The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Aart J E Van Bel - One of the best experts on this subject based on the ideXlab platform.
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multivesicular bodies participate in a cell wall associated defence response in barley leaves attacked by the pathogenic powdery mildew fungus
Cellular Microbiology, 2006Co-Authors: Ralph Huckelhoven, Karlheinz Kogel, Aart J E Van BelAbstract:Summary Localized cell wall modification and accumulation of antimicrobial compounds beneath sites of fungal attack are common mechanisms for plant resistance to fungal Penetration. In barley (Hordeum vulgare) leaves, light-microscopically visible vesicle-like bodies (VLBs) containing H2O2 or phenolics frequently accumulate around cell wall appositions (syn. papillae), in which the Penetration Attempt of the biotrophic powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) is halted. By ultrastructural analyses, we demonstrated that the Bgh-induced VLBs represent different structures. VLBs intensively stained by H2O2-reactive dyes were actually small papillae instead of cytoplasmic vesicles. Other VLBs were identified as osmiophilic bodies or multivesicular compartments, designated paramural bodies (PMBs) and multivesicular bodies (MVBs). MVBs seemingly followed two distinct pathways: either they were engulfed by the tonoplast for degradation in the vacuole or they fused with the plasma membrane to release their internal vesicles into the paramural space and hence could be the origin of PMBs. MVBs and PMBs appeared to be multicomponent kits possibly containing building blocks to be readily assembled into papilla and antimicrobial compounds to be discharged against fungal Penetration. Finally, we propose that released paramural vesicles might be similar to exosomes in animal cells.
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Multivesicular bodies participate in a cell wall‐associated defence response in barley leaves attacked by the pathogenic powdery mildew fungus
Cellular microbiology, 2006Co-Authors: Ralph Huckelhoven, Karlheinz Kogel, Aart J E Van BelAbstract:Localized cell wall modification and accumulation of antimicrobial compounds beneath sites of fungal attack are common mechanisms for plant resistance to fungal Penetration. In barley (Hordeum vulgare) leaves, light-microscopically visible vesicle-like bodies (VLBs) containing H(2)O(2) or phenolics frequently accumulate around cell wall appositions (syn. papillae), in which the Penetration Attempt of the biotrophic powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) is halted. By ultrastructural analyses, we demonstrated that the Bgh-induced VLBs represent different structures. VLBs intensively stained by H(2)O(2)-reactive dyes were actually small papillae instead of cytoplasmic vesicles. Other VLBs were identified as osmiophilic bodies or multivesicular compartments, designated paramural bodies (PMBs) and multivesicular bodies (MVBs). MVBs seemingly followed two distinct pathways: either they were engulfed by the tonoplast for degradation in the vacuole or they fused with the plasma membrane to release their internal vesicles into the paramural space and hence could be the origin of PMBs. MVBs and PMBs appeared to be multicomponent kits possibly containing building blocks to be readily assembled into papilla and antimicrobial compounds to be discharged against fungal Penetration. Finally, we propose that released paramural vesicles might be similar to exosomes in animal cells.
Sarit Kraus - One of the best experts on this subject based on the ideXlab platform.
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Multi-robot adversarial patrolling: Handling sequential attacks
Artificial Intelligence, 2019Co-Authors: Efrat Sless Lin, Noa Agmon, Sarit KrausAbstract:Abstract Robot teams are commonly used for security tasks, where they are required to repeatedly monitor an area in order to prevent Penetrations, initiated by an adversary. Current research in this field focuses mainly on detecting Penetration Attempts, but not on responding. Requiring the robots to also inspect and handle the Penetrations has a significant impact on the patrol, as each Penetration Attempt also influences the robots' behavior, making them vulnerable to multiple attacks. Moreover, a knowledgeable adversary can initiate two sequential attacks, where the second Attempt exploits the vulnerable points caused by the requirement that a robot handle the first Penetration Attempt. In this work, we consider the problem of sequential attacks and examine different robot policies against such adversarial behavior. We provide an optimal patrol strategy for various Penetration Attempt patterns. Our novel approach considers a full history-length policy, while previous work only handled very limited lengths of history. The use of a longer history improves the results. Moreover, we show how to significantly reduce, in practice, the exponential space state of the problem, while maintaining the optimality of the solution.
