bluuebunny/crossref_metadata_2025_split huggingface dataset:
Murine graft‐versus‐host disease induced using interferon‐γ‐deficient grafts features antibodies to double‐stranded DNA, T helper 2‐type cytokines and hypereosinophilia
Authors: Ellison Cynthia A. , Bradley David S. , Fischer Jacqie M. M. , Hayglass Kent T. , Gartner John G. 
Published: March 2003

SummaryAcute, lethal graft‐versus‐host disease (GvHD) develops in B6D2F1 hybrid recipients of wild‐type, C57BL/6, parental strain grafts; however, when interferon‐γ (IFN‐γ) gene knockout (gko) donors are used, the disease is prolonged and associated with a higher level of engraftment, particularly of T cells. Lesions containing large, mixed cellular infiltrates develop in the skin, liver, pancreas, salivary gland, lung and kidney. In our current study, we wished to determine whether GvHD features a preponderance of T helper 2 (Th2) cytokines in the absence of donor‐derived IFN‐γ, and whether autoantibody production, commonly associated with chronic GvHD, also occurs. Because mitogen responsiveness is consistently suppressed in mice with acute GvHD, we wished to measure this response in recipients of IFN‐γ gko grafts. Our findings indicate that spleen cells from the latter produce interleukin (IL)‐4, IL‐5 and IL‐13 in culture, but respond poorly to concanavalin A (Con A) and lipopolysaccharide (LPS). Their sera contain anti‐nuclear antibodies (ANA), some of which are specific for double‐stranded (ds)DNA and are predominantly immunoglobulin (Ig)M and IgG1. We also noted the presence of numerous eosinophils in the infiltrates developing within the target organs. In some respects, this syndrome bears resemblance to both systemic lupus erythematosus (SLE) and chronic GvHD. However, histological evidence of glomerulonephritis is lacking and proteinuria fails to develop in recipients of IFN‐γ gko grafts, suggesting that IFN‐γ may be necessary for the development of lupus nephritis. On a broader scope, our findings underscore the importance of IFN‐γ in the pathogenetic mechanism of GvHD, and demonstrate that the absence of this cytokine promotes the development of chronic GvHD and autoimmunity.
Big endothelin‐1 but not endothelin‐1 is present in the smooth muscle stroma of the prostate gland of the rat
Authors: Ventura S. , Salamoussa A. 
Published: March 2003

AbstractImmunohistochemical techniques were employed to localize the presence of endothelins in the mature rat prostate gland. Immunoreactivity for big endothelin‐1 but not endothelin‐1 was observed in the fibromuscular stroma of the rat prostate gland. No immunoreactivity was seen in the glandular epithelium. Double staining procedures showed big endothelin‐1 immunoreactivity to be co‐localized with α‐actin immunoreactivity. The stroma of the prostate gland also contained nerve fibres coursing through it which are immunopositive for tyrosine hydroxylase. These results suggest that big endothelin‐1 but not endothelin‐1 is co‐localized with α‐actin in the smooth muscle cells of the rat prostate gland. This implies that endothelin‐1 is synthesized on demand from big endothelin‐1 in the fibromuscular stroma of the rat prostate.
Phagocytic capacity of leucocytes in sheep mammary secretions following weaning
Authors: Tatarczuch Liliana , Bischof Robert J. , Philip Christopher J. , Lee Chee‐Seong 
Published: March 2003

AbstractLactating animals are particularly susceptible to mastitis during the early stages of mammary gland involution following weaning. In this study we compared the phagocytic capacity of cells collected from sheep mammary secretions at different stages of involution. The ability of neutrophils and macrophages to ingest latex beads in anin vitrophagocytosis assay was found to be dependent on how heavily the phagocytes were loaded with milk constituents. There was a decline in the phagocytic capacity of neutrophils from 1 to 2 days after weaning, while macrophages collected from fully involuted glands were more effective phagocytes compared with earlier stages (7–15 days) of involution. In addition, dendritic cells present in fully involuted mammary gland secretions (30 days after weaning) were highly phagocytic. These studies demonstrate that neutrophils and macrophages in sheep mammary secretions at early stages of involution are incapacitated, and as such may compromise the immune status of the mammary gland.
Density‐dependent starvation in a vertebrate without significant depletion
Authors: Goss‐Custard J.D. , West A.D. , Stillman R.A. , Durell S.E.A. LE V. DIT , Caldow R.W.G. , McGrorty S. , Nagarajan R. 
Published: March 2003

