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Necrotic Lesions (necrotic + lesion)

Distribution by Scientific Domains

Life Sciences	67%
Medical Sciences	21%
Earth and Environmental Science	7%

Distribution within Life Sciences

Plant Pathology	41%
Plant Science	37%

Selected Abstracts

Genotypic difference for the susceptibility of Japanese, Chinese and European pears to Venturia nashicola, the cause of scab on Asian pears

PLANT BREEDING, Issue 4 2008
K. Abe
Abstract Venturia nashicola, the cause of scab on Asian pears, is distinct from Venturia pirina, a causal fungus of European pear scab. Although scab caused by V. nashicola is one of the most serious diseases in the Japanese pear (Pyrus pyrifolia Nakai var. culta Nakai), information available regarding resistant breeding against V. nashicola is limited. In this study, 12 genotypes of Japanese pear, seven genotypes of Chinese pear (Pyrus ussuriensis Maxim.) and four genotypes of European pear (Pyrus communis L. var. sativa DC.) and/or their offspring were evaluated for susceptibility to V. nashicola with leaf and fruit inoculation tests. At 30,40 days after full bloom in their developmental stage, unfolded young leaves and fruit were inoculated with conidial suspensions of V. nashicola for each genotype, and the responses were rated at 30 days postinoculation for the inoculated leaves and at 42 days postinoculation for the inoculated fruits. No visible symptoms were found in European pear ,Bartlett' and ,La France' and their respective offspring ,290-36' and ,282-12', in the Japanese pear ,Kinchaku' and in the Chinese pears ,Cangxili' and ,Hongli'; these genotypes were evaluated as highly resistant to V. nashicola. Necrotic lesions without sporulation were observed in the Chinese pears ,Qiubaili', ,Manyuanxiang', ,Yuanbali' and ,Xiangyali', which were regarded as resistant. Sporulating lesions were formed on the other genotypes, such as the major Japanese pear cultivars ,Kosui' and ,Nijisseiki', which were regarded as susceptible. The response of inoculated leaves coincided well with that of inoculated fruit for each genotype. When the severity of scab symptoms on scab-susceptible genotypes was further rated with disease severity (DS) values, a genotypic difference was observed for overall DS values in a successive 2-year measurement among the susceptible genotypes. Based on the DS values of leaf and fruit scabs, the Japanese pears ,Niitaka', ,Shinko', ,Nijisseiki', ,Gold Nijisseiki', ,Osa Nijisseiki' and ,Shinsui' were considered to be less susceptible to V. nashicola than the typical susceptible cultivar ,Kosui'. [source]

Seasonal resin canal formation and necroses expansion in resinous stem canker-affected Chamaecyparis obtusa

FOREST PATHOLOGY, Issue 4-5 2002
T. YAMADA
Summary The season of disease development on the basis of two major internal symptoms, resin canal formation and necrotic lesion expansion in phloem, were anatomically determined in Chamaecyparis obtusa (Hinoki cypress) affected by resinous stem canker. Newly formed resin canals were mostly observed at first from July to August in samples of the canker-affected C. obtusa phloem. This result indicates the occurrence of stimuli causing resin canal formation and the beginning of the formation from May to July of the same year. This and the beginning of resin exudation observed in May or June indicated that resin, exuded at least before August, originated from resin canals formed in the previous year(s). The expansion of phloem necrotic lesions began in June and continued until October, and was conspicuous in the August samples. Stimuli causing necrotic lesion development were also suggested to occur from May to August of the same year. It is hypothesized that excess resin production induces lesion development and that expansion of necrotic lesion induces both resin exudation from previously formed resin canals and new resin canal formation. The causal agent of the disease could be activated in the late spring or summer season. Résumé Formation saisonnière de canaux résinifères et extension des nécroses chez Chamaecyparis obtusa atteint par le chancre résineux du tronc Chez Chamaecyparis obtusa affecté par le chancre résineux du tronc, la saison de développement de la maladie a été déterminée anatomiquement en se basant sur deux symptômes internes majeurs: la formation de canaux résinifères et l'extension des nécroses au niveau du phloème. Des canaux résinifères récemment formés ont surtout été observés à partir de juillet et en août dans le phloème de C. obtusa atteint par la maladie. Ce résultat montre l'existence de stimuli de la formation de canaux résinifères, ceux-ci commençant à se former en mai jusqu'en juillet. Jointe au fait que l'exsudation de résine a lieu en mai ou juin, cette observation montre que la résine (au moins celle exsudée avant août) provient des canaux formés au cours de la ou des années précédentes. L'extension de la nécrose du phloème débutait en juin, était forte en août et se poursuivait jusqu'en octobre. Il est suggéré que les stimuli du développement de la nécrose ont lieu entre mai et août de la même année. Il est supposé, d'une part que la production excessive de résine induit le développement des lésions, et d'autre part que l'extension des nécroses induit l'exsudation de résine à partir des canaux antérieurement formés ainsi que la formation de nouveaux canaux. L'agent causal de la maladie pourrait être activéà la fin du printemps ou en été. Zusammenfassung Saisonale Harzkanalbildung und Entwicklung der Nekrosen bei Chamaecyparis obtusa mit ,HarzigemStammkrebs' Bei Chamaecyparis obtusa mit Befall durch den ,Harzigen Stammkrebs' wurde die Phänologie der Krankheitsentwicklung anhand der Harzkanalbildung und der Ausbreitung der Nekrosen im Phloem anatomisch erfasst. Im krebsbefallenen Phloem wurden neu gebildete Harzkanäle zuerst im Juli und August beobachtet. Dies weist darauf hin, dass die Stimulation für die Harzkanalbildung und die Entwicklung der Harzkanäle in der Zeit von Mai bis Juli des laufenden Jahres erfolgt. Diese Beobachtung und der Beginn des Harzflusses, welcher im Mai und Juni auftritt, deuten darauf hin, dass der Harzfluss vor dem August aus Harzkanälen stammt, die bereits im Vorjahr oder noch früher angelegt worden waren. Die Expansion der Phloem-Nekrosen begann im Juni und hielt bis Oktober an, im August war sie besonders stark ausgeprägt. Der Reiz für die Ausdehnung der Nekrosen dürfte somit von Mai bis August des laufenden Jahres vorhanden sein. Es wird die Hypothese aufgestellt, dass die stark gesteigerte Harzproduktion die Nekrosenentwicklung fördert und dass die Expansion der Nekrosen sowohl den Harzfluss aus den früher gebildeten Harzkanälen anregt als auch die Bildung neuer Harzkanäle induziert. Der ursächliche Faktor für diese Krankheit dürfte im späten Frühjahr oder im Sommer aktiv sein. [source]

