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排序方式: 共有845条查询结果,搜索用时 15 毫秒
721.
Kenji Sugawara Hiroshi Watarai Yuji Ise Hisayoshi Yokose Yasuhiro Morii Nobuhiro Yamawaki Shigeru Okada Shigeki Matsunaga 《Marine drugs》2021,19(6)
Marine sponges are an excellent source of biologically active secondary metabolites. We focus on deep-sea sponges for our discovery study. A marine sponge Cladocroce sp. exhibited cytotoxic activity in the bioactivity screening. From this sponge a previously unreported cytotoxic glycosphingolipid, calyxoside B, was isolated and the structure of this compound was elucidated by analyses of MS and NMR spectra and chemical derivatization. We converted the ketone in the middle of a long aliphatic chain into an oxime to which was applied Beckmann rearrangement to afford two positional isomers of amides. The products were subjected to acidic hydrolysis followed by LC-MS analysis, permitting us to assign unequivocally the position of the ketone. Calyxoside B shows cytotoxicity against HeLa cells with an IC50 value of 31 µM and also weakly stimulated the production of cytokines in mice. 相似文献
722.
ABSTRACT: Stocks of walleye pollock Theragra chalcogramma collected from: (i) the Sea of Japan (off Rebun Island and Kumaishi); (ii) the Pacific coast (off Shikabe and eastern Hokkaido); and (iii) Nemuro Strait off Hokkaido, northern Japan, were examined for anisakid nematodes during December 1999 to February 2000, and the prevalence and abundance of Anisakis simplex and Contracaecum osculatum larvae were compared among the various sampling sites for fish of the same size and age. Anisakis simplex was generally more abundant than C. osculatum . Infection by A. simplex varied between the aforementioned stocks of walleye pollock as well as within stocks, whereby fish from off Rebun Island and Nemuro Strait were infected the most, followed by those from off the Pacific coast and Kumaishi. Infection by C. osculatum differed between the host stocks, and C. osculatum was the most abundant among the fish from Nemuro Strait. The infection variations seemed to be due to differences in host growth rate, host feeding habit, and the distribution of marine mammal final hosts. The results indicate that these two larval nematodes are useful biological indicators for the population study of walleye pollock in Japanese waters. 相似文献
723.
724.
The modified corneocyte surface area measurement as an index of epidermal barrier properties: inverse correlation with transepidermal water loss
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725.
726.
Norihisa Matsushita Kenji Fukuda Eiji Nagasawa ex-Professor Takakiyo Terashita Kazuo Suzuki 《Journal of Forest Research》1996,1(3):155-160
Isozyme patterns were examined to characterize biological species ofArmillaria in Japan. Of 25 different enzymes tested, glutamate dehydrogenase (GDH), lactate dehydrogenase (LDH), and aspartate aminotransferase
(AAT) showed the most stable and reliable activities. These isozyme patterns showed little variability between haploid and
diploid hyphae even under different cultural conditions among isolates tested. From the results, six Japanese biological species
were clearly characterized through combination of GDH and LDH isozymes. There were no differences on the whole in isozyme
patterns among European biological species ofArmillaria. 相似文献
727.
Physiological process of the symptom development and resistance mechanism in pine wilt disease 总被引:4,自引:0,他引:4
Kenji Fukuda 《Journal of Forest Research》1997,2(3):171-181
Pathophysiological changes during the symptom development of pine wilt disease are reconsidered from recent investigations.
The symptom development is divided into two stages: the early and the advanced stages. In the early stage, small number of
nematodes migrate in cortex, then in xylem of the stem, and induce denaturation and necrosis of parenchyma cells. These changes
in parenchyma are regarded as defense reactions of pines which result in terpene synthesis in xylem cells and embolism in
tracheids. Such changes in the early stage can be induced in both susceptible and resistant pine species by either virulent
or avirulent isolates of pinewood nematode (Bursaphelenchus xylophilus), or byB. mucronatus. No change occur in physiological status of leaves, and nematode reproduction is suppressed during this stage. Pine trees
can survive if symptom does not progress from this stage. The symptoms of the advanced stage usually occur only in susceptible
pines infected by virulent nematode isolates. At the beginning of the advanced stage, enhanced ethylene production by stem
which coincides with cambial destruction occurs, and results in embolism of the outermost xylem in the portion. The embolism
causes decrease in leaf water potential and cessation of photosynthesis. After cessation of photosynthesis, symptoms develop
drastically with a burst of nematode population. There seems to be some unknown mechanism which suppress nematode reproduction
and invasion to the cambial zone. This mechanism is thought to be photosynthesis-dependent, so that in photosynthesis-decrased
conditions, even avirulent nematodes can multiply and invade cambium to induce tree death. Water stress in hot and dry summer
should accelerates symptom development from the early to the advanced stage through such decrease of photosynthesis-dependent
“cambial resistance”. 相似文献
728.
