Optimization of virulence functions through glucosylation of Shigella LPS     

West NP  Sansonetti P  Mounier J  Exley RM  Parsot C  Guadagnini S  Prévost MC  Prochnicka-Chalufour A  Delepierre M  Tanguy M  Tang CM 《Science (New York, N.Y.)》2005,307(5713):1313-1317

Shigella, the leading cause of bacillary dysentery, uses a type III secretion system (TTSS) to inject proteins into human cells, leading to bacterial invasion and a vigorous inflammatory response. The bacterium is protected against the response by the O antigen of lipopolysaccharide (LPS) on its surface. We show that bacteriophage-encoded glucosylation of Shigella O antigen, the basis of different serotypes, shortens the LPS molecule by around half. This enhances TTSS function without compromising the protective properties of the LPS. Thus, LPS glucosylation promotes bacterial invasion and evasion of innate immunity, which may have contributed to the emergence of serotype diversity in Shigella.  相似文献   

Constituents of Asparagus officinalis evaluated for inhibitory activity against cyclooxygenase-2     

Jang DS  Cuendet M  Fong HH  Pezzuto JM  Kinghorn AD 《Journal of agricultural and food chemistry》2004,52(8):2218-2222

As part of a project directed toward the discovery of new cancer chemopreventive agents from plants, two new natural products, asparagusic acid anti-S-oxide methyl ester (1) and asparagusic acid syn-S-oxide methyl ester (2), a new acetylenic compound, 2-hydroxyasparenyn [3',4'-trans-2-hydroxy-1-methoxy-4-[5-(4-methoxyphenoxy)-3-penten-1-ynyl]-benzene] (3), as well as eleven known compounds, asparenyn (4), asparenyol (5), (+/-)-1-monopalmitin (6), ferulic acid (7), 1,3-O-di-p-coumaroylglycerol (8), 1-O-feruloyl-3-O-p-coumaroylglycerol (9), blumenol C, (+/-)-epipinoresinol, linoleic acid, 1,3-O-diferuloylglycerol, and 1,2-O-diferuloylglycerol, were isolated from an ethyl acetate-soluble fraction of the methanol extract of the aerial parts of Asparagus officinalis (Asparagus), using a bioassay based on the inhibition of cyclooxygenase-2 to monitor chromatographic fractionation. The structures of compounds 1-3 were elucidated by 1D- and 2D-NMR experiments ((1)H NMR, (13)C NMR, DEPT, COSY, HMQC, HMBC and NOESY). All the isolates were evaluated for their inhibitory effects against both cyclooxygenase-1 and -2, with the most active compound being linoleic acid.  相似文献   

Intraspecific variation of physiological and molecular response to cadmium stress in Populus nigra L     

Gaudet M  Pietrini F  Beritognolo I  Iori V  Zacchini M  Massacci A  Mugnozza GS  Sabatti M 《Tree physiology》2011,31(12):1309-1318

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Experimental bases for a chemical control of Coquillettidia mosquito populations     

Julien Sérandour  Patrick Ravanel  Michel Tissut  Guy Lempérière  Muriel Raveton 《Pesticide biochemistry and physiology》2011,101(2):65-70

Coquillettidia mosquitoes are not efficiently controlled by the conventional chemical practices which are known to be satisfactory against the larvae of other mosquito species. A research project was undertaken to conceive a new management strategy using plants as pesticide vectors to reach the Coquillettidia aquatic larvae. Therefore, larval mortality was measured in the presence of plants treated with phloem-translocated pesticides. The herbicide glyphosate at sub-lethal concentrations induced root epidermal cell lyses in maize plantlets cultivated in aqueous media, which clearly decreased larval fixation. Therefore, such herbicide strategy might operate through disturbing the larval physiological activities depending on fixation. The dimethoate insecticide did not affect root viability but at low concentrations seemed to disturb the plant–insect interactions. Larvae showed a lower attraction for roots and a considerable decrease in the root fixation rate. These larval behavior modifications were sufficient to induce mortality, probably due to a lack of fixation on plant roots. The effectiveness of plant foliar treatment with glyphosate or dimethoate under laboratory conditions suggested that it might be the basis for an efficient control strategy for Coquillettidia larvae and mosquitoes having the same living conditions in ponds and for which fixation on macrophyte roots is an absolute requirement (e.g.Mansonia, Mimomyia).  相似文献   

Monitoring the pollution risk and water use in orchard terraces with mango and cherimoya trees by drainage lysimeters     

Carmen Rocío Rodríguez Pleguezuelo  Víctor Hugo Durán Zuazo  José Ramón Francia Martínez  José Luis Muriel Fernández  Dionisio Franco Tarifa 《Irrigation and Drainage Systems》2011,25(2):61-79

