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排序方式: 共有866条查询结果,搜索用时 15 毫秒
61.
(+)-Neopeltolide is a marine macrolide natural product that exhibits potent antiproliferative activity against several human cancer cell lines. Previous study has established that this natural product primarily targets the complex III of the mitochondrial electron transport chain. However, the biochemical mode-of-actions of neopeltolide have not been investigated in detail. Here we report that (−)-8,9-dehydroneopeltolide (8,9-DNP), a more accessible synthetic analogue, shows potent cytotoxicity against human promyelocytic leukemia HL-60 cells preferentially under energy stress conditions. Nuclear morphology analysis, as well as DNA ladder assay, indicated that 8,9-DNP induced significant nuclear condensation/fragmentation and DNA fragmentation, and these events could be suppressed by preincubating the cells with a pan-caspase inhibitor, N-benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD). Immunoblot analysis demonstrated the release of cytochrome c from the mitochondria and the cleavage of full-length caspase-3 and poly(ADP-ribose) polymerase (PARP). These results indicated that 8,9-DNP induced caspase-dependent apoptotic programmed cell death under energy stress conditions. It was also found that 8,9-DNP induced non-apoptotic cell death in the presence/absence of zVAD under energy stress conditions. Immunoblot analysis showed the intracytosolic release of apoptosis-inducing factor (AIF), although it did not further translocate to the nucleus. It appears most likely that, in the presence of zVAD, 8,9-DNP triggered necrotic cell death as a result of severe intracellular ATP depletion. 相似文献
62.
Rabies is an enzootic viral disease widespread throughout the world. Although it is a vaccine-preventable disease, the annual number of human deaths caused by rabies is estimated to be 32,000 in Asia. Phylogenetic analysis based on sequence data of the partial N gene of rabies viruses in Asia has shown that the viruses are divided into five genogroups, distributed in Middle East, South Asia, South East Asia, Malay, and Arctic regions. The genetic relationships among these rabies viruses agree basically with the results of previous studies. Meanwhile, new types of vaccines are being developed by applying gene manipulation techniques to rabies virus in order to overcome the disadvantages of current vaccines. This article reviews the molecular epidemiology of rabies in Asia and progress made in the development of new-generation rabies vaccines with the goal of elimination or control of rabies in Asia. 相似文献
63.
Relationship between relative water content during reproductive development and winter wheat grain yield 总被引:2,自引:0,他引:2
Summary Water is often the most limiting factor to winter wheat (Triticum aestivum L.) production in the southern Great Plains of the U.S.A., yet the lack of reliable screening criteria has precluded direct selection for drought resistance in breeding programs. Previous work showed that leaf relative water content (RWC) was highly heritable when measured under field-drought conditions, but its adoption as a screening tool for yield improvement requires further investigation of the genetic relationship between grain yield and RWC. Plants representing high and low yield potential under drought stress, and a random group of plants, were selected from an F2 population having the pedigree, TAM W-101/Sturdy. Two sets of entries, each comprised of the two parents and 24 F2-derived lines, were evaluated under a rainshelter in the F3 (1986) and F4 (1987) generations to determine differences in leaf RWC during reproductive development. One set of entries did not receive any water after the jointing stage, and the other set was grown under well-watered conditions. A positive relationship was observed between grain yield and RWC measured during anthesis and mid-grain fill, as the high-yield selections maintained a significantly higher RWC than the low-yield selections. Grain yield and RWC were also positively associated among random selections segregating for both traits. Subsequent adjustment of genotype means for differences in reproductive development at time of sampling underscored the need to consider differences in maturity when RWC is the selection criterion. 相似文献
64.
Identification and characterization of foliar polyphenolic composition in sweetpotato (Ipomoea batatas L.) genotypes 总被引:1,自引:0,他引:1
Islam MS Yoshimoto M Yahara S Okuno S Ishiguro K Yamakawa O 《Journal of agricultural and food chemistry》2002,50(13):3718-3722
Trials over two years were conducted using 1389 sweetpotato (Ipomoea batatas L.) genotypes collected from all over the world to characterize the polyphenolic composition in sweetpotato leaves. Wide variation was observed in relation to their total and individual leaf polyphenolic constituents. In all genotypes studied, the total polyphenol contents of sweetpotato leaf ranged from 1.42 to 17.1 g/100 g dry weight. The six different polyphenolic compounds were identified and quantified by NMR, FABMS, and RPHPLC analysis procedures. This is the first report of polyphenolic compositions in sweetpotato leaves. The relative levels of polyphenolic acids in sweetpotato leaves were as follows: 3,5-di-O-caffeoylquinic acid > 4,5-di-O-caffeoylquinic acid > chlorogenic acid (3-O-caffeoylquinic acid) > 3,4-di-O-caffeoylquinic acid > 3,4,5-tri-O-caffeoylquinic acid > caffeic acid. The highest 3,4,5-tri-O-caffeoylquinic acid and 4,5-di-O-caffeoylquinic acid occurred at 221 and 1183.30 mg/100 g dry weight, respectively. 相似文献
65.
66.
