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171.
172.
Development of electrical rhythmic activity in early embryonic cultured chick double-heart monitored optically with a voltage-sensitive dye 总被引:1,自引:0,他引:1
Toshihiko Yada Tetsuro Sakai Hitoshi Komuro Akihiko Hirota Kohtaro Kamino 《Developmental biology》1985,110(2):455-466
Double-hearted embryos were produced by whole-embryo culture of chick embryos which were microsurgically cut through the tissue of the anterior intestinal portal at the 1- to 6-somite developmental stage, at the time when the cardiac primordia have not yet fused in the bulboventricular region. The cultured embryos were removed from an incubator usually at the 7- to 10-somite stages of development, and then spontaneous electrical action potentials and/or contractions were optically recorded simultaneously from both the right and left half-hearts, using a 10 X 10- element photodiode matrix array together with a voltage-sensitive merocyanine-rhodanine dye (NK 2761). At the 7- to 8-somite stages, spontaneous action potentials were detected from bilateral prebeating half-hearts or sometimes from one half-heart. In each half-heart, the first spontaneous beating was often observed in the half-heart of the 9 somite embryos. In the beating half-hearts regular activity was always observed, while in the prebeating half-hearts at the 7- to 8-somite stages, both the regular and irregular rhythms of action potentials were detected, and the incidence of occurrence of regular activity significantly outnumbered that of the irregular rhythm. The heart rate in the left half-heart was faster than that in the right half-heart in the great majority of the prebeating and beating double-hearted embryos. 相似文献
173.
Singh Avtar K. Dobashi Kazushige Gupta Mahesh P. Asayama Kohtaro Singh Inderjit Orak John K. 《Molecular and cellular biochemistry》1999,197(1-2):7-12
By using highly purified peroxisomes from rat liver, we have shown that peroxisomes contain manganese superoxide dismutase (MnSOD) activity and a 23 kDa protein immunoreactive with antibodies against purified mitochondrial MnSOD. Immunocytochemical studies have also revealed immunoreaction (immunogold) with MnSOD antibodies in mitochondria and peroxisomes. Studies of the intraperoxisomal localization of MnSOD have shown that in peroxisomes MnSOD is a component of the peroxisomal limiting membranes and dense core. Furthermore, the MnSOD level in peroxisomes was modulated by oxidative stress conditions such as ischemia-reperfusion or the treatment with ciprofibrate, a peroxisomal proliferator. These findings suggest that MnSOD in peroxisomes may play an important role in the dismutation of superoxide generated on the peroxisomal membrane for keeping the delicate balance of the redox state. 相似文献
174.
The ruthenium(III) complex [(Cp*)RuCl2]2 (Cp*=permethylcyclopentadienyl) catalyzes polymerization of propiolic acid to give a mixture of poly(propiolic acid), [---CH=C(COOH)---]n (1), and cyclic trimers, 1,2,4- and 1,3,5- benzenetricarboxylic acids. GPC analysis shows MN and MW values of the polymer of 4.0 × 103 and 4.3 × 103, respectively. Reaction of propiolic acid in the presence of the Ru(II) complex, (Cp*)RuCI(L) (L=1,5-cyclooctadiene and norbornadiene), gives the cyclic trimers rather than 1. [(Cp*)RuCl2]2 catalyzes polymerization of acetylenedicarboxylic acid and of propargyl alcohol to give the corresponding poly(acetylene) derivatives, [---C(COOH)=C(COOH)---]n (2) and [---CH=C(CH2OH)---]n (3), respectively. Polymerization of ethyl propiolate, 2-butyn-1,4-diol, phenylacetylene and (trimethylsilyl)acetylene using [(Cp*)RuCl2]2 gives the corresponding polymers [---CH=C(COOEt)---]n (4), [---C(CH2OH)=C(CH2OH)---]n (5), [---CH=CPh---]n (6) and [---CH=C(SiMe3)---]n (7) in low yields. 相似文献
175.
176.
Xylaria regalis, a wood-grown ascomycete isolated in Taiwan, produces β-glucosidase (EC 3.2.1.21) extracellularly. The β-glucosidase was
purified to homogeneity by ammonium sulfate precipitation, ion-exchange, and gel filtration chromatography. The molecular
mass of the purified enzyme was estimated to be 85 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. With
p-nitrophenyl β-D-glucopyranoside (PNPG) as the substrate at pH 5.0 and 50°C, the K
m
was 1.72 mM and V
max
was 326 μmol/min/mg. Optimal activity with PNPG as the substrate was at pH 5.0 and 50°C. The enzyme was stable at pH 5.0
at temperatures up to 50°C. The purified β-glucosidase was active against PNPG, cellobiose, sophorose, and gentiobiose, but
did not hydrolyze lactose, sucrose, Avicel, and o-nitrophenyl β-D-galactopyranoside. The activity of β-glucosidase was stimulated by Ca2+, Mg2+, Mn2+, Cd2+ and β-mercaptoethanol, and inhibited by Ag+, Hg2+, SDS, and p-chloromercuribenzoate (PCMB).
Received: 30 March 1996 / Accepted: 3 May 1996 相似文献
177.
Kohtaro Kirimura Satoshi Fukuda Hidetoshi Abe Shinji Kanayama Shoji Usami 《FEMS microbiology letters》1992,90(3):235-238
Abstract The mitochondrial DNA was isolated from Aspergillus niger WU-2223L, a citric acid-production strain, and characterized by restriction-endonuclease mapping. Cloned fragments which covered the total range of the mitochondrial DNA were assembled and utilized to construct the restriction-endonuclease map for nine restriction enzymes. This map showed that the mitochondrial DNA was a circular molecule of 32.6 kb. 相似文献