bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of cAMP on the T‐cell response to type II collagen
Authors: Ozegbe Patricia , Foey Andrew D. , Ahmed Salman , Williams Richard O.
Published: December 2003

There is considerable interest in the possible use of cAMP‐elevating agents in the treatment of autoimmune diseases such as rheumatoid arthritis. The objective of this study was to evaluate the impact of different cAMP‐elevating agents on the T‐cell response to type II collagen within the context of collagen‐induced arthritis, a murine model of rheumatoid arthritis. Spleen cells or lymph node cells from type‐II‐collagen‐immunized DBA/1 mice were cultured in the presence of type II collagen plus one of five different cAMP‐elevating agents: rolipram, forskolin, prostaglandin E2, 8‐bromo‐cAMP, or cholera toxin. Levels of interferon‐γ (IFN‐γ), interleukin‐4 (IL‐4) and IL‐5 were measured in culture supernatants by enzyme‐linked immunosorbent assay. All of the cAMP‐elevating agents tested were found to profoundly suppress IFN‐γ production in a dose‐dependent manner. IL‐4 and IL‐5 production was slightly up‐regulated at low concentrations of the cAMP‐elevating agents and was modestly suppressed at the highest concentrations of cAMP‐elevating agents. Experiments were then carried out to determine whether T cells were directly affected by cAMP‐elevating agents or whether the immunomodulatory effects were mediated via antigen‐presenting cells. Pulsing T cells alone for a brief period with cholera toxin produced an almost identical effect to pulsing antigen‐presenting cells alone, i.e. down‐regulation of proliferation, down‐regulation of IFN‐γ production with little effect on IL‐5 production. It was concluded that cAMP‐elevating agents suppressed T helper type 1 responses to type II collagen to a greater extent than T helper type 2 responses. The cAMP‐elevating agents could directly influence the activity of T cells but, in addition, influenced the ability of antigen‐presenting cells to support T helper type 1 responses.
Highly up‐regulated CXCR3 expression on eosinophils in mice infected with Schistosoma japonicum
Authors: Li He , Chunsong Hu , Guobin Cai , Qiuping Zhang , Qun Li , Xiaolian Zhang , Baojun Huang , Linjie Zhang , Junyan Liu , Mingshen Jiang , Jinquan Tan
Published: December 2003

CXCR3, predominately expressed on memory/activated T cells, is a receptor for both interferon‐γ inducible protein‐10/CXC ligand 10 (CXCL10) and monokine induced by interferon‐γ/CXCL9. We reported here that CXCR3 was highly up‐regulated on infiltrating eosinophils in Schistosoma japonicum egg‐induced granuloma in the mouse liver. It was also highly and functionally up‐regulated on peritoneal exudate eosinophils in mice infected with S. japonicum. The phenomena were demonstrated at protein and mRNA levels using immunohisto‐ and immunocytochemistry evaluation of biopsy, flow cytometry and real‐time quantitative reverse transcriptase–polymerase chain reaction technique, and verified by Northern blotting and chemotaxis assay in vitro. We also found that CCR3 expression on the infiltrating and peritoneal exudate cells was significantly decreased, CXCR4 expression was unchanged during the 42‐day period of infection. We screened mRNA expression levels of the all known chemokine receptors in purified peritoneal exudate eosinophils and liver granuloma dominated by eosinophils. CXCR3 was highly and functionally up‐regulated on peritoneal exudate eosinophils in mice infected with S. japonicum, meanwhile CCR3 was significantly and functionally down‐regulated in these cells. The findings could lead to a better understanding of the chemokine receptor expression pattern of eosinophils at inflamed tissue sites caused by parasites. These could be also crucial for establishing a therapeutic strategy for eosinophilic inflammation via intervention in chemokine actions.
Nuclear factor‐κB contributes to interleukin‐4‐ and interferon‐dependent polymeric immunoglobulin receptor expression in human intestinal epithelial cells
Authors: Ackermann Laynez W. , Denning Gerene M.
Published: December 2003

Polymeric immunoglobulins (pIgs) that are present at mucosal surfaces play key roles in both the innate and adaptive immune responses. These pIgs are delivered to the mucosal surface via transcytosis across the epithelium, a process mediated by the polymeric immunoglobulin receptor (pIgR). Previous studies demonstrate that expression of the pIgR is regulated by multiple immunomodulatory factors including interleukin‐4 (IL‐4) and interferon‐γ (IFN‐γ). In studies using human intestinal epithelial cells (HT29), multiple inhibitors of the transcription factor nuclear factor‐κB (NF‐κB), including a dominant negative IκBα‐serine mutant, inhibited both IL‐4‐ and IFN‐dependent increases in pIgR expression. Under identical conditions, NF‐κB inhibitors had no effect on cytokine‐dependent increases in expression of the transcription factor interferon regulatory factor‐1. Over‐expression of the IκBα‐serine mutant also inhibited reporter gene expression in response to IL‐4, TNF‐α, IL‐1β, and in some cases IFN‐γ using constructs with sequences from the pIgR promoter. Reduced levels of pIgR were observed even when inhibitors were added ≥24 hr after cytokines suggesting that prolonged activation of NF‐κB is required. Finally, reporter gene studies with NF‐κB enhancer elements indicated that IFN‐γ alone and IL‐4 in combination with other cytokines activated NF‐κB in HT29 cells. Together, these studies provide additional insight into the signalling pathways that contribute to expression of the pIgR, a critical player in mucosal immunity.
The classical and alternative pathways of complement activation play distinct roles in spontaneous C3 fragment deposition and membrane attack complex (MAC) formation on human B lymphocytes
Authors: Leslie Robert Graham Quinton , Nielsen Claus Henrik
Published: December 2003