SummaryIt is often difficult to quantify the separate contribution of exploitation and interference competition to the starvation of poor competitors yet, in vertebrates, it seems widely supposed that depletion is normally the mechanism underlying density‐dependent starvation. This paper presents arguments that density‐dependent starvation occurs through interference in wintering oystercatchersHaematopus ostraleguseating musselsMytilus eduliswithout prey depletion having a significant influence.Exclosure experiments and mussel bed surveys showed that oystercatchers (i) depleted mussel numerical density by up to 25% in their most preferred large prey size classes, but by only 12·1% overall; (ii) reduced mean mussel length by 1·5%; but (iii) had no detectable effect on the thickness of the shells and therefore the availability of mussels to the 60% of oystercatchers that opened mussels by breaking the shell.Oystercatcher intake rate did not fall until prey biomass had decreased to very low densities. Depletion was not nearly large enough for mussel biomass to be reduced to this point.The flesh content of individual mussels decreased from autumn to spring by 40–50% but oystercatchers did not increase their rate of foraging to compensate. Intake rate declined over the winter because of deteriorating mussel condition; very little was because of depletion.Over the current range of population size, the density‐dependent functions produced by a behaviour‐based individual’s model were the same whether depletion was allowed to occur or not, confirming that depletion played no role in the density‐dependent starvation.At current population sizes, intake rate was reduced as population density increased only through increased interference, this leading to starvation late in winter when mussel flesh content was low. It was not just the subdominant birds most susceptible to interference that starved, but the least efficient ones as well, even though the density dependence was not due to exploitation competition.
Ecosystem structure and productivity of tropical rain forests along altitudinal gradients with contrasting soil phosphorus pools on Mount Kinabalu, Borneo
Authors: Kitayama Kanehiro , Aiba Shin‐Ichiro 
Published: March 2003

Summary

We measured above‐ground net primary productivity (ANPP) and ecosystem structure and processes in eight rain forest stands at four elevations (700, 1700, 2700 and 3100 m) and on two geological substrates (sedimentary vs. ultrabasic rock) on Mount Kinabalu, Borneo.
All ultrabasic sites had smaller pools of total soil phosphorus (P) and of labile inorganic P than did the sedimentary sites at the same altitudes. We predicted that the magnitude of altitudinal changes in ANPP would be less on ultrabasic than on sedimentary substrates, reflecting lower temperature dependency of ANPP under stronger P limitation.
Although ANPP declined with increasing altitude on both substrates, the slopes of the two regression lines were similar. The intercept was, however, marginally greater on sedimentary than on ultrabasic substrate.
Stand‐level nutrient‐use efficiencies (the ratio of litterfall mass to nutrient return) for N and P were only affected by altitude on ultrabasic substrate where they increased exponentially. Mean foliar N and P contents per unit leaf area of the canopy species increased with altitude on both substrates, but differed between substrates at the same altitude only for P (lower on ultrabasic).
Leaf area index (LAI) decreased upslope on both substrates. We assumed that half of primary production was allocated below‐ground in order to evaluate stand level net assimilation rate (NAR). This was nearly constant on sedimentary substrate, but declined linearly with increasing altitude on ultrabasic substrate, where it may have to be added to LAI to explain ANPP patterns.
We suggest that on sedimentary substrate trees may be able to maintain NAR under colder environments by increasing foliar N and P per unit leaf area, but P deficiency prevents them from adjusting on ultrabasic substrate.
Clonal variation in the thermal response of the submerged aquatic macrophyte Potamogeton pectinatus
Authors: Pilon Jörn , Santamaría Luis 
Published: March 2003

