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21.
22.
D Taruscio C Morciano P Laricchiuta P Mincarone F Palazzo CG Leo S Sabina R Guarino J Auld T Sejersen D Gavhed K Ritchie M Hilton-Boon J Manson PG Kanavos D Tordrup V Tzouma Y Le Cam J Senecat G Filippini S Minozzi C Del Giovane H Schünemann JJ Meerpohl B Prediger L Schell R Stefanov G Iskrov T Miteva-Katrandzhieva P Serrano-Aguilar L Perestelo-Perez MM Trujillo-Martín J Pérez-Ramos A Rivero-Santana A Brand H van Kranen K Bushby A Atalaia J Ramet L Siderius M Posada I Abaitua-Borda V Alonso Ferreira M Hens-Pérez FJ Manzanares 《Orphanet journal of rare diseases》2014,9(Z1):O14
23.
C Möller G Weber MM Dreyfuss 《Journal of industrial microbiology & biotechnology》1996,17(5-6):359-372
Intraspecific variation among 84 isolates of the anamorphic fungusChaunopycnis alba from 26 different geographical locations was analyzed by investigating optimal growth temperatures, differences in the production of secondary metabolites and presence or absence of the cyclosporin synthetase gene. The genetic diversity was assessed using random amplified polymorphic DNA (RAPD). Analysis of these data showed high genetic, metabolic and physiological diversity within this species. Isolates from the Antarctic represented the most homogeneous group withinC. alba and together with isolates from the Arctic these polar strains differed from alpine, temperate and tropical strains by low optimal growth temperatures and by low production of secondary metabolites. Isolates from tropical climes were characterized by high optimal growth temperatures and by the production of comparatively diverse metabolite spectra. Most of the isolates that were similar in the combination of their physiological and metabolic characters were also genetically related. Isolates from different geographical origins did not show many similarities, with the exception of the cyclosporin A-producing isolates, and large diversity could be observed even within a single habitat. This leads us to the suggestion that for pharmaceutical screening programs samples should be collected from a diversity of different geographical and climatic locations. For the selection of strains for screening the RAPD assay seems to be the most powerful tool. It reflected the highest intraspecific diversity and the results corresponded well with the other characteristics. 相似文献
24.
Induced systemic resistance (ISR) in plants: mechanism of action 总被引:1,自引:0,他引:1
Plants possess a range of active defense apparatuses that can be actively expressed in response to biotic stresses (pathogens
and parasites) of various scales (ranging from microscopic viruses to phytophagous insect). The timing of this defense response
is critical and reflects on the difference between coping and succumbing to such biotic challenge of necrotizing pathogens/parasites.
If defense mechanisms are triggered by a stimulus prior to infection by a plant pathogen, disease can be reduced. Induced
resistance is a state of enhanced defensive capacity developed by a plant when appropriately stimulated. Systemic acquired
resistance (SAR) and induced systemic resistance (ISR) are two forms of induced resistance wherein plant defenses are preconditioned
by prior infection or treatment that results in resistance against subsequent challenge by a pathogen or parasite. Selected
strains of plant growth-promoting rhizobacteria (PGPR) suppress diseases by antagonism between the bacteria and soil-borne
pathogens as well as by inducing a systemic resistance in plant against both root and foliar pathogens. Rhizobacteria mediated
ISR resembles that of pathogen induced SAR in that both types of induced resistance render uninfected plant parts more resistant
towards a broad spectrum of plant pathogens. Several rhizobacteria trigger the salicylic acid (SA)-dependent SAR pathway by
producing SA at the root surface whereas other rhizobacteria trigger different signaling pathway independent of SA. The existence
of SA-independent ISR pathway has been studied in Arabidopsis thaliana, which is dependent on jasmonic acid (JA) and ethylene signaling. Specific Pseudomonas strains induce systemic resistance in viz., carnation, cucumber, radish, tobacco, and Arabidopsis, as evidenced by an enhanced defensive capacity upon challenge inoculation. Combination of ISR and SAR can increase protection
against pathogens that are resisted through both pathways besides extended protection to a broader spectrum of pathogens than
ISR/SAR alone. Beside Pseudomonas strains, ISR is conducted by Bacillus spp. wherein published results show that several specific strains of species B. amyloliquifaciens, B. subtilis, B. pasteurii, B. cereus, B. pumilus, B. mycoides, and B.sphaericus elicit significant reduction in the incidence or severity of various diseases on a diversity of hosts. 相似文献
25.
26.
Group B Streptococcus: global incidence and vaccine development 总被引:1,自引:0,他引:1
Johri AK Paoletti LC Glaser P Dua M Sharma PK Grandi G Rappuoli R 《Nature reviews. Microbiology》2006,4(12):932-942
An ongoing public health challenge is to develop vaccines that are effective against infectious diseases that have global relevance. Vaccines against serotypes of group B Streptococcus (GBS) that are prevalent in the United States and Europe are not optimally efficacious against serotypes common to other parts of the world. New technologies and innovative approaches are being used to identify GBS antigens that overcome serotype-specificity and that could form the basis of a globally effective vaccine against this opportunistic pathogen. This Review highlights efforts towards this goal and describes a template that can be followed to develop vaccines against other bacterial pathogens. 相似文献
27.
