bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation for aggressiveness within and between lineages of Xanthomonas oryzae pv. oryzae
Authors: Mundt C. C. , Nieva L. P. , Vera Cruz C. M. 
Published: March 2003

Isolates of Xanthomonas oryzae pv. oryzae (causal agent of bacterial blight of rice) from the Philippines representing two phylogenetic lineages, and five haplotypes within those two lineages, were evaluated for aggressiveness in two glasshouse trials. Aggressiveness was determined by clip‐inoculating leaves of a rice cultivar lacking known, effective major genes for resistance and measuring the lengths of resulting lesions. Variance components analysis indicated that 55 and 46% of the lesion length variation were genetic in origin for the first and second trials, respectively. Variation of lesion length among isolates within haplotypes was highly significant in both trials (P = 0·002 and 0·027), but the effects of lineage and haplotype within lineage were not (P = 0·08 and 0·30 for lineage and P= 0·23 and 0·07 for haplotype). These results suggest that substantial heritable variation for aggressiveness exists within Philippine populations of X. oryzae pv. oryzae. This variation appears to be more prevalent within than among known phylogenetic groups, although mean differences among phylogenetic groups may still be of significant biological importance.
Seasonal changes in susceptibility of Quercus suber to Botryosphaeria stevensii and Phytophthora cinnamomi
Authors: Luque J. , Parladé J. , Pera J. 
Published: March 2003

Monthly inoculations of both intact plants and excised shoots of Quercus suber with the pathogenic species Botryosphaeria stevensii and Phytophthora cinnamomi were performed to investigate seasonal changes in susceptibility of this forest tree species in relation to environmental parameters and plant water status. Infection symptoms were mainly detected on seedlings inoculated from spring to autumn (April through October) with either pathogen. Mean canker sizes also showed a seasonal pattern, the higher values being recorded in the same period as above. Lesion lengths were significantly (P < 0·001) related to environmental minimum temperature. Mean daily minimum temperatures within the range of 5–12°C clearly inhibited lesion development of P. cinnamomi, whereas B. stevensii showed a less pronounced decrease in canker expansion at the same temperature range. In excised shoots of Q. suber inoculated monthly with B. stevensii, a negative linear relationship was found between the studied range of plant relative water content (81–91%) and canker length. In contrast, the lesions caused by P. cinnamomi were not significantly (P = 0·32) related to any seasonal change in water content. Some control measures for the diseases caused by both pathogens are discussed on the basis of the seasonal changes in host susceptibility observed in this study.
Field testing of honeybee‐dispersed Trichoderma spp. to manage sunflower head rot (Sclerotinia sclerotiorum)
Authors: Escande A. R. , Laich F. S. , Pedraza M. V. 
Published: March 2003

Efficacy of Trichoderma spp. to reduce sunflower head rot caused by Sclerotinia sclerotiorum was evaluated in the field. A mixture of six isolates, including Trichoderma koningii, T. aureoviride and T. longibrachiatum, was tested in five field trials at Balcarce, Argentina. Trichoderma formulation (TF) included Trichoderma conidia and viable hyphal fragments, industrial talc and milled corn kernels. Honeybees (Apis mellifera) were used to disperse TF for six weeks from the onset of flowering. Two days after the first TF delivery, sunflower heads were inoculated with S. sclerotiorum ascospores. When 100 g TF was taken by honeybees in a 10‐h per day period, head rot incidence was significantly reduced. This approach was successful in reducing disease incidence until physiological maturity of the crop, in environments highly conducive to head‐rot development.
Effect of take‐all root infections on nitrate uptake in winter wheat
Authors: Schoeny A. , Devienne‐Barret F. , Jeuffroy M.‐H. , Lucas P. 
Published: March 2003