Measurement of lesion area and volume by three-dimensional spoiled gradient-echo MR imaging in osteonecrosis of the femoral head

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2003
Yuki Kishida
Abstract The purpose of this investigation is to evaluate the diagnostic ability of three-dimensional spoiled gradient-echo (3D SPGR) magnetic resonance (MR) imaging in cases of osteonecrosis of the femoral head (ONFH), and to determine the accuracy of 3D SPGR imaging in area and volume measurement of ONFH. T1-weighted spin-echo (SE) and 3D SPGR imaging were performed on 20 femoral heads obtained from patients with ONFH. After MR imaging, the femoral heads were cut parallel to the imaging plane and were evaluated histologically. Areas and volumes of necrotic lesions were measured with a computer program and the deviation between MR images and anatomical measurements was evaluated. A low signal intensity band on 3D SPGR MR images was observed in all femoral heads and corresponded histologically to repaired marrow with viable fibrous mesenchymal tissue. The area proximate to the low band area coincided with the necrotic region. Both area and volume measurements by T1-weighted SE and 3D SPGR images showed a strong correlation to histological measurements. The discrepancies between histological and imaging results were minimal in 3D SPGR imaging, especially at the anterior and posterior portions of the femoral head. Three-dimensional SPGR imaging provides more accurate measurements of the area and volume of a necrotic lesion than T1-weighted SE imaging. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source]

Effect of Diaporthe/Phomopsis Species Isolated from Soyabean and Abutilon theophrasti on Soybean Seed Germination

JOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2006
K. Vrandecic
Abstract Twelve isolates of Diaporthe/Phomopsis species from soybean (six isolates) and Abutilon theophrasti (velvetleaf) (six isolates) were studied for their pathogenicity to soybean and their effect on soybean seed germination and seedling survival after artificial seed inoculation. The following criteria were taken into consideration: number of germinated and rotten seeds, seedlings with necrosis, germ length and length of necrotic lesion. All tested Diaporthe/Phomopsis isolates caused seeds rot. P. longicolla isolates from soybean plants (PL1 and PL2) and isolates from velvetleaf (AbPL1 and AbPL2) exhibited statistically significant decrease in germ growth. These germs were only 1.0,1.8 cm long. No relation between length of germs and length of necrosis was found. The highest percentage of decayed seedlings was determined in the isolates AbPL1 and 2 as well as in PS 1 and PL 1 20 days after inoculation. Results of our research showed that Diaporthe/Phomopsis species from velvetleaf could be more pathogenic on soybean than isolates of the same species from soybean. [source]

Pathogenicity of Phytophthora austrocedrae on Austrocedrus chilensis and its relation with mal del ciprés in Patagonia

PLANT PATHOLOGY, Issue 4 2010
A. G. Greslebin
Field observations, isolations and pathogenicity tests were performed on Austrocedrus chilensis (Cupressaceae) trees to determine the pathogenicity of Phytophthora austrocedrae and its role in the aetiology of the cypress disease mal del ciprés (MDC) in Argentina. It was found that P. austrocedrae is a primary pathogen of A. chilensis. It was isolated from large necrotic lesions in the inner bark, and superficially in the sapwood, at the root collar and stem, in most of the MDC-affected stands surveyed along the range of A. chilensis in Argentina. The main symptom in naturally infected trees was a necrotic lesion extending from killed roots up to 1 m up the tree bole. Seedlings, saplings and adult trees were all susceptible to inoculation with P. austrocedrae. Under favourable experimental conditions (flooding), inoculated seedlings suffered massive mortality in less than a month. The importance of diseases caused by Phytophthora spp. in South American forests is discussed. [source]

