bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptation of Melampsora medusae to increasing temperature and light intensities on a clone of Populus deltoides
Authors: Prakash C. S. , Heather W. A.
Published: January 2008

Race 4A of Melampsora medusae Thum. produces an incompatible reaction on Populus deltoides Marsh. cv. W-79/307 when incubated at high temperature and low light intensity (26 °C and 100 μE∙m−2∙s−1) or low temperature and high light intensity (17 °C and 700 μE∙m−1∙s−1), but a compatible one at low temperature and low light intensity 17 °C and 100 μE∙m−2∙s−1). When in separate studies, a population of this race was sequentially cultured on detached leaves, at increasing temperatures (17, 20, 23, or 26 °C) or light intensities (100, 300, 500, or 700 μE∙m−2∙s−1), isolates that were adpated to each of these regimes were selected. Such isolates, particularly those from low temperature and low light intensity, exhibited some specificity to their "own" environments, although isolates selected at 26 °C and 500 μE∙m−2∙s−1 were most aggressive at all temperatures and light intensity regimes, respectively. Such adaptation appeared to result from pathogen response to host-mediated environmental selection pressure. Isolate, incubating environment, and their interaction were significant contributors to the variation in aggressiveness traits (disease timing and intensity). This rust demonstrates considerable ability to adapt to varying environmental conditions. Thus physical environmental variables may be important selective forces in the regulation of this pathosystem, as spatial and temporal heterogeneity of the environment in nature may result in polymorphism of the pathogen by disruptive selection.
Prefertilization ovule development in Capsella: the dyad, tetrad, developing megaspore, and two-nucleate gametophyte
Authors: Schulz Patricia , Jensen William A.
Published: January 2008

Ovules of Capsella bursa-pastoris at the dyad and tetrad stages of meiosis and at the megaspore and two-nucleate stages of the gametophyte were studied with the electron microscope. The cells of the dyad and tetrad are separated by aniline blue fluorescent cross walls and receive all types of organelles and autophagic vacuoles that were present in the meiocyte. Autophagic vacuoles enclose ribosomes and organelles and show reaction product for acid phosphatase. Autophagic vacuoles and some plastids are absorbed into the enlarging vacuoles of the growing megaspore. Other plastids appear to survive meiosis and there is no evidence for their de novo origin. Some mitochondria appear to degenerate in the enlarging megaspore but others look healthy and there is no evidence for the de novo origin of mitochondria. The nucleolus of the developing megaspore becomes very large and the cytoplasm is extremely dense with ribosomes. The cell wall is thickened by an electron-translucent, periodic acid – Schiff negative, aniline blue fluorescent material and contains plasmodesmata that link the megaspore with the nucellus. The plasmalemma of the growing megaspore produces microvilluslike extensions into this wall that disappear with the formation of the two-nucleate gametophyte. Plasmodesmata disappear from the cell wall at the four-nucleate stage.
Induced susceptibility and enhanced resistance at the cellular level in barley coleoptiles. II. Timing and localization of induced susceptibility in a single coleoptile cell and its transfer to an adjacent cell
Authors: Kunoh H. , Kuroda K. , Hayashimoto A. , Ishizaki H.
Published: January 2008

The primary growth of both Erysiphe graminis de Candolle and E. pisi de Candolle on the same cell or adjacent cells of barley coleoptiles was observed by light microscopy to determine factors conditioning host cells toward susceptibility. Erysiphe pisi never successfully penetrated (0% efficiency) when it was the sole inoculum. By contrast it penetrated with varied efficiencies when initiation of cytoplasmic aggregates induced by it followed that of E. graminis by 4.0–19.0 h on the same coleoptile cells. When E. graminis induced a cytoplasmic aggregate 4.0–9.0 h earlier than E. pisi in a single coleoptile cell, induced susceptibility was minimal around the E. graminis penetration site, within 100 μm of the site, in the cell. When the time intervals were 9.25 – 14.0 h, induced susceptibility was maximal around the E. graminis penetration site, within 100 μm, and minimal when the fungi were more than 200 μm apart. When the time intervals were more than 14.0 h, induced susceptibility was evenly dispersed throughout the entire cell and transfer of susceptibility to laterally adjacent cells occurred only under these time conditions. Erysiphe pisi penetrations on coleoptile cells were influenced by its growth or the host cell's response before actual penetration occurred.
Suppressive effect of preirradiation with blue light on near ultraviolet light induced conidiation in Alternaria tomato
Authors: Kumagai Tadashi
Published: January 2008

Conidiophore formation in Alternaria tomato (Cke.) Weber (ATCC 38852) was induced by irradiation with near ultraviolet light, and conidia formed in subsequent darkness. However, blue light applied before the inductive near ultraviolet radiation suppressed the induction. Preirradiation with blue light just before the inductive near ultraviolet radiation was most suppressive. An action spectrum for this suppression showed a peak around 447 nm, with a shoulder between 400 and 440 nm, a minor peak around 478 nm in the blue region, and another near 385 nm in the near ultraviolet region. This action spectrum is very similar to the ubiquitous blue light response (cryptochrome).
A newly discovered host of the sea-grass epiphyte Smithora naiadum (Bangiophyceae, Rhodophyta)
Authors: Hansen Gayle I.
Published: January 2008

The epiphytic red alga, Smithora naiadum, once thought to occur exclusively on natural (or synthetic) sea-grass blades, has been found to grow on Plocamium cartilagineum, a red alga common in the understory of Phyllospadix scouleri.
Homothallism in Nectria galligena
Authors: El-Gholl N. E. , Barnard E. L. , Schroeder R. A.
Published: January 2008

