bluuebunny/crossref_metadata_2025_split huggingface dataset:
C‐reactive protein‐mediated phagocytosis of Leishmania donovani promastigotes does not alter parasite survival or macrophage responses
Authors: Bodman‐Smith Katherine B. , Mbuchi Margaret , Culley Fiona J. , Bates Paul A. , Raynes John G. 
Published: December 2004

SUMMARY C‐reactive protein (CRP) is an acute phase protein that binds to surface structures of a number of different organisms. Leishmania donovani express CRP ligand when first entering the mammalian host and CRP has been shown to alter macrophage function. The aim of this study was to investigate the functional significance of CRP‐mediated uptake of L. donovani on survival of the parasite within human macrophages and macrophage cell responses to the infection. CRP opsonized L. donovani uptake was inhibitable by including excess CRP in the fluid phase, suggesting Fc receptor usage rather than indirect complement‐mediated uptake. Comparing equivalent initial infection loads, parasite survival over 72 h within peripheral blood derived macrophages (PBMs) and differentiated U937 cells was unaltered by CRP. Whereas CRP increased macrophage responses to phosphorylcholine coated erythrocytes, no significant alteration in tumour necrosis factor‐α, interleukin (IL)‐10 or IL‐12 production from PBMs was observed between CRP opsonized or unopsonized L. donovani promastigotes. Thus, in contrast to other systems, where CRP opsonization results in macrophage activation, Leishmania can use CRP to improve infection without inducing detrimental macrophage activation.
In vivo inhibition of inducible nitric oxide synthase decreases lung injury induced by Toxocara canis in experimentally infected rats
Authors: Espinoza Elsa Y. , Pérez‐Arellano José L. , Carranza Cristina , Collía Francisco , Muro Antonio 
Published: December 2004

SUMMARY The direct effect of nitric oxide (NO) on the viability of Toxocara canis larvae was studied. We observed that the nitric oxide donors, SIN‐1 and SNOG, exert no cytotoxic effect on the in vitro viability of T. canis larvae. In addition, we developed a model in rats to elucidate the role of NO during T. canis infection. We evaluated different indicators in four experimental groups: morphological parameters, the total number cells and cell types recovered, nitrite and protein concentration, lactate dehydrogenase and alkaline phosphatase enzymatic activity in the bronchoalveolar lavage fluid, lung index and detection of anti‐T. canis specific antibodies. We observed significant differences between non‐infected and infected groups. The infected animals treated with the inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine were less damaged than infected, non‐treated animals. Our results suggest that the in vivo inhibition of the synthesis of NO triggered by iNOS diminishes the deleterious effects of the parasite upon the host, especially the vascular alterations in the lungs. We could show that in vivo production of NO induced by infection with T. canis results in direct host damage. Thus, this induction may constitute an evasion/adaptation mechanism of the parasite.
Cellular responses and cytokine profiles in Ascaris lumbricoides and Trichuris trichiura infected patients
Authors: Geiger Stefan M. , Massara Cristiano L. , Bethony Jeffrey , Soboslay Peter T. , Carvalho Omar S. , Corrêa‐Oliveira Rodrigo 
Published: December 2004

SUMMARY The impact of intestinal helminth infection, i.e. Ascaris lumbricoides and Trichuris trichiura, on cellular responsiveness and cytokine production was investigated in young adults. Ascaris‐specific cellular responsiveness was higher in parasite‐free endemic controls than in patients infected with T. trichiura, or A. lumbricoides, or patients co‐infected with both parasites. Also, mitogen‐induced tumour necrosis factor (TNF)‐α, interleukin (IL)‐12 and interferon (IFN)‐γ secretion by peripheral blood mononuclear cells (PBMC) was higher in negative endemic controls than in infected individuals. Ascaris antigen‐specific production of TNF‐α, IL‐12 and IFN‐γ was low in singly Ascaris as well as in co‐infected patients, whereas secretion of IL‐10 and IL‐13 was elevated and similarly high in all patient groups. The detection of Trichuris‐specific and Ascaris‐specific IgG4 revealed significantly higher serum antibody levels in Trichuris or Ascaris patients when compared to endemic controls (P < 0·05), whereas parasite‐specific IgE antibody levels were similarly high in infected individuals and in endemic controls. In summary, chronically infected Ascaris and Trichuris patients with a high parasite load presented reduced cellular reactivity and lower type 1 TNF‐α, IFN‐γ and IL‐12 responses when compared with endemic controls, whereas type 2 IL‐10 and IL‐13 productions were similar in all groups from the endemic area. The former may support parasite persistence, whereas substantial type 2 cytokine release may promote protective immunity, suggesting an adaptation of the host to control the parasite burden while minimizing immune‐mediated host self‐damage.
Immune rejection of Trichostrongylus colubriformis in sheep; a possible role for intestinal mucus antibody against an L3‐specific surface antigen
Authors: Harrison G. B. L. , Pulford H. D. , Hein W. R. , Barber T. K. , Shaw R. J. , Mcneill M. , J WAKEFIELD St. , Shoemaker C. b 
Published: December 2004