SEAN is an application that predicts single nucleotide polymorphisms (SNPs) using multiple sequence alignments produced from expressed sequence tag (EST) clusters. The algorithm uses rules of sequence identity and SNP abundance to determine the quality of the prediction. A Java viewer is provided to display the EST alignments and predicted SNPs. 相似文献
28.
Biological control is an accepted important component of current plant disease management strategies. Introduction of bacterized
seeds carrying bacterial isolates with proven growth-promotion capabilities and antagonistic characteristics offer a valid
alternative to chemical protectants. Root colonization of disease-susceptible (PS 1024) and moderately resistant (PS1042)
varieties of soyabean (Glycine Max L) by fluorescent pseudomonad (FLPs) strains GRP3, PEn-4, PRS1, and WRS-24 was studied in relation to natural occurrence of anthracnose caused by Colletotrichum dematium (Pers Ex Fr.) Grove. Rhizoplane population of FLPs was maintained at a critical level (5.3 cfu) up to 30 days of plant growth,
followed by a steep decline. Indigenous FLPs population, however, remained nearly unchanged (3.0 to 2.4 log g−1 root) between 30 days and 75 days of plant growth. The relative FLPs population in rhizosphere was lower than that in rhizoplane.
Although intervarietal difference was observed, the root/shoot length remained unaffected. Compared to nonbacterized control,
dry root weight was improved by FLPs treatment. Severity of foliar anthracnose was reduced significantly after FLPs treatment
in the variety PS 1042. Because the point of FLPs treatment (seed bacterization) was away from the site of disease appearance
(leaf), operation of induced systemic resistance in strains PEn-4 and GRP3 appears imminent. 相似文献
29.
Canals R Xia XQ Fronick C Clifton SW Ahmer BM Andrews-Polymenis HL Porwollik S McClelland M 《BMC genomics》2012,13(1):212
ABSTRACT: BACKGROUND: The contribution of a gene to the fitness of a bacterium can be assayed by whether and to what degree the bacterium tolerates transposon insertions in that gene. We use this fact to compare the fitness of syntenic homologous genes among related Salmonella strains to reveal differences not apparent at the gene sequence level. RESULTS: A transposon Tn5 derivative was used to construct mutants in Salmonella Typhimurium ATCC14028 (STM1) and Salmonella Typhi Ty2 (STY1), which were then grown in rich media. The locations of 234,152 and 53,556 integration sites, respectively, were mapped by sequencing. These data were compared to similar data available for a different Ty2 strain (STY2) and essential genes identified in E. coli K-12 (ECO). Of 277 genes considered essential in ECO, all had syntenic homologs in STM1, STY1, and STY2, and all but nine genes were either devoid of Tn insertions or had very few. For three of these nine genes, part of the annotated gene lacked Tn integrations (yejM, ftsN and murB). At least one of the other six genes, trpS, had a potentially functionally redundant gene encoded elsewhere in Salmonella but not in ECO. An additional 165 genes were almost entirely devoid of transposon integrations in all three Salmonella strains examined, including many genes associated with protein and DNA synthesis. Four of these genes (STM14_1498.L, STM14_2872, STM14_3360.RJ, and STM14_5442) are not found in E. coli. Notable differences in the extent of gene selection were also observed among the three different Salmonella isolates. Mutations in hns, for example, were selected against in STM1 but not in the two STY strains, which have a defect in rpoS rendering hns nonessential. CONCLUSIONS: Comparisons among transposon integration profiles from different members of a species and among related species, all grown in similar conditions, identify differences in gene fitness among syntenic homologous genes. Further differences in fitness profiles among shared genes can be expected in other selective environments, with potential relevance for comparative systems biology. 相似文献
30.
Jessika Füssel Phyllis Lam Gaute Lavik Marlene M Jensen Moritz Holtappels Marcel Günter Marcel MM Kuypers 《The ISME journal》2012,6(6):1200-1209
Nitrite oxidation is the second step of nitrification. It is the primary source of oceanic nitrate, the predominant form of bioavailable nitrogen in the ocean. Despite its obvious importance, nitrite oxidation has rarely been investigated in marine settings. We determined nitrite oxidation rates directly in 15N-incubation experiments and compared the rates with those of nitrate reduction to nitrite, ammonia oxidation, anammox, denitrification, as well as dissimilatory nitrate/nitrite reduction to ammonium in the Namibian oxygen minimum zone (OMZ). Nitrite oxidation (⩽372 nM NO2− d−1) was detected throughout the OMZ even when in situ oxygen concentrations were low to non-detectable. Nitrite oxidation rates often exceeded ammonia oxidation rates, whereas nitrate reduction served as an alternative and significant source of nitrite. Nitrite oxidation and anammox co-occurred in these oxygen-deficient waters, suggesting that nitrite-oxidizing bacteria (NOB) likely compete with anammox bacteria for nitrite when substrate availability became low. Among all of the known NOB genera targeted via catalyzed reporter deposition fluorescence in situ hybridization, only Nitrospina and Nitrococcus were detectable in the Namibian OMZ samples investigated. These NOB were abundant throughout the OMZ and contributed up to ∼9% of total microbial community. Our combined results reveal that a considerable fraction of the recently recycled nitrogen or reduced NO3− was re-oxidized back to NO3− via nitrite oxidation, instead of being lost from the system through the anammox or denitrification pathways. 相似文献