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961.
Gotoh M Ribeiro N Michels B Elhabiri M Albrecht-Gary AM Yamashita J Hato M Ourisson G Nakatani Y 《化学与生物多样性》2006,3(2):198-209
Mixtures of amphiphilic cholesteryl phosphate (CP), sitosteryl phosphate (SP), or cholesteryl phosphocholine (CPC) with the nonphosphoryl diacyl lipid dimyristoylglycerol (DMG) or with cholesterol give self-organized systems (giant vesicles) in a wide range of pH, as demonstrated by fluorescence microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The water permeability of a 1 : 1 molar mixture of CPC and DMG was also measured by a stopped-flow/light-scattering method. The novel self-organized systems are akin to natural eukaryotic ones, the only difference being the site of the phosphate-containing head-group, located on cholesterol instead of DMG. They might be present in some organisms not yet studied for the composition of their membranes. 相似文献
962.
Kawada T Yamazaki T Akiyama T Uemura K Kamiya A Shishido T Mori H Sugimachi M 《American journal of physiology. Heart and circulatory physiology》2006,291(5):H2187-H2191
Although an axoplasmic Ca(2+) increase is associated with an exocytotic acetylcholine (ACh) release from the parasympathetic postganglionic nerve endings, the role of voltage-dependent Ca(2+) channels in ACh release in the mammalian cardiac parasympathetic nerve is not clearly understood. Using a cardiac microdialysis technique, we examined the effects of Ca(2+) channel antagonists on vagal nerve stimulation- and ischemia-induced myocardial interstitial ACh releases in anesthetized cats. The vagal stimulation-induced ACh release [22.4 nM (SD 10.6), n = 7] was significantly attenuated by local administration of an N-type Ca(2+) channel antagonist omega-conotoxin GVIA [11.7 nM (SD 5.8), n = 7, P = 0.0054], or a P/Q-type Ca(2+) channel antagonist omega-conotoxin MVIIC [3.8 nM (SD 2.3), n = 6, P = 0.0002] but not by local administration of an L-type Ca(2+) channel antagonist verapamil [23.5 nM (SD 6.0), n = 5, P = 0.758]. The ischemia-induced myocardial interstitial ACh release [15.0 nM (SD 8.3), n = 8] was not attenuated by local administration of the L-, N-, or P/Q-type Ca(2+) channel antagonists, by inhibition of Na(+)/Ca(2+) exchange, or by blockade of inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] receptor but was significantly suppressed by local administration of gadolinium [2.8 nM (SD 2.6), n = 6, P = 0.0283]. In conclusion, stimulation-induced ACh release from the cardiac postganglionic nerves depends on the N- and P/Q-type Ca(2+) channels (with a dominance of P/Q-type) but probably not on the L-type Ca(2+) channels in cats. In contrast, ischemia-induced ACh release depends on nonselective cation channels or cation-selective stretch activated channels but not on L-, N-, or P/Q type Ca(2+) channels, Na(+)/Ca(2+) exchange, or Ins(1,4,5)P(3) receptor-mediated pathway. 相似文献
963.
Kanno Y Jikumaru Y Hanada A Nambara E Abrams SR Kamiya Y Seo M 《Plant & cell physiology》2010,51(12):1988-2001
ABA plays important roles in many aspects of seed development, including accumulation of storage compounds, acquisition of desiccation tolerance, induction of seed dormancy and suppression of precocious germination. Quantification of ABA in the F(1) and F(2) populations originated from crosses between the wild type and an ABA-deficient mutant aba2-2 demonstrated that ABA was synthesized in both maternal and zygotic tissues during seed development. In the absence of zygotic ABA, ABA synthesized in maternal tissues was translocated into the embryos and partially induced seed dormancy. We also analyzed the levels of ABA metabolites, gibberellins, IAA, cytokinins, jasmonates and salicylic acid (SA) in the developing seeds of the wild type and aba2-2. ABA metabolites accumulated differentially in the silique and seed tissues during development. Endogenous levels of SA were elevated in aba2-2 in the later developmental stages, whereas that of IAA was reduced compared with the wild type. These data suggest that ABA metabolism depends on developmental stages and tissues, and that ABA interacts with other hormones to regulate seed developmental processes. 相似文献
964.
965.
8-Oxo-7,8-dihydroguanine (8-oxo-Gua, also known as 8-hydroxyguanine) is a major base lesion that is generated by reactive oxygen species in both the DNA and nucleotide pool. The role of DNA glycosylases, which initiate base excision repair, in the mutagenic processes of 8-oxo-Gua in DNA and 8-oxo-7,8-dihydro-2′-deoxyguanosine 5′-triphosphate (8-oxo-dGTP, also known as 8-hydroxy-2′-deoxyguanosine 5′-triphosphate) were investigated using supF shuttle plasmids propagated in human cells. The DNA glycosylases, OGG1, MUTYH, NTH1, and NEIL1, in 293T cells were individually knocked-down by siRNAs and plasmid DNAs containing an 8-oxo-Gua:C/8-oxo-Gua:A pair, and 8-oxo-dGTP plus unmodified plasmid DNA were then introduced into the knocked-down cells. The knock-down of OGG1, MUTYH, NTH1, and NEIL1 resulted in a significant increase in G:C → T:A transversions caused by the 8-oxo-Gua:C pair in the shuttle plasmid. The knock-down of MUTYH resulted in a reduction in A:T → C:G transversions induced by 8-oxo-dGTP and the 8-oxo-Gua:A pair, but the knockdown of OGG1, NTH1, and NEIL1 had no effect on mutagenesis. These results indicate that all of the above DNA glycosylases suppress mutations caused by 8-oxo-Gua:C in DNA. In contrast, it appears that MUTYH enhances A:T → C:G mutations caused by 8-oxo-dGTP. 相似文献
966.