The contributions of the classical (CP) and alternative (AP) pathways of complement activation to the spontaneous deposition of C3 fragments and the formation of membrane attack complexes (MAC) on human B lymphocytes, were assessed by incubating peripheral blood mononuclear cells with autologous serum in the absence and presence of selective inhibitors of the AP and CP, respectively. While the total amount of C3 fragments deposited was relatively unaffected by blocking either pathway individually, deposition was virtually abrogated by their combined blockade. A marked difference was observed, however, in the nature of the fragments deposited as a result of CP and AP activation: C3b fragments deposited via the CP were extensively (∼ 90%) converted to the terminal degradation product, C3dg, whereas about 50% of those deposited by the AP persisted as C3b/iC3b fragments. The extent of MAC formation was also found to be highly pathway dependent, with the AP being about 15‐fold more efficient at initiating this process than the CP. A model accounting for the effectiveness of the AP in both preserving C3 fragment integrity and initiating MAC is presented.
Differential production of cytokines, reactive oxygen and nitrogen by bovine macrophages and dendritic cells stimulated with Toll‐like receptor agonists
Authors: Werling Dirk , Hope Jayne C. , Howard Chris J. , Jungi Thomas W.
Published: December 2003

Toll‐like receptors (TLR) have been described as partially sharing signalling pathways but showing unique ligand specificity and tissue distribution. Here, the response of bovine macrophages (Mφ) and dendritic cells (DC), both derived from monocytes, was compared by exposing them to the TLR‐specific ligands lipopolysaccharide, poly(I:C)‐double‐stranded RNA, and CpG‐DNA, as well as inactivated Gram‐negative and Gram‐positive bacteria, shown to bind to TLR. The production of NO, superoxide anion, interleukin‐10 (IL‐10), IL‐12 and tumour necrosis factor (TNF) was determined. Compared to monocytes, Mφ expressed more TLR2 and similar levels of TLR4 mRNA transcripts, as analysed by quantitative polymerase chain reaction, whereas DC expressed reduced amounts. Although both DC and Mφ recognized the TLR ligands, dramatic differences were seen in their reaction pattern to them. Both cell types responded with the production of TNF, but DC produced more IL‐12, whereas Mφ produced more IL‐10, regardless of the TLR agonist used. Co‐stimulation with interferon‐γ influenced the amount of cytokine production, but did not alter the cell type‐specific response pattern. Compared to Mφ, DC produced > 10 times less NO upon triggering with TLR ligands. In addition, DC produced superoxide anion to opsonized and non‐opsonized zymosan, but not to phorbol 12‐myristate 13‐acetate, a response pattern confirmed for human Mφ and DC, respectively. Different protein kinase C isoforms and extracellular signal‐regulated kinase patterns were detected in cell lysates of resting and stimulated Mφ and DC. Collectively, our results point to profound differences in pathogen‐derived signal–response coupling occurring commensurate with distinct functions carried out by Mφ or DC.
Surfactant protein A, an innate immune factor, is expressed in the vaginal mucosa and is present in vaginal lavage fluid
Authors: MacNeill Colin , Umstead Todd M. , Phelps David S. , Lin Zhenwu , Floros Joanna , Shearer Debra A. , Weisz Judith
Published: December 2003

Surfactant protein A (SP‐A), first identified as a component of the lung surfactant system, is now recognized to be an important contributor to host defence mechanisms. SP‐A can facilitate phagocytosis by opsonizing bacteria, fungi and viruses, stimulate the oxidative burst by phagocytes and modulate pro‐inflammatory cytokine production by phagocytic cells. SP‐A can also provide a link between innate and adaptive immune responses by promoting differentiation and chemotaxis of dendritic cells. Because of the obvious relevance of these mechanisms to the host defence and ‘gate keeping’ functions of the lower genital tract, we examined human vaginal mucosa for SP‐A protein and transcripts and analysed vaginal lavage fluid for SP‐A. By immunocytochemistry, SP‐A was identified in two layers of the vaginal epithelium: the deep intermediate layer (the site of newly differentiated epithelial cells); and the superficial layer (comprising dead epithelial cells), where SP‐A is probably extracellular and associated with a glycocalyx. Transcripts of SP‐A were identified by Northern blot analysis in RNA isolated from vaginal wall and shown, by sequencing of reverse transcription–polymerase chain reaction products, to be derived from each of the two closely related SP‐A genes, SP‐A1 and SP‐A2. SP‐A was identified in vaginal lavage fluid by two‐dimensional gel electrophoresis, and confirmed by mass spectrometry. This study provides evidence, for the first time, that SP‐A is produced in a squamous epithelium, namely the vaginal mucosa, and has a localization that would allow it to contribute to both the innate and adaptive immune response. The findings support the hypothesis that in the vagina, as in lung, SP‐A is an essential component of the host‐defence system. A corollary hypothesis is that qualitative and quantitative alterations of normal SP‐A may play a role in the pathogenesis of lower genital tract inflammatory conditions.
In vivo, RFX5 binds differently to the human leucocyte antigen‐E, ‐F, and ‐G gene promoters and participates in HLA class I protein expression in a cell type‐dependent manner
Authors: Rousseau Philippe , Masternak Krzysztof , Krawczyk Michal , Reith Walter , Dausset Jean , Carosella Edgardo D. , Moreau Philippe
Published: December 2003