The effect of take‐all root lesions on nitrate uptake of wheat was investigated in two experiments under controlled conditions. Plants were supplied with a nutrient solution labelled with 15N during stem elongation and flowering to assess the distribution of the isotopic tracer in the different plant organs, and particularly in root segments located on both sides of take‐all lesions. The 15N atom percentage excess measured in root segments located below lesions longer than 1 cm was reduced on average by half compared with that in healthy roots and root segments above lesions, reflecting a reduction in nitrogen uptake by these root segments. This reduction probably resulted from the invasion and breakdown of phloem vessels by the fungus hyphae, interrupting energy supply and thus the uptake process. Severely infected plants showed an increase in the uptake rate per unit of efficient root, which appeared to be a compensatory response to reduction of efficient root biomass in order to satisfy shoot nitrogen demand. However, this compensatory response was insufficient to ensure nitrogen accumulation equivalent to that of healthy plants, as reductions in nitrogen accumulated in roots and aerial parts at flowering were up to 56 and 49%, respectively, for plants with more than 50% of the root system below lesions longer than 1 cm.
In Vitro and In Vivo Inhibition of Immunoglobulin Secretion by the Immunosuppressive Compound HR325 is Reversed by Exogenous Uridine
Authors: Thomson T. A. , Spinella‐Jaegle S. , Francesconi E. , Meakin C. , Millet S. , Flao K. L. , Hidden H. , Ruuth E. 
Published: March 2003

The objective was to demonstrate that the immunosuppressive agent HR325 (an inhibitor of dihydroorotate dehydrogenase, DHODH) inhibits immunoglobulin (Ig) secretion both in vitro and in vivo and that this effect can be reversed with exogenous uridine. In vitro
, Ig secretion from mouse splenocytes was induced by lipopolysaccharide (LPS) for 5 days. HR325 inhibited the secretion of IgM and IgG with IC
50
values of 2.5 and 2 µ
m
, respectively. Adding uridine (50 µ
m
) increased these values to 70 and 60 µ
m
, respectively. Similarly, the IC
50
values of another DHODH inhibitor, brequinar sodium, were also attenuated by uridine from 0.04 to 1 µ
m
for IgM, and 0.012 to 10 µ
m for IgG. HR325 (and a structural analogue A771726) inhibited LPS‐induced kappa light‐chain cell surface expression on 70Z/3 cells, a property also reversed by uridine. In vivo
, the secondary anti‐sheep red blood cell (SRBC) antibody response (unaffected by uridine alone) was inhibited by HR325 and brequinar with respective ID
50
values of 38 and 0.6 mg/kg per oral (p.o.). Immunosuppression with HR325 (50 mg/kg) and brequinar (1 mg/kg) was abrogated by uridine. Uridine had no effect on cyclophosphamide‐induced (10 mg/kg p.o.) immunosuppression. These data are consistent with the immunosuppressive mechanism of HR325 being the result of pyrimidine depletion
in vitro
and
in vivo .
Activated T Cells in the Surface Secretion on the Adenoid – a Flow Cytometric Study
Authors: IVARSSON M. , LUNDIN B. S. , LUNDBERG C. 
Published: March 2003

We previously demonstrated the presence of leucocytes in the adenoid surface secretion with the ability of immunoglobulin A (IgA), IgM and IgG production as well as production of cells with phagocytic capacity. In the present study, we investigated the presence of activated T cells in the secretion.Adenoid surface secretion from 12 children subjected to adenoidectomy was obtained with an imprint method. From six children, peripheral blood was also obtained. By flow cytometry, the number of lymphocytes, granulocytes, epithelial cells and red blood cells was analysed as well as the expression on lymphocyte subsets of the following antigens: CD3, CD4, CD8, CD19, CD25, CD38, CD45RO, CD45RA, HLA‐DR, TcRgd, CD161 and l‐selectin.The majority of T cells were activated and to a significantly higher degree were CD45RO+, CD161+ and l‐selectin−, as compared with the corresponding peripheral blood. The median percentage of B cells and T cells in the secretion were 81 and 13%, respectively.In conclusion, the proportion of B and T cells in the adenoid surface secretion is significantly different as compared with the peripheral blood. The T cells in the adenoid surface secretion are to a high degree activated. The results suggest that the leucocytes in the surface secretion are part of the mucosal defence.
Pharmacological Disintegration of Lipid Rafts Decreases Specific Tetramer Binding and Disrupts the CD3 Complex and CD8 Heterodimer in Human Cytotoxic T Lymphocytes
Authors: Uhlin M. , Masucci M. G. , Levitsky V. 
Published: March 2003

