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1.
Midgut juice of Plutellaxylostella strain PXR which is resistant to Cry1Ac was biochemically characterized relative to the susceptible PXS strain. The midgut juice of PXR (PXR-Juice) was shown to process Cry1Ac protoxin to 60 kDa active toxin with the same processing pattern as that of juice from PXS (PXS-Juice) in SDS–PAGE. PXS larvae which were given the Cry1Ac toxin pre-processed with PXR-Juice were killed with the same rate as that with Cry1Ac pre-activated by trypsin. PXR-Juice was found to contain three times larger amount of 66 kDa protein (P66) than PXS-Juice and the N-terminal amino acid sequence of P66 was matched to that of glucosinolate sulfatase in data base search. The protein band of P66 was coincided with the band of p-nitro phenyl sulfatase activity in zymogram. P66 purified to homogeneity in SDS-PAGE bound to Cry1Ac and soybean agglutinin, and KD for Cry1Ac was estimated to be 718 nM with surface plasmon resonance analysis. Using purified sulfatase, Km and Vmax were estimated and involvement of the enzyme in the PXR resistance was discussed.  相似文献   

2.
Novel primers for rep-PCR were developed with the original software and based on `ancient diverged periodical sequences'. Rep-PCR with these primers was applied to study genetic relationships among 51 Xanthomonas campestris strains. The strains were collected from different countries including Russia, Japan, UK, Germany and Hungary. Reference strains of three X. campestrispathovars and five other Xanthomonas species were included. Based on qualitative differences in amplification profiles, the strains were divided into four major groups. Two subgroups recognised within X. campestrispopulation were similar to RFLP haplotypes. The third subgroup included strains of two other pathovariants and Japanese isolates of X. campestris pv. campestriswhile the fourth group comprised the other species of Xanthomonas. The analysis of the diversity within X. campestris resulted in the conclusion that isolates belong to distinct clonal populations (subgroups). The differences between the subgroups of X. campestris were only slightly smaller than between species of Xanthomonas. A PCR fragment about 600 bp amplified by primer KRPN2 was found in nearly all tested strains of X. campestris.SCAR primers designed for this marker produced a single specific band for strains of X. campestris, but not for other Xanthomonas, Pseudomonas and Erwiniastrains tested. Application of the new primer set for rep-PCR offers a rapid, simple and reproducible method for identification of bacterial strains. The X. campestris-specific SCAR primers may be used in diagnostics of this important plant pathogen.  相似文献   

3.
A bacterium was isolated from superficial bark necroses on young poplars and its pathogenicity demonstrated by inoculation experiments. The organism was identified asXanthomonas campestris. Cross-inoculations showed that a previously undescribed pathovar was involved. It is suggested to designate this organismX. campestris pv.populi.Samenvatting Uit een oppervlakkige bastnecrose bij jonge populieren werd massaal een bepaalde bacterie geïsoleerd. Met deze bacterie werden gezonde populieren in het veld geïnoculeerd via verwonding van de bast. Als gevolg van de inoculaties ontwikkelden zich bij ongeveer 40% van de geïnoculeerde bomen hetzelfde type bastnecrosen, terwijl bij de controleplanten geen enkele reactie optrad. Uit de kunstmatig verkregen necrosen werd dezelfde bacterie geïsoleerd.Identificatie met biochemische en serologische methoden toonde aan dat de bacterieXanthomonas campestris was.Vervolgens werden in de kas kruisinoculaties uitgevoerd met verschillende xanthomonaden op populier, wilg, kool en geranium. DeX. campestris isolaten uit populier tastten behalve populier ook wilg aan. De andere gebruikte stammen waren waardplant-specifiek, al bleven sommigen ervan minstens acht maanden in leven in een niet-waardplant, evenwel zonder symptomen te veroorzaken. Geconcludeerd wordt, dat de bastnecrosen zijn veroorzaakt door een nog niet beschreven pathovar vanX. campestris. Voorgesteld wordt om deze bacterieXanthomonas campestris pv.populi te noemen.  相似文献   