Dermacentor -borne necrosis erythema and lymphadenopathy: clinical and epidemiological features of a new tick-borne disease

CLINICAL MICROBIOLOGY AND INFECTION, Issue 4 2004
J. A. Oteo
Abstract This paper describes the epidemiological and clinical features of a tick-borne disease differing somewhat from other tick-borne diseases found previously in Spain. All patients were bitten by Dermacentor marginatus or a large tick. The clinical features include a crustaceous or necrotic lesion at the site of the tick's attachment, surrounded by an erythema (erythema migrans-like) and painful regional lymphadenopathies. The probable aetiological agent is Rickettsia slovaca. Similar cases have been reported in other European countries. [source]

Seasonal resin canal formation and necroses expansion in resinous stem canker-affected Chamaecyparis obtusa

Susceptibility of cones and seeds to fungal infection in a pine (Pinus spp.) collection

FOREST PATHOLOGY, Issue 6 2000
V. Vujanovic
Summary Thirty-one fungi, members of Ascomycota and Deuteromycota, were isolated from cones/seeds of 28 hosts (Pinus spp.) originating from East Asia, Europe and North America, and growing at the Montreal Botanical Garden, Canada. A total of 21 taxa of these isolated fungi are considered pathogens. The damage severity was most prevalent on Diploxylon pines of European provenance (Pinus nigra, Pinus mugo and Pinus sylvestris), and one indigenous North American species (Pinus albicaulis). Twelve fungi occurred on different hosts, i.e. Sphaeropsis sapinea (12), Herpotrichia juniperi (8), Truncatella hartigii (7), Ceuthospora sp. (5), Fusarium, spp. (5), Pestalotiopsis funerea (3), Phomopsis sp. (3), Valsa spp. (anamorph. Cytospora) (3), Diaporthe sp. (3), Fusicoccum sp. (2) and Sirococcus strobilinus (2). Sphaeropsis sapinea, Herpotrichia juniperi, Phomopsis conorum, Truncatella hartigii, Tubercularia sp. and Valsa spp. were related to high cone and seed damage. For the most frequently observed Sphaeropsis sapinea damage, the subgenus Haploxylon was less susceptible than Diploxylon, and P. sylvestris less than P. nigra and P. mugo. Pinus resinosa showed more tolerance to S. sapinea. Truncatella hartigii was more frequently associated with necrotic lesions on cones/seeds in comparison with Pestalotiopsis funerea. The results are discussed in the context of arboretum, seed orchard, nursery and quarantine management. [source]

Immunological basis of the development of necrotic lesions following Mycobacterium avium infection

IMMUNOLOGY, Issue 4 2002
Manuela Flórido
Summary Normal C57BL/6 mice infected with 106 colony-forming units of a highly virulent strain of Mycobacterium avium developed a progressive infection characterized by loss of T cells from the tissues and infiltration with high numbers of heavily infected macrophages. In contrast, when C57BL/6 mice were infected with 102 colony-forming units of the same strain they retained T cells and T-cell reactivity in the tissues, and granulomas evolved into large masses that, at 4 months of infection, exhibited central necrosis. The development of these necrotic lesions did not occur in nude mice, nor in mice genetically deficient in CD4, interleukin-12 (IL-12) p40, interferon-, (IFN-,) and CD40 and were reduced in mice deficient in CD54 or IL-6. They were less numerous but bigger in mice deficient in IL-10 or the inducible nitric oxide synthase, correlating with the increased resistance to mycobacterial proliferation of these strains as compared to control mice. The appearance of necrosis was not affected in mice deficient in CD8,, T-cell receptor ,, tumour necrosis factor receptor p55, and perforin, nor was it affected in mice over-expressing bcl2. The appearance of necrosis could be prevented by administering antibodies specific for CD4, IL-12p40, or IFN-, from the second month of infection when organized granulomas were already found. Our results show that the immunological mediators involved in the induction of protective immunity are also major players in the immunopathology associated with mycobacteriosis. [source]

Application of Congo Red agar for detection of Streptococcus dysgalactiae isolated from diseased fish

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2009
M. Abdelsalam
Summary The strong clinical similarity between Lancefield group C Streptococcus dysgalactiae subsp. dysgalactiae (GCSD) and Lactococcus garvieae infections, characterized by development of necrotic lesions in the caudal peduncle of infected fish, has hindered differentiation of these two strains, making rapid and accurate diagnosis of diseased fish in fish farms difficult. GCSD from diseased fish were presumptively identified and isolated using Todd-Hewitt agar containing 30 ,g ml,1 of Congo Red dye (TH-CR). TH-CR agar was also used to detect and presumptively identify the GCSD obtained from artificially or naturally infected fish. Orange GCSD colonies distinct from the L. garvieae colonies were observed on the TH-CR agar; thus, TH-CR agar can be used to detect and identify GCSD isolated from infected fish. [source]

