bluuebunny/crossref_metadata_2025_split huggingface dataset:
Targeting dendritic cells with CD44 monoclonal antibodies selectively inhibits the proliferation of naive CD4+ T‐helper cells by induction of FAS‐independent T‐cell apoptosis
Authors: Termeer Christian , Averbeck Marco , Hara Hisamichi , Eibel Herrmann , Herrlich Peter , Sleeman Jonathan , Simon Jan C. 
Published: December 2004

SummaryCD44 is a multifunctional adhesion molecule that has been shown to be a costimulatory factor for T‐cell activation in vitro and in vivo. The aim of the present study was to expand these findings by characterizing the role of CD44 during dendritic cell (DC) antigen presentation to naive, resting T cells. Certain monoclonal antibodies (mAbs) directed against all CD44 isoforms (pan CD44), or against the epitope encoded by the alternatively spliced exon v4 (CD44v4), dose‐dependently inhibited the capacity of murine DC to induce proliferation of naive alloreactive T cells. Preincubation of the T cells or DC with these CD44 mAbs revealed that the effect was dependent upon mAb binding to DC, but not to T cells. DC treated with anti‐pan CD44 and anti‐CD44v4 mAbs induced CD4+ T‐cell apoptosis, as shown by annexin V staining and TdT‐mediated biotin–dUTP nick‐end labelling (TUNEL) assays. However, CD4+ T‐cell apoptosis was not dependent on the Fas/Fas ligand (Fas/FasL) system, as DC from FasL‐deficient (Gld) mice and T cells from Fas‐deficient (Lpr) mice were still susceptible to apoptosis induced by CD44‐treated DC. To investigate whether CD44 treatment of DC affects early T‐cell/DC interactions, time‐lapse video microscopy was performed using peptide‐specific T cells from T‐cell receptor (TCR) transgenic mice. Interestingly, calcium signalling in CD4+ T cells was significantly diminished following interaction with CD44 mAb‐treated DC, but this was not observed in CD8+ T cells. Taken together, we found that perturbation of distinct epitopes of CD44 on DC interfere with early Ca2+ signalling events during the activation of CD4+ T cells, resulting in T‐cell apoptosis.
Identification of a novel human leucocyte antigen‐A*01‐restricted cytotoxic T‐lymphocyte epitope in the respiratory syncytial virus fusion protein
Authors: Rock Michael T. , Crowe James E. 
Published: December 2004

SummaryVirus‐specific cytotoxic T lymphocytes (CTL) play a major role in the clearance of respiratory syncytial virus (RSV) infection. To begin monitoring the immunological response to infection, especially in infants, it is important to identify human leucocyte antigen (HLA)‐restricted CTL epitopes. Herein, we used a novel, comprehensive peptide panel containing all possible 8‐, 9‐ and 10‐mer peptides spanning the RSV fusion protein to screen for novel HLA‐restricted T‐cell epitopes. These peptide sets were synthesized as 10‐mer peptides overlapping by nine amino acids and contained corresponding 8‐ and 9‐mer peptides generated by C‐terminal truncation. Unselected and uncultured peripheral blood mononuclear cells from healthy adult subjects were screened by interferon‐γ (IFN‐γ) Elispot assays against the peptide panel. Seven of 19 subjects displayed positive responses against 10 of the 565 peptides analysed. An HLA‐A*01‐restricted CTL epitope detected in three healthy adult subjects is characterized. This is the first RSV‐specific memory CTL response identified in the fusion protein of RSV.
Cytotoxic T lymphocytes recognize and lyse chondrocytes under inflammatory, but not non‐inflammatory conditions
Authors: Cohen E. Suzanne , Bodmer Helen C. 
Published: December 2004

