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51.
Effect of Dichloroacetate on Regional Energy Metabolites and Pyruvate Dehydrogenase Activity During Ischemia and Reperfusion in Gerbil Brain 总被引:1,自引:1,他引:0
The objective of this study was to determine whether administration of dichloroacetate (DCA), an activator of pyruvate dehydrogenase (PDH), improves recovery of energy metabolites following transient cerebral ischemia. Gerbils were pretreated with DCA, and cerebral ischemia was produced using bilateral carotid artery occlusion for 20 min, followed by reperfusion up to 4 h. DCA had no effect on the accumulation of lactic acid and the decrease in ATP and phosphocreatine (PCr) during the 20-min insult, nor on the recovery of these metabolites measured at 20 and 60 min reperfusion. However, at 4 h reperfusion, levels of ATP and PCr were significantly higher in DCA-treated animals than in controls, as PCr exhibited a secondary decrease in caudate nucleus of control animals. PDH was markedly inhibited at 20 min reperfusion in both groups, but was reactivated to a greater extent in DCA-treated animals at 60 min and 4 h reperfusion. These results demonstrate that DCA had no effect on the initial recovery of metabolites following transient ischemia. However, later in reperfusion, DCA enhanced the postischemic reactivation of PDH and prevented the secondary failure of energy metabolism in caudate nucleus. Thus, inhibition of PDH may limit the recovery of energy metabolism following cerebral ischemia. 相似文献
52.
The ratio of the extracellular to the intracellular activityof carbonic anhydrase (CA) in cells of Chlorella ellipsoideaC-27, adapted to low levels of CO2 for 24 h (low-CO2 cells),was about one to one. Treatment of intact cells with PronaseP inactivated about one-half of the extracellular CA activitywithout affecting photosynthetic activity. The CA activity incell homogenates and in cell-wall ghosts liberated during celldivision was completely inactivated by the same treatment. Pretreatmentwith Glycosidase mix, Chitosanase and Macerozyme enhanced theinactivation of the CA activity in intact cells. These resultssuggest that extracellular CA is evenly distributed throughoutthe whole cell-wall region. The apparent K1/2 for dissolved inorganic carbon (DIC) in low-CO2cells doubled when extracellular CA was inactivated by treatmentwith Pronase P, but the K1/2 obtained was still one-half ofthat in high-CO2 cells. Photosynthetic 14CO2-fixation in low-CO2cells was enhanced by acetazolamide, whereas H14CO3-fixationwas suppressed. The results suggest that CO2 is a dominant substrateutilized by cells and that HCO3 is utilized after conversionto CO2. The present results show that both intracellular andextracellular CA contribute to the increase in affinity forDIC during photosynthesis in low-CO2 cells of Chlorella ellipsoideaC-27. (Received May 7, 1990; Accepted July 18, 1990) 相似文献
53.
Matsuda Yoshihiro; Uzaki Tomoya; Iwasawa Norio; Tanaka Takaharu; Saito Tatsuaki 《Plant & cell physiology》1990,31(5):717-720
A cell wall lytic enzyme (gamete wall-autolysin) from Chlamydomonasreinhardtii specifically cleaved several synthetic model peptides,-neo-endorphin, dynorphin (113), neurotensin and mastoparan,at the peptide bonds between consecutive hydrophobic amino-acidresidues. The cleavage was not significantly affected by high-saltconditions which are known to inhibit digestion of the cellwall. (Received December 14, 1989; Accepted April 5, 1990) 相似文献
54.
K Ueno T Katayama T Miyamoto Y Koshihara 《Biochemical and biophysical research communications》1992,189(3):1521-1526
The effect of human interleukin-4 (hIL-4) on mineralization in human osteoblast-like cells was investigated. Confluent cells were incubated with hIL-4 for 16 or 30 days in the presence or absence, respectively, of alpha-glycerophosphate (alpha-GP), which accelerates the mineralization process. hIL-4 (0.3 ng/ml) induced mineralization with 1.9-, 26- and 37-fold increases of hydroxyproline, calcium, and osteocalcin content, respectively, in the presence of alpha-GP. Mineralization was not induced with other cytokines, hIL-1, hIL-2, hIL-6, or mIL-4. hIL-4 also induced mineralization in the absence of alpha-GP in a manner different from that of 1 alpha, 25(OH)2 vitaminD3 (1,25(OH)2VD3). These findings suggest that IL-4 may play an important role in bone formation. 相似文献
55.
Takashi Kamaishi Tetsuo Hashimoto Yoshihiro Nakamura Fuminori Nakamura Shigenori Murata Norihiro Okada Ken-ichi Okamoto Makoto Shimizu Masami Hasegawa 《Journal of molecular evolution》1996,42(2):257-263
Partial regions of the mRNA encoding a major part of translation elongation factor 1 (EF-1) from a mitochondrion-lacking protozoan,Glugea plecoglossi, that belongs to microsporidians, were amplified by polymerase chain reaction (PCR) and their primary structures were analyzed. The deduced amino acid sequence was highly divergent from typical EF-1's of eukaryotes, although it clearly showed a eukaryotic feature when aligned with homologs of the three primary kingdoms. Maximum likelihood (ML) analyses on the basis of six different stochastic models of amino acid substitutions and a maximum parsimony (MP) analysis consistently suggest that among eukaryotic species being analyzed,G. plecoglossi is likely to represent the earliest offshoot of eukaryotes. Microsporidians might be the extremely ancient eukaryotes which have diverged before an occurrence of mitochondrial symbiosis.
