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1.
Susan J. Sprague Marie-Hélène Balesdent Hortense Brun Helen L. Hayden Stephen J. Marcroft Xavier Pinochet Thierry Rouxel Barbara J. Howlett 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):33-40
Resistance of Brassica napus (oilseed rape, canola) conferred by three different major resistance genes has been overcome by changes in virulence of Leptosphaeria maculans populations in France and Australia. In South Australia where B. napus cultivars with major gene resistance derived from Brassica rapa ssp. sylvestris were grown extensively, resistance was rendered ineffective within 3 years of commercial release of the cultivar. Disease
severity was higher on cultivars with sylvestris-derived resistance than cultivars with polygenic resistance. This Australian situation is compared to that in France, where
resistance conferred by the Rlm1 gene was overcome nation-wide in 5 years under commercial cropping practices, and also where a source of resistance introgressed
into B. napus from B. juncea was rendered inefficient in 3 years in experimental field plots near Rennes. 相似文献
2.
Collet E Lemée-Cailleau MH Buron-Le Cointe M Cailleau H Wulff M Luty T Koshihara SY Meyer M Toupet L Rabiller P Techert S 《Science (New York, N.Y.)》2003,300(5619):612-615
We report the direct observation by x-ray diffraction of a photoinduced paraelectric-to-ferroelectric structural phase transition using monochromatic 100-picosecond synchrotron pulses. It occurs in tetrathiafulvalene-p-chloranil, a charge-transfer molecular material in which electronic and structural changes are strongly coupled. An optical 300-femtosecond laser pulse switches the material from a neutral to an ionic state on a 500-picosecond time scale and, by virtue of intrinsic cooperativity, generates self-organized long-range structural order. The x-ray data indicate a macroscopic ferroelectric reorganization after the laser irradiation. Refinement of the structures before and after laser irradiation indicates structural changes at the molecular level. 相似文献
3.
Uystepruyst C Coghe J Dorts T Harmegnies N Delsemme MH Art T Lekeux P 《Veterinary research》2002,33(6):709-724
The aim of this study was to evaluate the effect of body positioning immediately after delivery on respiratory and metabolic adaptation to extra-uterine life in newborn calves. One hundred and one Belgian White and Blue calves were delivered at term by an elective caesarean section and were assigned into three categories according to the body position imposed immediately after umbilical cord rupture: 71 calves were placed in lateral recumbency; 16 calves were placed in sternal recumbency and 14 calves were suspended by the hind legs for less than 90 seconds (75 +/- 5 s). Following this initial body position, the calves were allowed to move without restraint. They were examined at birth, 5, 15, 30, 45 and 60 minutes, and 2, 3, 6, 12 and 24 hours after birth by the following measurements: physical examination, heart rate, arterial blood gas analysis, pulmonary function tests using the esophageal balloon catheter technique, arterial and venous blood acid-base balance analysis, rectal temperature, jugular venous blood sampling for the determination of blood glucose, plasma lactate and serum cortisol concentrations, haematologic variables and passive immune transfer variables. Body positioning immediately after delivery clearly influenced respiratory and metabolic adaptation to extra-uterine life in term calves delivered by an elective caesarean section. Systematic sternal recumbency and suspension by the hind legs for less than 90 seconds immediately after umbilical cord rupture had a positive functional impact on postnatal pulmonary mechanics and gas exchange and on postnatal correction of mixed acidosis present at birth, contributing in turn to an enhanced passive immune transfer. These two body positions should be encouraged to improve adaptation at birth in healthy term calves delivered by an elective caesarean section. Evaluation of possible side-effects is required before application in severely asphyxiated calves. 相似文献
4.
