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1.
Hert AP Roberts PD Momol MT Minsavage GV Tudor-Nelson SM Jones JB 《Applied and environmental microbiology》2005,71(7):3581-3588
In a previous study, tomato race 3 (T3) strains of Xanthomonas perforans became predominant in fields containing both X. euvesicatoria and X. perforans races T1 and T3, respectively. This apparent ability to take over fields led to the discovery that there are three bacteriocin-like compounds associated with T3 strains. T3 strain 91-118 produces at least three different bacteriocin-like compounds (BCN-A, BCN-B, and BCN-C) antagonistic toward T1 strains. We determined the relative importance of the bacteriocin-like compounds by constructing the following mutant forms of a wild-type (WT) T3 strain to evaluate the antagonism to WT T1 strains: Mut-A (BCN-A-), Mut-B (BCN-B-), Mut-C (BCN-C-), Mut-AB, Mut-BC, and Mut-ABC. Although all mutant and WT T3 strains reduced the T1 populations in in planta growth room experiments, Mut-B and WT T3 were significantly more effective. Mutants expressing BCN-B and either BCN-A or BCN-C reduced T1 populations less than mutants expressing only BCN-A or BCN-C. The triple-knockout mutant Mut-ABC also had a significant competitive advantage over the T1 strain. In pairwise-inoculation field experiments where plants were coinoculated with an individual mutant or WT T3 strain and the T1 strain, the mutant strains and the WT T3 strain were reisolated from more than 70% of the lesions. WT T3 and Mut-B were the most frequently reisolated strains. In field experiments where plants were group inoculated with Mut-A, Mut-B, Mut-C, Mut-ABC, and WT T1 and T3 strains, Mut-B populations dominated all three seasons. In greenhouse and field experiments, the WT and mutant T3 strains had a selective advantage over T1 strains. Bacterial strains expressing both BCN-A and BCN-C appeared to have a competitive advantage over all other mutant and WT strains. Furthermore, BCN-B appeared to be a negative factor, with mutant T3 strains lacking BCN-B having a selective advantage in the field. 相似文献
2.
Molly Sharlach Douglas Dahlbeck Lily Liu Joshua Chiu José M. Jiménez-Gómez Seisuke Kimura Daniel Koenig Julin N. Maloof Neelima Sinha Gerald V. Minsavage Jeffrey B. Jones Robert E. Stall Brian J. Staskawicz 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(3):601-609
The RXopJ4 resistance locus from the wild accession Solanum pennellii (Sp) LA716 confers resistance to bacterial spot disease of tomato (S. lycopersicum, Sl) caused by Xanthomonas perforans (Xp). RXopJ4 resistance depends on recognition of the pathogen type III effector protein XopJ4. We used a collection of Sp introgression lines (ILs) to narrow the RXopJ4 locus to a 4.2-Mb segment on the long arm of chromosome 6, encompassed by the ILs 6-2 and 6-2-2. We then adapted or developed a collection of 14 molecular markers to map on a segregating F2 population from a cross between the susceptible parent Sl FL8000 and the resistant parent RXopJ4 8000 OC7. In the F2 population, a 190-kb segment between the markers J350 and J352 cosegregated with resistance. This fine mapping will enable both the identification of candidate genes and the detection of resistant plants using cosegregating markers. The RXopJ4 resistance gene(s), in combination with other recently characterized genes and a quantitative trait locus (QTL) for bacterial spot disease resistance, will likely be an effective tool for the development of durable resistance in cultivated tomato. 相似文献
3.
A. P. Hert P. D. Roberts M. T. Momol G. V. Minsavage S. M. Tudor-Nelson J. B. Jones 《Applied microbiology》2005,71(7):3581-3588
In a previous study, tomato race 3 (T3) strains of Xanthomonas perforans became predominant in fields containing both X. euvesicatoria and X. perforans races T1 and T3, respectively. This apparent ability to take over fields led to the discovery that there are three bacteriocin-like compounds associated with T3 strains. T3 strain 91-118 produces at least three different bacteriocin-like compounds (BCN-A, BCN-B, and BCN-C) antagonistic toward T1 strains. We determined the relative importance of the bacteriocin-like compounds by constructing the following mutant forms of a wild-type (WT) T3 strain to evaluate the antagonism to WT T1 strains: Mut-A (BCN-A−), Mut-B (BCN-B−), Mut-C (BCN-C−), Mut-AB, Mut-BC, and Mut-ABC. Although all mutant and WT T3 strains reduced the T1 populations in in planta growth room experiments, Mut-B and WT T3 were significantly more effective. Mutants expressing BCN-B and either BCN-A or BCN-C reduced T1 populations less than mutants expressing only BCN-A or BCN-C. The triple-knockout mutant Mut-ABC also had a significant competitive advantage over the T1 strain. In pairwise-inoculation field experiments where plants were coinoculated with an individual mutant or WT T3 strain and the T1 strain, the mutant strains and the WT T3 strain were reisolated from more than 70% of the lesions. WT T3 and Mut-B were the most frequently reisolated strains. In field experiments where plants were group inoculated with Mut-A, Mut-B, Mut-C, Mut-ABC, and WT T1 and T3 strains, Mut-B populations dominated all three seasons. In greenhouse and field experiments, the WT and mutant T3 strains had a selective advantage over T1 strains. Bacterial strains expressing both BCN-A and BCN-C appeared to have a competitive advantage over all other mutant and WT strains. Furthermore, BCN-B appeared to be a negative factor, with mutant T3 strains lacking BCN-B having a selective advantage in the field. 相似文献
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5.
