Biological aspects of the multiplication of the plague virus of small ruminants or SRP virus on cell cultures     

A Laurent 《Revue d'élevage et de médecine vétérinaire des pays tropicaux》1968,21(3):297-308

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Fracture of multiply-bolted joints under lateral force perpendicular to wood grain     

Motoi Yasumura  Laurent Daudeville 《Journal of Wood Science》2000,46(3):187-192

The crack initiation and propagation of multiplybolted joints subjected to lateral forces perpendicular to the grain were analyzed. Two types of bolted joint were subjected to lateral loads perpendicular to the grain. One had joints of two bolts aligned with the wood grain (type H), and the other had joints of two or three bolts aligned perpendicular to the grain (type V). The crack initiation and propagation were analyzed by means of the average stress method (ASM) and linear elastic fracture mechanics (LEFM), respectively. The maximum loads calculated by LEFM agreed comparatively well with the experimental results, and it was proved that the LEFM was an appropriate tool to analyze the fracture of multiply-bolted joints subjected to a force perpendicular to the grain. It was also found that the multiply-bolted joints failed with the fracture of the wood before the joints yielded, and that it caused a considerable decrease of the maximum loads. The reduction of strength should be considered in the design of multiply-bolted joints subjected to lateral forces perpendicular to the grain.Part of this work was presented at the annual meeting of the Architectural Institute of Japan, Hikone, September 1996  相似文献   

Metabolism of [14C]-2,4-dichlorophenol in edible plants     

Laurent F  Debrauwer L  Pascal-Lorber S 《Pest management science》2006,62(6):558-564

Several 2,4-dichlorophenoxyacetic acid (2,4-D)-sensitive plants have been modified by genetic engineering with tfdA gene to acquire 2,4-D tolerance. The expression product of this gene degrades 2,4-D to 2,4-dichlorophenol (DCP), which is less phytotoxic but could cause a problem of food safety. After a comparison of 2,4-D and DCP metabolism in transgenic 2,4-D-tolerant and wild cotton (Gossypium hirsutum L.), a direct study of DCP metabolism in edible plants was performed. After petiolar uptake of a [U-phenyl-(14)C]-DCP solution followed by a 48 h water chase, aqueous extracts were analysed by high-performance liquid chromatography. Metabolites were thereafter isolated and their structural identities were determined by enzymatic and chemical hydrolyses and mass spectrometry analyses. The metabolic fate of DCP was equivalent to 2,4-D metabolism in transgenic 2,4-D-tolerant cotton. In addition, DCP metabolism was similar in transgenic and wild cotton. The major terminal metabolites were DCP-saccharide conjugates in all species, essentially DCP-(6-O-malonyl)-glucoside or its precursor DCP-glucose. The significance of this metabolic pathway with regard to food safety is discussed.  相似文献   

Biogeochemical cycles of nutrients in tropical Eucalyptus plantations: Main features shown by intensive monitoring in Congo and Brazil     

Jean-Paul Laclau  Jacques Ranger  José Leonardo de Moraes Gonçalves  Valérie Maquère  Alex V. Krusche  Armel Thongo M’Bou  Yann Nouvellon  Laurent Saint-André  Jean-Pierre Bouillet  Marisa de Cassia Piccolo  Philippe Deleporte 《Forest Ecology and Management》2010,259(9):1771-1785

The sustainability of fast-growing tropical Eucalyptus plantations is of concern in a context of rising fertilizer costs, since large amounts of nutrients are removed with biomass every 6–7 years from highly weathered soils. A better understanding of the dynamics of tree requirements is required to match fertilization regimes to the availability of each nutrient in the soil. The nutrition of Eucalyptus plantations has been intensively investigated and many studies have focused on specific fluxes in the biogeochemical cycles of nutrients. However, studies dealing with complete cycles are scarce for the Tropics. The objective of this paper was to compare these cycles for Eucalyptus plantations in Congo and Brazil, with contrasting climates, soil properties, and management practices.The main features were similar in the two situations. Most nutrient fluxes were driven by crown establishment the two first years after planting and total biomass production thereafter. These forests were characterized by huge nutrient requirements: 155, 10, 52, 55 and 23 kg ha^?1 of N, P, K, Ca and Mg the first year after planting at the Brazilian study site, respectively. High growth rates the first months after planting were essential to take advantage of the large amounts of nutrients released into the soil solutions by organic matter mineralization after harvesting. This study highlighted the predominant role of biological and biochemical cycles over the geochemical cycle of nutrients in tropical Eucalyptus plantations and indicated the prime importance of carefully managing organic matter in these soils. Limited nutrient losses through deep drainage after clear-cutting in the sandy soils of the two study sites showed the remarkable efficiency of Eucalyptus trees in keeping limited nutrient pools within the ecosystem, even after major disturbances. Nutrient input–output budgets suggested that Eucalyptus plantations take advantage of soil fertility inherited from previous land uses and that long-term sustainability will require an increase in the inputs of certain nutrients.  相似文献   

Effect of ramial wood amendment on sorghum production and topsoil quality in a Sudano-Sahelian ecosystem (central Burkina Faso)     

Bernard G. Barthès  Aurélien Penche  Edmond Hien  Philippe Deleporte  Cathy Clermont-Dauphin  Laurent Cournac  Raphaël J. Manlay 《Agroforestry Systems》2015,89(1):81-93