Susumu Kurinobu Daryono Prehatin Naiem Mohanmad Kenji Matsune Osamu Chigira 《Journal of Forest Research》2007,12(3):230-236
A growth model for a plantation of Paraserianthes falcataria was provisionally derived from measurements of 32 permanent plots taken over a period of 2 years in Pare, Indonesia. This
model first predicts height growth with the polymorphic site index equation. Then density-related growth and mortality, that
is, diameter and stand density, are calculated to satisfy the mathematical relationship for the reciprocal and self-thinning
equations, both of which were based on the maximum size–density line with the slope of −1.759 identified in this study. Cumulative
predictions on diameter and stand density, starting with each of three age classes, 3, 4, and 5 years after planting, and
continuing for the next 2 years, agreed well with the observations of age-class mean. An exception was for stands that were
7 years old, which were marginal, but closest to the rotation age of 8 years. Contrasting height/diameter relationships among
the three age classes were described reasonably well with this model, and the predicted basal growth area was found to agree
fairly well with observations. These results suggest that the growth model presented here has good potential for applying
size–density control for plantations of P. falcataria. However, measurements for an additional few years might be necessary to derive a model that will more accurately predict
diameter size at the rotation age. 相似文献
729.
Development of high-performance UF-bonded reed and wheat straw medium-density fiberboard 总被引:10,自引:1,他引:10
Guangping Han Shuichi Kawai Kenji Umemura Min Zhang Takahisa Honda 《Journal of Wood Science》2001,47(5):350-355
Urea formaldehyde resin-bonded reed and wheat straw fiberboards were produced from the fibers made under different steam cooking conditions in refining processes at densities of 500 and 700kg/m3. The effect of steam cooking conditions on the board properties was examined. The steam pressure and cooking time for reed and wheat straws were 0.4MPa/10min and 0.4MPa/5min, respectively, and 0.6MPa/3min and 0.6MPa/10min for both straws. The effect of steam cooking treatment before the fiber refining process on the wettability and weight losses of the straws was also investigated. The results indicated that the mechanical properties and linear expansion of the straw medium-density fiberboard (MDF) were improved with increasing steam cooking pressure and time during the refining process, whereas the thickness swelling (TS) did not vary much. The wettability of the straws was improved by cooking treatment. The steam cooking conditions had little effect on the wettability of the straw surfaces. For reed and wheat straws, the weight losses increased with increasing steam pressure and cooking time. In addition, it was found that the properties of MDF were significantly higher than those of particleboard, especially the internal bond (IB), where the IB values of MDF were more than 10 times higher than those of particleboard. All the properties of the straw MDF, except the TS of wheat board, can meet the requirement of JIS fiberboard standard. The high performances of MDF could be due to the improved wettability and the removal of extractives during the refining process. 相似文献
730.
Satoshi Kambayashi Kouji Minami Yuka Ogawa Takehiro Hamaji Chung Chew Hwang Masaya Igase Hiroko Hiraoka Takako Shimokawa Miyama Shunsuke Noguchi Kenji Baba Takuya Mizuno Masaru Okuda 《Canadian journal of veterinary research》2015,79(3):201-209
The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) causes resistance to nitrosoureas in various human cancers. In this study, we analyzed the correlation between canine lymphomas and MGMT in vitro. Two of five canine lymphoma cell lines required higher concentrations of lomustine to inhibit cell growth by 50%, but their sensitivity to the drug increased when they were cultured with an MGMT inhibitor. Fluorometric oligonucleotide assay and real-time polymerase chain reaction of these cell lines revealed MGMT activity and high MGMT mRNA expression, respectively. We analyzed the methylation status of the CpG islands of the canine MGMT gene by the bisulfite-sequencing method. Unlike human cells, the canine lymphoma cell lines did not show significant correlation between methylation status and MGMT suppression levels. Our results suggest that in canine lymphoma MGMT activity may influence sensitivity to nitrosoureas; thus, inhibition of MGMT activity would benefit nitrosourea-resistant patients. Additional studies are necessary to elucidate the mechanism of regulation of MGMT expression. 相似文献