Impact of fertilization on tree-ring delta15N and delta13C in beech stands: a retrospective analysis     

Elhani S  Guehl JM  Nys C  Picard JF  Dupouey JL 《Tree physiology》2005,25(11):1437-1446

We studied the effects of two fertilization treatments (N and NPKCa) on wood nitrogen (N) isotope composition (delta(15)N), water-use efficiency (WUE) estimated by carbon isotope composition (delta(13)C) analyses, and ring width of trees in 80-year-old beech (Fagus sylvatica L.) stands in the forest of Fougères, western France. Four replicates were fertilized in two successive years (1973 and 1974), 20 years before core sampling. Unfertilized control trees displayed a decreasing delta(15)N trend with time. The N and NPKCa treatments both increased delta(15)N compared with the control treatment. Wood extraction by organic solvents enhanced the delta(15)N signal. Thus, N addition to the beech ecosystem, even in moderate amounts, could be traced back in tree-ring delta(15)N, suggesting that wood N isotope analysis is a promising tool for studying the long-term effects of N deposition on forests. Although WUE decreased for about 6 years after N fertilization, WUE in NPKCa-treated trees did not differ significantly from that in control trees. Results were similar whether based on cellulose or total wood delta(13)C analysis, suggesting that extraction of cellulose is not necessary when studying fertilization impacts on WUE. The NPKCa treatment had a large impact on radial growth, causing a significant long-lasting increase of 29% compared with the control treatment. Nitrogen alone did not change radial growth significantly.  相似文献   

Antibiotic susceptibility of bacteria isolated from infections in cats and dogs throughout Europe (2002–2009)     

Stéphane Kroemer  Farid El Garch  Delphine Galland  Jean-Luc Petit  Frédérique Woehrle  Henri-Jean Boulouis 《Comparative immunology, microbiology and infectious diseases》2014

A monitoring program of the pre-treatment susceptibility of clinical isolates of bacteria from diseased dogs and cats was active between the years 2002 and 2009. Susceptibility of each isolated strain to a panel of nine antibiotics (amoxicillin/clavulanic acid, ampicillin, penicillin, clindamycin, doxycycline, enrofloxacin, marbofloxacin, trimethoprim and trimethoprim/sulfamethoxazole) was assessed. The Minimum Inhibitory Concentration (MIC) of marbofloxacin was also determined by a standardized microdilution technique following CLSI recommendations. In total, 1857 bacterial strains were collected throughout Europe from cases of otitis, respiratory, urinary and dermatological infections. Although bacterial susceptibility varied for each of the antibiotics within the panel, patterns of susceptibility were similar to those described in the literature for comparable time periods and geographical areas. With a clinical resistance varying from 0 to 14.48% against the isolated strains, marbofloxacin susceptibility was very high and remains an effective antibiotic for the treatment of otitis, urinary, respiratory and dermatological infections in companion animals.  相似文献   

Marennine,Promising Blue Pigments from a Widespread Haslea Diatom Species Complex     

Romain Gastineau  Fran?ois Turcotte  Jean-Bernard Pouvreau  Michèle Moran?ais  Jo?l Fleurence  Eko Windarto  Fiddy Semba Prasetiya  Sulastri Arsad  Pascal Jaouen  Mathieu Babin  Laurence Coiffard  Céline Couteau  Jean-Fran?ois Bardeau  Boris Jacquette  Vincent Leignel  Yann Hardivillier  Isabelle Marcotte  Nathalie Bourgougnon  Réjean Tremblay  Jean-Sébastien Deschênes  Hope Badawy  Pamela Pasetto  Nikolai Davidovich  Gert Hansen  Jens Dittmer  Jean-Luc Mouget 《Marine drugs》2014,12(6):3161-3189

In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries.  相似文献   

MIOR: an individual-based model for simulating the spatial patterns of soil organic matter microbial decomposition   总被引：1，自引：1，他引：1  

D. Masse  C. Cambier    A. Brauman    S. Sall    K. Assigbetse  & J.-L. Chotte 《European Journal of Soil Science》2007,58(5):1127-1135

  相似文献   

Castanea sativa Mill. leaves as new sources of natural antioxidant: an electronic spin resonance study     

Calliste CA  Trouillas P  Allais DP  Duroux JL 《Journal of agricultural and food chemistry》2005,53(2):282-288

The antioxidant potential of Castanea sativa Mill. leaf (sweet chestnut) was explored as a new source of active extracts. The capacity of the different fractions issued from aqueous, methanol, and ethyl acetate extracts to inhibit the stable free radical 2,2-diphenyl-1-pycryl-hydrazyl, superoxide anion, and hydroxyl radical was measured by electronic spin resonance. Their scavenging potential was analyzed versus their amount of phenolic compounds. Among the active fractions, the most effective one was A6, an ethyl acetate fraction, which contained a high level of total phenolic compounds (29.1 g/100 g). Thus, a different extraction procedure was performed to concentrate the active compounds of A6 in the new C. sativa leaf extract (CSLE). Compared to reference antioxidants (quercetin and vitamin E) and standard extracts (Pycnogenol, from French Pinus maritima bark, and grape marc extract), it was observed that A6 and CSLE have high antioxidant potentials, equivalent to at least those of reference compounds.  相似文献   

Assessment of strawberry aroma through solid-phase microextraction-gas chromatography and artificial neuron network methods. Variety classification versus growing years     

de Boishebert V  Urruty L  Giraudel JL  Montury M 《Journal of agricultural and food chemistry》2004,52(9):2472-2478