Summary

Broadly distributed plants have to cope with dramatic differences across latitude in the prevailing environmental temperature. We investigated the effect of water temperature on plant morphology, biomass accumulation and oxygen‐exchange for five clones of the submerged aquatic macrophyte Potamogeton pectinatus L., originating from 42 to 68°N.
We tested whether P. pectinatus clones show local adaptation to the prevailing environmental temperatures (in which case high‐latitude clones would perform better at lower temperatures and vice versa). Alternatively, pronounced phenotypic plasticity in the response to temperature could enable individual clones to perform well over a wide range of environmental temperatures (i.e. high degree of thermal tolerance).
The overall pattern of thermal response was similar for all clones. In addition, we detected acclimative phenotypic plasticity in both physiological and morphological plant parameters. The optimum temperatures for gross or for net photosynthesis did not vary with growth temperature, but morphological acclimation partly compensated for the loss of photosynthetic capacity at higher temperatures, enabling comparable rates of ambient gross photosynthesis. Respiratory reactions also showed some degree of thermal acclimation to higher temperatures.
As a result of the combined effects of changes in morphology and physiology, all clones produced similar amounts of plant biomass over a relatively wide range of water temperatures. We therefore conclude that P. pectinatus is thermally tolerant and not locally adapted.
New imaging modes for lenslet‐array tandem scanning microscopes
Authors: Watson T. F. , Jus̆kaitis R. , Wilson T. 
Published: March 2003

SummaryThe tandem scanning microscope permits confocal images to be obtained in real time and viewed directly by eye. The light budget of these instruments may be increased from a few percent to a few tens of percent by incorporating an array of microlenses so as to increase the amount of illumination light that reaches the specimen. These instruments are configured for fluorescence imaging together with laser illumination. We describe how the versatility of the instrument may be enhanced to permit the use of incoherent light sources as well as extending the imaging modes to include bright‐field reflection.
Expression and regulation of corticotropin‐releasing hormone binding protein (CRH‐BP) in rat adrenals
Authors: Chatzaki E. , Margioris A. N. , Gravanis A. 
Published: March 2003

AbstractCorticotropin‐releasing hormone (CRH) is present in the adrenal gland acting as a paracrine factor via stimulation of the locally expressed CRH receptors. In this study, we examined if the adrenal CRH system also contains a key component of the neuronal CRH‐containing system, the CRH‐binding protein (CRH‐BP). Our data show that: (i) the CRH‐BP transcript is detectable using RT‐PCR in total RNA isolated from rat adrenals, and (ii) its protein product is also found by western blot analysis in cell lysates. (iii) Immunohistochemical staining showed that adrenomedullary chromaffin cells produce the bulk of adrenal CRH‐BP, an ability retained by the PC12 rat pheochromocytoma cell line. (iv) Regulation of adrenal CRH‐BP expression by major modulators of the CRH system was also examined. Protein expression appears to be under the positive control of CRH itself, protein kinase A effector cAMP, glucocorticoids and interleukin (IL)‐6. It is thus evident that CRH‐BP may play a role in mediating their effects in the adrenal. (v) Differentiation of PC12 into neuron‐like cells resulted in a significant increase in CRH‐BP, parallel to the induction of the CRH peptide itself. In conclusion, CRH‐BP mRNA and protein are present in normal rat adrenomedullary chromaffin cells and in the PC12 rat pheochromocytoma cell line, making the adrenal CRH system directly comparable with those described in the CNS.
Phosphatidylinositol 3‐kinase is a central mediator of NMDA receptor signalling to MAP kinase (Erk1/2), Akt/PKB and CREB in striatal neurones
Authors: Perkinton Michael S. , Ip James , Wood Gemma L. , Crossthwaite Andrew J. , Williams Robert J. 
Published: March 2003

AbstractCa2+influx through NMDA receptors can initiate molecular changes in neurones which may underlie synaptic plasticity, neuronal development, survival and excitotoxicity. Signalling through the MAP kinase (Erk1/2) cascade may be central to␣these processes. We previously demonstrated that Ca2+‐permeable AMPA receptors activate Erk1/2 through a phosphatidylinositol 3‐kinase (PI 3‐kinase)‐dependent mechanism. We now report that NMDA receptor activation of Erk1/2 was also blocked by inhibitors of PI 3‐kinase (LY 294002, wortmannin). In addition, pre‐treatment of neurones with pertussis toxin inhibited NMDA‐induced Erk1/2 activation, indicating a role for heterotrimeric Gi/oproteins. PI 3‐kinase directs activation of the serine‐threonine kinase Akt (PKB). Treatment of striatal neurones with glutamate induced a rapid Ca2+‐dependent and PI 3‐kinase‐dependent phosphorylation of Akt (Ser473), which was not blocked by the Mek inhibitors PD98059 or U0126. Targets for Erk1/2 and Akt pathways include transcription factors. Glutamate‐induced phosphorylation of cAMP response element binding protein (CREB; Ser133) was partially blocked with either PD98059, U0126, LY294002 or wortmannin but was very strongly inhibited on co‐application of LY294002 and PD98059. We propose that NMDA receptor stimulation can activate Erk1/2 and Akt signalling pathways in a PI 3‐kinase dependent manner which may target CREB in the nucleus.
Continuous imaging of amino‐acid translocation in intact mycelia of Phanerochaete velutina reveals rapid, pulsatile fluxes
Authors: Tlalka M. , Watkinson S. C. , Darrah P. R. , Fricker M. D. 
Published: March 2003

