Induction of reactive oxygen generation and functional changes in mitochondria and their involvement in the development of bacterial rot in lettuce caused by Pseudomonas cichorii

Pseudomonas cichorii is the major causal agent of bacterial rot disease in lettuce, and apoptosis-like programmed cell death is closely associated with disease development. Depletion of cellular ATP and expression of the alternative oxidase gene was observed in lettuce leaves inoculated with P. cichorii suggesting mitochondrial dysfunction. Cytochemical observation showed production of reactive oxygen species in mitochondria of P. cichorii-inoculated lettuce leaf cells. Release of cytochrome c into the cytosol was also induced by inoculation with the bacterium. Superoxide production was observed in the mitochondrial fraction isolated from P. cichorii-infected leaves much more intense than water-treated leaves. Loss of swelling ability was also observed in the mitochondrial fractions following inoculation with P. cichorii. Intriguingly, inhibitors of the mitochondrial respiratory complex III prevented loss of swelling ability, whereas superoxide generation was scarcely affected by inhibitors of mitochondrial permeability transition in the mitochondrial fractions. Inhibitors of the mitochondrial respiratory complex III and mitochondrial permeability transition delayed not only P. cichorii-induced cell death, but also disease development. In contrast, P. cichorii-induced DNA fragmentation was not inhibited in the presence of either type of inhibitor. The findings suggest that mitochondria may play a crucial role in DNA fragmentation-independent cell death pathway(s).     

Optimal placement of the region of interest for bolus tracking on brain computed tomography angiography in Beagle dogs

This study aimed to determine the optimal placement of the region of interest (ROI) among four anatomical sites—pulmonary artery (PA), pulmonary vein (PV), aortic arch (AA), and carotid artery (CA)—in computed tomography (CT) brain angiography with automatic bolus tracking in healthy beagle dogs. Six beagles were included, and CT brain angiography was performed four times for each dog, to cover each ROI. The scan parameters, amount, and injection rate of the contrast medium were the same. The major intracranial arteries were selected for quantitative and qualitative evaluation: caudal cerebellar artery (CcA), basilar artery (BA), rostral cerebellar artery (RcA), caudal cerebral artery (CCA), middle cerebral artery (MCA), and rostral cerebral artery (RCA). Quantitative evaluation showed significantly higher CT attenuation values for the RcA, CCA, and MCA in the PA group and RcA and MCA in the PV group than in the CA group. Qualitative analysis revealed significantly higher scores for the BA, CCA, and MCA in the PA and PV groups than in the CA group. Venous contamination did not differ significantly among the ROIs, but the mean scores of the AA and CA groups were higher than those of the PA and PV groups. CT brain angiography using bolus tracking in the beagle dogs showed that the ROI should be placed at the PA or PV rather than at the CA for optimal images with strong contrast enhancement of the BA, RcA, CCA, and MCA and minimal venous contamination.     

A rapid molecular method for diagnosing epidemic dermatophytosis in a racehorse facility

Reasons for performing study: Identification of the species and strain of dermatophyte can play an effective role in control of disease outbreaks by establishing the source of infection. Current methods of identification are based on cultural and microscopic methods, often involving weeks before a positive identification are made. A rapid molecular diagnostic method would therefore be an important laboratory technique, but requires confirmation in equine clinical practice. Objectives: To test the sensitivity and specificity of molecular diagnostic methods applied to a racehorse herd from the Korean Racehorse Authority (KRA). Methods: A total of 57 DNA samples were collected from hairs and crusts of skin lesions in KRA racehorses with histories and clinical signs suggestive of dermatophytosis, which was confirmed by dermatophyte‐specific PCR amplification analysis using the primer pair for the chitin synthase 1 (CHS1) gene. Results: Thirty‐eight racehorses were definitively diagnosed with dermatophytosis using molecular and traditional diagnostic methods. PCR fingerprinting profiles using simple repetitive (GACA)₄ primers showed that all diagnosed horses had the same pattern profile. Oligonucleotide sequencing of CHS1 gene PCR products confirmed Trichophyton mentagrophytes as the infectious agent. Conclusions: This study demonstrates that the PCR‐based molecular diagnostic method is sensitive and specific and offers fast precise diagnosis of dermatophytosis in horses.     

