Two phases of intracellular reactive oxygen species production during victorin-induced cell death in oats

Reactive oxygen species (ROS) are thought to be involved in various forms of programmed cell death (PCD) in animal and plant cells. PCD, along with the production of ROS, occurs during plant–pathogen interactions. Here we show that victorin, a host-specific toxin produced by Cochliobolus victoriae, which causes victoria blight of oats, induces two phases of intracellular ROS production in victorin-sensitive oat mesophyll cells. The initial production of ROS is restricted at mitochondria and not accompanied with cellular oxidative damage. Later production of ROS is dispersed into cells concomitant with lipid peroxidation, chloroplast dysfunction, and cell death. Superoxide dismutase can clearly suppress the initial ROS production and delay the progression of cell death. These data indicate that the initial ROS production may be involved in the cell death induction process, and the later ROS production may play important roles in events leading to cellular disruption.     

Significance of PWT4–Rwt4 interaction in the species specificity of Avena isolates of Magnaporthe oryzae on wheat

We examined whether PWT4, an avirulence gene of Avena isolates of Magnaporthe oryzae toward wheat, corresponded to Rwt4, a resistance gene identified in wheat cultivar Norin 4, in a one-to-one manner. Twelve wheat cultivars were inoculated with 65X1, an F₁ culture with PWT4 derived from a cross between an Avena isolate (Br58) and a Triticum isolate (Br48). Three wheat cultivars (Norin 26, Shin-chunaga, Cheyenne) were resistant and therefore selected as possible carriers of Rwt4. The three cultivars were then inoculated with a population derived from a backcross of 61M2 carrying PWT4 with Br48 carrying pwt4. Segregation analyses revealed that PWT4 operates against the three cultivars. If PWT4 corresponds to Rwt4 in a one-to-one manner, all three cultivars should carry Rwt4. To test if this is the case, the three cultivars were crossed with Chinese Spring (a noncarrier of Rwt4) and Norin 4. When F₂ seedlings from Chinese Spring × Norin 26, Chinese Spring × Shin-chunaga, and Chinese Spring × Cheyenne were inoculated with 61M2, resistant and susceptible seedlings segregated in a 3 : 1 ratio. On the other hand, crosses between the three cultivars and Norin 4 yielded no susceptible F₂ seedlings. These results indicate that all three cultivars carry Rwt4. Considering all results, we concluded that PWT4 corresponds to Rwt4 in a one-to-one manner. An inoculation test with Chinese Spring–Cheyenne chromosome substitution lines indicated that Rwt4 is located on chromosome 1D.     

Role of Cylindrosporium-type conidia of Mycosphaerella pomi (Pass.) Lindau: cause of Brooks fruit spot of apple, as an infection source in apple orchards

Ascospores of Mycosphaerella pomi, the pathogen of Brooks fruit spot of apple, were produced in pseudothecia on previously infected and overwintered apple leaves from late April through early August in Aomori Prefecture, Japan. In June 2003, the ascospores were germinating and producing Cylindrosporium-type conidia on apple fruit and leaf surfaces in an orchard. After ascospores were sprayed on apple leaves, Cylindrosporium-type conidia developed on the leaf surfaces. Such Cylindrosporium-type conidia caused typical symptoms of Brooks fruit spot on apple trees after inoculations. These results suggested that the Cylindrosporium-type conidia also serve as an infection source, in addition to the ascospores, for Brooks fruit spot in apple orchards.     

Frequency of Alternaria brassicicola in commercial cabbage seeds in Japan

Plug seedlings, widely used in cabbage cultivation in Japan, are often infected by seed-borne pathogens, especially the serious pathogen Alternaria brassicicola. Because information on seed infestation is scant in Japan, we investigated fungal infestation in commercial batches of cabbage seeds produced between 1984 and 2001. A total of 123 lots were divided into six groups by production period (1984–1989, 1994–1998, and 2001) and by use or nonuse of fungicide. One hundred seeds from each lot were incubated separately on agar at 25°C to isolate the predominant fungus. Alternaria brassicicola was isolated most frequently, 0%–94% of the seeds depending on seed lot or 6%–21% of the seeds grouped by production period and fungicide treatment. Thus, the pathogen was isolated even from seeds refrigerated for 17 years. Alternaria brassicicola accounted for 57%–95% of all isolated fungi by the group and was higher on older or fungicide-treated seeds. Seeds that were not treated with fungicide in lots grouped by production districts in western Japan were infested with A. brassicicola at a rate of over 12%, higher than that in the eastern region (<4%). Infestation was higher in the warmer areas of Japan. Eighty-five isolates, other than A. brassicicola, produced spots on cabbage cotyledons, although they were not isolated as frequently: less than 5% of seeds by group separated by production period and fungicide treatment. Most of these isolates were Alternaria alternata. This is the first report on the frequency of fungal infestation of commercial cabbage seeds in Japan.     

