The huanglongbing (HLB) disease of citrus trees, caused by Candidatus Liberibacter asiaticus and Ca. Liberibacter americanus, was first reported in Brazil in March, 2004. The presence of the disease has caused serious concerns
among growers. Pruning experiments were conducted to determine if removal of symptomatic branches or the entire canopy (decapitation)
would eliminate infected tissues and save HLB-affected trees. Pruning was done in five blocks on a total of 592 3- to 16 year-old
‘Valência’, ‘Hamlin’ or ‘Pêra’ sweet orange trees showing no symptoms or with two levels of symptom severity. Ten decapitated
trees per block were caged and all trees were treated with insecticides to control the psyllid vector, Diaphorina citri. Mottled leaves reappeared on most symptomatic (69.2%) as well on some asymptomatic (7.6%) pruned trees, regardless of age,
variety, and pruning procedure. Presence of the pathogen (Ca. Liberibacter americanus) in all symptomatic trees was confirmed by PCR. In general, the greater the symptom severity before
pruning the lower the percentage of trees that remained asymptomatic after pruning. 相似文献
Six isolates of Mycoplasma bovoculi obtained from cattle herds with bovine keratoconjunctivitis were analyzed by gel electrophoresis and immunoblotting techniques. All six strains showed similarity in their protein profiles although no two patterns were identical. Antigenic differences between strains were detected in immunoblots reacted with post-exposure calf serum. A common 94 kDa protein band designated p94 was detected in all six strains reacted with monoclonal antibody MA25.5 developed to one of the strains. The p94 was also recognized in these strains by the calf serum. Trypsin treatment of intact mycoplasma cells resulted in the removal of p94 from immunoblots reacted with MA or hyperimmune rabbit serum. Other trypsin-resistant antigens shared between strains or being strain-specific in nature were identified when trypsin-treated mycoplasma cells were reacted with hyperimmune rabbit serum. The p94 antigen was shown to be of mycoplasmal origin by radio-immunoprecipitation using the MA or hyperimmune rabbit serum. These studies identify the presence of a surface antigen (p94) on M. bovoculi membrane in all strains examined that is trypsin sensitive by the use of monoclonal antibody, calf serum and hyperimmune rabbit serum.
Résumé
Six souches de Mycoplasma bovoculi, d'origine bovine (animaux affectés de keratoconjunctivite) ont été analysées par des techniques d'éléctrophorèse et par ‘immunoblotting’. Les six souches ont montré des similitudes dans leurs profils proteiniques. Cependant, aucun profil n'a été identique. Des differences antigéniques entre les souches ont étés detectées suite au traitement des immunoblots avec un sérum bovin infecté par M. bovoculi. L'anticorps monoclonal MA25.5 dirigé contre une des souches a réagi avec une bande proteinique (94 kDa) commune aux six souches. Cette bande a été designee p94. Cette bande p94 a été également identifiée chez tous les souches en utilisant le sérum bovin. Le traitement des mycoplasmes intactes par la trypsine a éliminé la bande p94 des immunoblots: cela a été démontr é par l'usage d'un anticorps monoclonal, ou par un sérum hyperimmun de lapin. D'autres antigènes résistants à la trypsine, communs ou spécifiques aux souches ont été identifiés quand les mycoplasmes traités par le trypsine ont été mélangés au sérum hyperimmun de lapin. La radioimmunoprécipitation par l'anticorps monoclonal ou le sérum hyperimmun de lapin a demontré que l'antigène p94 est d'origine mycoplasmique. Ces études identifient la présence d'un antigène de surface (le p94) localisé sur la membranc de M. bovoculi chez toutes les souches examinées. Cet antigène est sensible à la trypsine. Cela a été montré avec l'anticorps monoclonal, le sérum bovin et le sérum hyperimmune du lapin. 相似文献
In this work, the forward extraction of defatted wheat germ protein (DWGP) by reverse micelles was studied. The reverse micellar systems were formed by sulphosuccinic acid bis (2-ethylhexyl) ester sodium salt (AOT), isooctane and KCl solution. The effects of AOT concentration, pH, KCl concentration, extraction time, the amounts of defatted wheat germ flour (DWGF), W0 (the molar ratio of water to surfactant, i.e. W0 = [H2O]/[AOT]) and temperature on the forward extraction efficiency of DWGP were tested. On the basis of single-factor experiments, the optimum extraction was achieved by response surface methodology (RSM). The experimental results lead to the conclusion that the highest forward extraction efficiency of DWGP was reached at the AOT concentration 0.06 g/mL, pH 8, KCl concentration 0.1 mol/L, time 30 min, the amounts of DWGF 0.500 g, W0 25 and temperature 36 °C. Under these conditions, the forward extraction efficiency of DWGP achieved 37%. 相似文献