4.
Common bacterial blight (CBB) in edible beans (Phaseolus vulgaris), incited Xanthomonas campestris pv. phaseoli, reduces bean yields and seed quality. The main objective of this study was to determine resistance to common bacterial blight in bean genotypes. Twenty-two bean genotypes grown in Turkey including common and snap bean cultivars/lines were collected from different parts of Turkey and tested for resistance against to Xanthomonas campestris pv. phaseoli strain MFD-11. All the common and snap bean lines/cultivars tested were moderately susceptible, susceptible or highly susceptible, except AG-7117 which was found resistant to Xanthomonas campestris pv. phaseoli. This is the first report of a resistance source in a common bean line (AG-7117) against Xanthomonas campestris pv. phaseoli.  相似文献   

5.
Methanolic extracts of seeds and fruits of the chinaberry tree,Melia azedarach L. (Meliaceae), showed strong antifeedant activity against 2nd instar larvae ofSesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae), a very serious pest of maize(Zea mays L.) in Mediterranean countries. Extracts were applied in an artificial diet at concentrations of 1000 and 2000 ppm. The parameters used to evaluate the activity were larval growth rates; quantity of food ingested; phagodepression/phagostimulation index; quantity of frass produced; quantity of material ingested; duration of larval development; and cumulative mortality. Seed extract showed high bioactivity at both doses, while fruit extract proved to be less active, and only at the higher dose used (2000 ppm) did it display a slight antifeedant activity. The activity of theM. azedarach seed extract at the higher dose (2000 ppm) was comparable to that of pure azadirachtin applied at a dose of 1.25 ppm, or to ‘Mubel’, a commercial extract ofAzadirachta indica A. Juss. (Meliaceae), applied at a dose of 75 ppm.  相似文献   

6.
Severe rot was found at the base of leaves and stems of chingensai (Brassica campestris L. chinensis group) in Okayama Prefecture in 2000. The causal fungi were morphologically identified as Pythium ultimum Trow var. ultimum and P. aphanidermatum (Edson) Fitzpatrick. This is the first report of rot caused by Pythium species on chingensai. We named this disease Pythium rot of chingensai.  相似文献   

7.
Forty-four bacterial isolates were obtained from infected wheat, barley and various grasses from different regions of Iran. All isolates were bacteriologically similar toXanthomonas campestris and some of their physiological and biochemical features can be useful for a primary differentiation between them. Depending on their pathogenicity, the isolates were split into two groups; the wheat group isolated from wheat, barley and grasses could infect artificially wheat, barley, rye,Agropyron elongatum, Bromus inermis, andLolium multiflorum but not oat, whereas the barley group obtained from cultivated or wild barley was pathogenic to barley only. From their bacteriological characteristics and host range, the barley and the wheat group isolated were identified asX. campestris pvs.hordei andcerealis, respectively.Aegilops sp.,Sclerochloa dura, andHeteranthelium sp. were, for the first time, shown to be hosts ofX. c. pv.cerealis.  相似文献   

8.
The effect of an enriched methanolic extract ofMelia azedarach L. (Meliaceae) fruits on the size of the corpora allata (CA), the juvenile hormone (JH) titer and the protein content in the hemolymph of two lepidopteran pests in Egypt,Spodoptera littoralis (Boisd.) andAgrotis ipsilon (Hufn.), was studied. Different concentrations of the extract were incorporated into an artificial diet on which the larvae were allowed to feed. InS. littoralis, a significant reduction in the CA volume of larvae treated at the 1000 ppm extract levelvs that of control larvae was observed. In A.ipsilon, a reduction was found in the right CA gland only. Larvae of both species that had fed on a diet withMelia extract had a higher mean JH-II titer in the hemolymph than did control larvae. In both species, the content of hemolymph protein was decreased significantly after feeding for 6 days on a diet treated with concentrations above 50 ppm extract, followed by 6 days on a normal diet. The results show that aM. azedarach fruit extract has an effect on the neuroendocrine control in the insects. The effect on the hemolymph protein levels is discussed in connection with changes in the morphology/physiology of the gut.  相似文献   