SUMMARY Sheep that have been immunized by multiple truncated infections with the parasitic nematode Trichostrongylus colubriformis contain anti‐larval activity in their intestinal mucus and high‐speed mucus supernatants. This activity induces T. colubriformis L3 to clump in vitro and causes a significant reduction in larval establishment in naive sheep after infusion of larvae and mucus into the intestinal lumen via a duodenal cannula. In this report, we provide evidence that one factor contributing to the anti‐larval activity of immune mucus is antibody against a 35‐kDa L3‐specific cuticular antigen. The anti‐larval activity in mucus is > 100 kDa by membrane filtration, is heat labile and sensitive to either protease digestion or reduction with DTT. Immunoblotting showed that mucus and supernatants of ultracentrifuged mucus from immune sheep contained IgG1 and IgA antibodies that recognized predominantly a larval antigen with an estimated molecular weight of 35 kDa on SDS‐PAGE. Antibodies eluted from the surface of washed larvae that had been incubated in immune mucus also reacted specifically with the 35 kDa antigen on blots of larval homogenate. Immunofluorescence and immunogold electron microscopy showed that the 35 kDa antigen is present on the epicuticle of L3 and is shed during the moult to L4. The antigen is not present in eggs, L1, L2, L4 or adult worms and is found only in extracts of sheaths and L3 before infection and up to 4 days after infection. We hypothesize that the binding of antibody to the larval surface prevents larvae from establishing at their preferred site, causing them to be eliminated from the intestine. Monoclonal antibody PAB‐1 recognizes the 35 kDa T. colubriformis larval antigen and also cross‐reacts with antigens of similar molecular weight on blots of L3 extracts of the parasitic nematodes Haemonchus contortus and Ostertagia circumcincta; and with a 22‐kDa antigen on blots of L3 extracts from Cooperia curticei and Nematodirus spathiger. This indicates that an antigenically related surface antigen with immunizing potential is present on several nematode species and can be identified by mAb PAB‐1. The 35 kDa T. colubriformis larval antigen and related molecules in other nematodes are potential novel targets for stimulating host‐protective immunity against nematode infections.
Relations between stomatal closure, leaf turgor and xylem vulnerability in eight tropical dry forest trees
Authors: BRODRIBB T. J. , HOLBROOK N. M. , EDWARDS E. J. , GUTIÉRREZ M. V. 
Published: December 2004

ABSTRACTThis study examined the linkage between xylem vulnerability, stomatal response to leaf water potential (ΨL), and loss of leaf turgor in eight species of seasonally dry tropical forest trees. In order to maximize the potential variation in these traits species that exhibit a range of leaf habits and phenologies were selected. It was found that in all species stomatal conductance was responsive to ΨL over a narrow range of water potentials, and that ΨL inducing 50% stomatal closure was correlated with both the ΨL inducing a 20% loss of xylem hydraulic conductivity and leaf water potential at turgor loss in all species. In contrast, there was no correlation between the water potential causing a 50% loss of conductivity in the stem xylem, and the water potential at stomatal closure (ΨSC) amongst species. It was concluded that although both leaf and xylem characters are correlated with the response of stomata to ΨL, there is considerable flexibility in this linkage. The range of responses is discussed in terms of the differing leaf‐loss strategies exhibited by these species.
Relationship between growth rates and xylem hydraulic characteristics in young, mature and old‐growth ponderosa pine trees
Authors: DOMEC J‐C. , GARTNER B. L. 
Published: December 2004