Isolation of a cyprinid herpesvirus 2 from goldfish, Carassius auratus (L.), in the UK

JOURNAL OF FISH DISEASES, Issue 11 2007
K R Jeffery
Abstract Haematopoietic necrosis virus [cyprinid herpesvirus 2 (CyHV-2)] was isolated during disease outbreaks in goldfish, Carassius auratus, at an ornamental fish retail site in southern England in 2004. Signs of disease included lethargy and inappetence and were first seen after water temperatures increased from 14,15 to 19,21 °C. External gross pathology included pale patches on the gills and skin and internally the spleen was enlarged, often with distinctive white nodules. The most prominent histopathological changes observed were necrotic lesions in the spleen and kidney and focal patches of necrosis in the gill lamellae. Necrotic cells often contained nuclei with marginated chromatin and pale intranuclear inclusions. Ultrastructural examination of the spleen tissue revealed typical herpesvirus-like particles measuring 100 nm in diameter. The virus was isolated from extracts of gill tissue in KF-1 cells at 20 °C and oligonucleotide primer sets were designed based on conserved gene sequences and used to amplify viral DNA by polymerase chain reaction (PCR). The PCR assays were then used to detect the virus in DNA extracted from tissues sampled during earlier disease investigations at the retail site owner's holding facility in 2002 and 2003 and stored at ,70 °C since then. Polymerase gene-specific PCR amplification products obtained from tissue samples and from the virus isolated in cell culture shared 100% nucleotide sequence identity with the published sequence for CyHV-2. [source]

ANTIBACTERIAL ACTIVITY AND BINDING ABILITY OF BOVINE LACTOFERRIN AGAINST PSEUDOMONAS SPP.

JOURNAL OF FOOD SAFETY, Issue 1 2008
WOAN-SUB KIM
ABSTRACT The antibacterial activity of bovine lactoferrin was tested against Pseudomonas fluorescens and Pseudomonas syringae. The activity was studied by monitoring the growth of a Pseudomonas spp. in the presence or absence of bovine apo-lactoferrin, bovine holo-lactoferrin or native-lactoferrin in liquid media at different concentrations. Lactoferrin-binding proteins in the membrane fractions of Pseudomonas spp. were detected using far-Western blot analysis. The addition of bovine lactoferrin to the medium inhibited the growth of all tested strains. Furthermore, the growth of P. fluorescens and P. syringae was strongly inhibited by bovine apo-lactoferrin. The estimated molecular weights of lactoferrin-binding proteins in P. fluorescens were 70, 49, 47 and 25 kDa, and 70, 48 and 28 kDa in P. syringae. PRACTICAL APPLICATIONS Pseudomonas fluorescens is an important psychrotrophic bacterium responsible for undesirable flavors in milk and dairy products. Thus, flavor and texture defects, such as bitterness and running paste, were also reported. In addition, Pseudomonas syringae causes various diseases on many different susceptible plant species, generally producing chlorotic and necrotic lesions on leaves and fruits. The resultant bacterial spoilage causes considerable economic losses for the food and dairy industries. At present, antiseptics and agricultural chemicals are used for defense of foods and vegetables from these bacteria, but such substances are known to deleteriously affect the human body. The results of this study demonstrate that bovine lactoferrin significantly inhibits the growth of P. fluorescens and P. syringae. The results indicate that the incorporation of bovine lactoferrin is expected to protect dairy products, food and fruits from pathogenic bacteria. [source]

Measurement of lesion area and volume by three-dimensional spoiled gradient-echo MR imaging in osteonecrosis of the femoral head

Alternaria alternata AT Toxin Induces Programmed Cell Death in Tobacco

JOURNAL OF PHYTOPATHOLOGY, Issue 10 2009
Elena T. Yakimova
Abstract Detached tobacco leaves were infiltrated with an AT toxin preparation from the foliar pathogen Alternaria alternata tobacco pathotype. The AT toxin preparation caused formation of necrotic lesions within 5 days post-infiltration in a concentration-dependent manner. Cell death was accompanied by increased levels of the stress metabolites hydrogen peroxide, malondialdehyde, free proline and by enhanced total protease activity. Lesion development and the production of stress metabolites were suppressed if the infiltration site was pre-infiltrated with caspase-specific peptide inhibitors (irreversible caspase-1 inhibitor acyl-Tyr-Val-Ala-Asp-chloromethylketone (Ac-YVAD-CMK) and the broad range caspase inhibitor benzyoxycarbonyl-Asp-2,6-dichlorobenzoyloxymethylketone (Z-Asp-CH2-DCB)), the serine protease inhibitor N,-p-tosyl- l -lysine chloromethylketone and the polyamine spermine. Extensive accumulation of reactive oxygen species (ROS), as determined by staining with 3-3,-diaminobenzidine and 2,,7,-dichlorofluorescein diacetate, was found in the AT toxin-challenged lesions. The data show that AT toxin-induced cell death in tobacco is a type of programmed cell death in which caspase-like proteases and ROS signalling play a prominent role. [source]