Cylindrocarpon heteronema (Berk. & Br.) Wollenw. was obtained from perithecia of Nectria galligena Bres. which occurred on the bark of galled branches of Swietenia mahagoni Jacq. collected in Fort Lauderdale, Florida. Hyphal tips were taken from germ tubes of single cells from multiseptate macroconidia and from each cell of germinating ascospores. Nuclear staining revealed that the cells of the macroconidia and ascospores are uninucleate. All hyphal tips produced perithecia on carnation leaf pieces resting on water agar. This study establishes the homothallic nature of this fungus.
Growth of micropropagated lowbush blueberry with defined fungi in irradiated peat mix
Authors: Litten Walter , Smagula John M. , Dalpé Yolande
Published: January 2008

There is an interest in vegetative multiplication of high-yielding clones of Vaccinium angustifolium Ait. to establish or enhance blueberry production. This study evaluates mycorrhizal inoculation as an aid in such propagation from microcuttings. Shoots of Vaccinium angustifolium (clone 7062) generated in vitro were rooted in a peat–vermiculite–perlite substrate with or without ericoid mycorrhizal fungi fortification by Hymenoscyphus ericae or Scytalidium vaccinii and with or without peat sterilization by γ irradiation. Both in irradiated peat mix inoculated with S. vaccinii and in unirradiated peat mix with H. ericae, microcuttings grew taller and branched more than with the four other treatments. The profusely rooted plantlets available from all treatments of the cuttings put on significantly more total length of stems and branches after 167 days in the greenhouse when growing with either inoculant in unirradiated peat than in the unirradiated peat without inoculation. However, the magnitude of difference might be of borderline importance in commercial nursery operations. A higher level of copper and zinc in stem tissue was observed in stem tissue of plants grown with H. ericae with or without irradiation but not with S. vaccinii. Key words: ericoid mycorrhizae, micropropagation, Hymenoscyphus ericae, Scytalidium vaccinii, Vaccinium angustifolium.
Characterization of vascular lignification in Arabidopsis thaliana
Authors: Dharmawardhana D. P. , Ellis B. E. , Carlson J. E.
Published: January 2008

The developmental timing of lignin biosynthesis and the nature of the polymer have been studied in Arabidopsis thaliana using biochemical and histological techniques. Embryos and developing seedlings were stained with basic fuchsin, and the internal vascular strands were imaged by the optical serial sectioning capability of confocal laser scanning microscopy. Lignin could not be detected in seedlings until approximately 36 h after germination. As the radicle, hypocotyl, and cotyledon expanded, lignification proceeded as a temporally coordinated event closely linked to appearance of spiral or annular thickenings in the developing vasculature. Although A. thaliana does not undergo secondary growth, the plants were extensively lignified by the bolting stage. Chemical analysis demonstrated that Arabidopsis lignin contains primarily guaiacyl units, accompanied by lesser amounts of syringyl structures. Key words: Arabidopsis, lignin, development, confocal microscopy.
Ultrastructural and genetic characterization of a mutant exhibiting starch accumulation and premature leaf senescence in Medicago sativa
Authors: McKersie Bryan D. , Peterson R. L. , Bowley Stephen R. , Das Shankar
Published: January 2008

A mutant was isolated from irradiated seed of alfalfa, Medicago sativa L. cv. Excalibur. The mutant plant, Ex-139, displayed symptoms of premature senescence in the leaf palisade mesophyll. The leaves emerged as a normal phenotype, but light microscopy revealed that they rapidly began to accumulate starch in plastids of some cells in the palisade mesophyll. This accumulation of starch was followed by general cellular autolysis leading to the formation of necrotic regions in the palisade mesophyll. The adjacent epidermal and spongy mesophyll cells were not structurally affected. The mutant otherwise exhibited normal growth and development and was fertile. Inheritance studies indicated that the trait was transmitted to the progeny, preferentially but not exclusively, through the female, which suggests that either there is differential selection among male and female gametes or the trait is controlled by extranuclear DNA. This mutant should be useful in the study of the link between senescence and carbohydrate metabolism and in alfalfa genetics. Key words: starch metabolism, plastid, chloroplast genome, biparental inheritance.
Electrical impedance analysis in plant tissues: in vivo detection of freezing injury
Authors: Zhang M. I. N. , Willison J. H. M.
Published: January 2008

Freezing injury of potato tuber tissue was studied by measuring electrical impedance, in the range of 100 Hz to 800 KHz, while the tissue was subjected to a −3 °C environment. It was found that a greater proportion of total impedance was due to electrode polarization in frozen tissues than in nonfrozen tissues. In frozen tissue, electrode impedance could be so great that tissue impedance could not be measured reliably. Analysis of tissue impedance using complex nonlinear least squares revealed some dynamics of the process of tissue freezing. After 1 h of exposure to freezing conditions, extracellular resistance began a sustained decrease. This can be explained by electrolyte leakage to extracellular space, presumably as a result of membrane injury. The capacitances of both plasma membrane and tonoplast also decreased with freezing. Key words: potato (Solanum tuberosum L.) tuber, electrical impedance, freezing injury, membrane capacitance.
Photosynthesis, pigments, and chloroplast ultrastructure of an Antarctic liverwort from sun-exposed and shaded sites
Authors: Post Adele , Vesk Maret
Published: January 2008