ABSTRACTThe first objective of the present study was to quantify the effects of tree age and stem position on specific conductivity (ks), vulnerability to embolism and water storage capacity (capacitance) in trunks of young, mature and old‐growth ponderosa pine. The second objective was to determine relationships between hydraulic characteristics and radial and height growth rates to increase the understanding of possible tradeoffs. Within sapwood at all heights and in all ages of trees, outer sapwood had 25–60% higherksthan inner sapwood. The water potential at which embolism started (air entry point) was 1.3 MPa lower in inner sapwood than outer sapwood within the mature trees, but there was no difference in the other trees. There was no significant difference in capacitances between the tops of the old growth trees, the mature trees and the young trees. Taking all data together, the capacitances increased sharply with an increase inksand an increase in vulnerability to embolism. The hydraulic characteristics of the three age classes were correlated with the height growth rate but not with the diameter growth rate. Within these age classes, highkswas associated with the slowest yearly increase in sapwood area and with a low percentage of latewood, whereas high vulnerability to embolism and high capacitance were more closely associated with high height growth rates.
Responses to UV‐B radiation in Trifolium repens L. – physiological links to plant productivity and water availability
Authors: HOFMANN R. W. , CAMPBELL B. D. , BLOOR S. J. , SWINNY E. E. , MARKHAM K. R. , RYAN K. G. , FOUNTAIN D. W. 
Published: December 2004

ABSTRACTThis study used comparisons across nine populations of Trifolium repens (white clover) in conjunction with drought to examine physiological responses to ultraviolet‐B radiation (UV‐B). Plants were exposed for 12 weeks to supplementation with 13.3 kJ m−2 d−1 UV‐B, accompanied by 4 weeks of drought under controlled environmental conditions. UV‐B increased the levels of UV‐B‐absorbing compounds and of flavonol glycosides and this effect was synergistically enhanced by water stress. These changes were more pronounced for the ortho‐dihydroxylated quercetin, rather than the monohydroxylated kaempferol glycosides. UV‐B increased leaf water potential (ψL) by 16% under drought and proline levels by 23% under well‐watered conditions. The intraspecific comparisons showed that higher UV‐B‐induced levels of UV‐B‐absorbing compounds, of quercetin glycosides and of ψL were linked to lower plant productivity and to higher UV‐B tolerance under well‐watered conditions. These findings suggest that: (1) slow‐growing T. repens ecotypes adapted to other stresses have higher capacity for physiological acclimation to UV‐B; and (2) that these attributes also contribute to decreased UV‐B sensitivity under drought.
Rubisco expression in rice leaves is related to genotypic variation of photosynthesis under elevated growth CO2 and temperature
Authors: GESCH R. W. , KANG I.‐H. , GALLO‐MEAGHER M. , VU J. C. V. , BOOTE K. J. , H. ALLEN L. , BOWES G. 
Published: December 2004

ABSTRACTGenetic modifications of agronomic crops will likely be necessary to cope with global climate change. This study tested the hypotheses that genotypic differences in rice (Oryza sativa L.) leaf photosynthesis at elevated [CO2] and temperature are related to protein and gene expression of Rubisco, and that high growth temperatures under elevated [CO2] negatively affect photosystem II (PSII) photochemical efficiency. Two rice cultivars representing an indica (cv. IR72) and japonica type (cv. M103) were grown in 350 (ambient) and 700 (elevated) µmol CO2 mol−1 at 28/18, 34/24 and 40/30 °C sinusoidal maximum/minimum, day/night temperatures in outdoor, sunlit, environment‐controlled chambers. Leaf photosynthesis of IR72 favoured higher growth temperatures more than M103. Rubisco total activity and protein content were negatively affected in both genotypes by high temperatures and elevated CO2. However, at moderate to high growth temperatures, IR72 leaves averaged 71 and 39% more rbcS transcripts than M103 under ambient and elevated CO2, respectively, and likewise had greater Rubisco activity and protein content. Expression of psbA (D1 protein of PSII) in IR72 leaves increased with temperature, whereas it remained constant for M103, except for a 20% decline at 40/30 °C under elevated CO2. Even at the highest growth temperatures, PSII photochemical efficiency was not impaired in either genotype grown under either ambient or elevated CO2. Genotypic differences exist in rice for carboxylation responses to elevated CO2 and high temperatures, which may be useful in developing genotypes suited to cope with global climate changes.
Calcium‐dependent K current in plasma membranes of dermal cells of developing bean cotyledons
Authors: ZHANG W.‐H. , WALKER N. A. , PATRICK J. W. , TYERMAN S. D. 
Published: December 2004

