bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limited movement of Cucumber mosaic virus (CMV) in yellow passion flower in Brazil
Authors: Gioria R. , Espinha L. M. , Rezende J. A. M. , Gaspar J. O. , Kitajima E. W. 
Published: March 2003

Symptoms of Cucumber mosaic virus (CMV) on yellow passion flower (Passiflora edulis f. flavicarpa) are characterized by bright yellow mottling on leaves, starting at random points on the vine and diminishing in intensity towards the tip, which becomes symptomless as it grows. To determine whether symptomless portions of vines are CMV‐free or represent latent infection, leaves with and without symptoms were collected from infected vines in the field. Biological, serological (plate‐trapped antigen enzyme‐linked immunosorbent assay, PTA‐ELISA), Western blot and dot‐blot hybridization assays showed that portions of the vines without symptoms were CMV‐free. Vegetatively propagated vines with symptoms showed remission of symptoms on newly developed leaves. One year later, no CMV was detected in the upper leaves of these plants. Mechanically inoculated passion flower seedlings behaved similarly; symptoms were shown by few leaves after inoculation. Afterwards, plants became symptomless and CMV was not detected in the upper leaves or root system, 40 or 85 days after inoculation. The mechanism responsible for remission of symptoms accompanied by CMV disappearance is not known.
Genetic variability within Phaeoisariopsis griseola from Central America and its implications for resistance breeding of common bean
Authors: Mahuku G. S. , Jara C. , Cuasquer J. B. , Castellanos G. 
Published: March 2003

The genetic and virulence variability of 112 isolates of Phaeoisariopsis griseola, collected from various locations in Central America, were studied using seven random amplified polymorphic DNA (RAPD) primers and 12 common‐bean differential genotypes. Broad molecular diversity (H = 0·92) among isolates was found using RAPD markers. Fifty pathotypes were identified on 12 differential bean genotypes, 29 of which were represented by only one isolate. Only 18 pathotypes were found in two or more countries. Pathotype 63‐63 was the most virulent and caused leaf spots on all 12 common‐bean differential genotypes. Comparison of virulence phenotypes and RAPD profiles to known Andean P. griseola isolates confirmed that all isolates belonged to the Mesoamerican group. Pairwise comparison between individual RAPD loci showed that the majority were in gametic phase linkage disequilibrium, revealing that P. griseola maintains a genetic structure that is consistent with asexual reproduction. The molecular and virulence diversities of P. griseola isolates from Central America imply that using single resistance genes to manage angular leaf spot is inadequate and stacking resistance genes may be necessary to manage the disease effectively.
Rapid preparation of Fusarium DNA from cereals for diagnostic PCR u sing sonification and an extraction kit
Authors: Knoll S. , Mulfinger S. , Niessen L. , Vogel R. F. 
Published: March 2003

Several PCR methods have recently been developed for Fusarium analysis in pure cultures. To use these new techniques in mycological studies and in industrial quality control, a protocol was set up for the rapid preparation of fungal DNA from cereals. An ultrasonification probe (sonotrode) and a lysis buffer were used for mechanical lysis of mycelia from infected grains. Following ultrasonification, DNA was isolated using a commercially available kit. DNA preparation was completed within 5 min per sample. The method resulted in DNA of sufficient quality and quantity for diagnostic PCR. Group‐ and species‐specific primers were used to detect DNA of Fusarium graminearum and F. culmorum in species‐specific assays as well as trichothecene‐producing Fusarium spp. in a group‐specific system. A minimum of one F. graminearum‐infected grain added to an uninfected 40 g wheat sample was detectable with a species‐specific PCR. The PCR signals produced with primers specific for the tri5 gene of trichothecene‐producing Fusarium spp. and with primers for the detection of F. graminearum (gaoA) were in accordance with corresponding concentrations of deoxynivalenol (DON) found in samples by HPLC analysis. The speed of the protocol developed may promote the use of PCR in routine applications in an agro‐industrial context.
Modulation of CD8 and CD3 by HIV or HIV Antigens
Authors: Jason J. , Inge K. L. 
Published: March 2003