We analysed the regulation of human leucocyte antigen (HLA)‐E, ‐F and ‐G genes, focusing on the SXY module, a promoter region that controls major histocompatibility complex (MHC) class II expression and participates in the expression of classical HLA class I molecules. It comprises the X1, X2 and Y boxes, bound by RFX, X2‐BP/ATF/CREB and NFY factors, respectively. The complex recruits the master control factor CIITA. The SXY module is conserved in HLA‐E and HLA‐F gene promoters, whereas in the HLA‐G promoter, the only conserved boxes are S and X1. Chromatin immunoprecipitation assays, performed on HLA‐G positive and negative cell lines, demonstrated the in situ binding of RFX5 and CIITA to HLA‐E and HLA‐F, but not to HLA‐G, promoters. In B cells from bare lymphocyte syndrome patients lacking RFX5 or CIITA, we observed lower steady‐state levels of HLA‐E and HLA‐F transcripts but did not find any significant decrease in the cell‐surface expression of HLA‐E/classical HLA class I. In RFX5‐deficient fibroblasts, the cell‐surface expression of HLA molecules was decreased. RFX5 and CIITA are thus not involved in HLA‐G expression and their importance for the surface expression of HLA‐E/classical HLA class I molecules may vary depending on the cell type.
Efficient induction of T helper type 1‐mediated immune responses in antigen‐primed mice by anti‐CD3 single‐chain Fv/interleukin‐18 fusion DNA
Authors: Kim E. J. , Cho D. , Kim T. S.
Published: December 2003

Two types of T helper (Th) cells – Th1 and Th2 – play different roles in protection and immunopathology. The Th1 cell‐mediated immune response plays an important role in inducing the host defence against intracellular bacteria and also in cancer immunotherapy. To effectively induce Th1 immune responses, we constructed a mammalian expression plasmid (pAnti‐CD3sFv/IL‐18) carrying a fusion gene in which anti‐CD3 single‐chain Fv (sFv) cDNA, the smallest unit of antibody recognizing the CD3 epsilon moiety of the T‐cell receptor, was covalently linked to mature interleukin (IL)‐18 cDNA. Intramuscular injection of ovalbumin (OVA)‐sensitized BALB/c mice with pAnti‐CD3sFv/IL‐18 DNA efficiently increased the production of both OVA‐specific interferon‐γ and anti‐OVA immunoglobulin G2a, compared to injection with pAnti‐CD3sFv DNA. In addition, pAnti‐CD3sFv/IL‐18 was more efficient than a mixture of pAnti‐CD3sFv + pIL‐18 in inducing OVA‐specific, Th1 immune responses and also in inhibiting OVA‐specific, IL‐4 production. These studies indicate that vaccination with pAnti‐CD3sFv/IL‐18 fusion DNA efficiently induces the Th1 immune response in antigen‐sensitized mice.
Intracellular expression of interleukin‐4 and interferon‐γ by a Mycobacterium tuberculosis antigen‐stimulated CD4+ CD57+ T‐cell subpopulation with memory phenotype in tuberculosis patients
Authors: Jiménez‐Martínez Maria C. , Linares Marisela , Báez Renata , Montaño Luis F. , Martínez‐Cairo Salvador , Gorocica Patricia , Chávez Raúl , Zenteno Edgar , Lascurain Ricardo
Published: December 2003

In some chronic pathological conditions, antigen persistence activates and expands the CD4+ CD57+ T‐cell subset. The host immune response against tuberculosis infection is maintained through the continuous presence of antigen‐stimulated effector/memory helper T cells. To determine whether CD4+ CD57+ T cells were also expanded in human tuberculosis, we analysed (by flow cytometry) the phenotype of peripheral blood CD4+ T cells from 30 tuberculosis patients and 30 healthy controls. We observed a significant increase in the CD4+ CD57+ T‐cell subset in tuberculosis patients in comparison to healthy controls (P < 0·001). Most CD4+ CD57+ T cells exhibited a CD28− CD45RO+ CD62L− phenotype, which is associated with memory cells. In vitro, a higher number of antigen‐stimulated CD4+ CD57+ T cells produced intracellular interferon‐γ and interleukin‐4 compared with antigen‐stimulated CD4+ CD57− T cells (P < 0·001). These findings suggest that the majority of CD4+ CD57+ T cells correspond to a phenotype of activated memory T cells.
Nerve fibres are required to evoke a contact sensitivity response in mice
Authors: Beresford Lorna , Orange Oliver , Bell Eric B. , Miyan Jaleel A.
Published: December 2003