ABSTRACTIn developing seeds of bean (Phaseolus vulgaris L.), phloem‐imported assimilates (largely sucrose and potassium) are released from coats to seed apoplasm and subsequently retrieved by the dermal cell complexes of cotyledons. To investigate the mechanisms of K+ uptake by the cotyledons, protoplasts of dermal cell complexes were isolated and whole‐cell currents across their plasma membranes were measured with the patch‐clamp technique. A weakly rectified cation current displaying a voltage‐dependent blockade by external Ca2+ and acidic pH, dominated the conductance of the protoplasts. The P haseolus v ulgaris Cotyledon Dermal‐cell pH and Calcium‐dependent Cation Conductance (Pv‐CD‐pHCaCC) was highly selective for K+ over Ca2+ and Cl–. For K+ current through Pv‐CD‐pHCaCC a sigmoid shaped current–voltage (I–V) curve was observed with negative conductance at voltages between −200 and −140 mV. This negative K+ conductance was Ca2+ dependent. With other univalent cations (Na+, Rb+, NH4+) the currents were smaller and were not Ca2+ dependent. Reversal potentials remained constant when external K+ was substituted with these cations, suggesting that Pv‐CD‐pHCaCC channels were non‐selective. The Pv‐CD‐pHCaCC would provide a pathway for K+ and other univalent cation influx into developing cotyledons. These cation influxes could be co‐ordinated with sucrose influx via pH and Ca2+dependence.
Variation in the response of melon genotypes to Fusarium oxysporum f.sp. melonis race 1 determined by inoculation tests and molecular markers
Authors: Burger Y. , Katzir N. , Tzuri G. , Portnoy V. , Saar U. , Shriber S. , Perl‐Treves R. , Cohen R. 
Published: December 2004

Screening of genotypes of melon (Cucumis melo) for resistance to wilt caused by Fusarium oxysporum f.sp. melonis is often characterized by wide variability in their responses to inoculation, even under carefully controlled conditions. The variability at the seedling stage of 17 genotypes susceptible to race 1 was examined in growth‐chamber experiments. Disease incidence varied from 0 to 100% in a genotype‐dependent manner. Using four combinations of light (60 and 90 µE m−2 s−1) and temperatures of (27 and 31°C), only light intensity showed a statistically significant effect. Marker‐assisted selection for fusarium resistance breeding using cleaved amplified polymorphic sequence (CAPS) and sequence‐characterized amplified region (SCAR) markers were compared using a single set of genotypes that included 24 melon accessions and breeding lines whose genotype regarding the Fom‐2 gene was well characterized. The practical value of the markers for discriminating a range of genotypes and clarifying the scoring of phenotypes was also tested using a segregating breeding population which showed codominant SCAR markers to be useful in marker‐assisted selection.
Vascular colonization patterns in susceptible and resistant tomato cultivars inoculated with Fusarium oxysporum f.sp. lycopersici races 0 and 1
Authors: Rodríguez‐Molina M. C. , Medina I. , Torres‐Vila L. M. , Cuartero J. 
Published: December 2004

The vascular colonization pattern of Fusarium oxysporum f.sp. lycopersici races 0 and 1 in tomato was studied in five susceptible and five resistant cultivar–fungus combinations during a 26‐day period after inoculation by root immersion. Propagules spread discontinuously along the stems in all five cultivars 1 day after inoculation, irrespective of cultivar resistance. Five days later the fungus was limited to the stem bases in all cultivars. Between the fifth and 12th days, stem colonization by the fungus stopped in all cultivar–race combinations. Thereafter, the situation remained stable in resistant combinations, with inoculum distributed discontinuously, and no disease symptoms were apparent. By contrast, in the susceptible combinations a gradual upward colonization of the stems was seen such that fungal distribution was no longer discontinuous and disease symptoms appeared. These results suggest that a fungal ‘incubation’ period in the base of the vascular system is required before a secondary invasion of tissues occurs in susceptible genotypes. The slope of the regression line fitted between the height reached by the fungus up the stem (y) and the time after inoculation (x) provides a measure of the horizontal (polygenic) resistance in tomato cultivars
PCR‐based specific and sensitive detection ofPectobacterium carotovorumssp.carotovorumby primers generated from a URP‐PCR fingerprinting‐derived polymorphic band
Authors: Kang H. W. , Kwon S. W. , Go S. J. 
Published: December 2004

