bluuebunny/crossref_metadata_2025_split huggingface dataset:
FlaC, a protein of Campylobacter jejuni TGH9011 (ATCC43431) secreted through the flagellar apparatus, binds epithelial cells and influences cell invasion
Authors: Song Y. C. , Jin S. , Louie H. , Ng D. , Lau R. , Zhang Y. , Weerasekera R. , Al Rashid S. , Ward L. A. , Der S. D. , Chan V. L. 
Published: July 2004

SummaryType III secretion systems identified in bacterial pathogens of animals and plants transpose effectors and toxins directly into the cytosol of host cells or into the extracellular milieu. Proteins of the type III secretion apparatus are conserved among diverse and distantly related bacteria. Many type III apparatus proteins have homologues in the flagellar export apparatus, supporting the notion that type III secretion systems evolved from the flagellar export apparatus. No type III secretion apparatus genes have been found in the complete genomic sequence of Campylobacter jejuni NCTC11168. In this study, we report the characterization of a protein designated FlaC of C. jejuni TGH9011. FlaC is homologous to the N‐ and C‐terminus of the C. jejuni flagellin proteins, FlaA and FlaB, but lacks the central portion of these proteins. flaC null mutants form a morphologically normal flagellum and are highly motile. In wild‐type C. jejuni cultures, FlaC is found predominantly in the extracellular milieu as a secreted protein. Null mutants of the flagellar basal rod gene (flgF) and hook gene (flgE) do not secrete FlaC, suggesting that a functional flagellar export apparatus is required for FlaC secretion. During C. jejuni infection in vitro, secreted FlaC and purified recombinant FlaC bind to HEp‐2 cells. Invasion of HEp‐2 cells by flaC null mutants was reduced to a level of 14% compared with wild type, suggesting that FlaC plays an important role in cell invasion.
Mycobacterial lipoarabinomannan and related lipoglycans: from biogenesis to modulation of the immune response
Authors: Briken Volker , Porcelli Steven A. , Besra Gurdyal S. , Kremer Laurent 
Published: July 2004

SummaryThe cell wall component lipoarabinomannan (ManLAM) from Mycobacterium tuberculosis is involved in the inhibition of phagosome maturation, apoptosis and interferon (IFN)‐γ signalling in macrophages and interleukin (IL)‐12 cytokine secretion of dendritic cells (DC). All these processes are important for the host to mount an efficient immune response. Conversely, LAM isolated from non‐pathogenic mycobacteria (PILAM) have the opposite effect, by inducing a potent proinflammatory response in macrophages and DCs. LAMs from diverse mycobacterial species differ in the modification of their terminal arabinose residues. The strong proinflammatory response induced by PILAM correlates with the presence of phospho‐myo‐inositol on the terminal arabinose. Interestingly, recent work indicates that the biosynthetic precursor of LAM, lipomannan (LM), which is also present in the cell wall, displays strong proinflammatory effects, independently of which mycobacterial species it is isolated from. Results from in vitro assays and knock‐out mice suggest that LM, like PILAM, mediates its biological activity via Toll‐like receptor 2. We hypothesize that the LAM/LM ratio might be a crucial factor in determining the virulence of a mycobacterial species and the outcome of the infection. Recent progress in the identification of genes involved in the biosynthesis of LAM is discussed, in particular with respect to the fact that enzymes controlling the LAM/LM balance might represent targets for new antitubercular drugs. In addition, inactivation of these genes may lead to attenuated strains of M. tuberculosis for the development of new vaccine candidates.
Natural variation and QTL analysis for cationic mineral content in seeds of Arabidopsis thaliana
Authors: VREUGDENHIL D. , AARTS M. G. M. , KOORNNEEF M. , NELISSEN H. , ERNST W. H. O. 
Published: July 2004

ABSTRACTNaturally occurring genetic variation for contents of cationic minerals in seeds of Arabidopsis thaliana was studied by screening a series of accessions (ecotypes) for Ca, Fe, K, Mg, Mn, Na, Zn, and for total contents of P. Variation was observed for all minerals and correlations between contents of various minerals were present, most noticeably between Ca and Mg, P and Mg, and P and Mn. The genetic basis of this variation was further studied by QTL analysis, using the Landsberg erecta (Ler) × Cape Verde Islands (Cvi) recombinant inbred population. For all minerals, except Na, one or more QTL were detected, explaining up to 78% of the variation. The map positions of several QTL were confirmed by analysis of near isogenic lines, carrying small Cvi introgressions in Ler background. Interesting co‐locations of QTL suggest pleiotropic effects, due to physiological coupling of the accumulation of certain minerals or to linkage of different genes. By comparing the map positions of QTL with the positions of genes expected to play a role in cation translocation, several candidate genes are suggested.
Effect of respiratory homeostasis on plant growth in cultivars of wheat and rice
Authors: KURIMOTO K. , DAY D. A. , LAMBERS H. , NOGUCHI K. 
Published: July 2004