Adaptations to severe environmental conditions were studied in the only recorded continental Antarctic hepatic, Cephaloziella exiliflora (Tayl.) Steph. During the summer growing season Antarctic plants melt out and many are exposed fully to the sun. C. exiliflora plants collected from sun-exposed and shaded sites were compared. Most plants were sun exposed, with dark purple leaves containing an anthocyanin-like pigment bound within the thick cell walls of the leaves. The purple plants grew in a dense turf, were larger with more closely spaced leaves, and had a higher carotenoid to chlorophyll ratio than the green plants. Shaded green plants contained more chlorophyll per unit weight. The chlorophyll a to chlorophyll b ratio did not vary. At low irradiances the green plants had higher photosynthetic oxygen evolution rates. Comparing leaves in similar positions along the stems showed that the chloroplasts in green leaves contained more appressed thylakoids than the chloroplasts in purple leaves. These differences are consistent with responses to varying light exposure. An understanding of these effects of changing irradiance on bryophytes is needed for monitoring the impact of increased ultraviolet light owing to the seasonal depletion of stratospheric ozone. Key words: Bryophyta, leafy liverwort, Antarctic, ultrastructure, photosynthesis.
Hybridization of Carduus nutans and Carduus acanthoides (Compositae): morphological variation in F1 hybrids and backcrosses
Authors: Warwick S. I. , Thompson B. K. , Black L. D.
Published: January 2008

The aim of this study was to compare patterns of morphological variation in F1 hybrids and backcrosses obtained artifically in the greenhouse relative to the parental species Carduus acanthoides (2n = 22) and Carduus nutans (2n = 16), which form a naturally occurring hybrid complex in Grey County, Ontario. The identity of parental, hybrid, and backcross genotypes was confirmed using allozyme markers. The data were used to test for hybrid (H) intermediacy in morphological traits that differentiate the two parental taxa (acronyms A and N are used for C. acanthoides and C. nutans, respectively) and to determine patterns of variation on the same traits among the four classes of backcross plants (NH, HN, AH, and HA, seed × pollen parent, respectively). Canonical multivariate analysis indicated that in general, F1 hybrids had intermediate morphologies compared with parental genotypes, although differences were observed among characters with respect to the degree of morphological intermediacy of hybrids. The backcrosses were divided into two groups, i.e., those backcrossed with C. acanthoides (AH and HA) and those with C. nutans (NH and HN). However, backcrosses also showed considerable morphological overlap with F1 hybrids. These results exemplify the utility of joint comparisons of morphology and genotypic constitution (allozymes) in the hybridization studies, and they emphasize the limitations in describing hybrid classes solely by morphological criteria. Key words: Carduus nutans, Carduus acanthoides, hybrids, backcrosses, morphological variation.
Leaf developmental plasticity of Ranunculus flabellaris in response to terrestrial and submerged environments
Authors: Bruni Nadia C. , Dengler Nancy G. , Young Jane P.
Published: January 2008

Environmentally induced developmental plasticity is characteristic of many heterophyllous semiaquatic species, including Ranunculus flabellaris. Underwater shoots of this species form leaves with elongate narrow lobes, while aerial shoots form leaves with shorter, broader lobes. In this study, a series of transfer experiments was undertaken to determine the competence of developing leaves to respond to a change in environmental conditions. Plants were transferred from terrestrial to submerged conditions at 8, 16, and 24 days after the approximate time of initiation of leaf 4; these times correspond to the developmental stages before differences in size and shape of aerial and underwater leaves can be detected, the time of divergence, and postdivergence when leaves are about half expanded. Morphological and anatomical traits of mature leaves grown terrestrially, submerged, or after transfer at 8, 16, or 24 days were measured and assessed using analysis of variance and principal components analysis. We found that some traits of leaves (such as lobe number) transferred at 8 days were similar, but not identical, to those of the water control, indicating that some features are determined prior to structural divergence. Leaves transferred at 16 and 24 days were intermediate between the land and water controls in most respects, indicating that traits such as epidermal and mesophyll cell shape are determined gradually during expansion. Other anatomical features, such as development of a palisade layer and extent of intercellular space, did not differ between transfer treatments and the water control, indicating that these features can respond to ambient conditions late in development. Keywords: heterophylly, leaf development, plasticity, Ranunculus, principal components analysis.
Associated field mycobiota on malt barley
Authors: Andersen Birgitte , Thrane Ulf , Svendsen Anne , Rasmussen Ilse A.
Published: January 2008

The field mycobiota associated with malt barley was characterized over a period of 2 years, and changes in the mycobiota present on different cultivars were evaluated after treatment with pesticides or no treatment. The study showed that spraying, with pesticides did not result in changes in the composition of field mycobiota compared with the pesticide-free barley. The determining factor on the mycobiota was the location. The dominant species on barley was Alternaria infectoria Simmons. The most frequent Fusarium species detected were F. tricinctum (Corda) Sacc. and F. avenaceum (Fr.) Sacc. Results implied an interaction between Alternaria and Fusarium on the surface of the kernels. Keywords: pesticide-free malt barley, dematiaceous fungi, Alternaria infectoria, Fusarium.
Vesicular – arbuscular mycorrhizae in prairie pothole wetland vegetation in Iowa and North Dakota
Authors: Wetzel Paul R. , Valk Arnold G. van der
Published: January 2008