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AAMAS - Multi-robot adversarial patrolling: facing coordinated attacks
2014Co-Authors: Efrat Sless, Noa Agmon, Sarit KrausAbstract:The use of robot teams is common for performing patrol tasks, in which the robots are required to repeatedly visit a target area (perimeter, in our case) controlled by an adversary, in order to detect Penetrations. Previous work has focused on determining the optimal patrol algorithm when facing a general adversary that tries to penetrate once through the patrol path. There, the robots' goal is to detect Penetrations, i.e., the robots do not change their behavior once a Penetration is detected. Requiring the robots to physically inspect Penetration Attempts can have far reaching consequences on the performance of the patrol algorithm. Specifically, it creates vulnerability points along the patrol path that a knowledgeable adversary can take advantage of. In this work we investigate the problem of coordinated attacks, in which the adversary initiates two attacks in order to maximize its chances of successful Penetration, assuming a robot from the team will be sent to examine a Penetration Attempt. We suggest an algorithm that computes the optimal robot strategy for handling such coordinated attacks, and show that despite its exponential time complexity, practical run time of the algorithm can be significantly reduced without harming the optimality of the strategy.
Ralph Huckelhoven - One of the best experts on this subject based on the ideXlab platform.
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multivesicular bodies participate in a cell wall associated defence response in barley leaves attacked by the pathogenic powdery mildew fungus
Cellular Microbiology, 2006Co-Authors: Ralph Huckelhoven, Karlheinz Kogel, Aart J E Van BelAbstract:Summary Localized cell wall modification and accumulation of antimicrobial compounds beneath sites of fungal attack are common mechanisms for plant resistance to fungal Penetration. In barley (Hordeum vulgare) leaves, light-microscopically visible vesicle-like bodies (VLBs) containing H2O2 or phenolics frequently accumulate around cell wall appositions (syn. papillae), in which the Penetration Attempt of the biotrophic powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) is halted. By ultrastructural analyses, we demonstrated that the Bgh-induced VLBs represent different structures. VLBs intensively stained by H2O2-reactive dyes were actually small papillae instead of cytoplasmic vesicles. Other VLBs were identified as osmiophilic bodies or multivesicular compartments, designated paramural bodies (PMBs) and multivesicular bodies (MVBs). MVBs seemingly followed two distinct pathways: either they were engulfed by the tonoplast for degradation in the vacuole or they fused with the plasma membrane to release their internal vesicles into the paramural space and hence could be the origin of PMBs. MVBs and PMBs appeared to be multicomponent kits possibly containing building blocks to be readily assembled into papilla and antimicrobial compounds to be discharged against fungal Penetration. Finally, we propose that released paramural vesicles might be similar to exosomes in animal cells.
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Multivesicular bodies participate in a cell wall‐associated defence response in barley leaves attacked by the pathogenic powdery mildew fungus
Cellular microbiology, 2006Co-Authors: Ralph Huckelhoven, Karlheinz Kogel, Aart J E Van BelAbstract:Localized cell wall modification and accumulation of antimicrobial compounds beneath sites of fungal attack are common mechanisms for plant resistance to fungal Penetration. In barley (Hordeum vulgare) leaves, light-microscopically visible vesicle-like bodies (VLBs) containing H(2)O(2) or phenolics frequently accumulate around cell wall appositions (syn. papillae), in which the Penetration Attempt of the biotrophic powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) is halted. By ultrastructural analyses, we demonstrated that the Bgh-induced VLBs represent different structures. VLBs intensively stained by H(2)O(2)-reactive dyes were actually small papillae instead of cytoplasmic vesicles. Other VLBs were identified as osmiophilic bodies or multivesicular compartments, designated paramural bodies (PMBs) and multivesicular bodies (MVBs). MVBs seemingly followed two distinct pathways: either they were engulfed by the tonoplast for degradation in the vacuole or they fused with the plasma membrane to release their internal vesicles into the paramural space and hence could be the origin of PMBs. MVBs and PMBs appeared to be multicomponent kits possibly containing building blocks to be readily assembled into papilla and antimicrobial compounds to be discharged against fungal Penetration. Finally, we propose that released paramural vesicles might be similar to exosomes in animal cells.