AbstractAccumulating evidence strongly supports the role of lipid rafts in the regulation of T‐lymphocyte activation, but the organization and molecular composition of these cholesterol‐ and sphingolipid‐rich membrane microdomains in different subsets of T cells remain poorly investigated. Here, we show that pharmacological disruption of lipid rafts in human CD8+ cytotoxic T‐lymphocyte (CTL) clones disturbs the integrity of CD3 complex and CD8 heterodimer, without affecting the reactivity with T‐cell receptor (TCR)‐specific antibodies. This demonstrates that interaction with completely assembled CD3 complex is not required for the stable expression of TCR at the cell surface. The effect of raft disruption on CD3 and CD8 expression correlates with failure to bind specific tetrameric complexes by a proportion of surface TCR molecules. However, the interaction of specific tetramer with the rest of surface TCR pools appears to be unaffected, demonstrating that TCR‐signalling complexes may differ in their requirement for cholesterol to stably maintain their composition and to rearrange for efficient tetramer binding. Together with previously published data, our results support the existence of molecular and/or structural heterogeneity of lipid rafts that may play an important role in controlling distinct functional properties of T‐cell subsets.
Recent, arctic deltaic sedimentation: Olivier Islands, Mackenzie Delta, North‐west Territories, Canada
Authors: JENNER K. A. , HILL P. R. 
Published: March 2003

Despite a low tidal range and relatively low wave conditions, the Mackenzie Delta is not prograding seaward but rather is undergoing transgressive shoreface erosion and drowning of distributary channel mouths. In the Olivier Islands region of the Mackenzie Delta the resultant morphology consists of a network of primary and secondary channels separated by vegetated islands. New ground is formed through channel infilling and landward‐directed bar accretion. This sedimentation is characterized by seven sedimentary facies: (1) hard, cohesive silty clay at the base of primary channels which may be related to earlier, offshore deposition; (2) ripple laminated sand beds, believed to be channel‐fill deposits; (3) ripple laminated sand and silt, interpreted as flood‐stage subaqueous bar deposits; (4) ripple laminated or wavy bedded sand, silt and clay, representing the abandonment phase of channel‐fill deposits and lateral subaqueous bar deposition from suspension settling; (5) a well sorted very fine sand bed, presumed to result from a single storm event; (6) parallel or wavy beds of rooted silt, sand and clay, interpreted as lower energy emergent bar deposits; and (7) parallel or wavy beds of rooted silt and clay, believed to represent present‐day subaerial bar aggradation. The distribution of sedimentary facies can be interpreted in terms of the morphological evolution of the study area. Initial bar deposition of facies 3 and channel deposition of facies 2 was followed by lateral and upstream bar sedimentation of facies 3 and 4 which culminated with the deposition of the storm bed of facies 5. Facies 6 and 7 signify bar stabilization and abandonment.Patterned ground formed by thermal contraction and preserved in sediments as small, v‐shaped sand wedges provides the most direct sedimentological indicator of the arctic climate. However, winter ice and permafrost also govern the stratigraphic development of interchannel and channel‐mouth deposits. Ice cover confines flow at primary channel mouths, promoting the bypassing of sediments across the delta front during peak discharge in the spring. Permafrost minimizes consolidation subsidence and accommodation in the nearshore, further enhancing sediment bypass. Storms limit the seaward extent of bar development and promote a distinctive pattern of upstream and lateral island growth. The effects of these controls are reflected in the vertical distribution of facies in the Olivier Islands. The sedimentary succession differs markedly from that of a low‐latitude delta.
Initial motion and pivoting characteristics of sand particles in uniform and heterogeneous beds: experiments and modelling
Authors: Wallbridge  , Voulgaris  , Tomlinson  , Collins  
Published: March 2003