9.
The GRAS compounds cinnamaldehyde (at 30 ppm), acetaldehyde (at 70 ppm), benzalde-hyde (at 50 ppm) and potassium metabisulphite (at 250 ppm) either completely inhibited or significantly reduced thein vitro mycelial growth ofGliocephalotrichum microchlamydosponim,Colletotrichum gloeosporioides andBotryodiplodia theobromae, the causative fungi of brown spot, anthracnose and stem end rot, respectively, of rambutan fruits,Nephelium lappaceum. The four compounds also significantly reduced the severity of all three diseases and the activity of pectic lyase and polygalacturonase enzymes secreted by the three fungi.  相似文献   

10.
为探索棉铃虫Helicoverpa armigera液泡型ATP酶(vacuolar-type proton ATPase,V-ATP酶)亚基A对棉铃虫生长发育的影响及其在Bt杀虫机制中的作用,采用PCR结合RACE技术克隆了棉铃虫V-ATP酶亚基A基因序列,通过实时荧光定量PCR技术测定了其在棉铃虫不同发育历期和幼虫肠道不同组织中的表达量;并比较了4龄幼虫取食含Cry1Ac蛋白饲料后中肠中该基因表达量的变化。结果显示,棉铃虫V-ATP酶亚基A基因全长2 578 bp(Gen Bank登录号KP090287),开放阅读框1 863 bp,编码621个氨基酸。V-ATP酶亚基A高度保守,不同物种间氨基酸序列同源性大于90%。V-ATP酶亚基A在棉铃虫整个生育期都有表达,在4龄幼虫体内表达量最高,是卵期的3.00倍;在幼虫肠道不同组织中,中肠中表达量最高,是后肠中的2.65倍。4龄棉铃虫幼虫取食含Cry1Ac蛋白的人工饲料后,中肠V-ATP酶亚基A的表达受到抑制,表达量为对照的0.39~0.81倍。表明V-ATP酶亚基A基因可能参与棉铃虫的生长发育和代谢过程,并可能与抵御Cry1Ac的毒杀作用有一定关系。  相似文献   

11.
Black rot, caused by Xanthomonas campestris pv. campestris (Xcc), is a major disease constraint to cabbage production by smallholder farmers in Africa. Variability exists within the pathogen, and yet differentiation of Xcc strains from other closely-related xanthomonads attacking crucifers is often difficult. The Biolog system, fatty acid methyl ester analysis using microbial identification system (MIS), rep-PCR and pathogenicity tests were used to identify and characterise Xcc strains from Tanzania. Great diversity was observed among Xcc strains in their Biolog and rep-PCR profiles. Specific rep-PCR genomic fingerprints were linked to some geographical areas in the country. Most of the Xcc strains were clustered in two groups based on their fatty acid profiles and symptom expression in cabbage although some deviant strains were found. Each of the methods allowed a degree of identification from species, pathovar to the strain level. Biolog and MIS identified all Xcc strains at least to the genus level. Additionally, Biolog identified 47% of Xcc strains to the pathovar and 43% to strain level, whereas MIS identified 43% of the strains to pathovar level. In the absence of a database, the utility of rep-PCR for routine diagnosis of strains was limited, although the procedure was good for delineation of Xcc to the strain level. These findings indicate the existence of Xcc strains in Tanzania that are distinct from those included in Biolog and MIS databases. The limitations noticed warrant continued improvement of databases and inclusion of pathogenicity testing, using universally susceptible cultivars, as an integral part of strain identification.  相似文献   