Vesicular–arbuscular mycorrhizae (VAM) fungal colonization was measured in June and August 1993 for 19 plant species in several vegetation zones in three wetlands in central Iowa and in three wetlands in North Dakota, U.S.A. Percent VAM fungal colonization in all the plants sampled varied greatly with species, ranging from 0.2 to 52.1% (mean = 13, SE = 2.4) in Iowan wetlands and 7.3 to 71.8% (mean = 32, SE = 4.7) in North Dakotan wetlands. The Iowan wetlands had more fertile soils (higher organic matter, higher phosphorus, and lower pH) than the North Dakotan wetlands. Soil salinity was higher in the North Dakotan wetlands. A principal components analysis of environmental factors (soil water matric potential, soil pH, available soil phosphorus, soil specific conductance, and season) indicated that when data for all plant species were pooled, there were only three significant components: location (which reflected differences between Iowa and North Dakota in soil pH, phosphorus, specific conductance, and season), vegetation zone (low prairie, wet meadow, shallow emergent), and soil matric potential. Multiple regression analysis of these principal components and plant species as independent variables and percent VAM fungal colonization as the dependent variable were performed. Regression analyses were also done with VAM fungal colonization as the independent variable and the principal components as the dependent variables on three individual species, Poa pratensis, Spartina pectinata, and Scirpus acutus, which are common to both geographic regions. For the pooled plant species, only plant species and the location principal component were statistically significant. For Poa pratensis, Spartina pectinata, and Scirpus acutus, only the first principal component was statistically significant. The results of this study are consistent with previous studies that suggest plant host species, soil phosphorus, and soil pH influence VAM fungal colonization. Because this study was done during an exceptionally wet year, seasonal changes in mycorrhizal colonization caused by a seasonal decline in soil moisture did not occur as predicted. Keywords: vesicular–arbuscular mycorrhizae, wetland vegetation, environmental gradients, Iowa, North Dakota.
Développement de l'inflorescence et des fleurs du Philodendron acutatum Schott (Araceae)
Authors: Boubes Chafika , Barabé Denis
Published: January 2008

The inflorescence of Philodendron acutatum possesses female flowers in the inferior part and male flowers in the distal part. The male flowers possess from three to six stamens, rarely seven to nine. The female flowers possess a multilocular ovary comprising from 8 to 12 locules. Each locule corresponds to a closed carpel. The stylar canals remain separate up to the upper part of the gynoecium. In this inflorescence, one observes an intermediary zone comprising bisexual flowers with fused or free carpels and stamens, inserted in the same whorl. Generally, the portion of the bisexual flower facing the male zone is formed by stamens, and that facing the female zone is formed by an incomplete gynoecium comprising few carpels. The separation between the two parts of a bisexual flower is generally clear; however, in rare cases, a stamen appears between two carpels, or a carpel between two stamens. Nevertheless, in all cases, the different flower parts are inserted on the same whorl. The presence of bisexual flowers corresponds probably to a morphogenetic gradient at the level of the overall inflorescence. The genes controlling the expression of flower sex are probably governed by chemical processes that act at the level of the overall inflorescence. Keywords: morphogenesis, gradient, flower, development, inflorescence.
Mating type segregation inChoanephora cucurbitarumfollowing sexual reproduction
Authors: Yu M. Q. , Ko W. H.
Published: January 2008

Zygospore progeny from the cross between + and − isolates of Choanephora cucurbitarum consisted of +, −, and ± types. The + and − zygospore isolates were stable, giving rise to hyphal fragment cultures and sporangiospores with the same mating type as their respective parent. However, the ± zygospore isolates were unstable, segregating to +, −, and ± types during asexual propagations. During long-term storage, the + and − isolates were also very stable, but ± isolates were not. All the ± isolates originating from single zygospores, hyphal fragments, or sporangiospores produced azygospores, suggesting that azygospores of this fungus are produced by mating-type heterokaryotic mycelia. Keywords: azygospore, Choanephora cucurbitarum, germsporangiospore, germsporangium, zygospore germination.
A comparison of analytical approaches for assessing freezing damage in black spruce using electrolyte leakage methods
Authors: Odlum K. D. , Blake T. J.
Published: January 2008

To compare different methods of quantifying shoot frost damage during controlled plant freezing tests, frost hardening of black spruce (Picea mariana (Mill.) BSP) seedlings exposed to three temperature hardening regimes over 16 weeks was assessed using electrolyte leakage and intact seedling methods. Electrolyte leakage was expressed as index of injury and was quantified either as the temperature needed to induce an index of injury of 5% (DT5) or as the critical temperature (CT), the mildest temperature at which damage was first detected statistically. Damage to intact shoots was expressed as percent shoot browning and was quantified as the temperature at which 50% of needle tissue on the shoots was damaged (sLT50) or as the temperature at which 50% of terminal buds were killed (bLT50). Seedling response to hardening temperature varied, depending on the method used to quantify frost hardiness. When expressed as critical temperature, hardening continued over the 16 weeks at a constant rate with no differences detected between treatments. Intact seedling shoot damage, sLT50 and bLT50, described a hardening process in which there was a large initial increase in hardening in the first 8 weeks, with less hardening occurring during the subsequent 8 weeks. Also, significant temperature effects were detected, with the greatest hardening occurring in a cool temperature (4 °C), the least in a warm temperature (20 °C), and an intermediate amount in a moderate temperature (10 °C). When quantified as DT5, the pattern of hardening was somewhat intermediate to the other two. Methods of determining frost hardiness were highly correlated, with the strongest correlation being between sLT50 and bLT50 (r2 = 0.903). Both electrolyte leakage methods, DT5 and CT, were linearly related to one another (r2 = 0.666) and were more sensitive than the intact seedling methods, since they both detected damage at warmer temperatures. DT5 was better correlated to intact measures of hardiness than was CT. Keywords: black spruce, index of injury, frost hardiness, critical temperature, damaging temperature, LT50.
Actin rings in cytokinesis of apical cells in red algae
Authors: Garbary David J. , McDonald A. Rosa
Published: January 2008