SummaryThe human major histocompatibility complex (MHC) class I allele HLA‐B27 is strongly associated with seronegative spondyloarthropathies including ankylosing spondylitis and reactive arthritis. Although of unknown aetiology, one hypothesis suggests that a cytotoxic T cell (CTL) response against a self‐antigen at sites of inflammation, such as entheses or joints may be involved. The chondrocyte is one of the major specialized cell types found both in articular cartilage and cartilaginous entheses and therefore is a possible source of such an antigen. CTL recognition of these cells is a potential mechanism for inflammation and cartilage damage, both through direct lysis of chondrocytes and the secretion of pro‐inflammatory cytokines such as tumour necrosis factor and interferon‐γ (IFN‐γ). We test the feasibility of this hypothesis by examining the ability of chondrocytes to present antigen to CTL in vitro. Chondrocytes isolated from the ribcages of mice did not constitutively express detectable levels of MHC class I by fluorescence‐activated cell sorting analysis. In addition, they were resistant to lysis by alloreactive and influenza A virus nucleoprotein (NP)‐specific CTL. However, treatment of chondrocytes with IFN‐γ up‐regulated MHC class I expression and rendered the cells susceptible to lysis by CTL. Similarly, IFN‐γ‐treated chondrocytes infected with influenza A virus were recognized by NP‐specific CTL, though with variable efficiency. Thus, we suggest that under certain circumstances CTL‐mediated lysis of chondrocytes is potentially a potent mechanism for cartilage damage in vivo, but that low levels of MHC class I on healthy chondrocytes protects from immune recognition in health.
Characterization of the mouse analogues of CD59 using novel monoclonal antibodies: tissue distribution and functional comparison
Authors: Harris Claire L. , Hanna S. Melanie , Mizuno Masashi , Holt Dewi S. , Marchbank Kevin J. , Morgan B. Paul 
Published: December 2004

SummaryCD59, the sole membrane regulator of the membrane attack complex of complement, is broadly and abundantly expressed in man and other mammals. In mouse, CD59 is encoded by two homologous genes. The expression patterns and functional roles of the proteins encoded by these genes, mCD59a and mCD59b, have not been well characterized. Here we describe the generation of monoclonal and polyclonal antibodies detecting specifically mCD59a and mCD59b. These reagents have been used to study function and to ascertain the cell and tissue distributions of mCD59a and mCD59b. mCD59a was broadly distributed on endothelia, erythrocytes, platelets, and on numerous other cell types in organs, a distribution pattern resembling that of CD59 in other species. In marked contrast, expression of mCD59b was restricted to germ cell elements in the testis and mature spermatozoa. Both mCD59a and CD59b inhibited human and rodent complement with similar efficiency. These findings demonstrate that the broadly distributed mCD59a is the key regulator of the terminal complement pathway in mice whereas CD59b, expressed only in testis and on sperm, probably plays other roles in vivo.
Enhanced interleukin‐4 production in CD4+ T cells and elevated immunoglobulin E levels in antigen‐primed mice by bisphenol A and nonylphenol, endocrine disruptors: involvement of nuclear factor‐AT and Ca2+
Authors: Lee Mee H. , Chung Su W. , Kang Bok Y. , Park Jin , Lee Choon H. , Hwang Seung Y. , Kim Tae S. 
Published: December 2004

SummaryBisphenol A (BPA) and p‐nonylphenol (NP) are representative endocrine disruptors (EDs) that may have adverse effects on human health. The influence of these compounds on allergic immune responses remains unclear. In this study, we have examined the effects of BPA and NP on production of interleukin‐4 (IL‐4), a pro‐inflammatory cytokine closely associated with allergic immune responses. Both BPA and NP significantly enhanced IL‐4 production in keyhole limpet haemocyanin (KLH)‐primed CD4+ T cells in a concentration‐dependent manner. Treatment with BPA or NP in vivo resulted in significant increase of IL‐4 production in CD4+ T cells and of antigen‐specific immunoglobulin E (IgE) levels in the sera of KLH‐primed mice. Furthermore, BPA and NP enhanced the activation of IL‐4 gene promoter in EL4 T cells transiently transfected with IL‐4 promoter/reporter constructs, and the enhancing effect mapped to a region in the IL‐4 promoter containing binding sites for nuclear factor (NF)‐AT. Activation of T lymphocytes by phorbol 12‐myristate 13‐acetate/ionomycin resulted in markedly enhanced binding activities to the NF‐AT site, which significantly increased upon addition of BPA or NP, as demonstrated by the electrophoretic mobility shift assay, indicating that the transcription factor NF‐AT was involved in the enhancing effect of BPA and NP on IL‐4 production. The enhancement of IL‐4 production by BPA or NP was significantly reduced by nitrendipine, a blocker of Ca2+ influx, and by FK506, a calcineurin inhibitor. FK506 inhibited the NF‐AT–DNA binding activity and IL‐4 gene promoter activity enhanced by BPA or NP. These results represent the first report describing possible enhancement of allergic response by EDs through increasing IL‐4 production in CD4+ T cells and antigen‐specific IgE levels in the sera via the stimulation of Ca2+/calcineurin‐dependent NF‐AT activation.
Divorce, dispersal and incest avoidance in the cooperatively breeding superb fairy‐wrenMalurus cyaneus
Authors: Cockburn Andrew , Osmond Helen L. , Mulder Raoul A. , Green David J. , Double Michael C. 
Published: December 2004