Previous work has indicated that the dermis and epidermis of skin contains abundant nerve fibres closely associated with Langerhans' cells. We have investigated whether these nerve endings are necessary for inducing and evoking a contact sensitivity (CS) response. Topical application of a general or a peptide (calcitonin gene‐related peptide and substance P)‐specific neurotoxin was employed to destroy the nerve fibres at skin sites subsequently used to induce or evoke the CS response. Elimination of nerve fibres abolished both induction and effector stages of the specific CS response. Denervation did not destroy the local Langerhans' cells, which were observed in increased numbers, or prevent them from migrating to lymph nodes. The local CS response was also abolished by systemic deletion of capsaicin‐sensitive nerve fibres, suggesting that the loss of response was not non‐specific but associated with the loss of specific nerve fibres. The results indicate that peptidergic nerve fibres are required to elicit a CS response and may be vital to the normal function of the immune system.
Co‐administration of CD40 agonistic antibody and antigen fails to overcome the induction of oral tolerance
Authors: Chung Yeonseok , Kim Dong‐Hyeon , Lee Seung‐Ho , Kang Chang‐Yuil
Published: December 2003

T‐cell stimulation in the absence of a second, costimulatory signal can lead to anergy or deletion. There is growing evidence that peripheral tolerance to an exogenous antigen might be caused by the lack of costimulatory molecules on antigen‐presenting cells (APCs). In the present study, we examined whether tolerance against orally administered antigen could be reversed by maturation of APCs via CD40 signalling. Monoclonal antibody (mAb) to CD40 efficiently induced costimulatory molecules on APCs. Treatment with anti‐CD40 mAb potentiated the division of ovalbumin‐specific T cells in response to oral ovalbumin in secondary lymphoid organs. However, such treatment did not prolong the presentation of oral ovalbumin on APCs. Surprisingly, treatment of anti‐CD40 mAb at the time of oral administration of ovalbumin did not reverse the induction of tolerance to ovalbumin in either the high‐ or low‐dose regimens. Furthermore, the induction of oral tolerance in our model is not the result of negative signalling by cytotoxic T‐lymphocyte antigen‐4. These results indicate that tolerance for oral antigen could be established regardless of APC maturation by a CD40‐specific mAb, suggesting that there could be a unique mechanism to regulate immunity versus tolerance to encountered antigen in the gut‐associated lymphoid tissue.
An individual behaviour‐based model can predict shorebird mortality using routinely collected shellfishery data
Authors: Stillman Richard A. , West Andrew D. , Goss‐Custard John D. , Caldow Richard W. G. , Mcgrorty Selwyn , Durell Sarah E. A.Le V. Dit , Yates Michael G. , Atkinson Philip W. , Clark Nigel A. , Bell Michael C. , Dare Peter J. , Mander Matt
Published: December 2003

The debate over the interaction between shellfishing and shorebirds is long‐running. Behaviour‐based models predict how animal populations are influenced by environmental change from the behavioural responses of individual animals to this change. These models are a potential tool for addressing shellfishery problems, but to be of value they must produce reliable predictions using data that are readily available or can be collected relatively quickly.

We parameterized a behaviour‐based model for the oystercatcher population of the Wash, UK, for 1990–99 using data from shellfishery (mussels and cockles), shorebird and climate monitoring schemes. During the 1990s the overwinter mortality rates of Wash oystercatchers varied widely. The model correctly identified the years in which the observed overwinter mortality was either low (1–2%) or high (10–26%) from annual variation in the food supply, oystercatcher population size and temperature.

Many oystercatchers were observed and predicted to die when only a fraction of the available food was consumed. Within the model at least, this was because interference competition excluded the least dominant birds from part of the food supply and the least efficient foragers died before the food supply was fully depleted. A simplified model, which excluded interference and individual variation, incorrectly predicted that all birds survived in all years. Models that exclude these two components of behaviour will tend to underestimate the effect of mussel and cockle food shortage on oystercatchers. Shellfishery management based on such predictions may cause high oystercatcher mortality rates even though enough food would appear to be reserved for the birds.

Synthesis and applications. This study shows how a behaviour‐based model can be parameterized and predict annual variation in oystercatcher mortality using data routinely collected from the Wash. The principle on which the model is based, that animals behave in order to maximize their chances of survival and reproduction, applies to any system, and the shellfishery, bird and climate data used to parameterize the model are widely available. The model can be used to advise how to manage shellfisheries, by predicting the proportion of the stock that needs to remain unfished in order to maintain low oystercatcher mortality rates.
Responses of periphyton and insects to experimental manipulation of riparian buffer width along forest streams
Authors: Kiffney Peter M. , Richardson John S. , Bull Jennifer P.
Published: December 2003

Riparian trees regulate aquatic ecosystem processes, such as inputs of light, organic matter and nutrients, that can be altered dramatically when these trees are harvested. Riparian buffers (uncut strips of vegetation) are widely used to mitigate the impact of clear‐cut logging on aquatic ecosystems but there have been few experimental assessments of their effectiveness.

