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991.
Several analogs of abscisic acid (ABA) were prepared and their biological activities were assayed. Among the compounds tested, 5-(l, 2-epoxy-2, 6, 6-trimethyl-l-cyclohexyl)-, 5-(l-hydroxy-2, 6, 6-trimethyl-2-cyclohexen-l-yl)- and 5-(l-hydroxy-2-methylene-6, 6-dimethyl-l-cyclohexyl)-3-methyl-cis, trans-2, 4-pentadienoic esters (V, IX, XXIII and XXV) were found to be potent plant growth inhibitors. Their activities were superior or comparable to that of ABA. 相似文献
992.
Adult frog (Xenopus laevis) hepatocytes were found to proliferate in a culture medium containing adult homologous serum. Insulin and dexamethasone were required for a net proliferation of hepatocytes. Dose-response analysis showed that a low concentration of serum (greater than or equal to 0.5%) was enough to induce DNA synthesis and mitosis, but a higher concentration (5%) caused certain necrotic changes. Under optimal conditions, there was a two- to threefold increase in nuclei per culture 10 days after serum treatment. Heterologous sera (fetal bovine, calf and chick) showed less proliferative activity. Based on our results, hepatocyte-proliferating activity in adult frog serum is considered to be heat-unstable and acidic protein(s). Thus, adult frog serum may contain hepatopoietin possibly different from well-known growth factors. 相似文献
993.
Nakayama K Kawato H Watanabe J Ohtsuka M Yoshida K Yokomizo Y Sakamoto A Kuru N Ohta T Hoshino K Yoshida K Ishida H Cho A Palme MH Zhang JZ Lee VJ Watkins WJ 《Bioorganic & medicinal chemistry letters》2004,14(2):475-479
The addition of substituents to the pyridopyrimidine scaffold of MexAB-OprM specific efflux pump inhibitors was explored. As predicted by a pharmacophore model, the incorporation substituents at the 2-position improved potency. Piperidines were found to be optimal, and further introduction of polar groups without compromising the activity was shown to be feasible. Careful positioning of the essential acidic moiety of the pharmacophore relative to the scaffold led to the discovery of vinyl tetrazoles with still greater potency. 相似文献
994.
Nuclear magnetic resonance (NMR) is a non-invasive technique which allows us to examine the biochemical, physiological and metabolic events occurring inside living tissue; such as vascular and other smooth muscles.It has been found that the smooth muscle metabolism is compartmented such that mitochondrial function fuels contraction and that much glycolytic ATP production is used for membrane pumps. Using NMR we have been able to observe the ATP and phosphocreatine (PCr) concentrations and estimate the ADP concentration, as well as flux through the creatine kinase (CK) system. It has also been found that the smooth muscle metabolism is able to maintain ATP concentration in the absence of mitochondrial function (cyanide inhibition). Therefore, the vessels are able to adapt to metabolic demands as necessary.NMR is versatile in the information it can provide because it has also yielded important contributions with regard to the intracellular pH and ionic status. For example, the intracellular free Mg2+ ([Mg2+]i) can be measured with NMR simultaneously with ATP concentrations and NMR has shown us that the [Mg2+]i is highly protected in the muscle (within confined range), but also responds to the environment around it.In this review we conclude that NMR measurements of smooth muscle research is a useful technique for assessing chronic and acute changes that occur in the tissue and during diseases. 相似文献
995.
Amanda Linkous Demosthenes Balamatsias Matija Snuderl Lincoln Edwards Ken Miyaguchi Teresa Milner Batsheva Reich Leona Cohen-Gould Andrew Storaska Yasumi Nakayama Emily Schenkein Richa Singhania Stefano Cirigliano Tarig Magdeldin Ying Lin Gouri Nanjangud Kalyani Chadalavada David Pisapia Howard A. Fine 《Cell reports》2019,26(12):3203-3211.e5
996.
997.
Chk tyrosine kinase phosphorylates Src-family kinases and suppresses their kinase activity. We recently showed that Chk localizes to the nucleus as well as the cytoplasm and inhibits cell proliferation. In this study, we explored the role of the N-terminal unique domain of Chk in nuclear localization and Chk-induced tyrosine phosphorylation in the nucleus. In situ binding experiments showed that the N-terminal domain of Chk was associated with the nucleus and the nuclear matrix. The presence of the N-terminal domain of Chk led to a fourfold increase in cell population exhibiting Chk-induced tyrosine phosphorylation in the nucleus. Expression of Chk but not kinase-deficient Chk induced tyrosine phosphorylation of a variety of proteins ranging from 23 kDa to approximately 200 kDa, especially in Triton X-100-insoluble fraction that included chromatin and the nuclear matrix. Intriguingly, in situ subnuclear fractionations revealed that Chk induced tyrosine phosphorylation of proteins that were associated with the nuclear matrix. These results suggest that various unidentified substrates of Chk, besides Src-family kinases, may be present in the nucleus. Thus, our findings indicate that the importance of the N-terminal domain to Chk-induced tyrosine phosphorylation in the nucleus, implicating that these nuclear tyrosine-phosphorylated proteins may contribute to inhibition of cell proliferation. 相似文献
998.
W. Thimdee G. Deein N. Nakayama Y. Suzuki K. Matsunaga 《Wetlands Ecology and Management》2008,16(6):463-470
Stable carbon and nitrogen isotope ratios were used to elucidate primary carbon sources and trophic relationships of the fish
and shrimp community in the Klong Ngao mangrove ecosystem, southern Thailand. There were no significant differences in isotopic
compositions of biota between mangrove and offshore sites (Welch–Aspin test). The δ15N values of eight fish species and two shrimp species at both sites were also not significantly different by the test, meaning
that at both sites they feed on the same diets due to the discharge of large quantities of mangrove sediments. The δ15N isotopic enrichment of consumers suggested that there are four trophic levels in the Klong Ngao food web, with at least
two fish species capable of switching feeding strategies and thus altering their apparent trophic positions. Phytoplankton
culture experiments indicated that mangrove-derived sediments could play an important role in stimulating phytoplankton growth
for low turbidity offshore areas, thus providing an alternate food source. The isotopic associations among sources and consumers
indicated that mangroves were the major carbon source supporting aquatic food webs in the Klong Ngao ecosystem. 相似文献
999.
1000.
Subcellular localization of glycolytic key enzymes in germinating castor bean endosperm 总被引:2,自引:0,他引:2
Phosphofructokinase and pyruvate kinase activities in castorbean endosperm increased during germination. Subcellular localizationof pyruvate kinase and phosphofructokinase in germinating endospermtissues was studied by differential and sucrose density gradientcentrifugation techniques. Eighty five percent or more of thepyruvate kinase and phosphofructokinase activities were locatedin cytosol. The remaining activities were mainly detected inproplastids. (Received June 30, 1977; ) 相似文献