Zykwinska A Boiffard MH Kontkanen H Buchert J Thibault JF Bonnin E 《Journal of agricultural and food chemistry》2008,56(19):8926-8935
Green labeled pectins were extracted by an environmentally friendly way using proteases and cellulases being able to act on proteins and cellulose present in cell walls. Pectins were isolated from different plant byproducts, i.e., chicory roots, citrus peel, cauliflower florets and leaves, endive, and sugar beet pulps. Enzymatic extraction was performed at 50 degrees C for 4 h, in order to fulfill the conditions required for microbiological safety of extracted products. High methoxy (HM) pectins of high molar mass were extracted with three different enzyme mixtures. These pectins were subsequently demethylated with two pectin methyl esterases (PMEs), either the fungal PME from Aspergillus aculeatus or the orange PME. It was further demonstrated that high molar mass low methoxy (LM) pectins could also be extracted directly from cell walls by adding the fungal PME to the mixture of protease and cellulase. Moreover, health benefit pectic oligosaccharides, the so-called modified hairy regions, were obtained after enzymatic treatment of the residue recovered after pectin extraction. The enzymatic method demonstrates that it is possible to convert vegetable byproducts into high-added value compounds, such as pectins and pectic oligosaccharides, and thus considerably reduce the amount of these residues generated by food industries. 相似文献
5.
Marie-Hélène Balesdent Karine Louvard Xavier Pinochet Thierry Rouxel 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):53-65
Nine avirulence genes (AvrLm1–AvrLm9) were identified in Leptosphaeria maculans, the causal agent of stem canker of oilseed rape (OSR), combinations of which could theoretically generate up to 512 different
races of the fungus. L. maculans displays a high evolutionary potential to adapt to novel resistance genes as illustrated by the Rlm1 breakdown in France, where virulent populations became prevalent within three growing seasons. An improved knowledge of the
race structure of the fungal population is therefore needed to ensure a better use of available major resistance genes. The
objective of this study was to characterise the L. maculans population structure in France using a large-scale, rationalised sample of isolates. Experimental fields, planted with “trap
plants” harbouring no major resistance gene, were sown at 20 locations. Single-pycnidium isolates were collected from leaf
lesions that developed in early autumn and 1797 isolates were genotyped at Avr loci. The frequency of AvrLm6 and AvrLm7 was higher than 99%, whereas avrLm2 and avrLm9 alleles were fixed in the population. AvrLm1, AvrLm4, AvrLm5 and AvrLm8 were polymorphic. AvrLm3 isolates were detected at a very low frequency (less than 1%). Only 11 races were identified in France, with one race prevalent,
namely Av5-6-7-(8) (i.e. virulent on Rlm1, Rlm2, Rlm3, Rlm4 and Rlm9), representing around 65% of the population. Disparities between the locations sampled were evident at all scales analysed.
Some virulent races, such as those harbouring avrLm5, were present before the introduction of the corresponding resistance gene in the commercial OSR crop. 相似文献
6.
Guyon F Douet C Colas S Salagoïty MH Medina B 《Journal of agricultural and food chemistry》2006,54(26):9918-9923
Despite the robustness of isotopic methods applied in the field of wine control, isotopic values can be slightly influenced by enological practices. For this reason, must concentration technique effects on wine isotopic parameters were studied. The two studied concentration techniques were reverse osmosis (RO) and high-vacuum evaporation (HVE). Samples (must and extracted water) have been collected in various French vineyards. Musts were microfermented at the laboratory, and isotope parameters were determined on the obtained wine. Deuterium and carbon-13 isotope ratios were studied on distilled ethanol by nuclear magnetic resonance (NMR) and isotope ratio mass spectrometry (IRMS), respectively. The oxygen-18 ratio was determined on extracted and wine water using IRMS apparatus. The study showed that the RO technique has a very low effect on isotopic parameters, indicating that this concentration technique does not create any isotopic fractionation, neither at sugar level nor at water level. The effect is notable for must submitted to HVE concentration: water evaporation leads to a modification of the oxygen-18 ratio of the must and, as a consequence, ethanol deuterium concentration is also modified. 相似文献
7.