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Identification and detection of three new F17 fimbrial variants in Escherichia coli strains isolated from cattle     

Morgan Bihannic  Reza Ghanbarpour  Frédéric Auvray  Laurent Cavalié  Pierre Chatre  Michèle Boury  Hubert Brugère  Jean-Yves Madec  Eric Oswald 《Veterinary research》2014,45(1)

F17 fimbriae are produced by pathogenic Escherichia coli involved in diarrhea and septicemia outbreaks in calves and lambs. These proteins result from the expression of four different clustered genes, namely f17A, f17D, f17C and f17G, encoding a pilin protein, a periplasmic protein, an anchor protein and an adhesin protein, respectively. Several variants of f17A and f17G genes have been reported and found genetically associated with typical virulence factors of bovine pathogenic E. coli strains. In this study, a new F17e-A variant, closely related to F17b-A, was identified from a collection of 58 E. coli isolates from diarrheic calves in Iran. While highly prevalent in Iranian F17-producing clinical isolates from calves, this variant was rare among E. coli from a French healthy adult bovine population, suggesting a possible association with virulence. The f17Ae gene was also found in the genome of the Shiga-like toxin variant Stx_1d–producing bovine E. coli strain MHI813, and belonged to a gene cluster also encoding a new F17-G3 variant, which greatly differed from F17-G1 and F17-G2. This gene cluster was located on a pathogenicity island integrated in the tRNA pheV gene. The gene coding for a third new F17f-A variant corresponding to a combination of F17c-A and F17d-A was also identified on the pVir68 plasmid in the bovine pathogenic E. coli strain 6.0900. In conclusion, we identified three new F17-A and F17-G variants in cattle E. coli, which may also have significant impact on the development of new diagnostics and vaccination tools.  相似文献   

Stimulation of airway neutrophils following dexamethasone administration and equid herpesvirus-2 challenge in horses     

Eric A. Richard  Pierre-Hugues Pitel  Laurent Lemaitre  Dominique Jas  Pierre Lekeux  Stéphane Pronost  Guillaume Fortier 《Veterinary journal (London, England : 1997)》2014,199(1):181-183

The aim of this study was to investigate neutrophil stimulation following experimentally-induced airway inflammation in healthy horses. Six horses received dexamethasone and four were then inoculated with equid herpesvirus-2 (EHV-2). Significant neutrophilia was detected in tracheal wash and bronchoalveolar lavage fluid for up to 6 days. Concentrations of neutrophil elastase (NE) and myeloperoxidase (MPO) were significantly increased compared to baseline for up to 14 days in tracheal washes and both markers were significantly correlated with neutrophil counts. Serum levels of surfactant protein D were not significantly modified throughout the study. These results suggest that dexamethasone administration with or without EHV-2 inoculation is associated with a sustainable activation and degranulation of neutrophils in the trachea along with moderate modifications detectable in the lower airways.  相似文献   

A human genome diversity cell line panel     

Cann HM  de Toma C  Cazes L  Legrand MF  Morel V  Piouffre L  Bodmer J  Bodmer WF  Bonne-Tamir B  Cambon-Thomsen A  Chen Z  Chu J  Carcassi C  Contu L  Du R  Excoffier L  Ferrara GB  Friedlaender JS  Groot H  Gurwitz D  Jenkins T  Herrera RJ  Huang X  Kidd J  Kidd KK  Langaney A  Lin AA  Mehdi SQ  Parham P  Piazza A  Pistillo MP  Qian Y  Shu Q  Xu J  Zhu S  Weber JL  Greely HT  Feldman MW  Thomas G  Dausset J  Cavalli-Sforza LL 《Science (New York, N.Y.)》2002,296(5566):261-262

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Microtomography of partially molten rocks: three-dimensional melt distribution in mantle peridotite   总被引：2，自引：0，他引：2  

Zhu W  Gaetani GA  Fusseis F  Montési LG  De Carlo F 《Science (New York, N.Y.)》2011,332(6025):88-91

The permeability of the upper mantle controls melt segregation beneath spreading centers. Reconciling contradictory geochemical and geophysical observations at ocean ridges requires a better understanding of transport properties in partially molten rocks. Using x-ray synchrotron microtomography, we obtained three-dimensional data on melt distribution for mantle peridotite with various melt fractions. At melt fractions as low as 0.02, triple junctions along grain edges dominated the melt network; there was no evidence of an abrupt change in the fundamental character of melt extraction as melt fraction increased to 0.2. The porosity of the partially molten region beneath ocean ridges is therefore controlled by a balance between viscous compaction and melting rate, not by a change in melt topology.  相似文献   

Magnetism on the angrite parent body and the early differentiation of planetesimals     

Weiss BP  Berdahl JS  Elkins-Tanton L  Stanley S  Lima EA  Carporzen L 《Science (New York, N.Y.)》2008,322(5902):713-716

Angrites are among the oldest known pristine basaltic meteorites and record the earliest stages of planet formation and differentiation. Our paleomagnetic analysis of three angrites found that they record a past magnetic field of approximately 10 microteslas on the angrite parent body extending from 4564 to at least 4558 million years ago. Because the angrite paleomagnetic record extends beyond the expected lifetime of the early circumstellar disk, these paleofields were probably generated internally on the angrite parent body, possibly by an early dynamo in a rapidly formed metallic core.  相似文献