical or basolateral secretion. In other studies, we found that oestradiol added to the culture media decreased the constitutive release of CCL20/MIP‐3α. Moreover, when added to the culture media along with LPS, oestradiol inhibited LPS‐induced increases in CCL20/MIP‐3α secretion into both the apical and basolateral compartments. In summary, these results indicate that CCL20/MIP‐3α is produced in response to PAMPs. Since CCL20/MIP‐3α is chemotactic for immature dendritic cells, B cells and memory T cells and has antimicrobial properties, these studies suggest that CCL20/MIP‐3α production by epithelial cells, an important part of the innate immune defence in the female reproductive tract, is under hormonal control and is responsive to microbial challenge.
Deciphering CD30 ligand biology and its role in humoral immunity
Authors: Kennedy Mary K. , Willis Cynthia R. , Armitage Richard J. 
Published: May 2006

SummaryLigands and receptors in the tumour necrosis factor (TNF) and tumour necrosis factor receptor (TNFR) superfamilies have been the subject of extensive investigation over the past 10–15 years. For certain TNFR family members, such as Fas and CD40, some of the consequences of receptor ligation were predicted before the identification and cloning of their corresponding ligands through in vitro functional studies using agonistic receptor‐specific antibodies. For other members of the TNFR family, including CD30, cross‐linking the receptor with specific antibodies failed to yield many clues about the functional significance of the relevant ligand–receptor interactions. In many instances, the subsequent availability of TNF family ligands in the form of recombinant protein facilitated the determination of biological consequences of interactions with their relevant receptor in both in vitro and in vivo settings. In the case of CD30 ligand (CD30L; CD153), definition of its biological role remained frustratingly elusive. Early functional studies using CD30L+ cells or agonistic CD30‐specific antibodies logically focused attention on cell types that had been shown to express CD30, namely certain lymphoid malignancies and subsets of activated T cells. However, it was not immediately clear how the reported activities from these in vitro studies relate to the biological activity of CD30L in the more complex whole animal setting. Recently, results from in vivo models involving CD30 or CD30L gene disruption, CD30L overexpression, or pharmacological blockade of CD30/CD30L interactions have begun to provide clues about the role played by CD30L in immunological processes. In this review we consider the reported biology of CD30L and focus on results from several recent studies that point to an important role for CD30/CD30L interactions in humoral immune responses.
Expression levels of Mycobacterium tuberculosis antigen‐encoding genes versus production levels of antigen‐specific T cells during stationary level lung infection in mice
Authors: Rogerson Brian J. , Jung Yu‐Jin , LaCourse Ronald , Ryan Lynn , Enright Nicholas , North Robert J. 
Published: May 2006

Summary Mycobacterium tuberculosis lung infection in mice was controlled at an approximately stationary level after 20 days of log linear growth. Onset of stationary level infection was associated with the generation by the host of T helper type 1 (Th1) immunity, as evidenced by the accumulation of CD4 Th1 cells specific for the early secretory antigen (ESAT‐6) of M. tuberculsosis encoded by esat6, and for a mycolyl transferase (Ag85B) encoded by fbpB. CD4 T cells specific for these antigens were maintained at relatively high numbers throughout the course of infection. The number of CD4 T cells generated against ESAT‐6 was larger than the number generated against Ag85B, and this was associated with a higher transcription level of esat6. The total number of transcripts of esat6 increased during the first 15 days of infection, after which it decreased and then approximately stabilized at 106·5 per lung. The total number of fbpB transcripts increased for 20 days of infection before decreasing and then approximately stabilizing at 104·8 per lung. The number of transcripts of esat6 per colony‐forming unit of M. tuberculosis fell from 8·6 to 0·8 after day 15, and of fbpB from 0·3 to less than 0·02 after day 10, suggesting that at any given time during stationary level infection the latter gene was expressed by a very small percentage of bacilli. Expressed at an even lower level was an M. tuberculosis replication gene involved in septum formation (ftsZ), indicating that there was no significant turnover of the M. tuberculosis population during stationary level infection.
Critical role of M. tuberculosis for dendritic cell maturation to induce collagen‐induced arthritis in H‐2b background of C57BL/6 mice
Authors: Kai Hirayasu , Shibuya Kazuko , Wang Yinan , Kameta Hirotaka , Kameyama Tomie , Tahara‐Hanaoka Satoko , Miyamoto Akitomo , Honda Shin‐ichiro , Matsumoto Isao , Koyama Akio , Sumida Takayuki , Shibuya Akira 
Published: May 2006