Actin rings are demonstrated for the first time in florideophyte red algae in Audouinella botryocarpa (Acrochaetiales) and Tiffaniella snyderae and Griffithsia pacifica (Ceramiales). Rings formed a complete circle in the peripheral cytoplasm prior to the development of the septum by furrowing. In the uninucleate A. botryocarpa, ring formation precedes mitosis. In all species F-actin initially has a diffuse to longitudinal alignment throughout the cell. The actin realigns and then contracts to form a dense actin ring. Following cell division, aggregations of actin are maintained along the transverse wall in at least G. pacifica and A. botryocarpa, and a dense ring of actin was observed around a pit plug in T. snyderae. The occurrence of actin rings in cell division of members of the Acrochaetiales and Ceramiales is consistent with ultrastructural observations on red algal unicells and suggests that actin rings are part of the ancestral cytokinetic mechanism in red algae. Keywords: actin rings, cell division, cytokinesis, cytoskeleton, microfilaments, Rhodophyta.
Pathogenic potential of a collagenase gene fromAeromonas veronii
Authors: Han Hyun-Ja , Taki Tatsuo , Kondo Hidehiro , Hirono Ikuo , Aoki Takashi
Published: January 2008

The role of collagenase as a mechanism of bacterial pathogenicity in some pathogenic bacteria has been reported. The information on the role of collagenase in Aeromonas spp. pathogenesis is scant. In the present study, a mutant Aeromonas veronii RY001 that is deficient in the putative collagenase gene acg was constructed and compared with the wild-type strain for virulence factors. Bacterial cells and cell-free extracellular products of the mutant had significantly less collagenolytic activity, but there were not significant differences in caseinolytic, gelatinolytic, and elastolytic activities. Adhesion and invasion abilities of the mutant strain on epithelioma papillosum of carp cells was only 56% of that of the wild-type strain, and the cytotoxicity of the mutant strain to epithelioma papillosum of carp cells was only 42% of that of the wild-type strain. The LD50values of the wild-type strain were determined as 1.6 × 106and 3.5 × 105cfu in goldfish and mice, respectively, whereas the mutant RY001 strain showed slightly higher values (i.e., 2.8 × 106and 1.4 × 106cfu in goldfish and mice, respectively). These results indicated the involvement of the collagenase gene in the pathogenesis of A. veronii.
Repeated batch cultivation of the hydrocarbon-degrading, micro-algal strain Prototheca zopfii RND16 immobilized in polyurethane foam
Authors: Ueno Ryohei , Wada Shun , Urano Naoto
Published: January 2008

This study reports on the stability of the cells of a heterotrophic green micro-algal strain Prototheca zopfii RND16 immobilized in polyurethane foam (PUF) cubes during degradation of mixed hydrocarbon substrate, which was composed of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), in 5 successive cycles of repeated batch cultivation at 30 °C. Both RND16 cells and mixed hydrocarbon substrate components had been entrapped in PUF cubes through cultivation. PUF-immobilized RND16 degraded n-alkanes almost completely, whereas the strain hardly degraded PAHs in PUFs, rather they accumulated in the matrices. It is noteworthy that this result is strikingly different from that of the free-living cell culture, where RND16 reduced concentrations of both n-alkanes and PAHs. However, PAHs accumulation in the PUFs did not impair the performance of the immobilized alga to utilize n-alkanes. These results suggest that the PUFs harboring RND16 cells could be used repeatedly for selective retrieval of PAHs from oil-polluted waters after preferential biodegradation of n-alkanes by algae.
Fibronectin enhancesCampylobacter fetusinteraction with extracellular matrix components and INT 407 cells
Authors: Graham L. L. , Friel T. , Woodman R. L.
Published: January 2008

Campylobacter fetus is a recognized pathogen of cattle and sheep that can also infect humans. No adhesins specific for C. fetus have to date been identified; however, bacterial attachment is essential to establish an infecting population. Scanning electron microscopy revealed C. fetus attachment to the serosal surface of human colonic biopsy explants, a location consistent with the presence of the extracellular matrix (ECM). To determine whether the ECM mediated C. fetus adherence, 7 C. fetus strains were assessed in a solid-phase binding assay for their ability to bind to immobilized ECM components. Of the ECM components assayed, adherence to fibronectin was noted for all strains. Attachment to ECM components was neither correlated with S-layer expression nor with cell-surface hydrophobicity. Ligand immunoblots, however, identified the S-layer protein as a major site of fibronectin binding, and modified ECM binding assays revealed that soluble fibronectin significantly enhanced the attachment of S-layer-expressing C. fetus strains to other ECM components. Soluble fibronectin also increased C. fetus adherence to INT 407 cells. This adherence was inhibited when INT 407 cells were incubated with synthetic peptides containing an RGD sequence, indicating that integrin receptors were involved in fibronectin-mediated attachment. Together, this data suggests that C. fetus can bind to immobilized fibronectin and use soluble fibronectin to enhance attachment to other ECM components and intestinal epithelial cells. In vivo, fibronectin would promote bacterial adherence, thereby, contributing to the initial interaction of C. fetus with mucosal and submucosal surfaces.
Identification of Streptococcus pneumoniae genes specifically induced in mouse lung tissues
Authors: Meng Jiang-Ping , Yin Yi-Bing , Zhang Xue-Mei , Huang Yuan-Shuai , Lan Kai , Cui Fang , Xu Song-Xiao
Published: January 2008