SummaryBetween 1988 and 2001, we studied social relationships in the superb fairy‐wrenMalurus cyaneus(Latham), a cooperative breeder with male helpers in which extra‐group fertilizations are more common than within‐pair fertilizations.Unlike other fairy‐wren species, females never bred on their natal territory. First‐year females dispersed either directly from their natal territory to a breeding vacancy or to a foreign ‘staging‐post’ territory where they spent their first winter as a subordinate. Females dispersing to a foreign territory settled in larger groups. Females on foreign territories inherited the territory if the dominant female died, and were sometimes able to split the territory into two by pairing with a helper male. However, most dispersed again to obtain a vacancy.Females dispersing from a staging post usually gained a neighbouring vacancy, but females gaining a vacancy directly from their natal territory travelled further, perhaps to avoid pairing or mating with related males.Females frequently divorced their partner, although the majority of relationships were terminated by the death of one of the pair. If death did not intervene, one‐third of pairings were terminated by female‐initiated divorce within 1000 days.Three divorce syndromes were recognized. First, females that failed to obtain a preferred territory moved to territories with more helpers. Secondly, females that became paired to their sons when their partner died usually divorced away from them. Thirdly, females that have been in a long relationship divorce once a son has gained the senior helper position.Dispersal to avoid pairing with sons is consistent with incest avoidance. However, there may be two additional benefits. Mothers do not mate with their sons, so dispersal by the mother liberates her sons to compete for within‐group matings. Further, divorcing once their son has become a breeder or a senior helper allows the female to start sons in a queue for dominance on another territory. Females that do not take this option face constraints on their ability to recruit more sons into the local neighbourhood.
Geographic variation in life‐history characteristics of amphibians: a review
Authors: Morrison Clare , Hero Jean‐Marc 
Published: December 2004

Summary

This review examines the intraspecific patterns and differences in life‐history traits of amphibian populations living at different altitudes and latitudes. Specifically we examined differences in development and growth (physiological constraints) and reproductive ecology (plasticity in reproductive traits).
Research published to date suggests that amphibian populations at higher altitudes and latitudes tend to: (a) have shorter activity periods, and hence shorter breeding seasons; (b) have longer larval periods; (c) are larger at all larval stages including metamorphosis; (d) are larger as adults; (e) reach reproductive maturity at older ages; (f) produce fewer clutches per year; (g) produce larger clutches absolutely and smaller clutches relative to body size; and (h) produce larger eggs.
These generalizations must be viewed with caution, due first to the small number of papers supporting them, and secondly to the inconsistent results published to date.
The implications of the intraspecific geographical variation in life history traits for general amphibian biology, amphibian population declines and conservation are discussed.
Factors affecting breeding dispersal of European ducks on Engure Marsh, Latvia
Authors: Blums Peter , Nichols James D. , Lindberg Mark S. , Hines James E. , Mednis Aivars 
Published: December 2004