Edward J. Minsavage 《Biotechnic & histochemistry》1955,30(5):231-233
Bacterial preparations, stained by the DeLamater (1951) method, are mounted in a fluid medium (Jensen, 1921) which consists of 75 parts heavy mineral oil and 25 parts alphabromonaphthalene. In these permanent preparations the bacteria appear to be undistorted and the nuclei can be seen clearly and in detail. 相似文献
6.
AB Chang NC Cox J Purcell JM Marchant PJ Lewindon GJ Cleghorn LC Ee GD Withers MK Patrick J Faoagali 《Respiratory research》2005,6(1):1-5
Background and methods
Human metapneumovirus (hMPV) is a recently discovered respiratory virus associated with bronchiolitis, pneumonia, croup and exacerbations of asthma. Since respiratory viruses are frequently detected in patients with acute exacerbations of COPD (AE-COPD) it was our aim to investigate the frequency of hMPV detection in a prospective cohort of hospitalized patients with AE-COPD compared to patients with stable COPD and to smokers without by means of quantitative real-time RT-PCR.Results
We analysed nasal lavage and induced sputum of 130 patients with AE-COPD, 65 patients with stable COPD and 34 smokers without COPD. HMPV was detected in 3/130 (2.3%) AE-COPD patients with a mean of 6.5 × 105 viral copies/ml in nasal lavage and 1.88 × 105 viral copies/ml in induced sputum. It was not found in patients with stable COPD or smokers without COPD.Conclusion
HMPV is only found in a very small number of patients with AE-COPD. However it should be considered as a further possible viral trigger of AE-COPD because asymptomatic carriage is unlikely. 相似文献7.
8.
Summary The use of reticulated polyurethane foam as a support material for the immobilization of methanogenic associations and its application to the anaerobic treatment of fine particulate solid wastes was investigated. The colonization of polyurethane support particles in a continuous upflow reactor fed on a mixture of acetate, propionate and butyrate, was both rapid and dense. The combination of rumen microorganisms and colonized support particles in a two-phase digester resulted in an efficient anaerobic decomposition of papermill sludge. 相似文献
9.
Intermediate filaments in nervous tissues 总被引:29,自引:30,他引:29
Intermediate filaments have been isolated from rabbit intradural spinal nerve roots by the axonal flotation method. This method was modified to avoid exposure of axons to low ionic strength medium. The purified filaments are morphologically 75-80 percent pure. The gel electrophoretogram shows four major bands migrating at 200,000, 145,000, 68,000, and 60,000 daltons, respectively. A similar preparation from rabbit brain shows four major polypeptides with mol wt of 200,000 145,000, 68,000, and 51,000 daltons. These results indicate that the neurofilament is composed of a triplet of polypepetides with mol wt of 200,000, 145,000, and 68,000 daltons. The 51,000-dalton band that appears in brain filament preparations as the major polypeptide seems to be of glial origin. The significance of the 60,000- dalton band in the nerve root filament preparation is unclear at this time. Antibodies raised against two of the triplet proteins isolated from calf brain localize by immunofluorescence to neurons in central and peripheral nerve. On the other hand, an antibody to the 51,000-dalton polypeptide gives only glial staining in the brain, and very weak peripheral nerve staining. Prolonged exposure of axons to low ionic strength medium solubilizes almost all of the triplet polypeptides, leaving behind only the 51,000- dalton component. This would indicate that the neurofilament is soluble at low ionic strength, whereas the glial filament is not. These results indicate that neurofilaments and glial filaments are composed of different polypeptides and have different solubility characteristics. 相似文献
10.
Molecular characterization of XopAG effector AvrGf2 from Xanthomonas fuscans ssp. aurantifolii in grapefruit 下载免费PDF全文
Alberto M. Gochez Deepak Shantharaj Neha Potnis Xiaofeng Zhou Gerald V. Minsavage Frank F. White Nian Wang Jason C. Hurlbert Jeffrey B. Jones 《Molecular Plant Pathology》2017,18(3):405-419
Xanthomonas fuscans ssp. aurantifolii group C strains exhibit host specificity on different citrus species. The strains possess a type III effector, AvrGf2, belonging to the XopAG effector gene family, which restricts host range on citrus. We dissected the modular nature and mode of action of AvrGf2 in grapefruit resistance. XopAG effectors possess characteristic features, such as a chloroplast localization signal, a cyclophilin‐binding domain characteristic amino acid sequence motif (GPLL) and a C‐terminal domain‐containing CLNAxYD. Mutation of GPLL to AASL in AvrGf2 abolished the elicitation of the hypersensitive response (HR), whereas mutation of only the first amino acid to SPLL delayed the HR in grapefruit. Yeast two‐hybrid experiments showed strong interaction of AvrGf2 with grapefruit cyclophilin (GfCyp), whereas AvrGf2‐SPLL and AvrGf2‐AASL mutants showed weak and no interaction, respectively. Molecular modelling and in silico docking studies for the cyclophilin–AvrGf2 interaction predicted the binding of citrus cyclophilins (CsCyp, GfCyp) to hexameric peptides spanning the cyclophilin‐binding domain of AvrGf2 and AvrGf2 mutants (VAGPLL, VASPLL and VAAASL) with affinities equivalent to or better than a positive control peptide (YSPSA) previously demonstrated to bind CsCyp. In addition, the C‐terminal domain of XopAG family effectors contains a highly conserved motif, CLNAxYD, which was identified to be crucial for the induction of HR based on site‐directed mutagenesis (CLNAxYD to CASAxYD). Our results suggest a model in which grapefruit cyclophilin promotes a conformational change in AvrGf2, thereby triggering the resistance response. 相似文献