12.
Extracellular polysaccharides (EPSs) likely provide phytopathogenic bacteria a selective advantage both inside and outside plants. Despite the relatively scant knowledge about EPS biosynthesis in phytopathogenic bacteria, it clearly is a well controlled, complex, energy-intensive process. Unexpectedly, three phytopathogenic bacteria have been found to autoregulate EPS production in response to extracellular signal compounds (pheromones) that they produce. Like many bacteria, Pantoea stewartii subsp. stewartii produces a N-acyl-homoserine lactone (AHL) autoinducer. However, unlike most AHL-dependent autoinduction systems, that in P. stewartii subsp. stewartii somehow represses EPS production in the absence of autoinducer. Instead of an AHL-dependent system (which it also has), Ralstonia solanacearum uses a novel autoregulator identified as 3-hydroxypalmitic acid methyl ester to regulate EPS biosynthesis. A lack of this autoregulator in R. solanacearum results in repression of EPS biosynthesis by a complex two-component sensor/response regulator signal cascade. Xanthomonas campestris pv. campestris has two partially overlapping autoregulatory systems. The autoregulators are incompletely characterized, but one diffusible signal factor (DSF) is thought to be a fatty acid derivative and the other diffusible factor (DF) may be a butyrolactone. The autoregulation pathways in X. campestris pv. campestris are essentially unknown, but EPS production is controlled by both the DSF and DF systems, whereas production of extracellular enzymes and pigment production are regulated independently. In a confined micro-environment, population density and intercellular concentrations of an autoregulator will increase in parallel, so autoregulation is one way that bacteria can coordinate gene expression to synthesize EPS only at high cell density. However, because there is often limited evidence that it is actually cell density that is being detected, researchers should not assume a priori that autoregulation must function for quorum sensing. Some possible reasons for why phytopathogenic bacteria would benefit from delaying EPS production are discussed.  相似文献   

13.
Xanthomonas campestris pv. phaseoli and X. campestris pv. phaseoli var. fuscans, the causal agents of the common and fuscous bacterial blight of beans, appear to be phenotypically identical except that the latter can produce a melanin-like pigment in culture. Ten isolates of X. campestris pv. phaseoli and 12 isolates of X. campestris pv. phaseoli var. fuscans were examined using pulsed-field gel electrophoresis (PFGE) and restriction fragment length polymorphism (RFLP). The average genome sizes for X. campestris pv. phaseoli and X. campestris pv. phaseoli var. fuscans were 3850.6±48.9 and 3584.3±68.1kb respectively. The genetic relatedness of the isolates was determined from macrorestriction patterns generated using XbaI. Cluster analysis indicated that the non-fuscous and fuscous strains are distinct. RFLP results, based on the highly conserved hrp genes and a pectate lyase gene from Xanthomonas, also indicated that the two bacteria are genetically different. The results obtained in this study suggest that this pathovar can be segregated into two subgroups under a recently proposed reclassification of the Xanthomonas genus.  相似文献   

14.
为探究甜菜夜蛾Spodoptera exigua中肠碱性磷酸酶(alkaline phosphatase protein 2,ALP2)是否为Cry1Ac杀虫蛋白的受体,采用同源克隆和RACE技术克隆了编码alp2基因的完整c DNA序列,利用荧光定量PCR比较了甜菜夜蛾幼虫中肠不同龄期ALP2表达量的差异,利用Ligand blot方法检测了中肠ALP2与Cry1Ac杀虫蛋白的结合。结果表明,alp2基因序列全长1 629 bp(Gen Bank序列号为KP420013),编码542个氨基酸,预测在氨基酸序列N端包含1个由21个氨基酸组成的信号肽,在C端存在1个GPI修饰的锚定位点,且在整个氨基酸序列中存在多个糖基化修饰位点。在整个甜菜夜蛾幼虫期均有ALP2表达,但不同龄期的表达量差异显著,1龄幼虫期表达量最低,4龄幼虫期最高。Ligand blot方法检测结果表明原核表达的ALP2片段与活化的Cry1Ac杀虫蛋白可以结合。研究表明,甜菜夜蛾中肠的ALP2可能是Cry1Ac的受体之一。  相似文献   