SummaryWe used up to 35 years of capture–recapture data from nearly 3300 individual female ducks nesting on Engure Marsh, Latvia, and multistate modelling to test predictions about the influence of environmental, habitat and management factors on breeding dispersal probability within the marsh.Analyses based on observed dispersal distances of common pochards and tufted ducks provided no evidence that breeding success in yeartinfluenced dispersal distance betweentandt+ 1.Breeding dispersal distances (yearttot+ 1) of pochards and tufted ducks were associated with a delay in relative nest initiation dates in yeart+ 1. The delay was greater for pochards (c. 4 days) than for tufted ducks (c. 2 days) when females dispersed > 0·8 km.Northern shovelers and tufted ducks moved from a large island to small islands at low water levels and from small islands to the large island at high water levels before the construction of elevated small islands (1960–82). Following this habitat management (1983–94), breeding fidelity was extremely high and not influenced by water level in the marsh for either species.Because pochard nesting habitats in black‐headed gull colonies were saturated during the entire study period, nesting females moved into and out of colonies with similar probabilities. Local survival probabilities and incubation body masses were higher for both yearlings (SY) and adults (ASY) nesting within gull colonies, suggesting that these females were of better quality than females nesting outside of the colonies.Tufted ducks showed higher probabilities of moving from islands to emergent marshes when water levels were higher both before and after habitat management. However, rates of movement for a given water level were higher during the period before management than after.Both pochards and tufted ducks exhibited asymmetric movement with respect to proximity to water, with higher movement probabilities to near‐water nesting locations than away from these locations.Multistate capture–recapture models provided analyses that were useful in investigating sources of variation in breeding dispersal probabilities.
How great tits maintain synchronization of their hatch date with food supply in response to long‐term variability in temperature
Authors: Cresswell Will , Mccleery Robin 
Published: December 2004

Summary

Breeding birds increase their fitness by synchronizing their production of chicks with a peak of food abundance. Synchronization is primarily achieved by varying first egg date, but yearly temperature variations may delay or accelerate the food peak after the first egg has been laid. We tested the extent to which great tits (Parus major L.) can strategically change their synchronization of hatch date with the food peak after the first egg has been laid by changing clutch size, laying interval and the amount of incubation. We also tested whether these possible synchronization change mechanisms resulted in changes in breeding success, because if the food peak is late relative to first egg date, we would predict more of the population to have larger clutches and/or a hatch date synchronous with the food peak date.
Great tits modified synchronization strategically by varying clutch size and the onset of incubation after clutch completion. When first egg date was early but then followed by cold weather so that the food peak was late, clutch sizes were larger, and when first egg date was late and temperatures were low, mean incubation periods were shorter if the food peak was early.
Over the 39‐year period of the study, the period between the first egg date and food peak increased significantly by 1·7 days more than the period between the food peak and hatch date. Great tits have maintained synchronization by significantly increasing their incubation period.
Overall, the proportion of nests that had synchronous hatch dates depended on the yearly temperature pattern: the decline in variance between date of clutch completion and hatch was significantly greater in years where prelaying temperatures were higher (i.e. early first egg dates) and has therefore increased in recent years because of climate change. In warm early seasons (and more often in recent years) more of the great tits that laid relatively late had sufficient time to complete their clutches before having to start incubation in order to hatch in time for the food peak.
The increased proportion of synchronized nests in recent years probably resulted in increased chick output: a greater proportion of recent nests successfully fledged all of the chicks that hatched and the number of young fledged per successful nest also increased in recent years. These changes may have arisen because the proportion of nests with disadvantageous asynchronous hatching and/or smaller clutches has decreased. As the proportion of great tits that start nesting too late to synchronize has declined so selection for early laying has also declined in recent years.
The effects of spawning age distribution on salmon persistence in fluctuating environments
Authors: Hill M. Forrest , Botsford Louis W. , Hastings Alan 
Published: December 2004

