ABSTRACT
Chestnut blight disease caused by Cryphonectria parasitica is widely distributed throughout chestnut tree plantations in Korea. We surveyed 65 sites located at 9 provinces in South Korea, and isolated 248 virulent and 3 hypovirulent strains of chestnut blight fungus. Hypovirulent strains had dsRNA virus in the cytoplasm, which is one of the typical characteristics of hypovirulent strains. In addition, they showed more characteristics of hypovirulent strains, i.e., suppressed conidiation, reduced pigmentation in colony color, and reduced phenol oxidase activity as well as reduced pathogenicity. Hypovirulent strains, KCPH-22, KCPH-135 and KCPH-136, had a genomic dsRNA band with the molecular weight of 12.7 kb, which is the L-dsRNA of CHV1. They also had a 2.7 kb defective dsRNA band. Single conidia isolated from hypovirulent strains were cultured and various phenotypes and absence of dsRNA bands were obtained from single conidial cultures, which means that hypovirulence transmission is unstable in asexual reproduction and variations in viral heredity by asexual reproduction. Biocontrol trial using hypovirulent strains was also carried out in the chestnut tree plantations, and canker expansion in the treated trees was stopped and healed by callus formation at the margin of the canker. These results show the potentials in successful biocontrol of chestnut blight if the vegetatively compatible hypovirulent strains could be directly used around the canker formed by compatible virulent strains.
Subject(s)
Bony Callus , Cytoplasm , Fungi , Heredity , Korea , Molecular Weight , Monophenol Monooxygenase , Phenotype , Pigmentation , Reproduction, Asexual , Spores, Fungal , Trees , VirulenceABSTRACT
Objective To investigate the histological distribution of phenol oxidase (PO) in body of Oncomelania hupensis. Methods Oncomelania hupensis snails collected from the riverside of Wuhu section of the Yangtze River were anatomized and the unimpaired software organs were sliced in frozen condition to get the continued sections, then the sections were incubated in pH 6.8 phosphate buffer containing 25 mmol/L catechol at 37 ℃ and investigated systematically for histological distribution of PO in snail bodies. Results The light microscope showed that there were black grannles of PO (histochemical reaction) in the liver, ctenidium, head-foot, tentacle and mantle collar of snail body. Conclusion PO exists in Oncomelania hupensis and locates in the liver, mantle collar, head-foot, tentacle and ctenidium.
ABSTRACT
Objective To understand whether phenol oxidase (PO) existed in the body of Oncomelania hupensis and to observe histological distribution of the enzyme. Methods Enzyme histochemical method: adult female and male snails collected from the riverside of Yangtze River of Wuhu section were anatomized and consequently incubated in pH 6.8 phosphate buffer containing 25 mmol/L catechol at 37 ℃. Then under a stereo microscope, some of the snails were observed and recorded for the existing condition and histological distribution of PO in their bodies. Fluorescent histochemical method: after the process of incubation mentioned above, catechol were exsucted from the group of other snails. Afterward, some phosphate buffer solution (pH 6.8) containing 0.05% sodium penobarbital was added into the group. Then the existing condition and histological distribution of PO were also observed and recorded under a fluorescent microscope. Results The first method indicated that the color of the liver surface turned from French grey to light grey in 5 minutes, to grey in 15 minutes and black in 30 minutes. The second method showed that fluorescien appeared on the surface of the snail liver. Conclusion PO exists in the bodies of male and female snails and locates in their livers.
ABSTRACT
Objective To explore the effect of phenol oxidase antigen on liver pathologic change in mice infected with Schistosoma japonicum. Methods 42d-aged adult worms were incubated in RPMI 1640 containing 0.05% sodium phenobarbital for 8 h. The worms were washed three times with PBS (pH 6.8) and homogenized with a Teflon pestle. The homogenate was then centrifuged at 3000 g for 20 min at 4 ℃. Supernatant fractions containing phenol oxidase (PO) were analyzed by means of polyacrylamide gel electrophoresis (PAGE). The rude antigen of PO was obtained by cutting the corresponding gel of PO activities. Three groups were set up to observe whether PO could induce protective immunity: experiment group, adjuvant control group and water control group. On day 42 post infection with (40?1) cercariae of Schistosoma japonicum, the mice were sacrificed to observe liver pathologic changes. Results The liver surface of PO immunized group was rather smooth and the liver color was slightly gray. A few pale nods were seen indistinctly but not clearly. Necrosis and inflammatory cell infiltration were not clear. There were many immature eggs without granuloma reaction. The mean diameter and area of the granuloma in the experiment group were less than those in the control group. There were significant differences among the 3 groups (P