SummaryCollagen‐induced arthritis (CIA) can be induced even in CIA‐resistant H‐2b background of C57BL/6 mice when these mice are immunized with type II collagen (CII) emulsified in complete Freund's adjuvant (CFA) containing high, but not low, dose of Mycobacterium tuberculosis. Here, we investigated the pathogenesis of CIA in C57BL/6 mice induced by the immunizing protocol. We examined expressions of cytokines, costimulatory molecules and major histocompatibility complex (MHC) class II in draining lymph nodes (DLN) in CIA‐induced C57BL/6 mice by quantitative reverse transcription–polymerase chain reaction. We also examined an effect of M. tuberculosis on the expression of these molecules on dendritic cells (DC) in vitro by flow cytometry. We finally examined an effect of M. tuberculosis in CFA used for immunization with CII antigen on priming of CD4+ helper T cells specific to CII in DLN of CIA‐induced C57BL/6 mice. The expression of interferon‐γ (IFN‐γ), Interleukin‐12p40 (IL‐12p40), costimulatory molecules CD40, CD80 and CD86 and MHC class II were up‐regulated in DLN of CIA‐induced C57BL/6 mice. Expressions of these costimulatory molecules were also up‐regulated on DC after stimulation with high, but not low, dose of M. tuberculosis in vitro. Furthermore, priming of CD4+ helper T cells specific to CII antigen in DLN required immunization with CII using CFA containing high, but not low, dose of M. tuberculosis. These results suggested that high dose of M. tuberculosis were required for maturation of DC enough to prime CD4+ helper T cells specific to CII antigen in DLN of H‐2b background of C57BL/6 mice.
Competing species in a changing climate: effects of recruitment disturbances on two interacting barnacle species
Authors: SVENSSON CARL JOHAN , JOHANSSON EMMELI , ÅBERG PER 
Published: May 2006

Summary

The climate is changing and data‐based simulation models can be a valuable tool for predicting population response to such changes and investigate the mechanisms of population change. In this study, a data‐based two‐species matrix model was constructed to explore the possible effects of elevated sea surface temperature (i.e. climate change) on the interaction between open populations of the south Atlantic barnacle species Chthamalus montagui and the boreal species Semibalanus balanoides in the north‐east Atlantic.
First, the model was used to perform an elasticity analysis to determine the relative importance of recruitment and survival in the interaction. Further, three scenarios of changes in recruitment, related to climate change, were investigated with model simulations: (i) increased frequencies of low recruitment for S. balanoides; (ii) increased frequencies of high recruitment for C. montagui; (iii) a combination of (i) and (ii).
Model simulations showed that in present environmental conditions, S. balanoides occupied most of the space and dominated the interaction through high recruitment and survival. These results matched independent field observations, which validated the model for further analyses.
The elasticity analyses showed that although free space was available there was competition for space during recruitment intervals. It was also shown that both populations were sensitive to changes in recruitment.
Introducing the three scenarios of recruitment disturbances led to large changes in species abundance and free space. The most significant changes were found when scenario (i) and (ii) were combined, producing a shift in species dynamics towards C. montagui dominance. This demonstrates that recruitment can be an important mechanism in the interaction between populations and that the population response to changes in recruitment depends on the added response of interacting species.
In a more general context, this model shows that increased sea surface temperature could rapidly lead to increased competition from southern species at higher latitudes. This might accelerate the effects of climate change on the species distribution at these latitudes and eventually lead to changes in community dynamics on temperate and subarctic shores.
Active and passive dispersal of an invading land snail in Mediterranean France
Authors: AUBRY SÉBASTIEN , LABAUNE CORINNE , MAGNIN FRÉDÉRIC , ROCHE PHILIP , KISS LAURENCE 
Published: May 2006