Karlheinz Kogel - One of the best experts on this subject based on the ideXlab platform.
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multivesicular bodies participate in a cell wall associated defence response in barley leaves attacked by the pathogenic powdery mildew fungus
Cellular Microbiology, 2006Co-Authors: Ralph Huckelhoven, Karlheinz Kogel, Aart J E Van BelAbstract:Summary Localized cell wall modification and accumulation of antimicrobial compounds beneath sites of fungal attack are common mechanisms for plant resistance to fungal Penetration. In barley (Hordeum vulgare) leaves, light-microscopically visible vesicle-like bodies (VLBs) containing H2O2 or phenolics frequently accumulate around cell wall appositions (syn. papillae), in which the Penetration Attempt of the biotrophic powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) is halted. By ultrastructural analyses, we demonstrated that the Bgh-induced VLBs represent different structures. VLBs intensively stained by H2O2-reactive dyes were actually small papillae instead of cytoplasmic vesicles. Other VLBs were identified as osmiophilic bodies or multivesicular compartments, designated paramural bodies (PMBs) and multivesicular bodies (MVBs). MVBs seemingly followed two distinct pathways: either they were engulfed by the tonoplast for degradation in the vacuole or they fused with the plasma membrane to release their internal vesicles into the paramural space and hence could be the origin of PMBs. MVBs and PMBs appeared to be multicomponent kits possibly containing building blocks to be readily assembled into papilla and antimicrobial compounds to be discharged against fungal Penetration. Finally, we propose that released paramural vesicles might be similar to exosomes in animal cells.
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Multivesicular bodies participate in a cell wall‐associated defence response in barley leaves attacked by the pathogenic powdery mildew fungus
Cellular microbiology, 2006Co-Authors: Ralph Huckelhoven, Karlheinz Kogel, Aart J E Van BelAbstract:Localized cell wall modification and accumulation of antimicrobial compounds beneath sites of fungal attack are common mechanisms for plant resistance to fungal Penetration. In barley (Hordeum vulgare) leaves, light-microscopically visible vesicle-like bodies (VLBs) containing H(2)O(2) or phenolics frequently accumulate around cell wall appositions (syn. papillae), in which the Penetration Attempt of the biotrophic powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) is halted. By ultrastructural analyses, we demonstrated that the Bgh-induced VLBs represent different structures. VLBs intensively stained by H(2)O(2)-reactive dyes were actually small papillae instead of cytoplasmic vesicles. Other VLBs were identified as osmiophilic bodies or multivesicular compartments, designated paramural bodies (PMBs) and multivesicular bodies (MVBs). MVBs seemingly followed two distinct pathways: either they were engulfed by the tonoplast for degradation in the vacuole or they fused with the plasma membrane to release their internal vesicles into the paramural space and hence could be the origin of PMBs. MVBs and PMBs appeared to be multicomponent kits possibly containing building blocks to be readily assembled into papilla and antimicrobial compounds to be discharged against fungal Penetration. Finally, we propose that released paramural vesicles might be similar to exosomes in animal cells.
Hideyoshi Toyoda - One of the best experts on this subject based on the ideXlab platform.
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Conidia of Erysiphe trifoliorum Attempt Penetration twice during a two-step germination process on non-host barley leaves and an artificial hydrophobic surface
Mycoscience, 2011Co-Authors: Yoshihiro Takikawa, Teruo Nonomura, Yoshinori Matsuda, Koji Kakutani, Hideyoshi ToyodaAbstract:In the present study, using a high-fidelity digital microscope, we observed the sequence of appressorial development on the germ tubes of a powdery mildew fungus isolated from red clover leaves. Based on its morphological characteristics and rDNA internal transcribed spacer (ITS) sequences, the fungus was identified as Erysiphe trifoliorum , and one of its isolates, designated as KRCP-4N, was used in this work. The conidial germination of isolate KRCP-4N was studied on host (red clover) and non-host (barley) leaves, as well as on an artificial hydrophobic membrane (Parafilm). More than 90% of conidia germinated synchronously and developed dichotomous appressoria (symmetrical double-headed appressoria) on all substrata used. On host leaves, all appressorium-forming conidia developed hyphae (colony-forming hyphae) from conidial bodies without extending germ tubes from the tips of the appressoria. On non-host leaves and on Parafilm-covered glass slides, however, all conidia extended germ tubes from one side of dichotomous appressoria (two-step germination). In addition to the dichotomous appressoria, we detected a few conidia that produced hooked appressoria and extended germ tubes from the tip of the appressorium. Penetration Attempts by KRCP-4N conidia on barley leaves were impeded by papillae formed at Penetration sites beneath these two types of appressorium. From these results, we conclude that the “two-step germination” of E. trifoliorum KRCP-4N conidia is the result of an unsuccessful Penetration Attempt, causing diversity in appressorial shape.