Extraction of an incisor embedded within the nasal cavity in two guinea pigs

Oral examination of two guinea pigs revealed that the unilateral incisor was absent. On radiographic examination, the incisor was identified within the nasal cavity in both patients. Under anesthesia in both patients, the skin was incised from the nostril to 1.5 cm proximal, and the premaxilla and part of the maxilla were exposed. The bone was removed using a surgical drill, and the incisor was exposed in the nasal cavity. The root was grasped with forceps and carefully extracted as it was degraded and very fragile. Diagnosis was easy using oral and radiographic examination. In guinea pig patients where an incisor is absent on oral examination, this condition should be considered.     

Fecal progestagen and estrone during pregnancy in a giraffe: a case report

The present study was carried out to measure fecal progestagen and estrone concentrations during pregnancy in a giraffe and examine the possibility of utilizing this assay system for pregnancy diagnosis. Fecal samples were collected from a giraffe during her third and fourth parities and mixed with methanol to prepare a fecal solution. Diluted fecal solution was used for direct enzyme immunoassay for progestagen and estrone. The newborn calf from the third parity was viable, although that from the fourth parity died 5 days after calving. In the third parity, the giraffe's progestagen and estrone concentrations increased transiently from days 30 to 120 of pregnancy. Then, they decreased and remained low until day 330. This was followed by a drastic rise in both concentrations as parturition approached. Parturition caused a reduction in the progestagen and estrone concentrations of the feces. In the fourth parity, the progestagen concentration increased gradually after mating until day 320. This was followed by a reduction in the concentration until parturition. However, the estrone concentration fluctuated, and the duration and extent of the prepartum rise in concentration were shorter and lower than those of the third parity. The hormone dynamics of the third parity suggest the possibility of early pregnancy diagnosis by measuring progestagen or estrone between days 30 and 120 after mating.     

A neonatal calf with concurrent meningoencephalitis by Enterobacter cloacae and enteritis by attaching and effacing Escherichia coli (O128)

A neonatal calf developed nervous symptoms followed by diarrhea. The principal pathological changes were fibrinopurulent meningitis with necrosis of the cerebral parenchyma, and attaching and effacing lesions in the intestine. Cerebral necrosis was frequently associated with vascular changes. Enterobacter cloacae was isolated from the brain and Escherichia coli (O128) from the intestinal content. These suggest that cerebral and intestinal lesions were caused by the isolated organisms, and that most necrosis of the cerebral parenchyma might be infarctive.     

Steric structure–activity relationships of the rice blasticide,S-2900 (diclocymet)

The four diastereomers of 2-cyano-N-[1-(2,4-dichlorophenyl)ethyl]-3,3-dimethyl-butyramide were prepared by a direct HPLC separation with chiral columns. The [(S)acid, (R)amine]-isomer (was the most antifungal among the diastereomers tested. Because of the lability of the clinical group in the acid moiety, the (RS)-(R)-isomer is being developed as a rice blasticide. (S-2900, proposed common name diclocymet).     

Dimethoxypyrimidines as Novel Herbicides. Part 1. Synthesis and Herbicidal Activity of Dimethoxyphenoxyphenoxypyrimidines and Analogues

A number of 6-(4-phenoxyphenoxy)pyrimidines and triazines were synthesized and their herbicidal activity was measured. Compounds with the methoxy groups at the 2- and 4-positions on the pyrimidine and triazine rings exhibited high herbicidal activity. Introduction of a substituent into the 5-position of the pyrimidine ring diminished the activity. In the phenoxyphenoxy substructure at the 6-position, the central ether bond can be replaced by a methylene group without loss of activity. The optimum substituent on the terminal phenyl ring was 3-trifluoromethyl. The compounds showed a strong Hill reaction inhibition, but unfortunately showed poor selectivity between weeds and crops.