To investigate whether human immunodeficiency virus (HIV)‐1 and HIV‐1 antigens modulate surface and cytoplasmic CD8 or CD3, as well as CD4, we used cell permeabilization reagents, surface/cytoplasmic fluorescent staining, multiparameter flow cytometric techniques and an in vitro culture system in which relatively few lymphocytes are actively infected with HIV. Human peripheral blood lymphocytes were: not stimulated, not stimulated but HIV‐inoculated, phytohaemagglutinin (PHA)‐stimulated, PHA/HIV‐inoculated (PHA/HIV), or placed into media with soluble gp120, Rev or Nef. HIV inoculation and Nef had striking modulatory effects on CD8. The cytoplasmic CD8 median fluorescent intensity (MFI) of positive lymphocytes was lower for cells in unstimulated/HIV‐infected cultures than unstimulated cultures (44 versus 62% of ex vivo value, P = 0.032) and lower for cells in PHA/HIV cultures than in PHA cultures (56 versus 100% of ex vivo, P = 0.041). The surface CD8 MFI values for Nef were significantly lower than the ex vivo value (75% of ex vivo, P = 0.006). At days 2–7 of culture, Rev was associated with slight reductions in surface CD4 MFI (58% of ex vivo versus 78% of ex vivo for unstimulated cultures, P = 0.047) and greater effects on cytoplasmic CD3 MFI (131 versus 179% of ex vivo for unstimulated cultures, P = 0.035), and surface CD8 MFI (70% of ex vivo, P = 0.006 versus ex vivo value). The globality of Rev's effects suggests these are related to a shared processing pathway, i.e. not due to direct interaction with CD3, CD4 and CD8; the effects of HIV inoculation and Nef on CD8 expression appear to be more CD8 specific. Because CD8 is essential for cytotoxic T‐cell function, its down‐modulation could inhibit this activity, including anti‐HIV cytotoxicity. Given the critical roles of CD3 and CD8 in T‐lymphocyte signal transduction and antigen responsiveness, the effects of HIV, Rev and Nef on these molecules have clinically significant implications concerning the pathogenesis and treatment of HIV.
Non‐Th2 Regulatory T‐Cell Control of Th1 Autoimmunity
Authors: Bach J.‐F. 
Published: March 2003

The Th1/Th2 concept brought an attractive explanation of the active self tolerance which appears to control the onset of pathogenic autoimmunity. New data coming from various independent horizons indicate that self immunoregulation could also depend to a large extent on non‐Th2 cells. Original data derived from the day‐3‐thymectomy model, selective T‐cell lymphocytopenia and nonobese diabetic mice are discussed in an effort to analyze similarities and differences in phenotype (CD25, CD62L and CD45RB) and cytokine pattern (notably interleukin (IL)‐4, IL‐10 and transforming growth factor (TGF)β) of regulatory cells involved in these models. The relationship of these cells with Th3, Tr1 and natural killer (NK) T cells are also discussed. The hypothesis is proposed that CD25 CD62L T cells mediate the physiologic regulation of self regulation whereas Th2 and Th3 cells are essentially induced following sensitization against autoantigens.
The Cellular Response Associated with Cervical Intraepithelial Neoplasia in HIV+ and HIV– Subjects
Authors: Ahmed S. M. , Al‐Doujaily H. , Reid W. M. N. , Johnson M. A. , Poulter L. W. 
Published: March 2003

This study investigates local alterations in T‐cell and macrophage subsets that occur in cervical epithelial neoplasia (CIN), in the presence and absence of human immunodeficiency virus (HIV) infection. Ectocervical biopsies from 10 women with CIN who were infected with HIV, and 10 women with CIN but no HIV infection were studied by immunocytochemistry.Significantly increased proportions of activated CD8+ T cells were seen in all CIN biopsies, and these proportions were further increased in the presence of HIV infection. Levels of CD8+TIA‐1+ cells were particularly increased in the CIN+HIV+ group. There was a lack of expression of CD28 on the CD8+ cells of the epithelium of CIN+HIV+ samples. A significant reduction in the proportion of epithelial inductive D1+ macrophages and an increase in D1+D7+‐suppressive cells were observed in the CIN+HIV+ cohort.The lack of expression of CD28 on the CD8+ cells of the epithelium of CIN+HIV+ samples in combination with the reduced CD4+ T‐cell numbers seen in the presence of HIV infection may contribute to the development of higher grade CIN in this susceptible group. This may be aggravated by the reduction in the D1+ epithelial inductive macrophages, which might reflect recruitment of more suppressive D1+D7+ cells. This would further compromise the ability of the local T‐cell system to respond to antigens and thus contribute to the development of neoplasia at this site. These results suggest that the increase in activated CD8+ T cells is a consequence rather than a cause of CIN.
An Established Immune Response against Ovalbumin is Suppressed by a Transferable Serum Factor Produced after Ovalbumin Feeding: A Role of CD25+ Regulatory Cells
Authors: Karlsson M. R. , Kahu H. , Hanson L. Å. , Telemo E. , Dahlgren U. I. 
Published: March 2003