ABSTRACTSome plants have the ability to maintain similar respiratory rates (measured at the growth temperature), even when grown at different temperatures, a phenomenon referred to as respiratory homeostasis. The underlying mechanisms and ecological importance of this respiratory homeostasis are not understood. In order to understand this, root respiration and plant growth were investigated in two wheat cultivars (Triticum aestivum L. cv. Stiletto and cv. Patterson) with a high degree of homeostasis, and in one wheat cultivar (T. aestivum L. cv. Brookton) and one rice cultivar (Oryza sativa L. cv. Amaroo) with a low degree of homeostasis. The degree of homeostasis (H) is defined as a quantitative value, which occurs between 0 (no acclimation) and 1 (full acclimation). These plants were grown hydroponically at constant 15 or 25 °C. A good correlation was observed between the rate of root respiration and the relative growth rates (RGR) of whole plant, shoot or root. The plants with high H showed a tendency to maintain their RGR, irrespective of growth temperature, whereas the plants with low H grown at 15 °C showed lower RGR than those grown at 25 °C. Among several parameters of growth analysis, variation in net assimilation rate per shoot mass (NARm) appeared to be responsible for the variation in RGR and rates of root respiration in the four cultivars. The plants with high H maintained their NARm at low growth temperature, but the plants with low H grown at 15 °C showed lower NARm than those grown at 25 °C. It is concluded that respiratory homeostasis in roots would help to maintain growth rate at low temperature due to a smaller decrease in net carbon gain at low temperature. Alternatively, growth rate per se may control the demand of respiratory ATP, root respiration rates and sink demands of photosynthesis. The contribution of nitrogen uptake to total respiratory costs was also estimated, and the effects of a nitrogen leak out of the roots and the efficiency of respiration on those costs are discussed.
The decrease in growth of phosphorus‐deficient maize leaves is related to a lower cell production
Authors: ASSUERO S. G. , MOLLIER A. , PELLERIN S. 
Published: July 2004

ABSTRACTThe spatial distribution of leaf elongation and adaxial epidermal cell production in leaf 6 of maize (Zea mays L. cv. Cecilia) plants grown in a growth chamber under two contrasting availabilities of P in the soil was investigated. Lower displacement velocities from 32.5 mm from leaf base and a shorter growth zone were found in low P (LP) leaves compared with control leaves. P deficiency significantly diminished maximum relative elemental growth rate and shifted its location closer to the leaf base. Cells were significantly longer in LP than in control leaves for all positions from the leaf base except at the end of the growth zone. For both treatments it took a similar time for a cell situated at the leaf base to reach the limit of the growth zone. The average length of the cell division zone was decreased by 21% in LP leaves. Significant differences were found in cell production and cell division rates from 12.5 mm from the leaf base although maximum values were similar between P treatments. A shorter zone of cell division with lower cell production rates along most of its length was the regulatory event that decreased cell production, and ultimately leaf elongation rates, in P‐deficient maize plants.
Low‐temperature photosynthetic performance of a C4grass and a co‐occurring C3grass native to high latitudes
Authors: KUBIEN D. S. , SAGE R. F. 
Published: July 2004