Antioxidative compounds from the outer scales of onion 总被引:2,自引:0,他引:2
Ly TN Hazama C Shimoyamada M Ando H Kato K Yamauchi R 《Journal of agricultural and food chemistry》2005,53(21):8183-8189
Antioxidative compounds were isolated from the methanol extract of dry outer scales of onion (Allium cepa L.). Nine phenolic compounds (1-9) were finally obtained by reversed-phase high-performance liquid chromatography, and their structures were elucidated by NMR and mass spectrometry analyses. They were the six known compounds, protocatechuic acid (1), 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (2), quercetin 4'-O-beta-D-glucopyranoside (3), quercetin (5), 4'-O-beta-d-glucopyranoside of quercetin dimer (7), and quercetin dimer (8), and three novel compounds, condensation products of quercetin with protocatechuic acid (4), adduct of quercetin with quercetin 4'-O-beta-D-glucopyranoside (6), and quercetin trimer (9). These phenolic compounds were tested for their antioxidant properties using autoxidation of methyl linoleate in bulk phase or free radical initiated peroxidation of soybean phosphatidylcholine in liposomes. The flavonoid compounds having o-dihydroxy substituent in the B-ring were shown to be effective antioxidants against nonenzymic lipid peroxidation. 相似文献
67.
Makoto Kimura 《Soil Science and Plant Nutrition》2005,51(2):159-181
As rice fields are managed for improved rice production, many studies on aquatic organisms in the floodwater have been restricted to agronomically important members such as blue-green algae (BGA) and Azolla , and ecological studies on common aquatic organisms were relatively limited to specific group members. In the present paper, studies on all the aquatic organisms in the floodwater, from protozoa to insects and fishes, were reviewed worldwide from the viewpoint of rice field ecology, paying attention to their populations, seasonal variations, antagonistic relations and biomass, and the effect of field management. Most studies conducted in India and in the Southeast Asian countries dealt with the BGA and green algal populations. In contrast, protozoa and aquatic animals were extensively studied in rice fields in Europe. Japanese studies in the past were intermediate between the previously cited studies. They generally described specific groups depending on the authors' interests, and surprisingly few studies dealt with the community level and prey-predator relationships. Field management such as fertilizer and pesticide application, water management and plowing was found to play a major role in determining the populations of aquatic organisms. Overview of research on aquatic organisms in the floodwater of rice fields suggests several directions for future studies. 相似文献
68.
Isolation and characterization of some antioxidative compounds from the rhizomes of smaller galanga (Alpinia officinarum Hance) 总被引:2,自引:0,他引:2
Ly TN Shimoyamada M Kato K Yamauchi R 《Journal of agricultural and food chemistry》2003,51(17):4924-4929
Antioxidative compounds were isolated from the methanol extract of fresh rhizome of smaller galanga (Alpinia officinarum Hance). Seven phenylpropanoids (1-7) were finally obtained by reversed-phase HPLC, and their structures were elucidated by MS and NMR analyses. They comprised the two known compounds, (E)-p-coumaryl alcohol gamma-O-methyl ether (1) and (E)-p-coumaryl alcohol (6), and the five novel compounds, stereoisomers of (4E)-1,5-bis(4-hydroxyphenyl)-1-methoxy-2-(methoxymethyl)-4-pentene (2a and 2b), stereoisomers of (4E)-1,5-bis(4-hydroxyphenyl)-1-ethoxy-2-(methoxymethyl)-4-pentene (3a and 3b), (4E)-1,5-bis(4-hydroxyphenyl)-1-[(2E)-3-(4-acetoxyphenyl)-2-propenoxy]-2-(methoxymethyl)-4-pentene (4), (4E)-1,5-bis(4-hydroxyphenyl)-2-(methoxymethyl)-4-penten-1-ol (5), and (4E)-1,5-bis(4-hydroxyphenyl)-2-(hydroxymethyl)-4-penten-1-ol (7). Compounds 1-7 were detected for the first time as constituents of galanga rhizomes and exhibited antioxidative activities against the autoxidation of methyl linoleate in bulk phase. 相似文献
69.
The recent discovery of mammalian bitter, sweet, and umami taste receptors indicates how the different taste qualities are encoded at the periphery. However, taste representations in the brain remain elusive. We used a genetic approach to visualize the neuronal circuitries of bitter and sweet tastes in mice to gain insight into how taste recognition is accomplished in the brain. By selectively expressing a transsynaptic tracer in either bitter- or sweet and/or umami-responsive taste receptor cells, and by comparing the locations of the tracer-labeled neurons in the brain, our data revealed the potential neuronal bases that underlie discrimination of bitter versus sweet. 相似文献
70.
CTLA-4 control over Foxp3+ regulatory T cell function 总被引:1,自引:0,他引:1
Wing K Onishi Y Prieto-Martin P Yamaguchi T Miyara M Fehervari Z Nomura T Sakaguchi S 《Science (New York, N.Y.)》2008,322(5899):271-275
Naturally occurring Foxp3+CD4+ regulatory T cells (Tregs) are essential for maintaining immunological self-tolerance and immune homeostasis. Here, we show that a specific deficiency of cytotoxic T lymphocyte antigen 4 (CTLA-4) in Tregs results in spontaneous development of systemic lymphoproliferation, fatal T cell-mediated autoimmune disease, and hyperproduction of immunoglobulin E in mice, and it also produces potent tumor immunity. Treg-specific CTLA-4 deficiency impairs in vivo and in vitro suppressive function of Tregs-in particular, Treg-mediated down-regulation of CD80 and CD86 expression on dendritic cells. Thus, natural Tregs may critically require CTLA-4 to suppress immune responses by affecting the potency of antigen-presenting cells to activate other T cells. 相似文献