To identify Streptococcus pneumoniae genes expressed specifically during infections, a selection system based on the in vivo expression technology (IVET) was established. galU, which is critical for capsular polysaccharide biosynthesis, and lacZY encoding β-galactosidase were employed as dual reporter genes to screen in-vivo-induced (ivi) genes of S. pneumoniae. The galU-deficient mutant of S. pneumoniae is incapable of utilizing galactose, thus failing to synthesize capsular polysaccharide, and therefore loses its ability to survive in the host. A promoter-trap library was constructed in S. pneumoniae, which was used to infect BALB/c mice in an intranostril model. Those strains recovered from lung tissue of mice and exhibiting a white colony phenotype on tryptic soy agar containing X-gal (5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside) were collected and identificated. A total of 15 unique sequences were obtained through in vivo screening. The ivi genes of S. pneumoniae are involved in many processes, such as colonization and adherence, energy metabolism, nutrient substance transport, transcription regulation, DNA metabolism, and cell wall synthesis. There are some hypothetical proteins whose functions are not clear. This novel IVET is a useful tool for identifying ivi genes in S. pneumoniae.
THE IMPACT OF HYPOTHYROIDISM ON MINERAL ELEMENTS IN RAT'S TISSUES USING PIXE
Authors: RAHIGHI J. , OLIAIY P. , SHOKOUHI F. , AGHAII A. , HADJZADEH M-AL-R.
Published: January 2008

Seven organs of 24 rats in two different groups of 12 namely experimental and control group were analyzed in order to determine their chemical compositions. Concentration of P , S , Cl , K , Ca , Ti , Fe , Cu , Zn and Br are presented and discussed in this paper. The results were compared by unpaired student t-test for both groups. Difference were considered to be significant when P < 0.05.
EAST CALCUTTA WETLANDS AS A SINK OF INDUSTRIAL HEAVY METALS: A PIXE STUDY
Authors: CHATTERJEE S. , CHATTOPADHYAY B. , MUKHOPADHYAY S. K. , MOHANTA B. , SUDARSHAN M. , CHAKRABORTY A.
Published: January 2008

Industrial wastes are considered as critical factors for disturbing natural ecosystems. The East Calcutta Wetlands, a Ramsar site in West Bengal, India, receives composite industrial effluents, subsequently bringing various kinds of heavy metals throughout the year. This wastewater is being utilized by the local people for pisciculture. The present investigation was carried out to study 1) elemental distribution various components of the wetland and 2) potentiality of water hyacinth in metal amelioration. Water and sediments were collected from four different spots along a wastewater-carrying canal having a stretch of 40km from the source point to the final confluence with river and from the wastewater fed fishpond. Fish (three common carps viz. Labeo rohita, Cirrhinus mrigala and Oreochromis niloticus) and water hyacinth were collected from fishpond mentioned above. Samples were analyzed by PIXE with 3MeV tandem Pelletron. Cr , which is a known metal contaminant of tannery effluent, was detected along with S , K , Ca , Ti , V , Mn , Fe , Ni , Cu , Zn , As , Br , Rb , Sr , Zr . Variable concentrations of some elements like Ca , Fe , Zn in different fish organs was noted in the experiment. Accumulation of Cr , Cu from the water bodies by water hyacinth suggesting their crucial role in heavy metal amelioration.
SAINT VENANT COMPATIBILITY EQUATIONS ON A SURFACE APPLICATION TO INTRINSIC SHELL THEORY
Authors: CIARLET PHILIPPE G. , GRATIE LILIANA , MARDARE CRISTINEL , SHEN MING
Published: January 2008

We first establish that the linearized change of metric and change of curvature tensors, with components in L2 and H-1 respectively, associated with a displacement field, with components in H1, of a surface S immersed in ℝ3 must satisfy in the distributional sense compatibility conditions that may be viewed as the linear version of the Gauss and Codazzi-Mainardi equations. These compatibility conditions, which are analogous to the familiar Saint Venant equations in three-dimensional elasticity, constitute the Saint Venant equations on the surface S.

We next show that these compatibility conditions are also sufficient, i.e. that they in fact characterize the linearized change of metric and the linearized change of curvature tensors in the following sense: If two symmetric matrix fields of order two defined over a simply-connected surface S ⊂ ℝ3 satisfy the above compatibility conditions, then they are the linearized change of metric and linearized change of curvature tensors associated with a displacement field of the surface S, a field whose existence is thus established.

The proof provides an explicit algorithm for recovering such a displacement field from the linearized change of metric and linearized change of curvature tensors. This algorithm may be viewed as the linear counterpart of the reconstruction of a surface from its first and second fundamental forms.