15.
Biological control efficiency of an antagonistic, endophytic strain of Bacillus subtilis (strain BB) was evaluated against three strains of the black rot pathogen, Xanthomonas campestris pv. campestris (Xcc), in four Brassica crops (cabbage, cauliflower, rape and broccoli) grown during three consecutive growing seasons and on two soil types, in two different areas in Zimbabwe. Strain BB controlled the disease caused by strain Xcc B-147 in all Brassica crops during the dry and short rainy seasons. A similar effect was observed in cabbage using the strain Xcc 33908. Biological control was effective in broccoli, but not in cabbage and rape during the main rainy season in clay loam soil and limited biological control effect was still observed when these crops were grown in sandy loam soil. The endophytic colonisation of cabbage roots by strain BB was confirmed by immuno-blotting during the whole growing season. Biological control of black rot with strain BB is discussed in relation to its effect on Xcc strains, Brassica crops and to the effect of weather and soil conditions.  相似文献   

16.
为更好地了解苏云金芽胞杆菌Bacillus thuringiensis毒素蛋白对二点委夜蛾Athetis lepigone的毒力以及作用机理,通过饲喂含有Cry1Ac、Cry1Ab、Cry2Ab和Vip3Aa四种不同Bt毒素蛋白饲料,测定Bt毒素蛋白对二点委夜蛾幼虫的毒力,并观察取食4种毒素蛋白后幼虫中肠组织的病理学变化。结果显示,二点委夜蛾幼虫取食毒素蛋白后72 h,Cry1Ab和Cry1Ac毒素蛋白对二点委夜蛾幼虫的杀虫活性较高,校正死亡率为84.7%和76.4%;Vip3Aa和Cry2Ab毒素蛋白的毒力较弱。二点委夜蛾幼虫取食4种Bt毒素蛋白后,中肠柱状细胞微绒毛脱落,杂乱地分散在肠腔内,杯状细胞变形和腔内微绒毛脱落,线粒体和内质网等变形破裂,细胞核的核膜消失、核质凝聚和形状发生变化,经Cry1Ab和Cry1Ac毒素蛋白处理后中肠细胞的病变症状和速度明显高于Cry2Ab和Vip3Aa毒素蛋白处理。表明Cry1Ab和Cry1Ac毒素蛋白对二点委夜蛾幼虫杀虫活性较高,显著高于Cry2Ab和Vip3Aa毒素蛋白,且对其中肠细胞的破坏作用也较强。  相似文献   

17.
Bacterial black spot disease of mango is caused by Xanthomonas campestris pv. mangiferaeindicae (Xcm), which consists of two genotypically and phenotypically distinct groups of strains. Monoclonal antibodies (MABs) were produced – 15 against CFBP 1717, a group I strain, and 9 against CFBP 2919 (yellow-pigmented), a group II strain – and were analyzed for their characteristics. On the avidin-biotin peroxidase complex enzyme-linked immunosorbent assay, the dilution limit of the MABs was between 100 and 200000 and was 10 times higher when measured on the corresponding ascitic fluid. All kinds of isotypes were represented among the MABs. All the Japanese Xcm strains, designated group I by hrp-restriction fragment length polymorphism (RFLP) analysis, reacted equally with MAB 1A7H12G3, which is the most specific for all but one worldwide group I strains, and to only one strain among group II. Also, to various extents, serological heterogeneity inside the two groups was consistently differentiated based on isozyme and RFLP analyses. MAB 1E2E1 against CFBP2919, because of its narrow specificity, and MAB 1A7H12G3 against CFBP1717, because of its broad specificity, will be useful for epidemiological studies or general control of the pathogen.  相似文献   