Immunolocalization and Histocytopathological Effects of Xanthomonas arboricola pv. pruni on Naturally Infected Leaf and Fruit Tissues of Peach (Prunus persica L. Batsch)

JOURNAL OF PHYTOPATHOLOGY, Issue 6 2008
J. Aarrouf
Abstract Immunofluorescence and cytohistochemical studies have been performed to understand the host,parasite relationships in the pathosystem: peach,Xanthomonas arboricola pv. pruni (Xap). Using a commercial immunodetection kit, Xap cells were specifically identified in tissues from infected leaves and fruits. Sections from infected leaves showed that the pathogen penetrates the mesophyll via stomata and develops in the intercellular spaces where it degrades the cell wall components. This leads to cell collapse and consequently to the formation of necrotic lesions. The same events have been noted in sections from infected fruits. However, the contaminated zones of mesocarp parenchyma exhibited cell dedifferentiation and generated somatic embryo-like structures. Sections from midrib samples collected at different distances from infected lamina revealed the presence of Xap cells in the sieve tubes and xylem suggesting a systemic trafficking of the pathogen. The results are discussed in terms of cytological effects and epidemiology of Xap. [source]

Heritability of Phenols in the Resistance of Theobroma cacao against Phytophthora megakarya, the Causal Agent of Black Pod Disease

JOURNAL OF PHYTOPATHOLOGY, Issue 9 2007
P. F. Djocgoue
Abstract The black pod disease caused by Phytophthora megakarya is responsible for 80% of the cocoa production loss in Cameroon. To assess the resistance of cocoa plants against this pathogen, necrotic lesions, phenolic content and qualitative alteration of phenolics were conducted in ICS84 and ICS95 clones (two Trinitario introduced from Trinidad) and their hybrids (families F30 and F25) derived from reciprocal cross breeding between these two parental clones after inoculation. The existence of strong hybrid vigour has been shown. Ninety percentage of the hybrid's genotypes manifested a positive heterosis effect for the development of lesion size. This suggests the existence of hybrid vigour with a genetic additive effect. F3086, F2509, F2552 and F2586 hybrids were characterized by localized lesions. Those hybrids genotypes can be considered as elite clones. In relation to analysis of total phenolics and lesion size, no maternal effect was detected in the transmission of these characters. A significant and negative correlation (r = ,0.683) (P < 0.01) has been observed between necrosis evolution and phenolics accumulation. The values of the heritability of lesion size and the total phenolic content in offsprings did not permit to show the maternal effect. Qualitative analyses of phenolics showed high flavonones content in cocoa leaves. Qualitative analyses of phenolics in ICS84, ICS95 clones and their hybrids showed a modification of the phenolics profiles, notably concerning apigenin and luteolin derivatives due to the inoculation. These compounds, along with others that were not identified, could have a role in the reaction and mechanism of defence of cocoa against P. megakarya. [source]

Light-Enhanced Resistance to Magnaporthe grisea Infection in the Rice Sekiguchi Lesion Mutants

JOURNAL OF PHYTOPATHOLOGY, Issue 4 2000
S. Arase
The rice sl mutant showed two types of responses to Magnaporthe grisea infection by light treatments. One was an sl -mutant-type response characterized by Sekiguchi lesion expression under light waves of 400,700 nm, and the other was a wild-type response characterized by blast and/or necrotic spot lesion expression in the dark or at wavelength between 290 and 330 nm. There was a large difference in the resistance to M. grisea infection between the mutant- and wild-type responses in the rice sl mutant. When the mutant-type response was induced in the rice sl mutant, the disease resistance was enhanced relative to that in the wild-type response. Enhanced resistance was demonstrated by two components: (a) the number of Sekiguchi lesions was reduced relative to that of blast or necrotic lesions; (b) sporulation of M. grisea was not induced in Sekiguchi lesions. The enhanced resistance was dependent on light of 400,700 nm. Zusammenfassung In Abhängigkeit von einer Bestrahlung mit Licht zeigte die sl -Mutante von Reis zwei Typen von Reaktionen auf Magnaporthe-grisea -Infektionen. Zum einen trat eine Reaktion vom sl-Mutantentyp auf, charakterisiert durch Expression von Sekiguchi-Läsionen bei Wellenlängen von 400 bi 700 nm. Zum anderen war eine Wildtypreak-tion festzustellen, bei der es zu Bräune und/oder Expression nekrotischer Flecken bei Dunkelheit oder bei Wellenlängen zwischen 290 und 330 nm kam. Hinsichtlich der Resistenz gegen die M.-grisea -Infektion bestand ein großer Unterschied zwischen den Mutanten- und den Wildtypreaktionen der sl -Mutante des Reis. Wurde die Reaktion vom Mutantentyp in der sl -Mutante induziert, so war die Krankheitsresistenz im Vergleich zur Wildtypreaktion erhöht. Die höhere Resistenz zeigte sich an zwei Komponenten: (a) die Zahl der Sekiguchi-Läsionen war kleiner als die der braunen bzw. nekrotischen Läsionen (b) in Sekiguchi-Läsionen wurde keine Sporulation von M. grisea induziert. Die erhöhte Resistenz war abhängig von Licht im Wellenlängenbereich 400 bis 700 nm. [source]

