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61.
K. Nagashima M. Ando 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,164(1):47-54
To characterize mechanisms of esophageal desalination, osmotic water permeability and ion fluxes were measured in the isolated esophagus of the seawater eel. The osmotic permeability coefficient in the seawater eel esophagus was 2·10-4 cm·s-1. This value was much lower than those in tight epithelial, although the eel esophagus is a leaky epithelium with a tissue resistance of 77 ohm·cm-2. When the esophagus was bathed in normal Ringer solutions on both sides no net ion and water fluxes were observed. However, when mucosal NaCl concentration was increased by a factor of 3, Na+ und Cl- ions were transferred from mucosa to serosa (desalination). If only Na+ or Cl- concentration in the mucosal fluid was increased by a factor of 3, net Na+ and Cl- fluxes were reduced to 30–40%, indicating that 60–70% of the net Na+ and Cl- fluxes are coupled mutually. The coupled NaCl transport seems to be effective in desalting the luminal high NaCl. The remaining 30–40% of the total Na+ and Cl- fluxes seems to be due to a simple diffusion, because these components are independent of each other and follow their electrochemical gradients, and also because these fluxes remain even after treatment with NaCN or ouabain. A half of the coupled NaCl transport could be explained by a Na+/H+–Cl-/HCO
3
-
double exchanger on the apical membrane of the esophageal epithelium, because mucosal amiloride and 4.4-diisothiocyanatostilbene-2,2-disulphonic acid inhibited the net Na+ and Cl- fluxes by approximately 30%. The other half of the coupled NaCl transport, which follows their electrochemical gradients, still remains to be explained.Abbreviations DIDS
4,4-diisothiocyanatostilbene-2,2-disulphonic acid
- NMDG
N-methyl-d-glucosamine
-
P
Cl
Cl- permeability coefficient
- PD
transepithelial potential difference
-
P
Na
Na+ permeability coefficient
-
P
osm
osinotic permeability coefficient
- TALH
thick ascending limb of Henle's loop 相似文献
62.
63.
Sequence diversity of small, round-structured viruses in the Norwalk virus group. 总被引:31,自引:4,他引:27 下载免费PDF全文
J Wang X Jiang H P Madore J Gray U Desselberger T Ando Y Seto I Oishi J F Lew K Y Green et al. 《Journal of virology》1994,68(9):5982-5990
64.
Junji Inokoshi Hiroshi Tomoda Hideaki Hashimoto Akemi Watanabe Hideo Takeshima Satoshi ōmura 《Molecular & general genetics : MGG》1994,244(1):90-96
Cerulenin, an antifungal antibiotic produced by Cephalosporium caerulens, is a potent inhibitor of fatty acid synthase in various organisms, including Saccharomyces cerevisiae. The antibiotic inhibits the enzyme by binding covalently to the active center cysteine of the condensing enzyme domain. We isolated 12 cerulenin-resistant mutants of S. cerevisiae following treatment with ethyl methanesulfonate. The mechanism of cerulenin resistance in one of the mutants, KNCR-1, was studied. Growth of the mutant was over 20 times more resistant to cerulenin than that of the wild-type strain. Tetrad analysis suggested that all mutants mapped at the same locus, FAS2, the gene encoding the subunit of the fatty acid synthase. The isolated fatty acid synthase, purified from the mutant KNCR-1, was highly resistant to cerulenin. The cerulenin concentration causing 50% inhibition (IC50) of the enzyme activity was measured to be 400 M, whereas the IC50 value was 15 M for the enzyme isolated from the wild-type strain, indicating a 30-fold increase in resistance to cerulenin. The FAS2 gene was cloned from the mutant. Sequence replacement experiments suggested that an 0.8 kb EcoRV-HindIII fragment closely correlated with cerulenin resistance. Sequence analysis of this region revealed that the GGT codon encoding Gly-1257 of the FAS2 gene was altered to AGT in the mutant, resulting in the codon for Ser. Furthermore, a recombinant FAS2 gene, in which the 0.8 Kb EcoRV-HindIII fragment of the wild-type FAS2 gene was replaced with the same region from the mutant, when introduced into FAS2-defective S. cerevisiae complemented the FAS2 pheno-type and showed cerulenin resistance. These data indicate that one amino acid substitution (Gly Ser) in the subunit of fatty acid synthase is responsible for the cerulenin resistance of the mutant KNCR-1. 相似文献
65.