SummaryLand snail dispersal abilities are considered poor; however, the current invasion of the French Mediterranean region byXeropicta derbentina(Krynicki 1836), as well as the past invasions of this region by several other species, seems to contradict this view.Using a multilevel approach, from individual experimentation to landscape analysis, the dispersal abilities and mechanisms allowing the passive dispersal ofX. derbentinaare studied.The colonization of Provence occurred by stratified diffusion, where short‐range active dispersal occurs side by side with long‐range passive dispersal.Active dispersal is not as limited as previously thought. In the field, the capture–mark–recapture method recorded a maximum distance covered of 42 m in 6 months within a radius of 38 m from the original release point.Temperature and humidity, and therefore the time of year, influence the main type of dispersal. Dispersal is active during wet periods and essentially passive in dry and hot months.Heat avoidance behaviour is one of the mechanisms allowing passive dispersal.Passive dispersal via human activities is the main determinant ofX. derbentinadistribution within the landscape. In comparison to other species,X. derbentinais found more often in the vicinity of a communication route.These results show that land snails can cover large distances in a lifetime. The potential for active and passive dispersal described in this paper enablesX. derbentinato be a successful invasive species and explains the rapid spread and current distribution of this species.
Consequences of spatial autocorrelation for niche‐based models
Authors: SEGURADO P. , ARAÚJO M. B. , KUNIN W. E. 
Published: May 2006

Summary

Spatial autocorrelation is an important source of bias in most spatial analyses. We explored the bias introduced by spatial autocorrelation on the explanatory and predictive power of species’ distribution models, and make recommendations for dealing with the problem.
Analyses were based on the distribution of two species of freshwater turtle and two virtual species with simulated spatial structures within two equally sized areas located on the Iberian Peninsula. Sequential permutations of environmental variables were used to generate predictor variables that retained the spatial structure of the original variables. Univariate models of species’ distributions using generalized linear models (GLM), generalized additive models (GAM) and classification tree analysis (CTA) were fitted for each variable permutation. Variation of accuracy measures with spatial autocorrelation of the original predictor variables, as measured by Moran's I, was analysed and compared between models. The effects of systematic subsampling of the data set and the inclusion of a contagion term to deal with spatial autocorrelation in models were assessed with projections made with GLM, as it was with this method that estimates of significance based on randomizations were obtained.
Spatial autocorrelation was shown to represent a serious problem for niche‐based species’ distribution models. Significance values were found to be inflated up to 90‐fold.
In general, GAM and CTA performed better than GLM, although all three methods were vulnerable to the effects of spatial autocorrelation.
The procedures utilized to reduce the effects of spatial autocorrelation had varying degrees of success. Subsampling was partially effective in avoiding the inflation effect, whereas the inclusion of a contagion term fully eliminated or even overcompensated for this effect. Direct estimation of probability using variable simulations was effective, yet seemed to show some residual spatial autocorrelation effects.
Synthesis and applications. Given the expected inflation in the estimates of significance when analysing spatially autocorrelated variables, these need to be adjusted. The reliability and value of niche‐based distribution models for management and other applied ecology purposes can be improved if certain techniques and procedures, such as the null model approach recommended in this study, are implemented during the model‐building process.
14 Effects of dual pulses gastric electrical stimulation on gastric tone and compliance
Authors: LEI Y , CHEN JDZ 
Published: May 2006

