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71.
Protein Kinases Are Involved in Prolonged Acetylcholine Release from Rat Hippocampus Induced by Thyrotropin-Releasing Hormone Analogue NS-3 总被引:2,自引:0,他引:2
Michiko Oka Yoshinori Itoh Yojiro Ukai Yoshiaki Yoshikuni Kiyoshi Kimura 《Journal of neurochemistry》1996,66(5):1889-1893
Abstract: The effects of various protein kinase inhibitors on acetylcholine release from the rat hippocampus induced by the local application of NS-3 (montirelin hydrate, CG-3703), a thyrotropin-releasing hormone analogue, into the medial septum-diagonal band were examined using in vivo microdialysis. Perfusion of NS-3 (1 µ M ) into the medial septum-diagonal band for 20 min produced a pronounced and prolonged increase in the hippocampal acetylcholine efflux. Pretreatment of the medial septum-diagonal band with either K-252a, a nonselective protein kinase inhibitor, or selective protein kinase A inhibitor H-89 almost completely blocked the acetylcholine efflux evoked by NS-3, and selective protein kinase C inhibitor calphostin C inhibited the action of NS-3. On the other hand, NS-3 (0.1–10 µ M ) or TRH (1–100 µ M ) increased the cyclic AMP efflux from the medial septum-diagonal band in a concentration-dependent manner, as measured by microdialysis. These findings suggest that protein kinases A and C in the neurons of the medial septum-diagonal band are involved in the mechanism of the prolonged stimulation of acetylcholine release from the hippocampus induced by thyrotropin-releasing hormone and its analogue, NS-3. 相似文献
72.
Susumu Kimura 《Microbiology and immunology》1996,40(9):645-650
Reactivation of herpes simplex virus type 1 (HSV-1) occurred rapidly in cells of latently infected adult mouse trigeminal ganglia which were cultured in serum-free medium in the presence of sufficient nerve growth factor (NGF). However, HSV-1 reactivation was delayed significantly in ganglionic cultures in the absence of exogenous NGF or in cultures treated with 2-aminopurine in the presence of NGF. The delayed viral reactivation in ganglionic cultures without NGF was accelerated by treatment with phorbol myristate acetate or dibutyryl cyclic AMP. Culture conditions which affected HSV-1 reactivation did not affect replication of HSV-1 in normal ganglionic cultures. 相似文献
73.
TheLysobacter lactamgenus YK90pcbAB gene encoding -(l--aminoadipyl)-l-cysteinyl-d-valine (ACV) synthetase is located immediately upstream of thepcbC gene in the same orientation in the gene cluster involved in cephalosporin biosynthesis. ThepcbAB gene encodes a large polypeptide composed of 3722 amino acid residues with a molecular mass of 411 593 Da. The predicted amino acid sequence has a high degree of similarity with those of known ACV synthetases from fungi and actinomycetes. Within thepcbAB amino acid sequence, three conserved and repeated domains of about 600 amino acids were identified. The domains also share a high degree of similarity with non-ribosomal peptide synthetases such as gramicidin synthatase 2 ofBacillus brevis. ThepcbAB gene was expressed under the control of thelac promoter inPseudomonas putida. Expression of the gene cluster involved in cephalosporin biosynthesis inP. putida led to the accumulation of -lactam antibiotics. Deletion analysis of an open-reading frame located between thecefE andcefD genes from the gene cluster revealed that it encoded deacetylcephalosporin C synthetase (cefF). From the results presented here and those of previous studies, the genes involved in cephalosporin biosynthesis inL. lactamgenus appear to be clustered in the orderpcb AB-pcbC- cefE-cefF-cefD-bla in the same orientation within a 17-kb region of DNA. 相似文献
74.
Ahmed S. Rahman Mieko Kimura Katsuhiko Yokoi Tanvir-E Naher Yoshinori Itokawa 《Biological trace element research》1996,53(1-3):57-64
Three groups of rats were fed two types of synthetic diets for 52 d. The—A group was allowed free access to a vitamin A-deficient
diet and showed classical signs of vitamin A deficiency. The brain was the only organ in our experiment where no significant
weight difference was present among the three groups. In the brain, calcium concentration was significantly higher in the—A
group when compared with the PF (Pair-fed; allowed restricted amount of control diet) and +A groups (allowed free access to
control diet). In the tibia, calcium and magnesium concentrations were significantly lower in the—A group when compared with
other two groups. Excessive accumulation of calcium in brain and apparently similar unbalance in bone, mineral concentration
were observed in central nervous system (CNS) degenerative diseases. Our results suggest that abnormal metabolism of calcium
and magnesium in some tissues and excessive accumulation of calcium in brain may be responsible for the development of neurological
disorders in vitamin A-deficient rats. 相似文献
75.
S. G. Nugroho J. Lumbanraja H. Suprapto Sunyoto H. Haraguchi M. Kimura 《Plant and Soil》1996,181(2):287-293
Yearly and seasonal (rainy and dry seasons) variations of CH4 emission from a Sumatra paddy field were measured for 3 years. The mean CH4 emission rates during the growth period were in the range of 16.0–26.1 mg CH4 m-2 h-1 for the chemical fertilizer plots and 23.3–34.9 mg CH4 m-2 h-1 for the plots with rice straw application, respectively. The increase in the amounts of CH4 emission by rice straw application were from 1.3 to 1.6 times. There was no significant difference in the mean CH4 emission rates between rainy and dry seasons.Total amounts of CH4 emitted during the period of rice growth were in the ranges of 29.5–48.2 and 43.0–64.6 g CH4 m-2 for the plots applied with chemical fertilizer and those with rice straw application, respectively. Nearly the same amounts of CH4 were emitted in the first and second half of the growth period, irrespective of rice straw application. 相似文献
76.