A 24‐mer primer pair was generated by sequencing a URP‐PCR fingerprinting‐derived polymorphic band that is uniquely shared inPectobacterium carotovorumssp. carotovorumstrains (Pcc). The primer set (EXPCCF/EXPCCR) amplified a single band of expected size (0·55 kb) from genomic DNA obtained from 29 Pcc strains and threePectobacterium carotovorumssp.wasabiae(Pcw) strains, but not from otherP. carotovorumsubspeciesatrosepticum,betavasculorumorodoriferum, or from otherErwiniaspp. or bacterial genera. TheRsaI digestion profile of the amplified bands divided Pcc strains into five groups with a unique profile from Pcw strains. First‐round PCR detected between 5 × 102and 1 × 103colony forming units (CFU) mL−1and detection sensitivity was increased to as few as 2–4 CFU mL−1after second‐round (nested) PCR. This PCR protocol was used directly to detect Pcc strains in infected plant tissues.
Extremes of Markov Chains with Tail Switching Potential
Authors: Bortot Paola , Coles Stuart 
Published: December 2004

SummaryA recent advance in the utility of extreme value techniques has been the characterization of the extremal behaviour of Markov chains. This has enabled the application of extreme value models to series whose temporal dependence is Markovian, subject to a limitation that prevents switching between extremely high and extremely low levels. For many applications this is sufficient, but for others, most notably in the field of finance, it is common to find series in which successive values switch between high and low levels. We term such series Markov chains with tail switching potential, and the scope of this paper is to generalize the previous theory to enable the characterization of the extremal properties of series displaying this type of behaviour. In addition to theoretical developments, a modelling procedure is proposed. A simulation study is made to assess the utility of the model in inferring the extremal dependence structure of autoregressive conditional heteroscedastic processes, which fall within the tail switching Markov family, and generalized autoregressive conditional heteroscedastic processes which do not, being non-Markov in general. Finally, the procedure is applied to model extremal aspects of a financial index extracted from the New York Stock Exchange compendium.
Free-Knot Polynomial Splines with Confidence Intervals
Authors: Mao Wenxin , Zhao Linda H. 
Published: December 2004

SummaryWe construct approximate confidence intervals for a nonparametric regression function, using polynomial splines with free-knot locations. The number of knots is determined by generalized cross-validation. The estimates of knot locations and coefficients are obtained through a non-linear least squares solution that corresponds to the maximum likelihood estimate. Confidence intervals are then constructed based on the asymptotic distribution of the maximum likelihood estimator. Average coverage probabilities and the accuracy of the estimate are examined via simulation. This includes comparisons between our method and some existing methods such as smoothing spline and variable knots selection as well as a Bayesian version of the variable knots method. Simulation results indicate that our method works well for smooth underlying functions and also reasonably well for discontinuous functions. It also performs well for fairly small sample sizes.
Susceptibility of oat cultivars to groat discoloration: causes and remedies
Authors: Newton A. C. , Lees A. K. , Hilton A. J. , Thomas W. T. B. 
Published: December 2004

AbstractFungal isolations and fungicide efficacy trials were carried out to determine the possible causes of discoloration in oat groats and potential control measures. Alternaria species and Microdochium nivale were isolated from field samples, and Fusarium poae was found in glasshouse tests. Symptoms could be induced reliably in the field through the use of a mist irrigation system. The cultivar ‘Gerald’ was most resistant followed by ‘Jalna’. Cultivar ‘Image’ was most severely affected by discoloration and ‘Millennium’ was of intermediate susceptibility. None of the 28 fungicide‐timing combinations used in the field trials affected the occurrence of discoloured groats. It was concluded that the best strategy for minimizing risk of discoloured groats would be screening new cultivars or breeding material in mist‐irrigated field trials for genetically based resistance.