Summary

Nitrogen translocation by woodland fungi is ecologically important, however, techniques to study long‐distance amino‐acid transport in mycelia currently have limited spatial and temporal resolution. We report a new continuous, noninvasive imaging technique for β‐emitters that operates with submillimetre spatial resolution and a practical sampling interval of 10–60 min.
Transport of the nonmetabolized, 14C‐labelled amino‐acid analogue, α‐aminoisobutyric acid (AIB) was imaged using a photon‐counting camera as it was transported in foraging mycelium of the cord‐forming woodland fungus, Phanerochaete velutina, grown over an intensifying screen in microcosms.
The maximum acropetal transport velocity of 14C‐AIB to the colony margin was 50 mm h−1 (average 23 mm h−1), with a mass transfer of 4.6–51.5 pmol 14C‐AIB h−1 per cord. Transport in cords had a pulsatile component with a period of 11–12 h.
Transport was significantly faster than diffusion, consistent with rapid cycling of nutrients throughout the mycelium between loading and sink regions. The increased spatial and temporal resolution of this method also revealed the rhythmic nature of transport in this fungus for the first time.
Green cotyledons of two Hakea species control seedling mass and morphology by supplying mineral nutrients rather than organic compounds
Authors: Lamont Byron B. , Groom Philip K. 
Published: March 2003

Summary

Hakea species dominate shrubby vegetation on seasonally dry, nutrient‐impoverished soils in Australia. We hypothesized that the exposed cotyledons control growth of the young seedling by providing it with mineral nutrients rather than C‐based compounds.
Two representative species with differing seed masses were tested. Cotyledon removal caused large reductions in plant mass and dimensions, but little effect on specific leaf area. Cotyledons expanded markedly on germination although their chlorophyll content was much lower than the first leaves. Shading the cotyledons or applying a C‐storage compound (inositol) to the soil had no consistent effect on seedling properties.
Cotyledon removal greatly reduced seedling P (especially), N, K, Ca, Mg and Cu, but not Fe or Mn, whereas shading the cotyledons had no effect. Transfer of mineral nutrients from the embryos to the seedlings in their natural soils varied from 90 to 2% (for P and Ca, respectively), and accounted for 79% of total content (P) to negligible (K, Ca, Fe) at 3 months. Cotyledons indirectly increased soil nutrient uptake. Addition of P, N or P + N after cotyledon removal had no benefit but addition of P + N + K + Mg + S restored morphology and nutrient content.
In nutrient and water‐limited habitats with abundant light, cotyledons in Hakea spp. might serve to maximize supply of mineral nutrients to the shoots, which then maximize C‐supply to the rapidly elongating roots.
Crown architecture of Populus spp. is differentially modified by free‐air CO2 enrichment (POPFACE)
Authors: Gielen B. , Calfapietra C. , Claus A. , Sabatti M. , Ceulemans R. 
Published: March 2003

Summary

Although canopy architecture is a prime determinant of forest functioning and productivity, it has received little attention when examining forest responses to rising atmospheric CO2 concentrations. In this study different characteristics of crown architecture of two Populus species and one hybrid were investigated within a high‐density poplar plantation. A free‐air CO2 enrichment (FACE) facility was used to mimic future elevated CO2 concentrations.
Canopy depth and branching patterns were studied, and detailed branch characteristics such as branch dimension, inclination, and internodal length were assessed for the three poplar species in the FACE and control treatments.
Effects of elevated CO2 were restricted to a significantly increased canopy depth and longer internodal lengths after two years of CO2 enrichment. Additionally, branch dimensions and sylleptic branch numbers were increased by FACE, but responses were variable among growing seasons and species. However, FACE did not affect branch angles of origin and termination.
Crown architecture was modified mainly through a growth stimulation in response to FACE. Nevertheless, important differences among species were observed which may influence future CO2 responses when competition will become more important.
Effects of relative humidity, light intensity and photoperiod on the colony development of Erysiphe sp. on Rhododendron
Authors: Kenyon D. M. , Dixon G. R. , Helfer S. 
Published: March 2003

