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991.
992.
Both the enantiomers of the axially chiral reagent, 2'-methoxy-1,1'-binaphthalene-2-carbohydroximoyl chloride (MBCC), were used to convert igalan, an alpha-exo-methylene-gamma-lactone, to yield 4,5-dihydroisoxazoles. The absolute configuration of igalan was determined to be (3aR,5R,6R,7aR)-6-ethenylhexahydro-6-methyl-3-methylen e-5-(1-methylethenyl)-2(3H)-benzofuranone (IUPAC name) on the basis of NOE correlations in these derivatives. The absolute configurations of other alpha-exo-methylene-gamma-lactones can be determined by the same method. 相似文献
993.
A new chlorinated red naphthoquinone pigment having antifungal activity, named chlorosesamone, was isolated from the roots of Sesamum indicum. Its structure was characterized as 2-chloro-5,8-dihydroxy-3-(3methyl-2-butenyl)- 1,4-na phthoquinone on the basis of spectral evidence. 相似文献
994.
995.
This study evaluated the effect of 6-h repeat culture before insemination of frozen-thawed, in vitro-matured oocytes on their fertilizability and developmental capacity. Immature oocytes were cultured for 18 h or 24 h and were frozen incrementally. Post-thaw oocytes were repeat cultured for 0 h (control) or 6 h before insemination. With fertilizability, the proportion of enlarged sperm head was significantly (P<0.05) higher in oocytes cultured for 24 h without repeat culture (24:0 h; 51.8%) than those cultured for 24 h with repeat culture (24:6 h; 26.1%) and nonfrozen oocytes (25.9%). However, the proportion of male pronucleus (MPN) in the group of 24:0 h (32.4%) was significantly (P<0.05) lower than that of nonfrozen oocytes (64.3%); the formation of the female pronucleus and MPN were also significantly (P<0.01) lower (17.2%) than that of nonfrozen oocytes (56.1%). Polyspermic oocytes cultured for 18 h with repeat culture for 6 h (18:6 h) were significantly (P<0.05) higher (47.5%) than for nonfrozen oocytes (25.6%). Development to 8-cell stage in the group of 18:6 h was significantly (P<0.05) lower (1.6%) than that of nonfrozen oocytes (18.5%). The cleavage rates in the groups of 24:0 h (16.3%) and 24:6 h (23.4%) were also significantly (P<0.05) lower than for nonfrozen oocytes (63.3%). Development to blastocysts was low (3.9%), but hatched blastocysts were observed in frozen-thawed oocytes cultured for 18:0 h. These results indicate the post-thaw 6-h repeat culture did not greatly improve the fertilizability and embryonic development of oocytes cultured for 18 h or 24 h before freezing. Frozen-thawed oocytes after 24 h in vitro maturation without repeat culture especially had impaired capacities for fertilizability and development. 相似文献
996.
Cocaine (COCA)-induced neurobehavioral symptoms, which can be observed simultaneously with exacerbation in biochemical markers, were evaluated in mice, and compared with the changes observed in a representative hepatic failure model induced by thioacetamide (TAA). The effects of pretreatment with buprenorphine (BUP) (0.25, 0.5 or 1 mg/kg i.p.), a mixed opioid agonist-antagonist and an antidote against fatal COCA toxicity, were also examined. At 5 min after the COCA administration (65 mg/kg i.p.), the liver ATP levels were attenuated, and an exacerbation of the CNS-stimulating effects of COCA could be characteristically observed for hepatotoxicity-related neurobehavioral symptoms (changes in alertness, interest, body tension, head movement and walking). At 24 h, the ALT (alanine aminotransferase) activity was elevated, and hepatotoxic attenuation was observed for all of the scores on the neurobehavioral symptoms; this was almost identical to the symptoms observed in the TAA-treated group of mice. Recovery was observed by 72 h for all of the morbid changes. The hepatotoxic biochemical changes and the sum score for all five neurobehavioral symptoms were significantly ameliorated by low doses (0.25 and 0.5 mg/kg) of BUP, both at 5 min and 24 h. 相似文献
997.
rDNA (18S-5.8S-25S rDNA) and 5S rDNA loci were visualized on the chromosomes of six species of the genus Oryza by fluorescence in situ hybridization (FISH) and the labeled rice chromosomes were identified based on their condensation patterns. As a result, the chromosomes harboring rDNA and/or 5S rDNA loci were determined in the complement for all the known rice genomes. Variation in the location of the rDNA loci indicated the transpositional nature of the rDNAs in the genus Oryza, as also suggested in Triticeae and Allium. Comparative analysis of the locations of rDNA loci among rice, maize and wheat revealed that variability in the physical location of the rDNA loci was characteristic of the genus Oryza and also of the genera of Gramineae. This variability in the location of the rDNA loci between evolutionarily related species is in sharp contrast to the conservation of the general order of genes in their genomes. 相似文献
998.