SummaryUnderstanding the role endogenous vs. exogenous forces play in determining the dynamics and abundance of natural populations has important implications for their conservation.Changes in environmental conditions often have different effects on closely related species. For instance, recent studies show that a physical shift in ocean conditions in the mid‐1970s in the California current have reduced coho salmon (Oncorhynchus kisutsch) populations, but not chinook salmon (O. tshawytscha).An important question is whether this pattern is due to differences in the ability of coho and chinook salmon to respond to changing ocean conditions or to differences in their life‐history traits.We analysed a series of population models to test whether observed abundance patterns of coho and chinook salmon could be explained by one of the major differences in their life history, the spawning age distribution; in the California current, female coho salmon are considered to be obligate semelparous, spawning at age 3, while chinook salmon are considered indeterminate semelparous, with populations spawning over a range of ages.Results from a deterministic model indicate that the sensitivity of the population growth rate to changes in ocean survival depends little on the spawning age structure, especially when the growth rate is small (λ ≈ 1).Analysis of linear and non‐linear stochastic models indicate that the probability of persistence increases with the width of the spawning age distribution, as the fraction of adults spawning at age 3 decreases from 100% to 95%. Further increases in the spawning age distribution have negligible affects on persistence.Because coho salmon are not absolutely obligate semelparous (e.g. as many as 25% of males can spawn precociously at age 2 and their effect on annual reproduction is unknown), this range of sensitivity does not provide a firm basis for assuming that the observed abundance patterns of coho and chinook is due to differences in their spawning age distribution.While other life‐history differences could play a role, we recommend that ongoing field studies focus on the different effects changing ocean conditions have on the survival of individual salmon species.
Sexual dimorphism in susceptibility to parasites and cell‐mediated immunity in great tit nestlings
Authors: Tschirren Barbara , Fitze Patrick S. , Richner Heinz 
Published: December 2004

SummaryParasites can affect host fitness, provoke host responses, and thereby mediate host life history evolution. As life history strategies are often sex‐specific, immunological or behavioural responses of the host aiming to reduce the impact of parasites may be sexually dimorphic, e.g. as a consequence of sex differences in the resource allocation trade‐off between parasite defence, morphological traits and body functions. Parasites may therefore affect males and females differently leading to sex specific patterns of parasite susceptibility.In an experimental field study, we manipulated the ectoparasite load of great tit nests (Parus major) and investigated its effects on male and female nestlings. As susceptibility to parasites may be linked to the ability of the nestlings to fight off parasites immunologically, we further investigated sex differences in cell‐mediated immunity using a phytohaemagglutinin (PHA) assay.Body mass, metatarsus length and overall body size, but not feather length, showed a sexual dimorphism at the end of the nestling period. A significant interaction between the effects of sex and parasite treatment on the sexually dimorphic traits indicates that the parasite effect is sex‐specific. While no differences in morphological traits were found in females raised in infested and uninfested nests, parasitized males were significantly smaller and lighter than males raised in uninfested nests. Further, we found a pronounced sexual dimorphism in the response to the PHA assay with males showing a reduced cellular immunity. The parasite treatment had a non‐significant effect on the PHA response and the PHA response of males and females were not influenced differently by parasites.Our study shows that sexual dimorphism in susceptibility to parasites and immunocompetence develops early in life, and suggests sex‐specific strategies in the allocation of limited resources. Possible mechanisms of sex differences in susceptibility to parasites and immunocompetence during postnatal growth and the consequences for optimal sex allocation strategies of the parents are discussed.
Detection of imperfect population synchrony in an uncertain world
Authors: Cazelles Bernard , Stone Lewi 
Published: December 2004

Summary

We propose the method of ‘phase analysis’ for studying the spatio‐temporal fluctuations of animal populations, and use this method for helping identify remarkable synchronized population fluctuations that may sometimes be found over very large spatial domains.
The method requires decomposing the observed time series of population fluctuations into two components – one that quantifies the changing phase of the signal, and the other that quantifies the changing amplitude.
Two populations are considered to be ‘phase synchronized’ if there is locking or synchrony between their phase components, while their associated amplitudes may nevertheless remain largely uncorrelated.
Since environmental noise often masks population synchrony, a null hypothesis approach is used to detect whether the phase variables are locked more than would be expected by chance alone.
The technique is thus particularly appropriate for ecological analyses where it is often important to study evidence of weak interactions in irregular non‐stationary and noisy time series. Because climatic patterns (and predicted climate changes) almost certainly influence population dynamics, the approach appears particularly relevant for analysing the potential links between climatic fluctuations and population abundance.