Growth and reproduction by powdery mildew pathogens is generally inhibited by decreasing relative humidity. With Erysiphe sp. on Rhododendron cv. Elizabeth, the initial stages of colony development were adversely affected by reducing the relative humidity from 100% to 70 and 85%. No significant effects on secondary or tertiary hyphal development were detected. Light intensity and photoperiod both had considerable effect on the induced resistance response of the host. Over the initial 5 days of colonization there were no significant differences between any of the treatments. After 13 days, however, expansion of fungal colonies at 180 photosynthetic active radiation (PAR) was limited solely to the area initially infested by primary hyphae. By comparison, in colonies grown at 80 PAR regardless of day length, secondary and tertiary hyphae had extended beyond the area first colonized. These effects resulted in differing morphologies, small colonies of densely packed hyphae formed at 180 PAR compared with open spreading colonies at 80 PAR.
Microtubule dynamics in compatible and incompatible interactions of soybean hypocotyl cells with Phytophthora sojae
Authors: Cahill D. , Rookes J. , Michalczyk A. , McDonald K. , Drake A. 
Published: March 2003

The arrangement of microtubules in soybean (Glycine max) cells was examined during compatible and incompatible interactions of hypocotyls of soybean cv. Harosoy (susceptible) and cv. Haro 1272 (resistant) with race 1 of the soybean‐specific pathogen Phytophthora sojae. Both reaction types were similar during the first 3 h after zoospore inoculation in terms of the number of cells penetrated, and depth penetrated into the cortex. By 3 h postinoculation, clear differences had developed between the two interaction types: incompatible interactions were characterized by a hypersensitive response that was confined to single penetrated cells; while compatibly responding cells appeared unchanged. Both types of response were characterized by autofluorescence of cell walls or cytoplasm and, at 6 h after inoculation, complete disorganization of cell cytoplasm. Reorientation and loss of microtubules was seen in the early stages of the incompatible interaction in association with cellular hypersensitivity, but not in compatible responses. In cells adjacent to those that reacted hypersensitively, there was little evidence of change in microtubule orientation. Treatment of hypocotyls with the microtubule depolymerizer oryzalin prior to inoculation did not alter the compatible response, but led to breakdown of the incompatible response. Changes in microtubule orientation and state are thus among the first structural changes that are visible within cells during incompatibility in this system.
Kinetics of CFU‐Mk after automated plateletpheresis
Authors: Wagner T. , Schwartz D. W. M. , Winter M. , Kabrna E. , Kollars M. , Schwarzinger I. , Lanzer G. , Mayr W. R. , Geissler K. 
Published: March 2003

Background and ObjectivesPlatelet count, thrombopoetin (TPO) level and the compartment of megakaryocyte progenitor cells (CFU‐Mk) are major determinants in the regulation of thrombopoiesis. The aim of this study was to investigate the potential changes in the compartment of CFU‐Mk and their correlation with serum TPO levels and platelet count after plateletpheresis.Materials and methodsTwelve healthy individuals were randomly assigned to undergo single‐donor plateletpheresis. A collagen‐based in vitro culture system was used to determine the number of peripheral blood (PB) CFU‐Mk before and after donation and on days 1, 4 and 7 thereafter. TPO levels were measured by a specific enzyme‐linked immunosorbent assay and whole blood counts were performed using an automated cell counter.ResultsThe pre‐apheresis platelet count (mean ± SEM: 276 ± 13 × 109/l) decreased after plateletpheresis to a nadir of 194 ± 8 × 109/l (P < 0·001), showed a gradual increase on days 1 and 4, and reached pre‐apheresis values by day 7 (280 ± 11). The serum TPO levels were found to be significantly increased on days 1 and 7 as compared to baseline levels (baseline value 103·3 ± 18·5 pg/ml versus day‐1 value 135·8 ± 25·8 pg/ml and day‐7 value 132 ± 30·19 pg/ml; P < 0·03 and P < 0·03, respectively). The numbers of CFU‐Mk in PB were significantly elevated on day 4 only (125 ± 21 colonies/ml of PB versus pre‐apheresis values of 68 ± 18 colonies/ml of PB, P < 0·005).ConclusionsThese findings suggest that platelet loss during plateletpheresis affects thrombopoiesis at the progenitor cell level, probably through alterations in TPO plasma concentrations.