Forests along 13 headwater stream reaches in south‐western British Columbia, Canada, were clear‐cut in 1998, creating three riparian buffer treatments (30‐m buffer, 10‐m buffer and clear‐cut to the stream edge), or left as uncut controls, each treatment having three or four replicates.

We predicted that periphyton biomass and insect consumers would increase as buffer width decreased, because of increased solar flux. We used two complementary studies to test this prediction.

In one study, we compared benthic communities before and after logging in all 13 streams; a second study focused on periphyton and insect colonization dynamics over 6‐week periods in each of four seasons in four streams, one in each treatment.

Photosynthetically active radiation, and mean and maximum water temperature, increased as buffer width narrowed.

Periphyton biomass, periphyton inorganic mass and Chironomidae abundance also increased as buffer width narrowed, with the largest differences occurring in the clear‐cut and 10‐m buffer treatments.

Photosynthetically active radiation, water temperature, periphyton biomass and periphyton inorganic mass were significantly greater in the 30‐m buffer treatment than in controls during some seasons.

Synthesis and applications.We have shown that a gradient of riparian buffer widths created a gradient in light and temperature that led to non‐linear increases in periphyton biomass and insect abundance. For example, Chironomidae abundance was generally greater in the 10‐m and 30‐m buffer treatments than in controls, whereas this was not always the case in the clear‐cut treatment. This pattern may be due to the high sediment content of the periphyton mat in the clear‐cut treatment, which potentially limited the response of some insects to increased food resources. Overall, our results indicate that uncut riparian buffers of 30‐m or more on both sides of the stream were needed to limit biotic and abiotic changes associated with clear‐cut logging in headwater, forested watersheds.
Bat activity and species richness on organic and conventional farms: impact of agricultural intensification
Authors: Wickramasinghe Liat P. , Harris Stephen , Jones Gareth , Vaughan Nancy
Published: December 2003

Agricultural intensification is perceived to be a major cause of the decline in many European bat populations. Because organic farming prohibits the use of agrochemicals, we compared organic vs. conventional farm types to test the hypothesis that agricultural intensification based on high levels of agrochemical use has been a factor in bat population declines. Bat activity and species richness were compared on matched pairs of organic and conventional farms.

Bat activity was quantified using acoustic surveys within specific habitats on farms in southern England and Wales. Eighty‐nine per cent of bat passes were identified to species level using artificial neural networks (ANN). A further 9% were identified to genus.

Total bat activity was significantly higher on organic farms than on conventional farms. Significantly more bat passes were recorded over water on organic farms than on conventional farms. Foraging activity (quantified in two ways: total feedings buzzes and feeding buzzes per pass) was significantly higher on organic farms than on conventional farms.

The dominant species on both farm types were Pipistrellus pipistrellus and Pipistrellus pygmaeus. Significantly more passes of Myotis species were recorded on organic farms than on conventional farms. This difference was also significant when water habitats were considered alone.

The activity of both Myotis daubentonii and Myotis brandtii was significantly higher on organic farms than on conventional farms. The activity of Myotis bechsteinii and Myotis brandtii was significantly higher over organic water habitats than over conventional water habitats. Rhinolophus hipposideros and Rhinolophus ferrumequinum were only recorded on organic farms in wooded, arable and pasture habitats.

Synthesis and applications. This study highlights the position of bats as bioindicators and victims of agricultural change. The differences in bat activity between farm types may reflect features such as taller hedgerows and better water quality on organic farms. Higher foraging activity also suggests that habitat quality in terms of prey availability is greater on organic farms. Less intensive farming benefits bats, and as the number of organic enterprises increases it may help to reverse declines in bat populations.
The joint effects of larval density and 14C‐cypermethrin on the life history and population growth rate of the midge Chironomus riparius
Authors: Hooper Helen L. , Sibly Richard M. , Maund Steve J. , Hutchinson Thomas H.
Published: December 2003

Chemical effects on organisms are typically assessed using individual‐level endpoints or sometimes population growth rate (PGR), but such measurements are generally made at low population densities. In contrast most natural populations are subject to density dependence and fluctuate around the environmental carrying capacity as a result of individual competition for resources. As ecotoxicology aims to make reliable population projections of chemical impacts in the field, an understanding of how high‐density or resource‐limited populations respond to environmental chemicals is essential.

Our objective was to determine the joint effects of population density and chemical stress on the life history and PGR of an important ecotoxicological indicator species, Chironomus riparius, under controlled laboratory conditions. Populations were fed the same ration but initiated at different densities and exposed to a solvent control and three concentrations of 14C‐cypermethrin in a sediment–water test system for 67 days at 20 ± 1 °C.

Density had a negative effect on all the measured life‐history traits, and PGR declined with increasing density in the controls. Exposure to 14C‐cypermethrin had a direct negative effect on juvenile survival, presumably within the first 24 h because the chemical rapidly dissipated from the water column. Reductions in the initial larval densities resulted in an increase in the available resources for the survivors. Subsequently, exposed populations emerged sooner and started producing offspring earlier than the controls. 14C‐cypermethrin had no effect on estimated fecundity and adult body weight but interacted with density to reduce the time to first emergence and first reproduction. As a result, PGR increased with cypermethrin concentration when populations were initiated at high densities.

