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251.
Synergistic inhibition of oxidation in dispersed phosphatidylcholine liposomes by a combination of vitamin E and cysteine 总被引:2,自引:0,他引:2
T Motoyama M Miki M Mino M Takahashi E Niki 《Archives of biochemistry and biophysics》1989,270(2):655-661
Oxidations of soybean phosphatidylcholine liposomes in an aqueous dispersion initiated by free radicals generated initially either in the aqueous phase or in the lipid phase were efficiently suppressed by vitamin E in the membranes. Vitamin E was consumed linearly with time and, when the inhibition period was over the oxidation proceeded rapidly at a rate similar to that in the absence of vitamin E. L-Cysteine was also effective by itself in scavenging radicals in the aqueous region, but it was consumed more rapidly than vitamin E. On the other hand, cysteine could not scavenge the radicals efficiently in a lipid region. Nevertheless, when vitamin E was incorporated into liposomes, the addition of cysteine in the aqueous phase prolonged the inhibition period and it reduced the rate of decay of vitamin E markedly even when the radicals were generated initially in the lipid bilayer. Furthermore, it was found by an electron spin resonance study that chromanoxyl radical disappeared quite rapidly when it was mixed with cysteine and that the spin adduct of cysteine radical was observed in the presence of alpha-(4-pyridyl-N-oxide)-N-tert-butyl nitrone. It was concluded that L-cysteine located in an aqueous region could regenerate vitamin E by reacting with vitamin E radical formed in a lipid region and show a synergistic antioxidant effect, although its efficiency of vitamin E regeneration was lower than that by vitamin C. 相似文献
252.
253.
Yamauchi O Yajima T Fujii R Shimazaki Y Yabusaki M Takani M Tashiro M Motoyama T Kakuto M Nakabayashi Y 《Journal of inorganic biochemistry》2008,102(5-6):1218-1226
Intramolecular M(II)...H-C interactions (M(II)=Cu(II), Pd(II)) involving a side chain alkyl group of planar d8 and d9 metal complexes of the N-alkyl (R) derivatives of N,N-bis(2-pyridylmethyl)amine with an N3Cl donor set were established by structural and spectroscopic methods. The methyl group from the branched alkyl group (R=2,2-dimethylpropyl and 2-methylbutyl) axially interacts with the metal ion with the M...C and M...H distances of 3.056(3)-3.352(9) and 2.317(1)-2.606(1) A, respectively, and the M-H-C angles of 122.4-162.3 degrees . The Cu(II) complexes showing the interaction have a higher redox potential as compared with those without it, and the (1)H NMR signals of the interacting methyl group in Pd(II) complexes shifted downfield relative to the ligand signals. Dependence of the downshift values on the dielectric constants of the solvents used indicated that the M(II)...H-C interaction is mainly electrostatic in nature and may be regarded as a weak hydrogen bond. Implications for possible environmental effects of the leucine alkyl group at the type 1 Cu site of fungal laccase are also discussed. 相似文献
254.
Ryuda M Tsuzuki S Tanimura T Tojo S Hayakawa Y 《Journal of insect physiology》2008,54(10-11):1440-1445
To examine the mechanism by which insects change their food preferences, a simple method was developed to measure their preferences. By using this method, we demonstrated preference of Drosophila melanogaster larvae of the yw control strain for a food based on soybeans over one based on cornmeal. We then screened for mutant strains with food preferences clearly different from the control yw strain, using the Gene Search collection of P-element insertions (GS strains). Among 380 GS strains screened using an assay plate-containing soybean and corn tastants, we identified one mutant, GS1189 that did not show any preference for either of the foods. Further behavioral assays indicated that the GS1189 larvae could have impaired olfactory and gustatory systems. The fact that the CG33071 gene expression was inactivated by the P-element insertion in the GS1189 strain, and that reversion of this gene completely recovered the normal food preference, indicates that this gene contributes to the control of food preferences in Drosophila larvae. 相似文献
255.
Hiroyuki Niida Kazuhiro Murata Midori Shimada Kumiko Ogawa Kumiko Ohta Kyoko Suzuki Hidetsugu Fujigaki Aik Kia Khaw Birendranath Banerjee M Prakash Hande Tomomi Miyamoto Ichiro Miyoshi Tomoyuki Shirai Noboru Motoyama Mireille Delhase Ettore Appella Makoto Nakanishi 《The EMBO journal》2010,29(20):3558-3570
Although the linkage of Chk1 and Chk2 to important cancer signalling suggests that these kinases have functions as tumour suppressors, neither Chk1+/− nor Chk2−/− mice show a predisposition to cancer under unperturbed conditions. We show here that Chk1+/−Chk2−/− and Chk1+/−Chk2+/− mice have a progressive cancer-prone phenotype. Deletion of a single Chk1 allele compromises G2/M checkpoint function that is not further affected by Chk2 depletion, whereas Chk1 and Chk2 cooperatively affect G1/S and intra-S phase checkpoints. Either or both of the kinases are required for DNA repair depending on the type of DNA damage. Mouse embryonic fibroblasts from the double-mutant mice showed a higher level of p53 with spontaneous DNA damage under unperturbed conditions, but failed to phosphorylate p53 at S23 and further induce p53 expression upon additional DNA damage. Neither Chk1 nor Chk2 is apparently essential for p53- or Rb-dependent oncogene-induced senescence. Our results suggest that the double Chk mutation leads to a high level of spontaneous DNA damage, but fails to eliminate cells with damaged DNA, which may ultimately increase cancer susceptibility independently of senescence. 相似文献
256.