18.
The PCR-RFLP of the 16S-23S rDNA spacer region was used to differentiate Xanthomonas species pathogenic to sugarcane. Strains of X. albilineans, X. campestris pv. vasculorum Types A and B, X. sacchari and Xanthomonas sp. from Trinidad, South Africa and India were examined. The amplification products were digested with Alu I, Hae III, Hpa II and Mbo I and the results showed that the different groups of bacterial strains exhibited distinct RFLP patterns for each tested endonuclease, except X. albilineans and X. sacchari which could only be differentiated from each other by the digestion with Hpa II. The results also allowed the separation of X.c. pv. vasculorum Type A from X.c. pv. vasculorum Type B and strongly suggested that the analyzed Xanthomonas sp. strains belong to X. sacchari. Nine X. campestris (pv. not determined) strains included in this study showed identical profiles to X.c. pv. vasculorum Type A group and DNA–DNA hybridization experiments confirmed these results. PCR-RFLP of the 16S-23S rDNA spacer region could be applied as a reliable method for differentiating the xanthomonads pathogenic to sugarcane.  相似文献   

19.
Tests of acute toxicity were performed on the most common species of aquarium fish, Poecilia reticulata. Guppies (P. reticulata) were exposed to progressive concentrations of methyl parathion (MP) and chlorpyrifos (CPF); a semi-static method according to guidelines of OECD was used. Tests of acute toxicity were conducted using 10 fish for each separate concentration and for the control group. The results were subjected to probit analysis to determine the 96 h LC50 values. The 96 h LC50 values of MP and CPF to P. reticulata were 8.48 ppm/L (5.98–10.89) and 0.176 ppm/L (0.313–0.224) respectively. In addition, behavioral changes at each concentration were observed for the individual fish. Fish were exposed for 96 h to different sublethal concentrations of MP and CPF (¼ LC50, 1/8 LC50 and 1/10 LC50) and their oxidative stress-induction potential was estimated in brain, liver and gills of fish. MDA content is induced in all tissues but maximum rise was observed in gills (161% and 153% for MP and CPF respectively). With regard to antioxidant defense system (ADS), GSH level decreased in the brain, liver and gills of tissues of MP treated fishes (22%, 6% and 13% respectively) and showed increase in brain and gills CPF treated (23% and 21% respectively). CAT, GST, GR and SOD levels fluctuated in all treatment groups relative to the control. Brain AChE showed dose-dependent inhibition in fish exposed to the higher concentrations reached 45% and 66% for MP and CPF respectively. Collective findings demonstrated that pesticide exposure of fish induced an increase in MDA and fluctuated ADS along with inhibited AChE. These findings may be used as valuable biomarkers for evaluation of water pollution.  相似文献   

20.
In this investigation, we have evaluated the effect of sodium fluoride (NaF) on hepatic function in pregnant and lactating mice and their suckling pups. Experiments were carried out on female Wistar mice given 500 ppm sodium fluoride (226 ppm fluoride ion) in their drinking water from the 15th day of pregnancy until day 14 after delivery. All mice were sacrificed on day 14 after parturition. Our results showed a significant decrease in serum levels of total protein and albumin, a marked hypoglycaemia and a significant decline in serum cholesterol and triglyceride levels in fluoride-treated mice and their pups. Whereas globulin and biluribin levels in serum were not significantly changed by NaF treatment. On the other hand, serum transaminase activities (aspartate transaminase; alanine transaminase), which well known as markers of liver function, were elevated indicating hepatic cells’ damage after treatment with fluoride. Lipid peroxidation increased in NaF-treated mice and pups, as revealed by high liver malondialdehyde levels, while serum total antioxidant status showed a significant decline. These biochemical modifications in NaF-treated mice also correspond histologically with extensive ballooning, hepatocellular necrosis and infiltration of mononuclear cells. These effects were not observed in controls.  相似文献   

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