Synthesis and applications. The results showed that the effects of 14C‐cypermethrin were buffered at high density, so that the joint effects of density and chemical stress on PGR were less than additive. Low levels of chemical stressors may increase carrying capacity by reducing juvenile competition for resources. More and perhaps fitter adults may be produced, similar to the effects of predators and culling; however, toxicant exposure may result in survivors that are less tolerant to changing conditions. If less than additive effects are typical in the field, standard regulatory tests carried out at low density may overestimate the effects of environmental chemicals. Further studies over a wide range of chemical stressors and organisms with contrasting life histories are needed to make general recommendations.
Potential indirect effects of shellfish culture on the reproductive success of benthic predators
Authors: Inglis Graeme J. , Gust Nick
Published: December 2003

Environmental assessments of coastal aquaculture are concerned mostly with direct impacts on natural assemblages in the vicinity of shellfish or fin‐fish farms. As the size and density of farmed sea space increases, there is greater potential for indirect effects on food webs beyond the immediate culture area.

We investigated the potential indirect effects of long‐line mussel Perna canaliculus farms on the demography of an important benthic predator, the sea star Coscinasterias muricata. Surveys beneath four active farms, an abandoned farm and three unfarmed areas of seabed in Pelorus Sound, New Zealand, described the direct effects of mussel culture on the distribution and abundance of sea stars and other benthic consumers. These data were used to calibrate a model that simulated the fertilization success of sea star populations in farmed and unfarmed areas of the bays.

Deposits of living mussels and mussel shells covered up to 55% of the seafloor beneath farm sites, but were absent from soft sediments at unfarmed sites. Mean densities of sea stars were up to 39 times larger at active farm sites than in unfarmed areas and were correlated with the abundance of living mussels on the seafloor.

Within individual farms, the distribution of sea stars was highly aggregated at small spatial scales, with most (63%) individuals occurring within 2 m of their nearest neighbour. In unfarmed areas, sea stars were widely dispersed (< 1 80 m−2).

Our simulations indicate that, because of the extremely clumped distributions of sea stars, spawning individuals at farm sites would on average have substantially greater fertilization success (c. 90% of eggs) than those foraging in areas where farms are absent (<< 2% of eggs), and total zygote production could be as much as 1500 times greater than in unfarmed areas.

Synthesis and applications. This study demonstrates the potential for significant bottom‐up effects of aquaculture on surrounding ecological assemblages. If, as has been suggested, sperm limitation is a major constraint on recruitment of asteroids and other invertebrate predators, supplemental provisioning from increased farm development could result in occasional outbreaks of populations, over a broader area than the farmed location. Without appropriate monitoring such events are likely to be dismissed as rare, natural phenomena rather than a consequence of shellfish culture.
Dung and nest surveys: estimating decay rates
Authors: Laing S. E. , Buckland S. T. , Burn R. W. , Lambie D. , Amphlett A.
Published: December 2003

Wildlife managers often require estimates of abundance. Direct methods of estimation are often impractical, especially in closed‐forest environments, so indirect methods such as dung or nest surveys are increasingly popular.

Dung and nest surveys typically have three elements: surveys to estimate abundance of the dung or nests; experiments to estimate the production (defecation or nest construction) rate; and experiments to estimate the decay or disappearance rate. The last of these is usually the most problematic, and was the subject of this study.

The design of experiments to allow robust estimation of mean time to decay was addressed. In most studies to date, dung or nests have been monitored until they disappear. Instead, we advocate that fresh dung or nests are located, with a single follow‐up visit to establish whether the dung or nest is still present or has decayed.

Logistic regression was used to estimate probability of decay as a function of time, and possibly of other covariates. Mean time to decay was estimated from this function.

Synthesis and applications.Effective management of mammal populations usually requires reliable abundance estimates. The difficulty in estimating abundance of mammals in forest environments has increasingly led to the use of indirect survey methods, in which abundance of sign, usually dung (e.g. deer, antelope and elephants) or nests (e.g. apes), is estimated. Given estimated rates of sign production and decay, sign abundance estimates can be converted to estimates of animal abundance. Decay rates typically vary according to season, weather, habitat, diet and many other factors, making reliable estimation of mean time to decay of signs present at the time of the survey problematic. We emphasize the need for retrospective rather than prospective rates, propose a strategy for survey design, and provide analysis methods for estimating retrospective rates.
Abundance and composition of plant species along grazing gradients in Australian rangelands
Authors: Landsberg J. , James C. D. , Morton S. R. , Müller W. J. , Stol J.
Published: December 2003

The widespread provision of livestock drinking water in previously dry Australian rangelands has supported concomitant increases in cumulative grazing pressure. While the associated impacts on plants of pastoral importance have been well documented, far less is known about the rest of the flora.

To address this deficiency, we measured the frequency of occurrence of all plant species at sites along water‐centred grazing gradients in commercial paddocks located in the rangelands of central and southern Australia. Four gradients were in chenopod shrubland vegetation, and four in acacia woodlands. Each gradient extended to a reference site remote from all waters, where grazing by stock was minimal. Five further sites were sampled along each gradient, at locations progressively closer to the gradient's watering point.

