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Akihiro Takahashi Shigeo Yamada Hirokazu Yamada Takashi Kawana 《Weed Biology and Management》2001,1(3):182-188
The effects of a novel pyrimidine herbicide, NS-245852 [2-chloro-6-fluorophenyl-4-(trifluoromethyl)thieno[2,3-d]pyrimidine-2-yl-ketone], on mitosis in oat ( Avena sativa L. cv. Zenshin) root tips were investigated by using light and immunofluorescence microscopy. The root growth was strongly inhibited at 10−7 mol L−1 of NS-245852, and swollen root tips were induced at 5 × 10−8 mol L−1 . As observed by the use of light microscopy, the herbicide produced disrupted mitosis and large polynucleate cells in the meristematic root tissue. These symptoms were similar to those of mitotic disrupter herbicides. The immunofluorescence microscopy studies of the root tip cells treated for 30 min revealed that spindle fibers and the preprophase band were reduced, although kinetochore fibers and the phragmoplast were not affected. Kinetochore fibers remained as small fluorescence spots, and the phragmoplast disappeared after a 3 h treatment. No microtubule arrays were observed by a longer treatment (longer than 3 h). Among the microtubule arrays, spindle fibers and the preprophase band were found to be the most sensitive to the herbicide, whereas kinetochore fibers were the most resistant. The phragmoplast was intermediate. Thus, the primary action of NS-245852 is the inhibition of polymerization of tubulin into microtubules. 相似文献
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Fujimoto Kiyoshi Miyagi Toyohiko Kikuchi Takao Kawana Toshio 《Mangroves and Salt Marshes》1996,1(1):47-57
Mangrove habitats on Kosrae are divided into three types, i.e., an estuary or delta type, a backmarsh or lagoon type and a coral reef or tidal-flat type. Most of the mangrove forests of Kosrae have been developed during the last 2000 years by accumulating mangrove peat with the gradual sea-level rise of 1 to 2 mm/yr except the landward part of the estuary or delta type. On the other hand, during the period of rapid sea-level rise of about 10 mm/yr between 4100 and 3700 yr B.P., the mangrove forests ceased peat accumulation and retreated landward. Until 3500 yr B.P., mangrove forests were distributed only in narrow bands in the inlets. Therefore, the critical rate of mangrove peat accretion with sea-level rise is estimated at more than 2 mm/yr and less than 10 mm/yr. If the anticipated sea-level rise exceeds this critical rate, all of the mangrove forests of Kosrae will retreat landward and reduce rapidly. 相似文献
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This study examined the effects of exposure to p-Nonylphenol (NP) on the motility of the spermatozoa of Japanese medaka (Oryzias latipes). Spermatozoa collected from adult males reared for 2 weeks in aqueous solutions of 20 and 100 μg/L NP showed similar swimming speeds but significantly lower percentages of motile spermatozoa than those of untreated controls. These results suggest that even a short exposure to NP might reduce significantly spermatozoan viability in fish. 相似文献
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Hayashi M Hamasu T Endoh D Kawana A Matsumoto M Okui T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2004,66(10):1177-1182
A fibroblast cell line derived from LEC rat was approximately twofold more sensitive to heat treatment at 45 degrees C than were that from WKAH rat in terms of heating time required to attain 50% loss of survival in a colony forming assay. The present study was carried out for understanding the mechanism underlying the higher sensitivity of LEC rat cells to heat treatment. Although apoptosis was not found in WKAH rat cells, the percentages of apoptotic cells in LEC rat cells significantly increased after heat treatment. LEC rat cells showed significantly lower sensitivity in induction of cell death and apoptosis to ceramide, a lipid signaling molecule that is associated with heat-induced apoptosis, than did WKAH rat cells. SP600125, an inhibitor of JNK suppressed the induction of cell death in both heated LEC and WKAH rat cells, but SB203580, an inhibitor of p38 mapk, did not. The relative surviving fractions of heated LEC and WKAH rat cells in the presence of both SB203580 and SP600125 were higher than those of cells in the presence of SP600125 alone. The amounts of hsp70 protein in WKAH rat cells increased from 4 to 12 hr after heat treatment, but did not in LEC rat cells. These results suggest that higher thermosensitivity in the fibroblast cell line from LEC rat is due to low inducibility of hsp70 protein after heat treatment. 相似文献
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Hayashi M Kawana A Endoh D Okui T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(2):191-194
No significant cytotoxic effect was observed in WKAH rat cells by the treatment of wortmannin, a radiation sensitizer, at concentrations lower than 30 microM for 24 hr. The relative surviving fractions of LEC rat cells were slightly, but significantly, lower than those of WKAH rat cells at each concentration of wortmannin. When the wortmannin-treated WKAH rat cells were X-irradiated, the relative surviving fractions decreased in a wortmannin concentration-dependent manner. On the contrary, no significant difference was observed between the survival curves of untreated and wortmannin-treated LEC rat cells after X-irradiation. 相似文献
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