Effect of the photocatalytic activity of TiO(2) on plasmid DNA 总被引:7,自引:0,他引:7
Ashikaga T Wada M Kobayashi H Mori M Katsumura Y Fukui H Kato S Yamaguchi M Takamatsu T 《Mutation research》2000,466(1):1-7
We investigated the photodynamic DNA strand-breaking activity of TiO(2). A solution of super-coiled pBR 322 DNA was irradiated with 5 J/cm(2) of UVA in the presence of TiO(2) and the products were analyzed by using gel electrophoresis. The ratio of open-circular DNA to super-coiled circular DNA was calculated from the resulting peak areas as a DNA strand-breaking index (SBI). The SBI of anatase-structure TiO(2) (band gap=3.23 eV) was greater than that of rutile structure (band gap=3.06 eV), and the level of SBI correlated with the photocatalytic activity for degradation of 2-propanol. The inhibitory effects of active oxygen scavengers, including DMSO, glutathione and histidine, on the DNA strand-breaking activity were examined. All of the scavengers except ascorbic acid showed inhibitory effects, as did several polyhydric alcohols including mannitol, a well-known hydroxyl radical scavenger. These results suggest that the photodynamic DNA strand-breaking activity of TiO(2) is due to active oxygen species, especially hydroxyl radicals. Polyhydric alcohols showed an inverse correlation between the inhibitory effect on DNA strand-breaking activity and the octanol/water partition coefficient (logP). 相似文献
999.
Takahashi H Kamada M Yamazaki Y Fujii N Higashitani A Aizawa S Yoshizaki I Kamigaichi S Mukai C Shimazu T Fukui K 《Planta》2000,210(3):515-518
Seedlings of most cucurbitaceous plants develop a peg (protuberance caused by cell outgrowth) on the transition zone between
the hypocotyl and root. The peg is necessary for removing the seed coat after germination. In our spaceflight experiments
on the STS-95 space shuttle, Discovery, we found that cucumber (Cucumis sativus L.) seedlings grown under microgravity conditions developed two pegs symmetrically at the transition zone. Thus, cucumber
seedlings potentially develop two pegs and do not require gravity for peg formation itself, but on the ground the development
of one peg is suppressed in response to gravity. This may be considered as negative control of morphogenesis by gravity.
Received: 17 August 1999 / Accepted: 4 October 1999 相似文献
1000.
Shimizu K Goto A Fukui M Taniguchi M Fujii S 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(5):2853-2861
Dendritic cells (DCs) loaded with alpha-galactosylceramide (alpha-GalCer) are known to be active APCs for the stimulation of innate NKT and NK cell responses in vivo. In this study, we evaluated the capacity of non-DCs to present alpha-GalCer in vitro and in vivo, particularly tumor cells loaded with alpha-GalCer (tumor/Gal). Even though the tumor cells lacked expression of CD40, CD80, and CD86 costimulatory molecules, the i.v. injection of tumor/Gal resulted in IFN-gamma secretion by NKT and NK cells. These innate responses to tumor/Gal, including the induction of IL-12p70, were comparable to or better than alpha-GalCer-loaded DCs. B16 melanoma cells that were stably transduced to express higher levels of CD1d showed an increased capacity relative to wild-type B16 cells to present alpha-GalCer in vivo. Three different tumor cell lines, when loaded with alpha-GalCer, failed to establish tumors upon i.v. injection, and the mice survived for at least 6 mo. The resistance against tumor cells was independent of CD4 and CD8 T cells but dependent upon NKT and NK cells. Mice were protected from the development of metastases if the administration of live B16 tumor cells was followed 3 h or 3 days later by the injection of CD1d(high)-alpha-GalCer-loaded B16 tumor cells with or without irradiation. Taken together, these results indicate that tumor/Gal are effective APCs for innate NKT and NK cell responses, and that these innate immune responses are able to resist the establishment of metastases in vivo. 相似文献