We have previously demonstrated that rats fed ovalbumin (OVA) develop a tolerogenic activity in serum, which upon transfer induces tolerance to OVA and suppression of the immune response to a bystander antigen. Here, we have extended these studies and analysed if the tolerogenic activity in serum could suppress an established immune response in the recipients. Rats were immunized with OVA, 4 and 1 week prior to the transfer of serum from either OVA‐fed or control animals.Rats that received serum from OVA‐fed donors had significantly lower delayed‐type hypersensitivity (DTH) reaction against OVA 1 week after the serum transfer compared with the controls, and the levels of immunoglobulin (IgG) anti‐OVA antibodies were significantly lower 2 and 4 weeks after serum transfer. Monomeric OVA in amounts corresponding to the OVA transferred with serum did not induce the reduction of DTH response or IgG anti‐OVA antibody levels. In vitro, the proliferation of OVA‐stimulated spleen cells, taken from recipients of tolerogenic serum, was significantly lower compared with spleen cells from the controls. The in vitro suppression seemed to be mediated by a population of CD25+ cells, because the removal of such cells from OVA‐stimulated spleen cell suspensions resulted in increased proliferation in cultures from rats receiving tolerogenic serum. Our results showed that the tolerogenic serum factor can suppress an established immune response in recipient animals, possibly through induction of regulatory CD25+ cells. Whether this capacity might be used to influence chronic inflammatory conditions needs to be investigated.
Bioclastic sediment lobes on a supply dominated Upper Cretaceous carbonate platform margin, Montagna della Maiella, Italy
Authors: VECSEI ADAM 
Published: March 2003

A thick bioclastic sediment wedge was deposited on the slope of the Maiella carbonate platform margin in the Late Campanian to Late Maastrichtian. The wedge consists of lobate depositional units (laterally and vertically convex structures). The complex internal geometries of the lobes combine characteristics of unidirectional sandwaves and the alternating point‐sources of deltas. Excellent outcrop permits a detailed documentation and discussion of the depositional processes.The sediment wedge constitutes a supersequence, which prograded along the platform margin as a result of high sediment supply and forced regression. Within the supersequence, a hierarchy of higher‐order stratigraphic units (sequence sets and sequences) are developed. The individual bioclastic sediment lobes are interpreted as systems tracts and parasequences of the sequences within the sequence sets.
Carbon‐isotope stratigraphy in shallow‐water carbonates: implications for Cretaceous black‐shale deposition
Authors: GRÖTSCH JÜRGEN , BILLING IAN , VAHRENKAMP VOLKER 
Published: March 2003

A Barremian to Albian succession on Mount Kanala, part of a Tethyan isolated carbonate platform, was investigated for its δ13C variations. The limestone sequence is composed of a series of peritidal shallowing‐upward cycles with clear petrographic evidence for strong early diagenetic overprinting related to repeated subaerial exposure. Despite significant impact of diagenesis, the observed changes in δ13C can be very well correlated with deep‐water sections from different ocean basins and shallow water carbonate platforms in the Middle East. This lends further support to the applicability of δ13C variations for stratigraphic purposes in shallow‐water limestones. Using the δ13C signal, time resolution in Lower Cretaceous platform carbonates can be significantly increased, independent of bio‐zonations often hampered by ecological variability.Cyclostratigraphic analysis of the Aptian part of the section shows that strong positive excursions of the cumulative departure from mean cycle thickness of the peritidal shallowing‐upward cycles coincide with global positive δ13C excursions. This, and the fact that positive shifts in the δ13C record are preserved within shallow water limestones, provide evidence that black‐shale accumulation in the ocean basins occurred during sea‐level rise and flooding of platform tops. Integration of carbon‐isotope‐, cyclo‐ and sequence‐stratigraphic results from different carbonate platforms indicate that strong positive global δ13C shifts and concurrent organic‐carbon burial during black‐shale deposition are ultimately caused by rapid rises of eustatic sea level. Hence, the rate of change of eustatic sea level is considered to play a crucial role in black‐shale accumulation in the global ocean basins during the Cretaceous.
Petrography and geochemistry of early‐stage, fine‐ and medium‐crystalline dolomites in the Middle Devonian Presqu’ile Barrier at Pine Point, Canada
Authors: Qing HAIRUO 
Published: March 2003