Finally, we show how these results can be applied to the "intrinsic theory" of linearly elastic shells, where the linearized change of metric and change of curvature tensors are the new unknowns. These new unknowns solve a quadratic minimization problem over a space of tensor fields whose components, which are only in L2, satisfy the Saint Venant compatibility conditions on a surface in the sense of distributions.
A REAL-TIME EMG-DRIVEN ARM WRESTLING ROBOT CONSIDERING MOTION CHARACTERISTICS OF HUMAN UPPER LIMBS
Authors: SONG QUANJUN , YU YONG , GE YUNJIAN , GAO ZHEN , SHEN HUANGHUAN , DENG XIAOHONG
Published: January 2008

An EMG-driven Arm Wrestling Robot (AWR) is developed for the purposes of studying neuromuscular control of human elbow movements. The AWR arm has two degrees-of-freedom, integrated with mechanical arm, elbow/wrist force sensors, servo motors, encoders, MEMS accelerometers, and a USB camera, and is used to estimate tension generated by individual muscles from recorded electromyograms (EMG). The surface electromyography signal from the upper limb is sampled from a real player in the same conditions. By using the method of wavelet packet transformation (WPT) and autoregressive model (AR), the characteristics of EMG signals can be extracted. Then, an artificial neural network is adopted to estimate the elbow joint force. The effectiveness of the control method using force control estimated via neural network using WPT and AR as inputs is confirmed by experiments. The purpose of this paper is to describe the design objectives, fundamental components, and implementation of our real-time, EMG-driven AWR arm.
Petrological and geochemical constraints on the composition of the lithospheric mantle beneath the Syrian rift, northern part of the Arabian plate
Authors: Ismail M. , Delpech G. , Cottin J.-Y. , Grégoire M. , Moine B. N. , Bilal A.
Published: January 2008

A suite of mantle xenoliths from the Neogene–Quaternary volcanic province of Jabel El Arab (Syria) is dominated by spinel±amphibole harzburgites, with rare lherzolites and wehrlites that were equilibrated at temperatures of 900–1100 °C. The major elements of pristine minerals and trace element compositions of clinopyroxene and amphibole indicate that the lithospheric mantle experienced various degrees of melt extraction (olivine Mg-number=89.4–91.8, spinel Cr-number=10.4–46.4), followed by a multistage metasomatic history. The primary clinopyroxene has variable and high Mg-number (89.1–93.6) and highly variable major element concentrations (Al
2
O
3
2.7–7.6 wt%, Na
2
O 0.5–2.5 wt% and Cr
2
O
3
0.4–2.5 wt%). Three groups of harzburgites were identified on the basis of petrographical, mineralogical and geochemical data. Group I harzburgites have compositions indicating a residual origin after polybaric partial melting with
F
<20%, which started in the garnet stability field and continued in the spinel stability field. Group II harzburgites are interpreted as a result of a percolation mechanism involving the infiltration of large volumes of undifferentiated basaltic melts through the residual lithosphere. Finally, the mineral major element compositions and the selectively enriched trace element contents of clinopyroxenes in group III harzburgites (high (La/Sm)
N
and Th, U, Sr and low high field strength element contents) are attributed to a percolation mechanism involving small volume melt fractions. Such small melt fractions correspond to CO
2
-bearing alkaline silicate magmas that have evolved to CO
2
-rich melts during repeated percolation-reaction within the Syrian lithospheric mantle. Shortly before eruption, some xenoliths were infiltrated by small silicate melt fractions, which produced discrete reaction zones composed of cpx±ol±sp±glass surrounding reacting primary spinels. The glass in the melt pockets has a trachytic to trachy-andesitic composition and its composition suggests that glass is derived from melting of pre-existing amphibole in the lithospheric mantle, triggered by infiltration of a Na-rich metasomatic agent.
The role of HIMU metasomatic components in the North African lithospheric mantle: petrological evidence from the Gharyan lherzolite xenoliths, NW Libya
Authors: Beccaluva L. , Bianchini G. , Ellam R. M. , Marzola M. , Oun K. M. , Siena F. , Stuart F. M.
Published: January 2008

The Neogene–Quaternary alkali-basalt–hawaiite lavas of the Gharyan volcanic field (NW Libya) contain mantle xenoliths. These mostly consist of protogranular spinel lherzolites with superimposed metasomatic textures represented by reaction patches where primary orthopyroxene (opx), clinopyroxene (cpx) and spinel (sp) are the main reacting phases. The secondary parageneses include clinopyroxene (cpx2), olivine (ol2) and feldspar (feld) as reaction rims around opx, spongy-textured clinopyroxene with recrystallized portions (cpx2±feldspar), and brown spinel destabilized in a higher Cr/(Cr+Al) black vermicular aggregate (sp2) generally associated with feldspar microlites. Cpx2 are typically depleted in Na
2
O and Al
2
O
3
relative to cpx; feldspar includes both alkali-feldspar (Or 17–51) and plagioclase (An 23–64). Bulk rocks have flat heavy rare earth element (HREE) patterns (1.2–2.3 times chondrite) and are variably enriched in light REE (LREE; La
N
/Yb
N
up to 6.6). The constituent clinopyroxenes are characterized by flat HREE distributions (8–14.5 times chondrite) and variable LREE enrichment with La
N
/Yb
N
up to seven, which generally conform to the bulk-rock chemistry. Samples relatively unaffected by metasomatism have clinopyroxene Sr–Nd isotopic composition (
87
Sr/
86
Sr down to 0.7023,
143
Nd/
144
Nd up to 0.5139) that approaches the depleted mantle (DM), suggesting that the lithospheric mantle beneath the area underwent a long-term depletion probably by pre-Palaeozoic extraction of basic melts. The remaining samples approach
87
Sr/
86
Sr
c
. 0.7030,
143
Nd/
144
Nd
c
. 0.5130, with
206
Pb/
204
Pb up to 19.66. These data imply that the causative agents of metasomatism were Na-alkali silicate melts with a clear HIMU affinity, in accordance with the isotopic signature of the host lavas (
87
Sr/
86
Sr=0.7032,
143
Nd/
144
Nd=0.5130,
206
Pb/
204
Pb=19.60). This prevalent HIMU geochemical signature is comparable with that recorded in Cenozoic alkaline basic lavas and associated mantle xenoliths from other occurrences of the northern–central African lithosphere, suggesting a common regional sub-lithospheric component. The relatively low
3
He/
4
He of the Gharyan xenoliths (5.3–6.5
R
a
) indicates that this component originates within the upper mantle and is unrelated to the deep-seated mantle plume source of the Ethiopian–Yemen plateau basalts. Therefore, the Cenozoic volcanic districts of the Saharan belt could be related to smaller-scale shallow mantle upwellings (also referred to as ‘hot fingers’) triggered by intraplate reactivation of regional tectonic lineaments within the Pan-African cratonic basement, as a foreland reaction of the African–Europe collisional system.
The Jurassic Ligurian Tethys, a fossil ultraslow‐spreading ocean: the mantle perspective
Authors: Piccardo G. B.
Published: January 2008