Hideaki Kabuto Isao Yokoi Mineo Takei Tadashi Kurimoto Akitane Mori 《Neurochemical research》1994,19(4):463-467
Serotonin (5-HT) plays an important role in the seizures of El mice since the seizure threshold of El mice correlates with the 5-HT concentration in the central nervous system. In this study, the anticonvulsant effect of a 5-HT reuptake blocker, citalopram, was evaluated behaviorally and biochemically. El mouse convulsions were inhibited by oral administration of citalopram for 2 weeks. Citalopram increased tryptophan and tyrosine amounts, and decreased the 5-HT, 5-hydroxy-indoleacetic acid, kynurenine, and dopamine amounts in the brain. These findings show that citalopram depresses monoaminergic metabolism. Given the known convulsant effect of kynurenine, it is suggested that its decrease by citalopram may involve attenuation of El mice seizures. 相似文献
66.
Long-chain fatty acids in germination-inhibiting animal-wastecomposts were identified by gas chromatography-mass spectrometryas myristic, palmitic, stearic, oleic, linoleic, and linolenicacids. These acids were found at concentrations greater than0.25 mg (g dry compost)1. The identified acids, togetherwith lauric acid, and five kinds of short- and medium-chainfatty acid, were tested for their effects on the germinationprocess of sorghum seeds. The authentic long-chain fatty acids, which were dissolved ina 1:9 (v/v) mixture of methanol and distilled water at 40 mgliter1, significantly reduced the -amylase activity,physiological water uptake, and ATP content of the germinatingseeds during the first 24h of imbibition, as well as the rateof germination of seeds. Among the tested fatty acids, myristicand palmitic acids were the most potent inhibitors of germination.The inhibitory effects of long-chain fatty acids were strongerthan those of the phenolic acids. The short- and medium-chainfatty acids did not have any significant germination-inhibitoryeffects at 40 mg liter1. The results indicate that thelong-chain fatty acids are the dominant inhibitors of germinationin animal-waste composts, and that the inhibition of the -amylaseactivity in germinating sorghum seeds is one aspect of the modeof action of these long-chain fatty acids.
1On leave from the Department of Crop Science, Faculty of Agriculture,University of Peradeniya, Sri Lanka. 相似文献
67.
Possible Involvement of Abscisic Acid in Increases in Activities of Two Vacuolar H+-Pumps in Barley Roots under Aluminum Stress 总被引:1,自引:0,他引:1
Kasai Minobu; Sasaki Masao; Tanakamaru Shigemi; Yamamoto Yoko; Matsumoto Hideaki 《Plant & cell physiology》1993,34(8):1335-1338
Levels of abscisic acid (ABA) in barley roots increased upontreatment with AlCl3. Treatment with AlCl3 or ABA increasedboth ATP-dependent and PPi-dependent H+-pumping activities intonoplast-enriched membrane vesicles. Increase in the H+-pumpingactivities caused by aluminum stress could result from increasedlevels of ABA.
1Present address: Department of Botany, Faculty of Science,Hirosaki University, Hirosaki, Aomori, 036 Japan 相似文献
68.
Kibong Oh Hideaki Matsuoka Yasuyuki Nemoto Osao Sumita Kosuke Takatori Hiroshi Kurata 《Applied microbiology and biotechnology》1993,39(3):363-367
The dynamic growth rate of a single hypha of Aspergillus niger was analysed using an automatic system. A colony of A. niger was in contact with saline, saline containing an antifungal agent, and flushing saline, in sequence. The growth rate of a test hypha selected arbitrarily from the colony responded dynamically to the antifungal agent. The minimum concentration that caused the complete inhibition of hyphal growth was defined as the minimum inhibitory concentration (MIC). The MIC values obtained were compared with those determined by conventional methods based on increasing rate of colony diameter or dry matter weight. 相似文献
69.
Hideaki Sato Hideki Hirayama Takeshi Yamamoto Yoshimasa Lchio Fumiaki Ishizawa Michinao Mizugaki 《Luminescence》1994,9(2):73-77
The purpose of the study was to evaluate the quality of Toki-shakuyaku-san extract granules (TJ-23) using chemiluminescence (CL). A linear relationship was obtained between the log value of the CL of TJ-23 and the reaction temperature. An excellent correlation (r= 0.999) was found between the slope of this curve (ΔA) and the colour intensity due to the browning reaction occurring at the early stage of the Maillard reaction. 相似文献
70.