Identification of novel hrp -regulated genes through functional genomic analysis of the Pseudomonas syringae pv. tomato DC3000 genome

MOLECULAR MICROBIOLOGY, Issue 5 2002
Julie Zwiesler-Vollick
Summary Pseudomonas syringae pv. tomato ( Pst ) strain DC3000 infects the model plants Arabidopsis thaliana and tomato, causing disease symptoms characterized by necrotic lesions surrounded by chlorosis. One mechanism used by Pst DC3000 to infect host plants is the type III protein secretion system, which is thought to deliver multiple effector proteins to the plant cell. The exact number of type III effectors in Pst DC3000 or any other plant pathogenic bacterium is not known. All known type III effector genes of P. syringae are regulated by HrpS, an NtrC family protein, and the HrpL alternative sigma factor, which presumably binds to a conserved cis element (called the ,hrp box') in the promoters of type III secretion-associated genes. In this study, we designed a search motif based on the promoter sequences conserved in 12 published hrp operons and putative effector genes in Pst DC3000. Seventy-three predicted genes were retrieved from the January 2001 release of the Pst DC3000 genome sequence, which had 95% genome coverage. The expression of the 73 genes was analysed by microarray and Northern blotting, revealing 24 genes/operons (including eight novel genes), the expression of which was consistently higher in hrp -inducing minimal medium than in nutrient-rich Luria,Bertani broth. Expression of all eight genes was dependent on the hrpS gene. Most were also dependent on the hrpL gene, but at least one was dependent on the hrpS gene, but not on the hrpL gene. An AvrRpt2-based type III translocation assay provides evidence that some of the hrpS -regulated novel genes encode putative effector proteins. [source]

Xanthomonas axonopodis pv. citri: factors affecting successful eradication of citrus canker

MOLECULAR PLANT PATHOLOGY, Issue 1 2004
James H. Graham
SUMMARY Taxonomic status:, Bacteria, Proteobacteria, gamma subdivision, Xanthomodales, Xanthomonas group, axonopodis DNA homology group, X. axonopodis pv. citri (Hasse) Vauterin et al. Microbiological properties:, Gram negative, slender, rod-shaped, aerobic, motile by a single polar flagellum, produces slow growing, non-mucoid colonies in culture, ecologically obligate plant parasite. Host range:, Causal agent of Asiatic citrus canker on most Citrus spp. and close relatives of Citrus in the family Rutaceae. Disease symptoms:, Distinctively raised, necrotic lesions on fruits, stems and leaves. Epidemiology:, Bacteria exude from lesions during wet weather and are disseminated by splash dispersal at short range, windblown rain at medium to long range and human assisted movement at all ranges. Crop loss:, Severe infections cause defoliation, blemished fruit, premature fruit drop, die-back of twigs and general debilitation of the tree. Distribution:, Citrus canker is not present in all subtropical to tropical regions of citriculture in the world, so considerable regulatory efforts are expended to prevent the introduction and spread of X. axonopodis pv. citri into areas in the Americas, Australia and elsewhere, with climates conducive to the disease. Importance:, Limited strategies exist for suppression of citrus canker on more susceptible cultivars. Blemished fruit are unmarketable and exposed fruit are restricted in market access. The economic impact of loss of markets is much greater than that from yield and quality reductions of the crop. Useful websites:,http://doacs.state.fl.us/canker , http://www.apsnet.org/education/lessonsplantpath/citruscanker/top.htm , http://www.apsnet.org/online/feature/citruscanker/ , http://www.plantmanagementnetwork.org/pub/php/review/citruscanker/ , http://www.abecitrus.com.br/fundecitrus.html , http://www.biotech.ufl.edu/PlantContainment/canker.htm , http://www.aphis.usda.gov/oa/ccanker/ . [source]

Pathogenicity of Phytophthora austrocedrae on Austrocedrus chilensis and its relation with mal del ciprés in Patagonia

Phytophthora pinifolia sp. nov. associated with a serious needle disease of Pinus radiata in Chile