Background:  Gastric Electrical Stimulation (GES) has been introduced as an innovative therapy for patients with refractory gastroparesis. Studies suggest that GES with short pulses (in the order of μs) improves symptoms of nausea and vomiting for some patients with gastroparesis, whereas GES with long pulses (in the order of μs) improves gastric motility.Aims:  To develop a novel method of GES: dual pulses GES and assess the effects of dual pulses GES on gastric tone and compliance.Methods:  The study was performed in 7 dogs implanted with a gastric cannula and a pair of gastric serosal electrodes. Dual pulses GES was used a stimulus composed of both short and long pulses. This experiment was repeated a number of times on different days with different stimulation parameters, including a variation in the number of short pulses (1 and 5), a variation in stimulation amplitude (2 mA, 4 mA and 6 mA). The parameters soliciting the most significant effects on gastric tone and vagal activity were used in the following gastric compliance study. Gastric tone and compliance were assessed with an electrical barostat. Sympathetic and vagal activities were measured by the spectral analysis of the heart rate variability (P1 represents sympathetic activity; P2 is vagal activity; P1/P2 reflects sympathovagal balance).Results:  1) Dual pulses GES with one short pulse and various amplitudes significantly elevated gastric volume: from 108.44 ± 4.49 ml at baseline to 139.14 ± 11.73 ml at 2 mA (p < 0.05); from 108.97 ± 6.09 ml at baseline to 155.4 ± 17.49 ml at 4 mA (p < 0.05); from 115.39 ± 13.21 ml at baseline to 223.66 ± 34.89 ml at 6 mA (p < 0.05); whereas vagal and sympathetic activity was not altered. 2) Dual pulse GES with 5‐short pulses significantly inhibited sympathetic activity and excited vagal activity. P1 reduced from 0.42 ± 0.02 to 0.32 ± 0.02 (p < 0.05); P1/P2 from 0.72 ± 0.05 to 0.48 ± 0.04, whereas P2 markedly increased from 0.58 ± 0.02 to 0.68 ± 0.02 (p < 0.05). 3) During dual pulse GES with 5‐short pulses, half‐maximal volume on the pressure–volume curve (P1/2) significantly reduced from 11.8 ± 1.1 mmHg to 8.6 ± 0.6 mmHg, (p < 0.05).Conclusions:  Dual pulses GES reduces gastric tone and increases gastric compliance. The variation in the number of short pulse affects the vagal and sympathetic activities. Whereas, the increase in stimulation strength enhances its effects on gastric tone.
15 The effect of Lower Esophageal Sphincter (LES) electrical stimulation on LES pressure
Authors: SANMIGUEL CP , HAGIIKE M , MINTCHEV MP , DELA CRUZ R , PHILLIPS E , CUNNEEN SA , CONKLIN JL , SOFFER EE 
Published: May 2006

Background:  Electrical stimulation (ES) of the stomach has been shown to modulate LESP. Electrical stimulation, using neural high frequency stimulation (NGES) can induce contractions of the smooth muscle of the gut. The purpose of this study was to determine if electrical stimulation of the LES can affect LESP.Methods:  Four female hound dogs, weight: 20–25 kg, underwent an esophagostomy that allowed the introduction of a sleeve manometry catheter into the esophagus. They were also implanted with a pair of electrodes along the longitudinal axis of the LES. After 3 weeks of recovery, they underwent esophageal manometry recording during control and ES, performed randomly on separate days, using 4 different stimulations: 1‐Low frequency: freq: 6 cycles/min, pulse: 350 milisec, amp: 5 mAmp; 2 High‐frequency: freq: 50 Hz, pulse: 1 milisec, amp: 5 mAmp; 3‐ NGES: freq: 50 Hz, pulse:20 milisec, amp:10 volts; 4‐ High‐frequency, circular: freq: 20 Hz, pulse:1 milisec, amp:5 mAmp. All recordings were performed 1 hour after consumption of 3 ounces of canned dog food, to prevent fluctuations in LESP and under mild sedation (acepromazine 0.5 mg kg­1). Tests consisted, during ES days, of 3 periods of 20 minutes each: control , stimulation and post stimulation. The effect of NGES was also tested under anesthesia and following administration of L‐NAME 50 mg kg­1 IV. and also atropine 0.05 mg kg­1 IV. Analysis: area under the curve (AUC) and pressure were compared among the 3 periods. Data shown as mean ± SD, ANOVA and t‐test, p < 0.05.Results:  Sustained increase in LESP was observed during low frequency stimulation, 32.1 ± 12.8 vs. 42.4 ± 18.0 vs. 50.1 ± 23.6, control vs. stimulation vs. post stimulation respectively, p = 0.013. AUC also significantly increased during and after stimulation, 39,320.3 ± 15,722 vs. 51,294 ± 21,826 vs. 59,823.6 ± 28,198.4 mmHgxsec, control vs. stimulation vs. post stimulation respectively, p = 0.01. There was no significant change with other types of ES. NGES induced an initial rise in LESP followed within few seconds by relaxation with slow resumption of pressure over a 1 minute period. L‐NAME increased LESP and augmented the initial rise in LESP following NGES but markedly diminished or abolished the relaxation phase. Atropine lowered LESP and abolished the initial rise in LESP induced by NGES.Conclusions:  Low frequency ES of the LES increases LESP in conscious dogs. NGES has dual effect on LESP: an initial stimulation, cholinergically mediated, followed by relaxation mediated by nitric oxide.