Jun?Motoyama Noriyuki?Yamashita Tomio?Morino Masashi?Tanaka Takeshi?Kobayashi Hiroyuki?HondaEmail author 《Biomagnetic research and technology》2008,6(1):2
Background
We have developed magnetite cationic liposomes (MCLs) and applied them as a mediator of local hyperthermia. MCLs can generate heat under an alternating magnetic field (AMF). In this study, the in vivo effect of hyperthermia mediated by MCLs was examined using 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary cancer as a spontaneous cancer model.Method
MCLs were injected into the mammary cancer and then subjected to an AMF.Results
Four rats in 20 developed mammary tumors at more than 1 site in the body. The first-developed tumor in each of these 4 rats was selected and heated to over 43°C following administration of MCLs by an infusion pump. After a series of 3 hyperthermia treatments, treated tumors in 3 of the 4 rats were well controlled over a 30-day observation period. One of the 4 rats exhibited regrowth after 2 weeks. In this rat, there were 3 sites of tumor regrowth. Two of these regrowths were reduced in volume and regressed completely after 31 days, although the remaining one grew rapidly. These results indicated hyperthermia-induced immunological antitumor activity mediated by the MCLs.Conclusion
Our results suggest that hyperthermic treatment using MCLs is effective in a spontaneous cancer model.257.
Two antagonistic gustatory receptor neurons responding to sweet‐salty and bitter taste in Drosophila
Makoto Hiroi Nicolas Meunier Frdric Marion‐Poll Teiichi Tanimura 《Developmental neurobiology》2004,61(3):333-342
In Drosophila, gustatory receptor neurons (GRNs) occur within hair‐like structures called sensilla. Most taste sensilla house four GRNs, which have been named according to their preferred sensitivity to basic stimuli: water (W cell), sugars (S cell), salt at low concentration (L1 cell), and salt at high concentration (L2 cell). Labellar taste sensilla are classified into three types, l‐, s‐, and i‐type, according to their length and location. Of these, l‐ and s‐type labellar sensilla possess these four cells, but most i‐type sensilla house only two GRNs. In i‐type sensilla, we demonstrate here that the first GRN responds to sugar and to low concentrations of salt (10–50 mM NaCl). The second GRN detects a range of bitter compounds, among which strychnine is the most potent; and also to salt at high concentrations (over 400 mM NaCl). Neither type of GRN responds to water. The detection of feeding stimulants in i‐type sensilla appears to be performed by one GRN with the combined properties of S + L1 cells, while the other GRN detects feeding inhibitors in a similar manner to bitter‐sensitive L2 cells on the legs. These sensilla thus house two GRNs having an antagonistic effect on behavior, suggesting that the expression of taste receptors is segregated across them accordingly. © 2004 Wiley Periodicals, Inc. J Neurobiol, 2004 相似文献
258.
Tsuyoshi Uchiyama Fumio Yoshikawa Akira Hishida Teiichi Furuichi Katsuhiko Mikoshiba 《The Journal of biological chemistry》2002,277(10):8106-8113
We have developed a novel recombinant hyperaffinity inositol 1,4,5-trisphosphate (IP(3)) absorbent, called the "IP(3) sponge," which we constructed on the basis of the ligand-binding site of the mouse type 1 IP(3) receptor (IP(3)R1). The IP(3) sponge exhibited approximately 1000-fold higher affinity for IP(3) than the parental IP(3)R1 and specifically competed with the endogenous IP(3)R for binding to IP(3). Trapping IP(3) with the IP(3) sponge inhibited IP(3)-induced Ca(2+) release (IICR) from cerebellar microsomes in a dose-dependent manner. The IP(3) sponge expressed in HEK293 cells also inhibited IICR in response to stimulation with carbachol or ATP. Its inhibitory effects were dependent upon the level of its expression over the increased IP(3) contents. Moreover, the IP(3) sponge significantly reduced the carbachol-induced phosphorylation of cAMP-response element-binding protein in HEK293 cells, indicating that the activation of cAMP-response element-binding protein by Ca(2+)-dependent phosphorylation may be partly attributable to IICR. 相似文献
259.
Fujimura M Ochiai N Oshima M Motoyama T Ichiishi A Usami R Horikoshi K Yamaguchi I 《Bioscience, biotechnology, and biochemistry》2003,67(1):186-191
We cloned and characterized Neurospora NcSSK22 and NcPBS2 genes, similar to yeast SSK22 mitogen-activated protein (MAP) kinase kinase kinase and the PBS2 MAP kinase kinase genes, respectively. Disruptants of the NcSSK22 gene were sensitive to osmotic stress and resistant to iprodione and fludioxonil. Their phenotypes were similar to those of osmotic-sensitive (os) mutants os-1, os-2, os-4, and os-5. The os-4 mutant strain transformed with the wild-type NcSSK22 gene grew on a medium containing 4% NaCl and was sensitive to iprodione and fludioxonil. In contrast, the NcPBS2 gene complemented the osmotic sensitivity and fungicide resistance of the os-5 mutant strain. We sequenced the NcPBS2 gene of the os-5 mutant strain (NM216o) and found five nucleotides deleted within the kinase domain. This result suggests that the gene products of os-4 and os-5 are components of the MAP kinase cascade, which is probably regulated upstream by two-component histidine kinase encoded by the os-1/nik1 gene. 相似文献
260.