PLANT PATHOLOGY, Issue 4 2008
A. Durán
During the course of the past three years, a new disease of Pinus radiata, referred to as ,Daño Foliar del Pino' (DFP) has appeared in the Arauco province of Chile and subsequently spread to other areas. The disease is typified by needle infections, exudation of resin at the bases of the needle brachyblasts and, in younger trees, necrotic lesions in the cambium, which eventually girdle the branches. The disease causes the death of young seedlings and mature trees can also succumb after a few years of successive infection, probably hastened by opportunistic fungi such as Diplodia pinea. Isolations on selective medium for Phytophthora spp. led to the consistent isolation of a Phytophthora sp. from needle tissue. DNA sequence comparisons for the ITS rDNA and cox II gene regions, and morphological observation showed that this oomycete represents a previously undescribed species for which the name Phytophthora pinifolia sp. nov. is provided. This new species is characterized by unbranched sporangiophores, and non-papillate, sub-globose to ovoid sporangia that are occasionally free from the sporangiophore with medium length pedicels. Despite using a number of oospore inducing techniques, oogonia/antheridia were not observed in isolates of P. pinifolia. Pathogenicity trials with P. pinifolia showed that it is pathogenic to P. radiata and causes rapid death of the succulent apical parts of young plants. Phytophthora pinifolia is the first Phytophthora known to be associated with needles and shoots of a Pinus sp. and its aerial habit is well matched with the occurrence and symptoms of DFP in Chile. [source]

New severe strains of Melon necrotic spot virus: symptomatology and sequencing

PLANT PATHOLOGY, Issue 5 2005
C. Kubo
New strains of Melon necrotic spot virus (MNSV), designated MNSV-YS and MNSV-KS, caused much more severe growth retardation on melon plants than MNSV-NH, which was previously reported as the most severe strain of MNSV in Japan. MNSV-YS spread much more quickly than MNSV-NH in infected plants, and induced more severe growth retardation, even though the appearance of necrotic lesions on inoculated cotyledons was much slower. MNSV-KS had properties intermediate between those of the other two strains. The results suggest that faster-spreading strains can multiply more rapidly as a result of lower levels of activity in inducing necrotic lesions in melon plants. The complete sequences of MNSV-YS and MNSV-KS were determined, and an RT,PCR,RFLP method based on these sequences was successfully developed to detect and discriminate between the three strains. [source]

A mutation in the Arabidopsis mTERF-related plastid protein SOLDAT10 activates retrograde signaling and suppresses 1O2 -induced cell death

THE PLANT JOURNAL, Issue 3 2009
Rasa Meskauskiene
Summary The conditional flu mutant of Arabidopsis thaliana generates singlet oxygen (1O2) in plastids during a dark-to-light shift. Seedlings of flu bleach and die, whereas mature plants stop growing and develop macroscopic necrotic lesions. Several suppressor mutants, dubbed singlet oxygen-linked death activator (soldat), were identified that abrogate 1O2 -mediated cell death of flu seedlings. One of the soldat mutations, soldat10, affects a gene encoding a plastid-localized protein related to the human mitochondrial transcription termination factor mTERF. As a consequence of this mutation, plastid-specific rRNA levels decrease and protein synthesis in plastids of soldat10 is attenuated. This disruption of chloroplast homeostasis in soldat10 seedlings affects communication between chloroplasts and the nucleus and leads to changes in the steady-state concentration of nuclear gene transcripts. The soldat10 seedlings suffer from mild photo-oxidative stress, as indicated by the constitutive up-regulation of stress-related genes. Even though soldat10/flu seedlings overaccumulate the photosensitizer protochlorophyllide in the dark and activate the expression of 1O2 -responsive genes after a dark-to-light shift they do not show a 1O2 -dependent cell death response. Disturbance of chloroplast homeostasis in emerging soldat10/flu seedlings seems to antagonize a subsequent 1O2 -mediated cell death response without suppressing 1O2 -dependent retrograde signaling. The results of this work reveal the unexpected complexity of what is commonly referred to as ,plastid signaling'. [source]

Limitation of nocturnal import of ATP into Arabidopsis chloroplasts leads to photooxidative damage,

THE PLANT JOURNAL, Issue 2 2007
Thomas Reinhold
Summary When grown in short day conditions and at low light, leaves of Arabidopsis plants with mutations in the genes encoding two plastidial ATP/ADP transporters (so-called null mutants) spontaneously develop necrotic lesions. Under these conditions, the mutants also display light-induced accumulation of H2O2 and constitutive expression of genes for copper/zinc superoxide dismutase 2 and ascorbate peroxidase 1. In the light phase, null mutants accumulate high levels of phototoxic protoporphyrin IX but have only slightly reduced levels of Mg protoporphyrin IX. The physiological changes are associated with reduced magnesium,chelatase activity. Since the expression of genes encoding any of the three subunits of magnesium,chelatase is similar in wild type and null mutants, decreased enzyme activity is probably due to post-translational modification which might be due to limited availability of ATP in plastids during the night. Surprisingly, the formation of necrotic lesions was absent when null mutants were grown either in long days and low light intensity or in short days and high light intensity. We ascribe the lack of lesion phenotype to increased nocturnal ATP supply due to glycolytic degradation of starch which may lead to additional substrate-level phosphorylation in the stroma. Thus, nocturnal import of ATP into chloroplasts represents a crucial, previously unknown process that is required for controlled chlorophyll biosynthesis and for preventing photooxidative damage. [source]