Ground‐layer species far outnumbered those in upper layers (466 and 134, respectively). Most were geographically localized (72% found at one gradient only) and locally uncommon (46% per gradient occurred with a frequency < 5% per site).

Species showing trends of decreasing frequency with proximity to water significantly outnumbered those showing increasing trends. Significantly more species that were recorded only once occurred at the sites furthest from water, where long‐term grazing pressure was least. Some gradients also showed an overall decline in species richness with increasing proximity to water.

Most species were native, and among these there were no clearly identifiable ‘global winners’ (i.e. no widespread species advantaged by grazing and associated disturbances). In contrast, the majority of the few exotic species, including two of the three most widespread species found, showed increasing abundance with proximity to watering points.

Synthesis and applications. The results from this study indicate consistent and substantial changes in plant composition that are probably related to the accumulated long‐term impacts of water‐centred grazing. The consequences are potentially severe, because artificial watering points are now extremely widespread in the Australian rangelands. Identification and protection of representative, water‐remote refugia for the most grazing‐sensitive species should therefore be a high priority for regional conservation.
The effects of the intensification of agriculture on northern temperate dung beetle communities
Authors: Hutton Stephen A. , Giller Paul S.
Published: December 2003

There is growing concern that the intensification of agriculture within southern Ireland is having detrimental effects on Irish fauna through habitat loss, reduction in biodiversity and pollution‐related events. To assess the impact of farm management on one group of important insects, the dung beetles, their abundance, biomass, diversity and species richness were examined using dung‐baited pitfall traps in intensive, organic and rough grazing farms.

We collected 39 631 dung beetles belonging to 24 different species. Eight species (Aphodius prodromus,A. sphacelatus,A. ater,A. rufipes,A. depressus,Sphaeridium lunatum,S. scarabaeoidesandMargarinotus carbonarius) accounted for 94% of the captures, but their relative dominance varied with farm type. 54% of total individuals captured were from organic sites, 30% from intensive sites and 16% from rough grazing sites.

Organic farms had significantly greater beetle biomass, diversity and species richness compared to intensive and rough grazing farms.Aphodiusabundance on organic farms was significantly greater than on intensive and rough grazing farms in spring and autumn.Aphodiusbiomass on organic farms was significantly greater than on rough grazing farms in spring, late summer and autumn, and greater in autumn compared with intensive farms.

A colonization experiment demonstrated that the variation in dung beetle abundance among different dung types depended on the farm type. This was not true for beetle biomass colonizing dung pads, where variation among different dung types and different farm types were independent. Multiple comparisons showed that under rough grazing and intensive management there was significantly greater beetle abundance and biomass found in dung from organic and intensive farms than from rough grazing farms. Dung from organic farms held a significantly greater beetle biomass than the intensive and rough grazing dung.

Synthesis and applications. Intensive agricultural management including the use of chemical fertilisers, veterinary drugs (e.g. ivermectin) and removal of herbaceous field boundaries could be detrimental to dung beetle biodiversity and dung decomposition. Organic farming has beneficial effects on dung beetle communities. Patchy ecosystems characterized by a diversity of ungulate species increase dung beetle diversity and hence improve dung decomposition.
Predicting the response of farmland bird populations to changing food supplies
Authors: Stephens Philip A. , Freckleton Robert P. , Watkinson Andrew R. , Sutherland William J.
Published: December 2003

Agricultural developments over recent decades have had significant negative effects on wildlife. Modern European agriculture faces many further developments in technology, finances and climate. A framework for predicting the consequences of these developments and for informing management that mitigates previous depredation of wildlife is essential.

Field trials, monitoring and experimental approaches are all invaluable tools for predicting the consequences of proposed agricultural practices. However, such trials are time‐consuming and expensive, with limited spatial and temporal scope. Increasingly, it is recognized that predictive modelling using computer simulations is essential for assessing the likely impacts of novel management practices.

Many agricultural developments are likely to have impacts on the availability of food for farmland wildlife. In this paper, we review modelling techniques that are available for predicting the consequences of changing food supplies for farmland birds, a group already shown to be sensitive to agricultural management.

We focus on two broad types of simulation modelling: phenomenological approaches (using aggregative responses or full population models), and behavioural depletion models (including daily ration and functional response approaches). We assess the strengths and weaknesses of each, particularly with regard to available data.

We conclude that given the constraints on current information, daily ration models probably represent the most useful form of simulation modelling for farmland birds. Few phenomenological population models link demography explicitly to food supply and collecting data on these links should be a priority of autecological studies. More empirical data on aggregative and functional responses is needed to identify the generality of these functions, and to confront uncertainties in their use.