Agricultural nonpoint-source pollution is the leading cause of water-quality degeneration of rivers and groundwater. In this context, the coast of Granada province (SE Spain) is economically an important area for the subtropical fruit cultivation. This intensively irrigated agriculture often uses excessive fertilizers, resulting to water pollution. Therefore, a 2-year experiment was conducted using drainage lysimeters to determine the potential risk of nutrient pollution in mango (Mangifera indica L. cv. Osteen) and cherimoya (Annona cherimola Mill. cv. Fino de Jete) orchards. These lysimeters were used to estimate the nutrient budgeting for each crop. NO₃-N, NH₄-N, PO₄-P and K losses according to lysimeters were, respectively, 55.1, 12.4, 3.7, and 0.6 for mango and 61.8, 17.8, 4.9, and 0.5 kg ha⁻¹ yr⁻¹, for cherimoya. NO₃, concentrations in the leachates ranged from 1.8 to 44.3 mg L⁻¹, and from 23.0 to 51.0 mg L⁻¹, for mango and cherimoya, respectively, in some cases exceeding the limits for safe drinking water. PO₄ also exceeded the permitted concentrations related to eutrophication of water, ranging from 0.07 to 0.5 mg L⁻¹ and from 0.12 to 0.68 mg L⁻¹ from mango and cherimoya lysimeters, respectively. With respect to the nutrient balance, N, P, and K removed by cherimoya fruits was 76.4, 5.5, and 22.6 kg ha⁻¹ yr⁻¹, and for mango fruits 30.2, 3.3 and 27.8 kg ha⁻¹ yr⁻¹, respectively. Nutrient losses in the leachates were surprisingly low, considering total N, P, and K applied during the year, in mango lysimeters 3.8, 0.11, and 12.6%, and in cherimoya lysimeters 7.7, 0.23 and 16.0%, respectively, indicating a potential soil accumulation and eventual loss risk, especially during torrential rains. Crop coefficient (Kc) values of mango trees varied within ranges of 0.35–0.67, 0.55–0.89, and 0.39–0.80 at flowering, fruit set, and fruit growth, respectively. Kc values for cherimoya trees had ranges of 0.58–0.67, 0.61–0.68, and 0.43–0.62 at flowering, fruit set and fruit growth, respectively. In this study, the Kc values of mango and cherimoya were significantly correlated to julian days. Therefore, the estimated WUE in the mango and cherimoya orchards reached 21.2 and 14.0 kg ha⁻¹ mm⁻¹, respectively. Thus, this study highlights the urgency to establish the optimal use of fertilizers and irrigation water with respect to crop requirements, to preserve surface-water and groundwater quality, thereby achieving more sustainable agriculture in orchard terraces.  相似文献   

THE EFFECT OF TEMPERATURE IN THE MASS ON THE CHEMICAL COMPOSITION OF SILAGE     

J. C. Murdoch  Muriel C.  Holdsworth 《Grass and Forage Science》1960,15(3):240-245

The effect of temperature on silage quality was investigated in a series of trials over a period of three years.
The results indicated that when conditions in the silage were favourable for the formation of lactic acid, either through treatment or because of the herbage itself, low temperatures in the mass had no adverse effect on silage quality.
Some results suggest that, with chopped or lacerated silage, low maximum temperatures are associated with better quality silage. The results, however, were not entirely consistent.
There appeared to be little or no advantage in allowing unchopped silage to heat to 100°F.  相似文献   

THE USE OF SODIUM METABISULPHITE IN SILAGE MAKING     

J. C. Murdoch  Muriel C.  Holdsworth 《Grass and Forage Science》1958,13(1):55-60

Three trials in which metabisulphite was used as a silage additive are described and the results discussed.
The data from two small-scale trials suggests that metabisulphite and molasses each have a similar effect on the quality of the silage produced, and that wilting appeared to be more effective than either of these two additives.
A comparison of silages in two large-scale trials indicates the necessity for uniform distribution of the metabisulphite.  相似文献   

Tomato as a source of and indicator plant for the potato spindle tuber virus     

W. B. Raymer  Muriel J. O’Brien  D. Merriam 《American Journal of Potato Research》1964,41(10):311-314

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Transmission of potato spindle tuber virus to tomato     

W. B. Raymer  Muriel J. O'Brien 《American Journal of Potato Research》1962,39(11):401-408

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Assignment testing reveals multiple introduced source populations including potential ash hybrids (Fraxinus excelsior × F. angustifolia) in Ireland     

Muriel Thomasset  Juan F. Fernández-Manjarrés  Gerry C. Douglas  Paola Bertolino  Nathalie Frascaria-Lacoste  Trevor R. Hodkinson 《European Journal of Forest Research》2013,132(2):195-209

Large-scale reforestation programmes are a major source of unwarranted gene flow and can have profound consequences on local genetic diversity. Recently, ash has been introduced to Ireland from continental Europe to stock plantations but has often exhibited poor stem form. It was not known whether these trees were Fraxinus excelsior, Fraxinus angustifolia or interspecific hybrids that are known to occur in continental Europe. F. excelsior is the only native ash in Ireland, so the introduced populations represent a potential threat for the genetic diversity of native populations. We characterized the introduced trees within two plantations (Clonee and Kildalkey) using morphological characters and six microsatellite markers. Samples from continental Europe were included for comparison. Plantations exhibited higher genetic diversity than control populations because our data suggest they contain a mixture of several provenances. There was a small but significant differentiation between plantations and control populations (Ф_CT = 0.0211). Bayesian analysis to infer population structure and to assign introduced individuals to reference populations clearly demonstrated the presence of hybrid individuals within the plantations. The percentage of trees detected with potential hybrid origin ranged from 28 to 58 % depending on the plantation and the threshold data analysis level chosen. Most hybrids could be considered cryptic because there was a lack of intermediate morphology for hybrid individuals that mainly clustered with F. excelsior. The results indicated that the source of material at the two plantation sites differed. Management options to minimize the impact of these introduced populations are discussed.  相似文献