Some new aspects of the pathology, pathogenesis, and aetiology of disseminated lung lesions in slaughter pigs

APMIS, Issue 5 2003
CAMILLA H. LILJEGREN
From 40 pigs rejected for human consumption at slaughter due to an apparent presence of pyemic lung lesions (defined as disseminated processes containing pus and/or necrotic material), the lungs, spleen, liver, and kidneys were subjected to an extended macroscopic examination. Several lung lesions were sampled from each animal for histological and bacteriological examination. Samples from the kidneys and spleens were also subjected to bacteriological examination. At gross level, four groups of lung lesions were identified: 1) disseminated foci with contents of pus and/or necrotic material (n=26); 2) disseminated or multifocally located ecchymoses with a central area of fibroplasia (n=9); 3) non-pneumonic lesions, i.e., disseminated areas of atelectasis (n=1) or haemorrhagic areas developing due to the process of slaughter (n=1); and 4) suppurative lesions without a disseminated distribution pattern (n=3). Histologically, the disseminated suppurative/necrotic foci were identified as: A) abscesses (n=10); B) necrotic lesions (n=6); and C) ectatic or ectatic-like bronchioles with contents of pus and necrotic material (n=10). The macroscopic observation of disseminated centres of fibroplasia with peripheral ecchymoses (n=9) was confirmed histopathologically. The livers of five pigs contained multiple areas of chronic interstitial fibrosis related to migration of Ascaris suum larvae ("milk spotted liver"). Such hepatic lesions were significantly (p<0.01) related to the simultaneous occurrence of disseminated pulmonary ecchymoses with a central area of fibroplasia. Generally, all lung lesions of each individual animal contained identical monocultures of bacteria following this pattern: Staphylococcus aureus (abscesses); Actinomyces hyovaginalis (necroses); S. aureus, A. hyovaginalis, and Arcanobacterium pyogenes (ectatic and ectatic-like bronchioles). Areas with fibrosis were sterile or contained bacteria considered to be a result of contamination. Apart from one kidney, from which S. aureus was cultured, all other organs were sterile. It is concluded that difficulties exist in differentiating pulmonary pyemic lesions from non-pyemic lesions at the gross level. Thus, it was not possible to distinguish between abscesses/necroses and ectatic bronchioles, the pathogenesis of the latter being uncertain. However, the chronic non-pyemic lesions related to the migration of A. suum larvae should be identified by the absence of pus/necrosis. S. aureus was predominantly isolated from abscesses, whereas, and most surprisingly, A. hyovaginalis was the dominant bacterium isolated from the pulmonary necroses. [source]

Assessment of a New Experimental Model of Isolated Right Ventricular Failure

ARTIFICIAL ORGANS, Issue 3 2009
Petronio G. Thomaz
Abstract We assessed a new experimental model of isolated right ventricular (RV) failure, achieved by means of intramyocardial injection of ethanol. RV dysfunction was induced in 13 mongrel dogs via multiple injections of 96% ethanol (total dose 1 mL/kg), all over the inlet and trabecular RV free walls. Hemodynamic and metabolic parameters were evaluated at baseline, after ethanol injection, and on the 14th postoperative day (POD). Echocardiographic parameters were evaluated at baseline, on the sixth POD, and on the 13th POD. The animals were then euthanized for histopathological analysis of the hearts. There was a 15.4% mortality rate. We noticed a decrease in pulmonary blood flow right after RV failure (P = 0.0018), as well as during reoperation on the 14th POD (P = 0.002). The induced RV dysfunction caused an increase in venous lactate levels immediately after ethanol injection and on the 14th POD (P < 0.0003). The echocardiogram revealed a decrease in the RV ejection fraction on the sixth and 13th PODs (P = 0.0001). There was an increased RV end-diastolic volume on the sixth (P = 0.0001) and 13th PODs (P = 0.0084). The right ventricle showed a 74% ± 0.06% transmural infarction area, with necrotic lesions aged 14 days. Intramyocardial ethanol injection has allowed the creation of a reproducible and inexpensive model of RV failure. The hemodynamic, metabolic, and echocardiographic parameters assessed at different protocol times are compatible with severe RV failure. This model may be useful in understanding the pathophysiology of isolated right-sided heart failure, as well as in the assessment of ventricular assist devices. [source]

Cryofibrinogenaemia with a good response to stanozolol

CLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 8 2000
F. Revenga
We report a 63-year-old patient with an IgA-kappa multiple myeloma in complete remission who developed necrotic lesions on both ears and papular, purpuric lesions on his legs and cheeks. Initial differential diagnosis included perniosis and skin necrosis secondary to interferon treatment but subsequent investigation revealed cryofibrinogenaemia as the underlying cause. Stanozolol therapy, 2 mg/12 h, achieved a complete clearance of the skin lesions. Cryofibrinogenaemia is a disease which can be under-diagnosed unless it is considered in the work-up of a patient with thrombotic skin lesions. Stanozolol is useful as first line therapy for this disorder. [source]