The petrography and geochemistry of fine‐ and medium‐crystalline dolomites of the Middle Devonian Presqu’ile barrier at Pine Point (Western Canada Sedimentary Basin) are different from those of previously published coarse‐crystalline and saddle dolomites that are associated with late‐stage hydrothermal fluids. Fine‐crystalline dolomite consists of subhedral to euhedral crystals, ranging from 5 to 25 μm (mean 8 μm). The dolomite interbedded with evaporitic anhydrites that occur in the back‐barrier facies in the Elk Point Basin. Fine‐crystalline dolomite has δ18Ο values between −1·6 to –3·8‰ PDB and 87Sr/86Sr ratios from 0·7079–0·7081, consistent with derivation from Middle Devonian seawater. Its Sr concentrations (55–225 p.p.m., mean 105 p.p.m.) follow a similar trend to modern Little Bahama seawater dolomites. Its rare earth element (REE) patterns are similar to those of the limestone precursors. These data suggest that this fine‐crystalline dolomite formed from Middle Devonian seawater at or just below the sea floor.Medium‐crystalline dolomite in the Presqu’ile barrier is composed of anhedral to subhedral crystals (150–250 μm, mean 200 μm), some of which have clear rims toward the pore centres. This dolomite occurs mostly in the southern lower part of the barrier. Medium‐crystalline dolomite has δ18O values between −3·7 to −9·4‰ PDB (mean −5·9‰ PDB) and 87Sr/86Sr ratios from 0·7081–0·7087 (mean 0·7084); Sr concentrations from 30 to 79 p.p.m. (mean 50 p.p.m.) and Mn content from 50 to 253 p.p.m. (mean 161 p.p.m.); and negative Ce anomalies compared with those of marine limestones. The medium‐crystalline dolomite may have formed either (1) during shallow burial at slightly elevated temperatures (35–40 °C) from fluids derived from burial compaction, or, more likely (2) soon after deposition of the precursor sediments by Middle Devonian seawater derived from the Elk Point Basin.These results indicate that dolomitization in the Middle Devonian Presqu’ile barrier occurred in at least two stages during evolution of the Western Canada Sedimentary Basin. The geochemistry of earlier formed dolomites may have been modified if the earlier formed dolomites were porous and permeable and water/rock ratios were large during neomorphism.
Miocene Gypcretes from the Calama Basin, northern Chile
Authors: Hartley Adrian J. , May Geoffrey 
Published: March 2003

Gypcretes of Miocene age are preserved beneath a 9·53 ± 0·36 Ma ignimbrite along the eastern margin of the Oligo‐Pleistocene Calama Basin, northern Chile. They are restricted to a single stratigraphic horizon developed within laterally extensive (>35 km) coalesced alluvial fan deposits, developed along the margin of an endorheic basin. Two types of gypcrete are recognized. Type 1 comprises almost completely gypsum‐cemented sandstones containing alabastrine nodules and columns, sub‐vertical and horizontal veins of fibrous gypsum and ‘v‐shaped’ cracks infilled by clastic material, and are interpreted as surface weathered gypsic crusts. Type 2 gypcretes are composed of massive, reddened poikilitic and mesocrystalline gypsum (up to 80% of the rock) with isolated bedding‐parallel, clast‐rich lenses (200 × 30 cm) and sub‐vertical veins of fibrous gypsum. The massive texture resembles that of well developed B horizons in Quaternary alluvial desert soils. The crystal forms suggest an origin as a subsurface gypsic crust formed by a combination of hydromorphic (poikilitic) and illuvial (mesocrystalline) processes with the fibrous gypsum veins suggestive of periodic surface exposure.Gypcrete horizons are up to 25 m thick and composed of both gypcrete types. They represent superimposed phases of surface and subsurface gypcrete development. Quaternary gypcretes are developed in arid climatic regimes, but are not considered to develop under hyper‐arid climates. An arid climate is considered to have prevailed in the study area up to 9·5 Ma after which a change to hyper‐aridity favoured gypcrete preservation.
Dolomite formation and biogeochemical cycles in the Phanerozoic
Authors: Burns Stephen J. , Mckenzie Judith A. , Vasconcelos Crisogono 
Published: March 2003