ABSTRACTThe photosynthetic performance of C4plants is generally inferior to that of C3species at low temperatures, but the reasons for this are unclear. The present study investigated the hypothesis that the capacity of Rubisco, which largely reflects Rubisco content, limits C4photosynthesis at suboptimal temperatures. Photosynthetic gas exchange, chlorophyllafluorescence, and thein vitroactivity of Rubisco between 5 and 35 °C were measured to examine the nature of the low‐temperature photosynthetic performance of the co‐occurring high latitude grasses,Muhlenbergia glomerata(C4) andCalamogrostis canadensis(C3). Plants were grown under cool (14/10 °C) and warm (26/22 °C) temperature regimes to examine whether acclimation to cool temperature alters patterns of photosynthetic limitation. Low‐temperature acclimation reduced photosynthetic rates in both species. The catalytic site concentration of Rubisco was approximately 5.0 and 20 µmol m−2inM. glomerataandC. canadensis, respectively, regardless of growth temperature. In both species,in vivoelectron transport rates below the thermal optimum exceeded what was necessary to support photosynthesis. In warm‐grownC. canadensis, the photosynthesis rate below 15 °C was unaffected by a 90% reduction in O2content, indicating photosynthetic capacity was limited by the capacity of Pi‐regeneration. By contrast, the rate of photosynthesis inC. canadensisplants grown at the cooler temperatures was stimulated 20–30% by O2reduction, indicating the Pi‐regeneration limitation was removed during low‐temperature acclimation. InM. glomerata,in vitroRubisco activity and gross CO2assimilation rate were equivalent below 25 °C, indicating that the capacity of the enzyme is a major rate limiting step during C4photosynthesis at cool temperatures.
Gene expression profiling and protection of Medicago truncatula against a fungal infection in response to an elicitor from green algae Ulva spp
Authors: CLUZET S. , TORREGROSA C. , JACQUET C. , LAFITTE C. , FOURNIER J. , MERCIER L. , SALAMAGNE S. , BRIAND X. , ESQUERRÉ‐TUGAYÉ M.‐T. , DUMAS B. 
Published: July 2004

ABSTRACTElicitors are molecules known to trigger plant defence responses against pathogens. In a search for new sources of eliciting compounds from marine algae, an extract was prepared from green algae, Ulva spp., and its elicitor activity was established on the model legume, Medicago truncatula. When infiltrated into plant tissues or sprayed onto the leaves, this extract induced the expression of the defence‐related marker gene PR10 without provoking necrosis. Spraying a solution at 500 µg mL−1 was sufficient to obtain maximum induction of PR10 after 2 d. Using a cDNA array enriched in genes potentially involved in plant defence, the expression of 152 genes was monitored after one or two consecutive treatments. A broad range of defence‐related transcripts was found to be up‐regulated, notably genes involved in the biosynthesis of phytoalexins, pathogenesis‐related proteins and cell wall proteins. In contrast, the expression of primary metabolism‐related genes did not change significantly. Consistent with its effect on defence gene expression, it was found that prior treatment of M. truncatula with the Ulva extract protected the plants against subsequent infection by the pathogenic fungus Colletotrichum trifolii.
Contourite origin for shelf and upper slope sand sheet, offshore Antarctica
Authors: Rodriguez Antonio B. , Anderson John B. 
Published: July 2004

AbstractA widespread (3200 km2), thick (10 cm to > 100 cm) sand deposit exists on the continental shelf and upper slope offshore of the Pennell Coast, Antarctica. The sand body occurs at water depths between 200 and 1200 m. The mean grain size of the sand varies from 3·3 phi to 1·2 phi, and the composition is dominantly volcanic. The only source for this volcanic material is Cape Adare, a volcanic headland. Sands are transported up to 70 km from Cape Adare by a westward‐flowing circumpolar boundary current that impinges on the upper slope and shelf. Radiocarbon dates from the sand and from the glacial unit beneath it indicate that the deposit formed within the past 9000 years. The occurrence of this sand sheet demonstrates the ability of contour currents to assemble extensive sand bodies on the shelf and upper slope and the relatively rapid rate at which these deposits may form.
Morphology and distribution of fossil soils in the Permo‐Pennsylvanian Wichita and Bowie Groups, north‐central Texas, USA: implications for western equatorial Pangean palaeoclimate during icehouse–greenhouse transition
Authors: Tabor Neil John , Montañez Isabel P. 
Published: July 2004