Experiments are described in which the threshold conditions for sediment entrainment are measured for uniform and mixed sand beds beneath both steady and combined steady/oscillatory flows. Derived critical shear stresses are compared with the mixed bed entrainment model of Wiberg & Smith (1987). As predicted by the model, coarser grains within a sand mixture are entrained at lower bed shear stresses than progressively finer grains. Entrainment occurs generally at lower shear stresses than predicted by the model, especially under unidirectional flows. This may be the result of grains resting in unusually unstable positions during the experiments because the beds are ‘unworked’ at the start of the experiments.The model of Wiberg and Smith predicts threshold conditions more accurately for the mixed beds if the bed pivoting angle is correctly defined. The pivoting angles of the beds used here are measured using a new technique designed specifically for comparison with the threshold data. The measured angles repeat the finding that the coarse grains are more mobile than the finer fractions of a mixture. The results are poorly described by the pivoting angle model presented by Wiberg & Smith (1987) and are better represented by a model of the form Φ = αDγ(Di/D50)β (after
Li & Komar, 1986), where α, γ and β are empirical constants. The threshold model is found to be more effective using the improved pivoting relationship.The entrainment of grains is found to be easier beneath unidirectional flows than combined flows, in accordance with previous authors’ findings. A suggestion that this result is caused by a change in the erosion mechanism beneath wave flows is made. Wave boundary layers may act as an extended laminar sublayer over bed grains and reduce the erosive efficiency of the overlying current flow. The results of the experiment have implications for the natural sorting mechanisms of sediment beds being deposited in near‐threshold flows.
Phylogeny of the Pyretophorus Series of Anopheles subgenus Cellia (Diptera: Culicidae)
Authors: Anthony ThomaS. G.. , And RalpH. E. HarbacH. , Kitching IaN. J.. 
Published: March 2003

SummaryA cladistic analysis based on morphological characters is presented for the Pyretophorus Series of subgenus Cellia of Anopheles. The cibarial armature was investigated for the first time since the pioneering work of Christophers (1933), which is still used to define taxonomic series within Cellia, and for the first time ever using scanning electron microscopy. Christophers’ observations of characters of the cibarial armature were corroborated and several novel characters discovered. Despite difficulties in delimiting and encoding morphological characters at the species level, the analysis provided insights into relationships within the Pyretophorus Series. The data support the monophyly of the Series and establish the Oriental species as a monophyletic group. The Afrotropical species are basal and paraphyletic relative to the Oriental species, with Anopheles christyi placed in the most basal position. The pattern of relationships suggests that the capacity to transmit malaria is an ancestral condition subsequently lost independently in several lineages.
Magnetic anomaly map for Northern, Western, and Eastern Europe*
Authors: Wonik Thomas , Trippler Klaus , Geipel Helmut , Greinwald Siegfried , Pashkevitch Inna 
Published: March 2003

All of the available data describing the Earth’s magnetic field in Northern, Western, and Eastern Europe (c. 3 × 106 data points) are compiled and presented at a scale of 1:20 400 000. The compilation meets two requirements (i) that the total field intensity anomalies reflect a survey acquired at an altitude of 3000 m above m.s.l. and during the same epoch, 1980.0; and (ii) that the anomalies are residuals after subtracting the common reference field DGRF1980. As the data span many epochs, geomagnetic data recorded at observatories and repeat stations were used to determine the best model for estimating the secular variation in all data up to 1980. This yielded magnetic anomalies with wavelengths up to the order of 2000 km. The precision of the resultant anomalies (amplitudes about – 1700 nT to 8000 nT) differ between ± 10 nT in Central Europe and ± 20 nT in the outer parts of the compilation.The resultant anomaly map contains a wealth of information to geoscientists studying global tectonic processes and the deep crustal composition of major continental crusts. It clearly shows the different anomaly patterns between the Palaeozoic and Precambrian crusts of Central and Eastern Europe. These anomalies are interpreted as lateral changes of magnetization in a horizontal plate. A comparison between the low‐level compilation and maps derived from the MAGSAT satellite at about 360 km altitude allows the description of the two different crust types in Europe.
Third‐order depositional sequences controlled by synsedimentary extensional tectonics: evidence from Upper Triassic carbonates of the Carnian Prealps (NE Italy)
Authors: Cozzi Andrea , Hardie Lawrence A. 
Published: March 2003

ABSTRACT The Upper Triassic platform‐margin deposits of the Carnian Prealps fail to show the succession of the two global sea‐level lowerings predicted for the Norian and Rhaetian by the Haq global sea‐level curve. In both cases a relative sea‐level rise occurs, a discrepancy that can be explained by an increase in tectonically controlled subsidence, a consequence of the plate‐scale rifting in the NW Tethys Gulf preceding oceanic spreading in the Jurassic. Pulses of tectonic subsidence followed by relative quiescence are capable of generating depositional sequences similar in gross geometry and duration to the third‐order eustatic cycles of Haq et al. The Late Triassic part of the Exxon global sea‐level curve, partly derived from correlatable strata within the same palaeogeographical domain, is likely to reflect pulses of tectonically induced subsidence rather than eustatic sea‐level changes.
Promoter elements involved in environmental and developmental control of potato proteinase inhibitor II expression
Authors: Lorberth Ruth , Dammann Christian , Ebneth Marcus , Amati Simone , Sánchez‐Serrano Jose J. 
Published: March 2003