SummaryBased on present knowledge of the purely chemical controls on the kinetics of massive dolomite formation, the abundance and distribution of dolomite throughout the Phanerozoic remains an enigma, sometimes referred to as the ‘dolomite problem'. Comparing dolomite abundance to secular variation in seawater chemistry indicates that some changes in seawater chemistry are more likely to have resulted from extensive dolomitization rather than to have caused it. The recently formulated microbial dolomite model provides the opportunity to view the geological history of dolomite formation from a new perspective. A biogeochemical approach to the ‘dolomite problem' reveals a plausible connection between Phanerozoic geochemical cycles and dolomite formation. In particular, periods of more extensive dolomitization broadly correlate with diverse indicators of decreased oxygen levels in the atmosphere and oceans. Lowered oxygen levels would have fostered a more active community of anaerobic microbes, including sulphate‐reducing bacteria, which in turn could have led to more extensive dolomitization of marine carbonates.
Preservation of cross‐strata due to the migration of subaqueous dunes: an experimental investigation
Authors: Leclair Suzanne F. 
Published: March 2003

AbstractThis experimental investigation examined the controls on the geometry of cross‐sets formed by subaqueous dunes. A range of steady, unidirectional flow conditions spanning the field of dune existence was investigated, and aggradation rate ranged from 0 mm s−1 to 0·014 mm s−1. Data from an ultrasonic depth profiler consist of high‐resolution temporal and spatial series of bed profiles from which dune height and length, migration rate and the depth of trough scour were measured. Cross‐set thickness and length were measured from sediment peels. The size and shape of dunes from an equilibrium assemblage change continuously. Individual dunes commonly increase in height by trough scouring and, occasionally, by being caught‐up by the upstream dune. Both types of behaviour occur suddenly and irregularly in time and, hence, do not appear to depend on dunes further upstream. However, dune climbing or flattening is a typical response of dunes that disappear under the influence of the upstream dune. All types of behaviour occur at any flow velocity or aggradation rate. Successive dune‐trough trajectories, defined by dunes showing various behaviours, affect the geometry of the preserved cross‐sets. Mean cross‐set thickness/mean dune height averages 0·33 (±0·7), and mean cross‐set length/mean dune length averages 0·49 (±0·08), and both show no systematic variation with aggradation rate or flow velocity. Mean cross‐set thickness/mean cross‐set length tends to decrease with increasing flow velocity and Froude number, therefore allowing a qualitative estimation of flow conditions. Quantitative analysis of the temporal changes in the geometry and migration rate of individual dunes allows the development of a two‐dimensional stochastic model of dune migration and formation of cross‐sets. Computer realizations produced stacks of cross‐sets of comparable shape and thickness to laboratory flume observations, indicating a good empirical understanding of the variability of dune‐trough trajectories. However, interactions among dunes and aggradation rates of the order of 10−2 mm s−1 should be considered in future improved models.
Transport and deposition of pyroclastic density currents over an inhabited area: the deposits of the AD 79 eruption of Vesuvius at Herculaneum, Italy
Authors: Gurioli L. , Cioni R. , Sbrana A. , Zanella E. 
Published: March 2003

AbstractGeological and volcanological studies were performed in the Herculaneum excavations, 7 km west of Vesuvius, Italy, to reconstruct the main features of the pyroclastic density currents and the temporal sequence of thead 79 eruptive events that destroyed and buried the town. The identification of two distinctive marker beds allows correlation of these deposits with the better‐known sequences to the south of Vesuvius, along the dispersal axis of the Plinian fall deposit. Detailed observations from stratigraphic sections show that the pyroclastic density current deposits are characterized by several sedimentary facies, each recording different depositional and emplacement mechanisms. Facies analysis reveals both lateral and vertical variations from massive to stratified deposits, which can be related to the combined effects of flow dynamics and local irregularities of the substratum at centimetre or metre scales. These topographic irregularities enhanced turbulence and allowed rapid transition from non‐turbulent to turbulent transport within the flow. Fabric data from these deposits, both from roof tile orientations and anisotropy magnetic susceptibility (AMS) analyses carried out on some of the pyroclastic deposits, suggest that the pyroclastic density currents were strongly affected by the presence of buildings. These obstacles probably caused deflection and separation of flows into multiple lobes that moved in different directions.