Summary Subcellular compartments comprising the endomembrane system in filamentous fungi are poorly characterized with most showing significant morphological differences from eukaryotic cells. For example, many filamentous fungi lack stacked Golgi-body cisternae, but contain Golgi equivalents — single cisternae or tubules which appear to serve the same functions. To help identify fungal endomembrane compartments and interrelationships between them we used a pharmacological agent, brefeldin A, known to affect specific endomembrane organelles in other organisms, most prominently the Golgi apparatus. At 10 g/ml brefeldin A, radial hyphal growth of the rice blast pathogenMagnaporthe grisea on solid agar medium was reduced by 96% over an initial 48 h, but recovered and was reduced by only 20% over a subsequent 72 h exposure. Light microscopic examination of individual living hyphae showed that apical elongation generally halted within 1 min after exposure to brefeldin A. Acute effects of 14 g/ml brefeldin A were characterized ultrasiructurally in cells prepared by freeze substitution. These included the appearance of two types of cisternae with unusual morphology, associated with ca. 45 nm diameter vesicles, as well as the unexpected persistence and increase in complexity of the Golgi equivalents. Also observed were (1) reduced numbers of apicale vesicles and disruption of Spitzenkörper organization, (2) apical clusters of 30–35 nm diameter microvesicles and associated tubular arrays, (3) dilation of rough endoplasmic reticulum, (4) packets of membrane-bounded electron-opaque cell wall inclusions, and (5) altered morphology of some vacuolar compartments. The distribution of concanavalin A binding sites, previously mapped to particular endomembrane compartments, was documented to aid the interpretation of these results. We conclude that brefeldin A effects on cells ofM. grisea differ from those reported with plant and animal cells, perhaps reflecting underlying differences in the endomembrane systems among these eukaryotes.Abbreviations BFA
brefeldin A
- ConA
concanavalin A
- ER
endoplasmic reticulum
- PDA
potato dextrose agar
- RER
rough endoplasmic reticulum 相似文献
77.
Gellan lyase was purified from the culture fluid of soil samples incubated in a medium containing gellan as a sole carbon source. The enzyme was a monomer with a molecular mass of 140 kDa and was most active at pH 7.5 and 45 degrees C. The enzyme was highly specific to gellan and lowered the viscosity of the polymer. 相似文献
78.
The carboxy-terminal region of mammalian HSP90 is required for its dimerization and function in vivo. 总被引:1,自引:0,他引:1 下载免费PDF全文
The majority of mouse HSP90 exists as alpha-alpha and beta-beta homodimers. Truncation of the 15-kDa carboxy-terminal region of mouse HSP90 by digestion with the Ca(2+)-dependent protease m-calpain caused dissociation of the dimer. When expressed in a reticulocyte lysate, the full-length human HSP90 alpha formed a dimeric form. A plasmid harboring human HSP90 alpha cDNA was constructed so that the carboxy-terminal 49 amino acid residues were removed when translated in vitro. This carboxy-terminally truncated human HSP90 alpha was found to exist as a monomer. In contrast, loss of the 118 amino acid residues from the amino terminus of human HSP90 alpha did not affect its in vitro dimerization. Introduction of an expression plasmid harboring the full-length human HSP90 alpha complements the lethality caused by the double mutations of two HSP90-related genes, hsp82 and hsc82, in a haploid strain of Saccharomyces cerevisiae. The carboxy-terminally truncated human HSP90 alpha neither formed dimers in yeast cells nor rescued the lethal double mutant. 相似文献
79.
Analysis of N-terminal processing of hepatitis C virus nonstructural protein 2. 总被引:11,自引:10,他引:1 下载免费PDF全文
We determined the partial amino (N)-terminal amino acid sequence of hepatitis C virus p21 (nonstructural protein 2 [NS2]). Cleavage at the p21 (NS2) N terminus depended on the presence of microsomal membranes. The amino-terminal position of p21 (NS2) was assigned to amino acid 810 of the hepatitis C virus strain IIJ precursor polyprotein. Mutation of the alanine residue at position P1 of the putative cleavage site inhibited membrane-dependent processing. This alteration in processing together with the fact that hydrophobic amino acid residues are clustered upstream of the putative cleavage site suggested the involvement of a signal peptidase(s) in the cleavage. Furthermore, mutation analysis of this possible cleavage site revealed the presence of another microsome membrane-dependent cleavage site upstream of the N terminus of p21 (NS2). 相似文献
80.
Connections among species-abundance (i-m
i
), species-frequency (i-F
i
), and species-sample size (S
n
-n) relationships were examined on the basis of the mapping data of a natural forest in Thailand. The spatial distribution of
individual trees without any discrimination of species was nearly random. Provided that the spatial distribution of each species
was random, thei-m
i
and thei-F
i
relationship was reconstructed from each other in terms of the total number of species (S) and the total number of individuals (N) in the data. The number of species (S
n
) in a subsample consisting ofn individuals was then obtained from thei-F
i
relationship. Logarithm ofS
n
increased with logn and showed a convex curve through the origin. The values of diversity indices based onN andS(orn andS
n
) were affected by sample size. These trends were further examined on the basis of 944 data sets of biotic communities and
three mathematical models of anS-N relationship. The properties of species-area relation were discussed in the light of these results. 相似文献