Delphine Ansan-Melayah Thierry Rouxel Jean Bertrandy Bruno Letarnec Edouard Mendes-Pereira Marie-Hélène Balesdent 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(9):835-841
Field experiments were conducted in Versailles, France, to assess blackleg resistance of Brassica napus cultivars Quinta and Glacier under natural infection conditions. Blackleg disease severity was assessed twice during growth of B. napus. Quinta resistance was highly expressed as only 13% to 18% of the plants exhibited leaf symptoms in December, whereas Glacier and other cultivars displayed more than 80% of infected plants. In June (harvest), 70% (first year) to 41.5% (second year) of Quinta plants were canker-free. In contrast, Glacier was as infected as the susceptible control cultivars, with more than 88% of plants displaying canker. The Leptosphaeria maculans population structure was examined in parallel. Based on soluble protein patterns, 9% of the 299 fungal isolates collected were characterized as Tox0 species, and belonged to the NA1 sub-group. All but two of Tox0 isolates were isolated from atypical dark necrotic leaf lesions, mainly occurring on Quinta. In contrast, the Tox+ isolates were recovered from typical leaf lesions. Following a cotyledon inoculation test on the differential set Westar, Quinta and Glacier, 92 to 95% of Tox+ isolates collected on susceptible cultivars were characterized as PG3 isolates, i.e. avirulent on Quinta. The remaining Tox+ isolates belong to PG4, i.e. virulent on the three cultivars. No PG2 isolate, i.e. avirulent on both Quinta and Glacier, was identified in the sampling. The present study suggests that specific resistance expressed at the cotyledon level can be efficient under field conditions where the corresponding avirulent races of the pathogen are prevalent. 相似文献
8.
Pommet M Redl A Guilbert S Morel MH 《Journal of agricultural and food chemistry》2005,53(10):3943-3949
Wheat gluten structure was modified in different ways: Disulfide bonds were reduced by sulfitolysis, or protein chains were enzymatically hydrolyzed at three different degrees of proteolysis. A kinetic study of the thermal reactivity of the modified glutens showed that gluten aggregation kinetic was slowed in consequence to the shift of gluten size distribution toward smaller proteins. In contrary to sulfitolysis, proteolysis also affected the gluten reactivity potential because of the formation of numerous nonreactive species. Moreover, the thermally induced browning reaction was greatly enhanced by proteolysis, which increased the amount of free amine residues, substrates of the Maillard reaction. On the contrary, a whitening effect was observed for reduced gluten with bisulfite. Proteolysis was also found to decrease plasticized gluten viscosity, to increase gluten-based materials water solubility, and to enhance gluten adhesiveness properties but to reduce its mechanical performance. Sulfitolysis was considered as a possible way of extending gluten processability by extrusion or injection molding, whereas proteolysis was found to confer enhanced gluten stickiness that suggests new potential end uses of gluten in the pressure sensitive adhesives domain. 相似文献
9.
10.
Domenek S Morel MH Bonicel J Guilbert S 《Journal of agricultural and food chemistry》2002,50(21):5947-5954
Size exclusion high-performance liquid chromatography analysis was carried out on wheat gluten-glycerol blends subjected to different heat treatments. The elution profiles were analyzed in order to follow the solubility loss of protein fractions with specific molecular size. Owing to the known biochemical changes involved during the heat denaturation of gluten, a mechanistic mathematical model was developed, which divided the protein denaturation into two distinct reaction steps: (i) reversible change in protein conformation and (ii) protein precipitation through disulfide bonding between initially SDS-soluble and SDS-insoluble reaction partners. Activation energies of gluten unfolding, refolding, and precipitation were calculated with the Arrhenius law to 53.9 kJ x mol(-1), 29.5 kJ x mol(-1), and 172 kJ x mol(-1), respectively. The rate of protein solubility loss decreased as the cross-linking reaction proceeded, which may be attributed to the formation of a three-dimensional network progressively hindering the reaction. The enhanced susceptibility to aggregation of large molecules was assigned to a risen reaction probability due to their higher number of cysteine residues and to the increased percentage of unfolded and thereby activated proteins as complete protein refolding seemed to be an anticooperative process. 相似文献