AbstractAnalysis of stacked Permo‐Pennsylvanian palaeosols from north‐central Texas documents the influence of palaeolandscape position on pedogenesis in aggradational depositional settings. Palaeosols of the Eastern shelf of the Midland basin exhibit stratigraphic trends in the distribution of soil horizons, structure, rooting density, clay mineralogy and colour that record long‐term changes in soil‐forming conditions driven by both local processes and regional climate. Palaeosols similar to modern histosols, ultisols, vertisols, inceptisols and entisols, all bearing morphological, mineralogical and chemical characteristics consistent with a tropical, humid climate, represent the Late Pennsylvanian suite of palaeosol orders. Palaeosols similar to modern alfisols, vertisols, inceptisols, aridisols and entisols preserve characteristics indicative of a drier and seasonal tropical climate throughout the Lower Permian strata. The changes in palaeosol morphology are interpreted as being a result of an overall climatic trend from relatively humid and tropical, moist conditions characterized by high rainfall in the Late Pennsylvanian to progressively drier, semi‐arid to arid tropical climate characterized by seasonal rainfall in Early Permian time. Based on known Late Palaeozoic palaeogeography and current hypotheses for atmospheric circulation over western equatorial Pangea, the Pennsylvanian palaeosols in this study may be recording a climate that is the result of an orographic control over regional‐scale atmospheric circulation. The trend towards a drier climate interpreted from the Permian palaeosols may be recording the breakdown of this pre‐existing orographic effect and the onset of a monsoonal atmospheric circulation system over this region.
Scale and timing of Rare Earth Element redistribution in the Taconian foreland of New England
Authors: Bock Barbara , Hurowitz J. A. , Mclennan S. M. , Hanson G. N. 
Published: July 2004

AbstractClastic sedimentary rocks, deposited on eastern North America in response to the Taconian Orogeny, commonly have Sm/Nd isotope relationships indicating substantial isotope disturbance near or subsequent to the time of sedimentation that may be associated with severe depletion in light rare earth elements (LREE). Affected units [Normanskill Formation (Austin Glen and Pawlet Members), Frankfort Formation and Perry Mountain Formation] are widely separated both geographically (western New York to western Maine) and stratigraphically (Middle Ordovician to Silurian). A model is proposed for the most likely explanation of the observed REE and Sm/Nd isotope relationships involving a two‐stage process. In the first stage, REE are redistributed on a mineralogical scale (dissolution/precipitation on a sample scale) often with the involvement of REE‐enriched trace phases such as apatite and monazite. This stage typically takes place during diagenesis but may also take place later during metamorphism and/or recent weathering, and results in isotope re‐equilibration on a sample scale. The second stage occurs when one or more of these phases is redissolved and REE are transported on large advective scales. Where LREE‐enriched phases are involved, this gives rise to LREE depletion in whole rocks. The timing of this second stage cannot be constrained from Sm/Nd isotope data and may take place at any time subsequent to the isotope re‐equilibration. Such complex histories of REE redistribution may result in serious errors in estimating Nd model ages but not in estimating the Nd isotope composition at the age of sedimentation. Thus, Sm/Nd ratios even of unmetamorphosed sedimentary rocks have to be carefully evaluated before the calculation of depleted mantle model ages for the provenance.
Time course of coagulation parameters, cytokines and adhesion molecules in Plasmodium falciparum malaria
Authors: Vogetseder Alexander , Ospelt Caroline , Reindl Markus , Schober Maria , Schmutzhard Erich 
Published: July 2004

SummaryWe studied 38 patients with malaria tropica over a period of 5 days during antiparasitic therapy. Serum or plasma levels of interleukin (IL) 1β, IL‐6, IL‐10, tumour necrosis factor‐α (TNF‐α), the soluble vascular adhesion molecule (sVCAM) and the soluble intracellular adhesion molecule (sICAM) were determined by enzyme‐linked immunosorbent assay. Protein C and antithrombin III activity were analysed by chromogenic tests and protein S activity by a clotting test. Antithrombin III, protein C and protein S activity was significantly lower in patients with severe malaria and displayed a highly significant increase in activity over the time of evaluation. Levels of sVCAM and sICAM were increased for the whole study period, but no significant differences were found between severe and mild malaria cases. Serum IL‐1β, IL‐6 and IL‐10 levels were significantly higher in patients with severe malaria, whereas no significant differences were found for TNF‐α. IL‐6 and IL‐10 decreased significantly over 5 days during schizontocidal therapy. Our data show an impairment of the coagulation system which correlates with pro‐inflammatory cytokines and therefore with the severity of the disease.
Determinants of health‐seeking behaviour for schistosomiasis‐related symptoms in the context of integrating schistosomiasis control within the regular health services in Ghana
Authors: Danso‐Appiah A. , De Vlas S. J. , Bosompem K. M. , Habbema J. D. F. 
Published: July 2004