Alpine–Apennine ophiolites derive from the Jurassic Ligurian Tethys oceanic basin formed by lithosphere extension and failure in the pre-Triassic Europe–Adria system. The basin was floored by mantle peridotites and was characterized by along-axis alternation of avolcanic and volcanic segments. Lithosphere extension and thinning caused asthenosphere adiabatic upwelling and decompressional melting. Mid-ocean ridge basalt (MORB)-type melts diffusely percolated through and reacted with the overlying lithospheric peridotites, which were strongly modified, both depleted (harzburgites and dunites) and enriched (plagioclase peridotites), by melt–peridotite interaction and melt refertilization. The stratigraphic–structural features (mantle at the sea floor and alternation of avolcanic and volcanic segments) coupled with petrological features (presence of alkaline melts and strongly heterogeneous, melt-modified peridotites) allow us to interpret
the Ligurian Tethys as a Jurassic analogue of modern ultraslow‐spreading oceans
. The Liguria Mode for the inception of an oceanic basin consists of: (1)
the rifting (continental) stage
, dominated by extension of continental lithosphere and tectonic exhumation of lithospheric mantle; (2)
the drifting (transition) stage
, characterized by melt-related processes (i.e. inception of asthenosphere partial melting and MORB melt percolation through the overlying mantle lithosphere); (3)
the spreading (oceanic) stage
, characterized by failure of the continental crust, sea‐floor exposure of mantle peridotites and discontinuous MORB extrusion.
Types of metasomatism in mantle xenoliths enclosed in Neogene-Quaternary alkaline mafic lavas from Catalonia (NE Spain)
Authors: Galán G. , Oliveras V. , Paterson B. A.
Published: January 2008

Mantle xenoliths in within-plate alkaline mafic lavas from NE Spain are mainly anhydrous spinel lherzolites and harzburgites, grading into each other, and subordinate pyroxenites. Peridotites followed an earlier melt depletion caused by mantle decompression and subsequent metasomatism. Two main types of metasomatism are differentiated affecting mainly the harzburgites: a silicate-melt metasomatism of Fe–Ti type and a carbonatite metasomatism. Both types are recognized in the nearby Pyrenean peridotite massifs, but the presence of hydrous minerals is less frequent in the xenoliths. The two metasomatic styles could have been generated by the intrusion of Cretaceous alkaline magmas, if a chromatographic fractionation–reaction process at decreasing melt mass took place. This would account for the evolution of the original alkaline silicate percolating melt towards a carbonatite-rich melt, allowing the coexistence in both space and time of the two metasomatic styles. Metasomatism in lherzolites could be explained in the same way. The pyroxenite xenoliths are interpreted as cumulates from these alkaline basic magmas that crop out in the area as rare camptonite dykes. Interaction with host lavas is minor and could explain the partial melting, enrichment and disequilibrium observed in a deformed composite xenolith and sporadic veins filled with glass.
Plume-related stable isotope compositions and fluid–rock interaction processes in the Basal Complex of La Palma, Canary Islands, Spain
Authors: Demény A. , Casillas R. , Vennemann T. W. , Hegner E. , Nagy G. , Ahijado A. , De La Nuez J. , Sipos P. , Pilet S. , Milton J.
Published: January 2008

Chemical and isotopic compositions of amphiboles, biotites, pyroxenes and feldspars from gabbros and basalts of La Palma, Canary Islands, were studied to determine primary, plume-related compositions and effects of late-stage water–rock interactions. All the studied amphiboles have Sr isotope ratios close to those typical for the mantle, excluding the possibility of significant seawater influence. The pyroxenes and amphiboles also have stable isotope compositions that are typical for mantle-derived phases, whereas biotites and feldspars show signs of interaction with meteoric water. On the basis of the oxygen isotopic compositions, the infiltrating meteoric water derived from precipitation at an approximate elevation of 3500 m above sea level, indicating that La Palma reached this height when the gabbro complexes were formed. The unaltered hydrogen and oxygen isotope compositions of amphiboles show a trend from normal mantle ranges to −90‰ and 5.1‰, respectively; these values are very close to compositions found in other Canary Island complexes by earlier studies, and support the theory that these compositions reflect a plume component originating from depth, rather than local phenomena.