In a previous work, the SPME-GC-MS method (chemical analysis) coupled with KSOM-ANN treatment of the results (statistical algorithm) has proved to be efficient to classify 70 strawberry samples harvested in the same year, through the 17 varieties to which they belonged, in a two-dimensional map. As an extension, the present study confirms that these results were not dependent on the year of strawberry production and discusses what effects were observed between results obtained in different years. Samples of different strawberry varieties were harvested during the three campaigns of 2000, 2001, and 2002 and analyzed independently. The chemical data matrix obtained in each case allowed the verification of the proposal that the same discriminative effect could be obtained independently of the year of production by using maps of different sizes. Therefore, 30 measures obtained from samples of 9 varieties in 2000, 54 measures from 13 varieties in 2001, and 80 measures from 20 varieties in 2002 were correctly classified by using 20, 35, and 56 hexagon maps, respectively. In a second analysis based on the 2002 production, the chemical differences between variety aromatic features were noted through the increasing size of the map used. Finally, results relative to 7 varieties cultivated in 2001 and 2002 and stored under exactly the same conditions were computed together for elaborating a single map. An interesting effect of double classification according to the year and the varieties was observed.  相似文献   

Impacts of tree canopy structure on wind flows and fire propagation simulated with FIRETEC     

François Pimont  Jean-Luc Dupuy  Rodman R. Linn  Sylvain Dupont 《Annals of Forest Science》2011,68(3):523-530

Introduction   

Forest fuel management in the context of fire prevention generally induces heterogeneous spatial patterns of vegetation. However, the impact of the canopy structure on both wind flows and fire behavior is not well understood.  相似文献   

Influence of irrigation on the distribution and control of the nematode Meloidogyne javanica by the biocontrol bacterium Pasteuria penetrans in the field     

Kounbobr Roch Dabiré  Saliou Ndiaye  Jean-Luc Chotte  Sabine Fould  Mamadou Thiam Diop  Thierry Mateille 《Biology and Fertility of Soils》2005,41(3):205-211

Pasteuria penetrans, a bacterial parasite of plant-parasitic nematodes, is used to control root-knot nematode Meloidogyne spp. populations in vegetable crops. But its efficiency is variable, mostly because of the patchy distribution of the bacteria in arable fields. As the infective P. penetrans are non-motile bacteria in soil, abiotic soil factors can affect the bacteria–nematode relationships. An epidemiological study, conducted in a vegetable field, showed that abiotic factors such as irrigation, soil water holding capacity and texture, affected the efficiency of P. penetrans. A correspondence analysis between these abiotic factors and the density of P. penetrans spores in the soil, and the proportion of Meloidogyne javanica juveniles infected by the bacteria, revealed that irrigation affected directly the distribution of the spores in soil pores related to their passive transport by water flow. Laboratory experiments conducted on the passive transport of spores confirmed that intensive irrigation leached the spores down the soil profile and decreased the percentage of infected Meloidogyne juveniles.  相似文献   

Radiolysis of kaempferol in water/methanol mixtures. Evaluation of antioxidant activity of kaempferol and products formed     

Marfak A  Trouillas P  Allais DP  Champavier Y  Calliste CA  Duroux JL 《Journal of agricultural and food chemistry》2003,51(5):1270-1277

Oxidative reaction between hydroxymethyl radical ((*)CH(2)OH) and kaempferol, in methanol and methanol/water mixtures, was studied by gamma-radiolysis using a (60)Co source. Radiolysis was performed with concentrations and doses ranging from 5 x 10(-)(5) M to 5 x 10(-)(3) M and from 0.5 kGy to 14 kGy, respectively. Kaempferol degradation was followed by HPLC. Results showed that (*)CH(2)OH reacts with kaempferol at the 3-OH group and produces two depsides (K1 and K2) and other products including K3. K1, K2, and K3 were identified by NMR, LC-MS, and HRMS. The kaempferol degradation pathway leading to the K1, K2, and K3 formation is proposed. It was observed that the more water concentration in the irradiation medium increases, the more K2 concentration increases. Comprehension of food preservation is not clear because many phenomena occurring during irradiation are not established. Radiolysis of kaempferol in water/methanol mixtures helps to elucidate the phenomenon and it is possible that during the treatment of nutriments by gamma-irradiation, a series of products such as depside K2 could be formed. Antioxidant properties of kaempferol radiolysis products were evaluated according to their capacity to decrease the EPR DPPH (1,1-diphenyl-2-picrylhydrazil) signal and to inhibit superoxide radicals formed by the enzyme reaction "xanthine + xanthine oxidase".  相似文献   

Middle Paleolithic assemblages from the Indian subcontinent before and after the Toba super-eruption     

Petraglia M  Korisettar R  Boivin N  Clarkson C  Ditchfield P  Jones S  Koshy J  Lahr MM  Oppenheimer C  Pyle D  Roberts R  Schwenninger JL  Arnold L  White K 《Science (New York, N.Y.)》2007,317(5834):114-116

The Youngest Toba Tuff (YTT) eruption, which occurred in Indonesia 74,000 years ago, is one of Earth's largest known volcanic events. The effect of the YTT eruption on existing populations of humans, and accordingly on the course of human evolution, is debated. Here we associate the YTT with archaeological assemblages at Jwalapuram, in the Jurreru River valley of southern India. Broad continuity of Middle Paleolithic technology across the YTT event suggests that hominins persisted regionally across this major eruptive event.  相似文献