SummaryThe proteinase inhibitor II (pin2) gene family exhibits two different modes of expression. It is, on the one hand, constitutively expressed in flowers of potato and tomato plants, and in potato tubers. On the other hand, its expression is induced in the plant foliage by mechanical wounding. To define cis‐regulatory elements involved in pin2 promoter activity, deletion analysis of a potato pin2 promoter has been performed in stably and transiently transformed potato and tobacco plants. Two different elements, a quantitative enhancer and a regulatory element, are required for promoter activity. While functional promoter elements required for pin2 activity in tubers and wounded leaves could not be separated, its expression in flowers is mediated by different cis‐acting sequences. Induction of pin2 expression in leaves by treatment with the plant growth regulators abscisic acid and jasmonic acid, and the general metabolite sucrose, depends on the presence of the regulatory element involved in expression in tubers and wounded leaves. Thus, pin2 expression in tubers and wounded leaves apparently results from the action of similar hormonal signals on closely linked promoter elements, while a different signal pathway leads to its constitutive expression in flowers.
A nuclear protein binding to dA/dT‐rich sequences upstream from the radish DMA promoter
Authors: Echeverria Manuel , Delcasso‐Tremousaygue Dominique , Delseny Michel 
Published: March 2003

SummaryThe external spacer (ES) of rRNA nuclear genes (rDNA) contains the sequences that control rDNA transcription initiation and enhancement. The ES is also characterized in most species by the presence of multiple repeated elements. In higher plants very few data are available on the cis‐ and fransacting elements which control rDNA transcription. Using electrophoretic mobility shift assays (EMSA) it is shown that nuclear extracts from young radish leaves (NER) contain a protein fraction which binds to specific sequences in the radish ES. DNase I footprinting analysis allows mapping of the NER protein binding to dA/dT homo‐polymer stretches and to a 13‐bp dA/dT‐rich short repeat, found both in the seven approximately 100 bp repeat regions (located ‐1077 to‐740 from transcription initiation site) and the region (‐120 to ‐55) containing the putative promoter for rDNA transcription initiation. Whether this ES binding is due to a single or several different proteins is not known. So far, protein(s) binding to dA/dT‐rich regions of a plant rDNA ES has not yet been described. Whether it is a specific RNA polymerase I transcription factor(s) or plays a more general role in genome expression remains to be elucidated.
Cytokinin induces the developmentally restricted synthesis of an extracellular protein in Physcomitrella patens
Authors: Neuenschwander Urs , Fleming Andrew J. , Kuhlemeier Cris 
Published: March 2003

SummaryEarly development of the moss Physcomitrella patens follows a simple course leading to the formation of a filamentous protonema containing only two cell‐types, chloronema and caulonema. The addition of the hormone cytokinin leads to the induction of multicellular buds from such protonema. The spectrum of extracellular proteins (ECPs) synthesized by P. patens has been investigated at defined stages of development and under defined hormone treatments. It is found that in contrast to the limited changes in intracellular protein synthesis detectable, in the extracellular environment major and specific changes in the patterns of proteins synthesized occur. For example, the presence of caulonema cells is characterized by the synthesis of a 25 kDa ECP whereas early chloronema differentiation is distinguished by the presence of a 38 kDa ECP. The analysis of the pattern of ECPs synthesized by developmental mutants altered in bud formation, and in response to cytokinin in tunicamycin treated protonema (in which bud induction is blocked) indicate that the synthesis of a 14 kDa ECP is specifically induced by cytokinin. This protein represents a novel cytokinin‐induced ECP.These data show that the differentiation of particular cell types in plants is associated with the synthesis of particular ECPs, and suggest that hormones which induce specific morphogenic events may do so via the synthesis of specific ECPs.