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Embryologia 09/2005; 2(14):133 - 144. · 2.21 Impact Factor
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ABSTRACT: The wavelength of natural sunlight reaching the Earth's surface was detected to be above 300 nm using a multichannel spectrodetector and the ratio of UV to photosynthetically active radiation (PAR) of sunlight in Japan (137 degrees E/35 degrees 11' N, altitude; 50 m) in early summer was estimated to be 0.07:1 (i.e., 7%). On the basis of this UV/PAR ratio, Chlorella ellipsoidea (IAM-27) cells were cultured in flasks under various conditions of UV irradiation in growth chambers. The growth (cell division) of these cells without near-UV radiation was inferior to that with near-UV radiation. Growth at a UV/PAR ratio of 7% (natural conditions), determined tentatively using our detector in the present study, was maximal similar to those at 14% and 28%; whereas that at 0.7% was somewhat less and that at 70% was considerably less. Growth was linked with the activities of stress enzymes. NAD(P)H-dependent oxidase [NAD(P)-DH] and xanthine oxidase (XOD), extracted from Chlorella exposed to near-UV radiation demonstrated lower activities than those from Chlorella not exposed to near-UV radiation. On the other hand, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APOD) extracted from Chlorella exposed to near-UV radiation have higher activities than those from unexposed Chlorella. Near-UV radiation clearly acted as an important factor for growth (cell division), at least at UV/PAR ratios of up to 0.28:1.
Environmental sciences: an international journal of environmental physiology and toxicology 02/2004; 11(4):189-98.
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ABSTRACT: The growth (cell division) of Chlorella cells cultured under photosynthetically active radiation (PAR) without near-UV radiation was inferior to that under PAR with near-UV radiation. To elucidate this phenomenon, the relationship between near-UV radiation and ethylene production in Chlorella cells was examined. The suppression of ethylene production by UV radiation suggests that this phenomenon is associated with the production of ethylene. Chlorella (a eukaryotic protista) was found to produce ethylene from methionine via S-adenosyl-methionine (SAM) and 1-aminocyclo-propane-1-carboxylate (ACC) as in higher plants, and the activity of ACC oxidase, a limiting factor of ethylene production, appears to be associated with the growth of Chlorella. A possible mechanism for the action of near-UV radiation on ethylene biosynthesis and growth suppression by ethylene is discussed.
Environmental sciences: an international journal of environmental physiology and toxicology 02/2004; 11(4):199-208.
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ABSTRACT: The mechanism of self incompatibility in pistils of Lilium longiflorum Thunb. cv. Hinomoto, which is overcome by heat treatment, was analyzed. Immersing detached pistils in a distilled water bath
held at 45°C for 5 min suppressed levels of ethylene and activities of 1-aminocyclopropane-1-carboxylate (ACC) oxidase at
6 h after self- and cross-incompatible pollination. However, the levels and activities showed no significant difference 48
h after pollination. Levels of ACC and activities of ACC synthase at 6 h after self-incompatible pollination were lower in
pistils with heat treatment. Moreover, the heat treatment suppressed the activity of superoxide dismutase and enhanced the
activity of catalase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase. In addition, the amount
of hydrogen peroxide (H2O2) was reduced by heat treatment. In summary, heat treatment suppressed the ethylene-forming system and also enhanced the hydrogen
peroxide-scavenging system in self-pollinated pistils associated with self incompatibility. A possible correlation between
self incompatibility and stress in pistils after self-incompatible pollination is discussed based on the results obtained
using heated pistils.
Sexual Plant Reproduction 01/2001; 13(4):201-208. · 1.87 Impact Factor
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ABSTRACT: Five enzymes involved in the generation and scavenging of reactive oxygen species, i.e., NADH/NADPH oxidase, xanthine oxidase (XOD), superoxide dismutase (SOD), ascorbate peroxidase, and catalase were assayed in various tissues of the Japanese monkey. Their activities were largely different between tissues. Generally, small intestine, kidney, and cerebellum contained larger amounts of these enzymes than other tissues. Multiplicities of these enzymes were analyzed by staining of their enzymatic activities after electrophoresis. The number of isozymes was 2 in the case of NADPH oxidase and catalase, and 3 in the case of XOD, SOD, and ascorbate peroxidase. The expression of these isozymes differed between tissues, suggesting the occurrence of tissue-specific systems to generate and scavenge reactive oxygen species in the Japanese monkey.
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ABSTRACT: An attempt was made to examine the possible connection between self-incompatibility in Lilium longiflorum and the stress response using pistils after self-incompatible pollination. The growth of pollen tubes in the pistil after self-incompatible pollination was promoted by treatment with germanium compounds [(GeCH 2 CH 2 COOH) 2 O 3 and GeO 2 ], which are scavengers of active oxygen species, such as O 2 − and H 2 O 2 . The promotion by germanium compounds of the growth of pollen tubes after self-incompatible pollination was reflected by the detection of elevated levels of activity of superoxide-forming NADPH-dependent oxidase, xanthine oxidase, superoxide dismutase, catalase and ascorbate peroxidase, all of which are associated with stress responses, in pistils upon self-incompatible pollination as compared to the activities of these enzymes after cross-compatible pollination. A possible connection between self-incompatibility and stress in pistils upon self-incompatible pollination is discussed on the basis of these results.