Synthesis and applications.Modelling techniques available for predicting the consequences of changing food supply for farmland birds have largely outstripped the availability of data required to parameterize them. We recommend the best available techniques given current constraints on data. Predictive models of biodiversity response should be more widely used when considering proposals for agricultural developments or agri‐environment schemes. Models will provide a basis for selecting between competing proposals, whilst their widespread usage will both permit more frequent model validation and aid in model development.
Soil seed banks and the potential restoration of forested wetlands after farming
Authors: Middleton Beth A.
Published: December 2003

Changes in farming practice provide an opportunity to restore once extensive forested wetlands on agricultural land. In some parts of the world, however, it has proved difficult to restore the full complement of plant species through natural regeneration. Similarly, the restoration of forested wetlands by replanting has often resulted in ecosystems of low diversity. Better methods of restoring these important ecosystems are now required and baldcypress swamps provide an opportunity to investigate alternative approaches to the restoration of forested wetlands. This study examined the composition of seed banks of farmed fields to determine their value in restoring swamps in the south‐eastern United States.

A seed bank assay of soils from baldcypress swamps was conducted to determine the extent to which seeds are maintained during farming for various lengths of time. Soils from swamps that were farmed for 0–50 years were collected near the northern boundary of the Mississippi Alluvial Valley along the Cache River, Illinois. Soils were placed in a glasshouse setting in flooded and freely drained conditions, and the numbers and species of seeds germinating were recorded.

Woody species including trees, shrubs, and vines were poorly represented in seed banks of both farmed and intact sites (51 and 9 sites, respectively). Missing dominants in the seed banks included tree species with short‐lived seeds such asTaxodium distichumandNyssa aquatica.Cephalanthus occidentalisconstituted the most abundantly dispersed seed of all woody species.

Herbaceous species were well represented in the seed banks of both farmed and intact swamps (species richness of 207 vs. 173 species, respectively) suggesting that herbaceous species may live longer than woody species in seed banks. Few of the herbaceous species decreased in seed density in seed banks with time under cultivation, although seed density was lower at sites that had not been farmed. Species that relied on vegetative organs for dispersal were absent in the seed banks of farmed sites includingHeteranthera dubia,Hottonia inflata,Lemna minor,Lemna trisulcaandWolffia columbiana. These species may require active reintroduction during restoration.

Synthesis and applications.Both restoration ecologists and managers of nature conservation areas need to be cognisant of seed bank and dispersal characteristics of species to effectively restore and manage forested wetlands. In the case of baldcypress swamps, critical components of the vegetation are not maintained in seed banks, which may make these floodplain wetlands difficult to restore via natural recolonization. Ultimately, the successful restoration of abandoned farm fields to forested wetlands may depend on the re‐engineering of flood pulsing across landscapes to reconnect dispersal pathways.
Meeting the ecological challenges of agricultural change: editors’ introduction
Authors: Ormerod S. J. , Marshall E. J. P. , Kerby Gillian , Rushton S. P.
Published: December 2003

The global need for agricultural production has never been greater. Nor has it ever been more complex due to the needs to balance global food security, optimum production, technological innovation, the preservation of environmental functions and the protection of biodiversity. The role of ecologists in finding this balance is pivotal.

In support of this role, ecologists now have very substantial experience of agricultural systems. We can understand, recognize and sometimes predict, at least qualitatively, the effects of pesticide applications, fertilizer use, drainage, crop choices and habitat modifications on farmland organisms, agro‐ecosystems or other ecosystems influenced by agricultural land.

In instances of greater uncertainty, for example under changing climates, where environmental stresses on ecosystems are interactive, and where ecosystem management or restoration must adapt to new technologies, the investigative skills and experience of ecologists are even more crucial in problem solving.

There are, nevertheless, contrasting examples of good and bad practice in knowledge‐transfer between ecologists and the communities who need our knowledge. The UK farm‐scale evaluations of genetically modified crops, for example, involved ecologists at all stages from design and data collection to advocating policy. By contrast, many European agri‐environment projects appear to have been developed and evaluated with only modest ecological advice. We advocate fuller involvement of ecologists in the development and evaluation of the European Union Common Agricultural Policy.

This special profile of seven agriculturally related papers illustrates effectively the array of approaches used by applied ecologists in addressing agricultural questions: modelling, meta‐analysis, surveys, transect studies, classical experiments, seedbank assays and process studies based on modern ecological methods. With over 20% of recent papers in the Journal of Applied Ecology reflecting agricultural issues, agro‐ecology continues to represent one of the pre‐eminent areas of applied ecology that is unlikely to diminish in importance.
Monetary Policy Announcements and Money Markets: A Transatlantic Perspective
Authors: Ehrmann Michael , Fratzscher Marcel
Published: December 2003

This paper investigates how money markets in the USA, Germany (up to 1998) and the euro area (since 1999) react to monetary policy announcements by the Federal Reserve, Bundesbank and ECB. We find that interest rates respond strongly to domestic monetary policy throughout, whereas the response to foreign monetary policy varies across markets and over time: both the German and the euro area market react to Federal Reserve announcements, whereas US markets do not generally respond to European monetary policy. Whereas announcements by the Bundesbank increased the volatility of German money markets, such effects are rarely found for the ECB, and have basically disappeared for the Federal Reserve. Moreover, the general linkage of money markets has increased considerably over time: interest rate developments and volatility in either the USA or the euro area are generally mirrored in the other market to a much larger extent than prior to EMU. We interpret these results as evidence that euro area and US markets not only have become more interdependent over time, but that the markets' understanding and anticipation of monetary policy decisions have improved over time.