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polymorphic change of appressoria by the tomato powdery mildew oidium neolycopersici on host tomato leaves reflects multiple unsuccessful Penetration Attempts
Fungal Biology, 2010Co-Authors: Teruo Nonomura, Ayae Nishitomi, Yoshinori Matsuda, Chiyomi Soma, Ling Xu, Koji Kakutani, Yoshihiro Takikawa, Hideyoshi ToyodaAbstract:Abstract The appressorial shapes of the powdery mildews are an important clue to the taxonomy of the powdery mildew fungi, but the conidia of the tomato powdery mildew Oidium neolycopersici KTP-01 develop non-lobed, nipple-shaped, and moderately lobed or multilobed appressoria on the same leaves. To remove this ambiguity, we performed consecutive observations of sequential appressorial development of KTP-01 conidia with a high-fidelity digital microscope. Highly germinative conidia of KTP-01, collected from conidial pseudochains formed on the tomato leaves, were inoculated into host tomato and nonhost barley leaves or an artificial hydrophobic membrane (Parafilm). Events from germination initiation to appressorium formation were synchronous in all conidia on all materials used for inoculation, but post-appressorial behaviors varied among the materials. Appressoria on the membrane-stuck glass slide formed several projections at different portions of the appressoria to repeat unsuccessful Penetration Attempts. Similar unsuccessful Penetration behavior by KTP-01 conidia was observed in the inoculations into leaves of barley plants, wild tomato species Lycopersicon peruvianum LA2172 (carrying the Ol-4 gene for powdery mildew resistance), and a susceptible host tomato ( Lycopersicon esculentum ) that had been inoculated with the barley powdery mildew ( Blumeria graminis f. sp. hordei , race 1) conidia. On the barley leaves, all Penetrations of KTP-01 were impeded by the papillae formed beneath the sites of the appressorial projections. On both the wild tomato and the race 1-inoculated cultivated tomato plants, KTP-01 conidia were prevented from forming functional haustoria by hypersensitive epidermal cell death; this hypersensitive reaction involved the Ol-4 gene in the wild tomato plants or the ‘induced resistance’ acquired by the nonpathogenic conidia previously inoculated into the cultivated tomato plants. All these KTP-01 conidia produced several projections on the appressoria during the repeated unsuccessful Penetration Attempts and eventually exhibited multilobed appressoria. On the host tomato leaves inoculated singly with KTP-01 conidia, fewer than 20 % of the conidia located appressoria on the central part of target epidermal cells and succeeded in forming functional haustoria at the first Penetration Attempt without forming an appressorial projection. These conidia exhibited non-lobed appressoria. The remaining conidia, however, whose appressoria were located on/near the border of the target epidermal cells, were more likely to fail to penetrate at the first Penetration, and then to develop additional projections for subsequent Penetrations. Most conidia succeeded in forming functional haustoria at the second to fourth Penetration Attempts, but a few conidia failed to produce haustoria at all Attempted Penetrations. Eventually, the conidia that succeeded at the second Penetration possessed a single appressorial projection (exhibiting the nipple-shaped appressoria), whereas the remaining conidia exhibited moderately lobed appressoria with two to four appressorial projections and multilobed appressoria, with more projections. Thus, the present study revealed that the basic shape of appressoria of KTP-01 was the non-lobed type, and that polymorphic changes of the appressoria occurred as a result of successive production of projections during repeated unsuccessful Penetration Attempts.