SummaryMorbidity control of schistosomiasis through integration within existing health care delivery systems is considered a potentially sustainable and cost‐effective approach. We conducted a questionnaire‐based field study in a Ghanaian village endemic for both urinary and intestinal schistosomiasis to determine whether infected individuals self‐reported to health centres or clinics and to identify factors that influenced their decision to seek health care. A total of 317 subjects were interviewed about having signs and symptoms suggestive of schistosomiasis: blood in urine, painful urination, blood in stool/bloody diarrhoea, abdominal pain, diarrhoea, swollen abdomen and fatigue within 1 month of the day of the interview. Fever (for malaria) was included as a disease of high debility for comparison. Around 70% with blood in urine or painful urination did not seek health care, whilst diarrhoea, blood in stool, abdominal pain and fever usually led to action (mainly self‐medication, with allopathic drugs being used four to five times more often than herbal treatment). On average 20% of schistosomiasis‐related signs and symptoms were reported to health facilities either as the first option or second and third alternative by some of those that self‐medicated. A few of those who visited a clinic or health centre as first option still self‐medicated afterwards. Children under 10 years and adults were more likely to seek health care than teenagers. Also, females were more likely to visit a health facility than males of the same age groups. Socio‐economic status and duration of symptoms did not appear to affect health‐seeking behaviour. ‘Do not have the money’ (43%) and ‘Not serious enough’ (41%) were the commonest reasons for not visiting a clinic, reported more frequently by lower and higher socio‐economic classes, respectively, for both urinary or intestinal schistosomiasis. The regular health service shows some potential in passive control of schistosomiasis as some, but far too few, people visit a health facility as first or second option.
The recent emergence of Leishmania tropica in Jericho (A'riha) and its environs, a classical focus of L. major
Authors: Al‐Jawabreh A. , Schnur L. F. , Nasereddin A. , Schwenkenbecher J. M. , Abdeen Z. , Barghuthy F. , Khanfar H. , Presber W. , Schönian G. 
Published: July 2004

SummaryBetween 1997 and 2002, 49 strains of Leishmania were isolated from the cutaneous lesions of Palestinians living in and around Jericho. A polymerase chain reaction (PCR) amplifying the ribosomal internal transcribed spacer 1 (ITS1‐PCR) was applied to their cultured promastigotes and to 207 individuals’ skin scrapings spotted on filter‐papers, 107 of which proved positive for leishmanial DNA. Species identification was performed by restricting the ITS1‐PCR amplification products from the cultured promastigotes and the amastigotes in the scrapings with the endonuclease HaeIII. Of the 49 cultures, 28 (57%) were L. major and 21 (43%) were L. tropica. Of the 107 dermal samples tested directly, 53 (49.5%) were infected with L. major, 52 (48.5%) with L. tropica and two remained unidentified. This is the first time L. tropica has been exposed in the population of the Jericho area and on such a large scale. The itinerant behaviour of some of this population precludes categorically declaring that L. tropica has recently become established in this classical focus of L. major. For this and although 88.2% of the cases of L. tropica claimed not to have travelled out of the vicinity of Jericho, local infected sand fly vectors of L. tropica must be caught, identified and, if possible, shown to harbour infections, and, if one exists, an animal reservoir host should also be exposed to endorse whether the cases caused by L. tropica were imported or autochthonous.
Two new cytoforms of the Simulium damnosum complex (Diptera: Simuliidae) from Malawi and Tanzania and potential onchocerciasis vectors
Authors: Krüger A. , Kalinga A. K. , Post R. J. , Maegga B. T. A. 
Published: July 2004

SummaryDuring a distribution survey of Simulium damnosum s.l. around the Tukuyu onchocerciasis focus at the northern tip of Lake Malawi/Nyasa (Tanzania), we discovered two new cytoforms of the S. damnosum complex in onchocerciasis‐free areas. The Nyika form is related to Simulium thyolense, a vector of onchocerciasis, and can be identified by the new inversion 3L‐L on the long arm of chromosome 3. It was found breeding in five rivers in northern Malawi and neighbouring Tanzania and is assumed to be zoophilic. The Njombe form represents a member of the Sanje group of the complex and is characterized by the new diagnostic inversion 2L‐35 on chromosome 2. So far, it is only known from around Njombe town in southern Tanzania, where it breeds at remarkably high altitudes. Anthropophily for the Njombe form is well known. The medical importance and systematic position of the new forms within the S. damnosum complex are discussed.