Hiroshi Kamiya Yoshihiro Kano Koji Mishima Katsuhiro Yoshioka Osamu Mitamura Yu Ishitobi 《Landscape and Ecological Engineering》2008,4(1):39-46
To study the long-term change in nutrient loads from the Hii River to Lake Shinji, water samples were taken repeatedly over
a year in 1983/1984 and again in 2001/2002. Annual total nitrogen (TN) loads, estimated from observations of water quality
and river flow, increased from 860 to 920 t with a corresponding increase in NO3–N concentration during the cool season. In contrast, total phosphorus (TP) loads decreased from 96 to 62 t. Annual TN and
TP loads, calculated using emission factors and annual statistics for the catchments, showed a tendency to decline from 1986
to 2002. No source could be identified which would result in the increase in TN in the catchments, therefore, the increase
in observed TN loads was considered to originate in other areas. Atmospheric nitrogen deposition transported from long distances
has elevated the sum of NH4–N and NO3–N concentration in rainwater in the cool season. Therefore, it was considered that this resulted in the increase in TN loads
in the Hii River. 相似文献
967.
968.
H Kamiya N Murata-Kamiya E Iida H Harashima 《Biochemical and biophysical research communications》2001,288(3):499-502
To examine the possibility that the Orf135 protein of Escherichia coli functions as a hydrolyzing enzyme for a damaged DNA precursor (deoxyribonucleoside 5'-triphosphate), we purified the recombinant Orf135 protein and incubated it with oxidized deoxynucleotides. Of the nucleotides tested, 2-hydroxydeoxyadenosine 5'-triphosphate, and somewhat less efficiently, 8-hydroxydeoxyguanosine 5'-triphosphate, were hydrolyzed by this protein. These damaged deoxynucleotides elicit transversion mutations in E. coli (Inoue, M., Kamiya, H., Fujikawa, K., Ootsuyama, Y., Murata-Kamiya, N., Osaki, T., Yasumoto, K., Kasai, H. (1998) J. Biol. Chem. 273, 11069-11074). These results suggest that this protein may be involved in the prevention of mutations induced by these oxidized deoxynucleotides. 相似文献
969.
An oxidized nucleotide affects DNA replication through activation of protein kinases in Xenopus egg lysates
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Toshinori Kai Rieko Matsunaga Masami Eguchi Hiroyuki Kamiya Hiroshi Kasai Motoshi Suzuki Shunji Izuta 《Nucleic acids research》2002,30(2):569-573
To elucidate the response to oxidative stress in eukaryotic cells, the effect of an oxidized nucleotide, 8-oxo-2′-deoxyguanosine 5′-triphosphate (8-oxo-dGTP), generated from dGTP with an active oxygen, on DNA synthesis was studied using a cell-free DNA replication system derived from Xenopus egg lysates with a single-stranded DNA template. Amounts of newly synthesized DNA were reduced according to the increasing concentration of 8-oxo-dGTP. Pulse labeling analysis revealed that 8-oxo-dGTP could delay DNA synthesis by reducing the rate of chain elongation. This delay was recovered by addition of a protein kinase inhibitor, staurosporine or bisindolylmaleimide I. These results indicate that a staurosporine- or bisindolylmaleimide I-sensitive protein kinase, such as a protein kinase C family member, may contribute to the delay of DNA synthesis by 8-oxo-dGTP. UV-irradiated single-stranded DNA also caused a delay of DNA synthesis on the undamaged template in the lysates. However, this delay was not recovered by staurosporine or bisindolylmaleimide I. Therefore, the mechanism of delay of DNA synthesis by 8-oxo-dGTP may be different from that by UV lesions. This is the first report that demonstrates an effect of an oxidized nucleotide on DNA replication in eukaryotes. 相似文献
970.
S. Ono M. Kuroda J. Higo N. Kamiya N. Nakajima H. Nakamura 《Journal of biological physics》2002,28(3):427-437
Free energy landscapes of peptide conformations werecalibrated by ab initiomolecular orbital calculations, after enhancedconformational sampling using the multicanonical molecular dynamicssimulations. Three different potentials of mean force for an isolateddipeptide were individually obtained using the conventional force fields,AMBER parm94, AMBER parm96, and CHARMm22. Each potential ofmean force was calibrated based on the umbrella sampling algorithm fromthe adiabatic energy map that was calculated separately by the abinitiomolecular orbital method. All the calibrated potentials of mean forcecoincided well. The calibration was applied to a peptide in explicit water,and the calibrated free energy landscapes did not depend on the force fieldused in conformational sampling, as far as the conformational space waswell sampled. 相似文献