Sequence availability: The nucleotide sequence data reported here appear in the GSDB, DDBJ, EMBL, and NCBI databases with the accession number D32139 相似文献
56.
57.
Two Polypeptides Inducible by Low Levels of CO2 in Soluble Protein Fractions from Chlorella regularis Grown at Low or High pH 总被引:1,自引:0,他引:1
Previous studies suggested that certain protein(s) other thancarbonic anhydrase might play an important role in the facilitatedtransport of dissolved inorganic carbon (DIC) from the mediumto the site of CO2 fixation by ribulose-1,5-bisphosphate carboxylase/oxygenasein the unicellular green alga Chlorella regularis adapted tolow-CO2 (ordinary air) conditions [Shiraiwa et al. (1991) Jpn.J. Phycol. 39: 355; Satoh and Shiraiwa (1992) Research in Photosynthesis,Vol. III, p. 779]. The proteins that might be involved in thisfacilitated transport of DIC were investigated by pulse-labelingof induced proteins with 35S-sulfate during adaptation of cellsgrown under high-CO2 conditions to low CO2. Analysis by SDS-PAGErevealed that synthesis of two polypeptides, with molecularmasses of 98 and 24 kDa, respectively, was induced under low-CO2conditions. The 24-kDa polypeptide was induced at pH 5.5 butnot at pH 8.0, whereas the 98-kDa polypeptide was induced atboth pH 5.5 and pH 8.0. The possible role of these polypeptidesin the facilitated transport of DIC in Chlorella regularis isdiscussed. (Received October 30, 1995; Accepted February 26, 1996) 相似文献
58.
Yuriko Osakabe Kazuya Nanto Hiroko Kitamura Shinya Kawai Yuki Kondo Tomoyuki Fujii Keiji Takabe Yoshihiro Katayama Noriyuki Morohoshi 《Planta》1996,200(1):13-19
The polypeptide encoded by the partial fragment of cDNA of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5), PALcDNAl (Osakabe et al., 1995, Plant Sci. 105: 217–226), isolated from Populus kitakamiensis (P. sieboldii x P. grandidentata), was expressed in Escherichia coli cells. The polypeptide was purified and an antiserum raised against it. The antiserum recognized a protein of 77 kDa on nitrocellulose blots after sodium dodecyl sulfate-poly-acrylamide gel electrophoresis of total protein and the partially purified PAL protein from P. kitakamiensis. Moreover,the antiserum recognized a protein on the blot after non-denaturing polyacrylamide gel electrophoresis of P. kitakamiensis proteins and this protein had PAL activity. Furthermore, the antibody inhibited PAL activity of extracts from stem tissues. These results showed that the antiserum against the partial PAL peptide recognized only the PAL subunits in extracts of P. kitakamiensis. Immunolocalization studies of P. kitakamiensis tissues revealed that the PAL protein was specifically localized in the xylem and the phloem fibers and no immunogold signal was found in the epidermis, the cortex, the pith, or the cambium of either stems or leaves.Abbreviations IgG
immunoglobulin G
- IPTG
isopropylthio--d-galactoside
- PAL
phenylalanine ammonia-lyase
The authors thank Dr. Kunio Hata of Nippon Paper Industries Co., Ltd. (Japan) for supplying P. kitakamiensis. This work was supported in part by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (No. 07406008). 相似文献
59.
F. Morishita A. Shimada Y. Takeda M. Fujimoto H. Katayama K. Yamada 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(8):467-472
To investigate the functions of GTP-binding protein(s) in the melanosome-aggregating response in fish melanophores, the effects
of activators of G-proteins, namely, mastoparan and compound 48/80, were examined in cultured melanophores of the balck-moor
goldfish, Carassius auratus. Both mastoparan and compound 48/80 induced an approximately 40% increase in the GTP-hydrolyzing activity in the melanophore
membranes compared to the basal level. In intact melanophores, these compounds inhibited the effect of 3-isobutyl-1-methylxanthine,
which induced the accumulation of intracellular cAMP. Pretreatment of melanophores with pertussis toxin at 1 μg ⋅ ml-1 for 15 h attenuated the inhibitory effect of mastoparan on the accumulation of cAMP. However, pretreatment with the toxin
only slightly attenuated the inhibitory effect of compound 48/80 on the accumulation of cAMP. In addition, compound 48/80
at 1 mg ⋅ ml-1 induced full aggregation of the melanosomes in melanophores, though mastoparan at 5 μmol ⋅ l-1 induced only 10–20% aggregation of melanophores. These results suggest that mastoparan and compound 48/80 can each activate
the inhibitory G-protein in goldfish melanophores, which results in inhibition of adenylate cyclase activity. This signal-transduction
pathway is involved in the aggregation of melanosomes in these cells.
Accepted: 3 June 1996 相似文献
60.