叶片表皮指纹在杜鹃花属分类中的意义

本实验于2004年在东北林业大学进行。用指甲油印记法在光学显微镜下观察了杜鹃花属6个种(牛皮杜鹃 Rh.aureaum,兴安杜鹃Rh. dauricum, 照白杜鹃Rh. micranthum,迎红杜鹃Rh. mucronulatum,苞叶杜鹃 Rh. Redowskianum 和大字杜鹃Rh. schlippenbachii)的表皮指纹特征。对叶片的形态特征包括叶片下表皮气孔类型、保卫细胞和副卫细胞的特征、叶片两面的普通细胞(形状和垂周壁特征)和表皮毛进行了较详细的描述。所研究的6种杜鹃花中,有3种气孔类型,其中兴安杜鹃、照白杜鹃、和迎红杜鹃为单细胞型气孔(Pericytic 型),苞叶杜鹃为不规则型气孔(Anomocytic 型),牛皮杜鹃和大字杜鹃是平轴式气孔(Diacytic 式)。不同种间,单细胞型和平轴式气孔的副卫细胞类型在形状和表面特征上有所不同。普通表皮细胞的表面观为从四边形、六边形, 多边形或不规则型, 垂周壁呈平直或弯曲状。兴安杜鹃、照白杜鹃和迎红杜鹃3种的叶片两面均有腺鳞。所有这些叶片特点表明上述6种杜鹃花的表皮指纹具有种的特性。图4表2参29。     

β-1,3-D-Glucan Transported from Golgi Apparatus of Japanese Pear Leaves is a Component of Extracellular Polysaccharides Accumulated after AK-toxin I Treatment

This fluorescence and immunoelectron microscopic study showed that β-1,3-D-glucan accumulated only in leaves of a susceptible cultivar of Japanese pear after treatment with a host-specific toxin, AK-toxin I, from Alternate, alternata Japanese pear pathotype. The positive fluorescent reaction of callose was detected only in aniline blue fluorochrome-stained sections from toxin-treated leaves of the susceptible cultivar: positive sites were observed on cell walls of leaf cells. The sites of callose deposition were probably consistent spatially with modified sites on the plasma membrane that were observed only in the toxin-treated leaves of the susceptible cultivar. The toxin-induced modifications, identified as damage to the plasma membrane, were characterized by invagination of the plasmalemma specifically at plasmodesmata and as the concomitant accumulation of extracellular polysaccharides at the invaginated sites. A positive reaction to anti-β-1,3-D-glucan antibody was detected at the polysaccharides, Golgi vesicles, and trans-Golgi network (TGN) of toxin-treated leaves of the susceptible cultivar, but not at Golgi vesicles and TGN of water-treated ones. The cis-, medial and trans-Golgi stacks of toxin-treated leaves of the susceptible cultivar were negative for the antibody. The results showed that the polysaccharides, Golgi vesicles and TGN contained abundant β-1,3-D-glucan and that the glucan was transported from the Golgi apparatus via Golgi vesicles to the modified sites in cells of toxin-treated leaves of the susceptible cultivar. Received 7 March 2002/ Accepted in revised form 10 June 2002     

亚洲梨黑星病菌致病性及其寄主抗病机制的研究进展

梨黑星病是亚洲梨的主要病害之一。该病是由纳雪黑星病菌(Venturia nashicola)感染所致。V.nashicola主要寄生在亚洲梨叶片表皮细胞壁的果胶质层中。该菌的感染可能主要与分泌的细胞外分泌物质、角质分解酶、过氧化氢和果胶质分解酶有关。而亚洲梨对V.nashicola的抗性可能主要与多聚半乳糖醛酸酶抑制蛋白、多种病程相关蛋白、富亮氨酸重复类受体蛋白激酶等有关。另外,不具直接杀菌能力的系统抗性诱导剂acibenzolar-S-methyl(ASM)在大田试验中对梨黑星病菌有较好控制效果。这与ASM诱导的植物防御反应,包括多聚半乳糖醛酸酶抑制蛋白和几丁质酶等有关。