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61.
62.
Ryozo Oishi Naoto Adachi Keishi Okada Nobuyuki Muroi Kiyomi Saeki 《Journal of neurochemistry》1990,55(6):1899-1904
To clarify the regulation of central histaminergic (HAergic) activity by cholinergic receptors, the effects of drugs that stimulate the cholinergic system on brain histamine (HA) turnover were examined, in vivo, in mice and rats. The HA turnover was estimated from the accumulation of tele-methylhistamine (t-MH) during the 90-min period after administration of pargyline (65 mg/kg, i.p.). In the whole brain of mice, oxotremorine, at doses higher than 0.05 mg/kg, s.c., significantly inhibited the HA turnover, this effect being completely antagonized by atropine but not by methylatropine. A large dose of nicotine (10 mg/kg, s.c.) also significantly inhibited the HA turnover. This inhibitory effect was antagonized by mecamylamine but not by atropine or hexamethonium. A cholinesterase inhibitor, physostigmine, at doses higher than 0.1 mg/kg, s.c., significantly inhibited the HA turnover. This effect was antagonized by atropine but not at all by mecamylamine. None of these cholinergic antagonists used affected the steady-state t-MH level or HA turnover by themselves. In the rat brain, physostigmine (0.1 and 0.3 mg/kg, s.c.) also decreased the HA turnover. This inhibitory effect of physostigmine was especially marked in the striatum and cerebral cortex where muscarinic receptors are present in high density. Oxotremorine (0.2 mg/kg, s.c.) and nicotine (1 mg/kg, s.c.) also decreased the HA turnover in the rat brain. However, these effects showed no marked regional differences. These results suggest that the stimulation of central muscarinic receptors potently inhibits the HAergic activity in the brain and that strong stimulation of central nicotinic receptors can also induce a similar effect. 相似文献
63.
64.
The inhibition of forskolin-stimulated adenylate cyclase activity by 5-hydroxytryptamine (5-HT) receptor agonists was measured in rat hippocampal membranes isolated from animals treated with vehicle or islet-activating protein (IAP; pertussis toxin). In vehicle-treated animals, 5-HT, 8-hydroxy-2-(di-n-propylamino)tetralin, buspirone, and gepirone were potent in inhibiting forskolin-stimulated adenylate cyclase activity with EC50 values of 60, 76, 376, and 530 nM, respectively. IAP treatment reduced by 30-55% the 5-HT1A agonist inhibition of adenylate cyclase activity via 5-HT1A receptors. The data indicate that the inhibitory guanine nucleotide-binding protein or Go (a similar GTP-binding protein of unknown function purified from brain) mediates the 5-HT1A agonist inhibition of hippocampal adenylate cyclase. 相似文献
65.
Zhi-Hui Su Osamu Tominaga Takeshi Ohama Eiji Kajiwara Ryoshuke Ishikawa Tokindo S. Okada Keiko Nakamura Syozo Osawa 《Journal of molecular evolution》1996,43(6):662-671
Molecular phylogenetic analyses using mitochondrial NADH dehydrogenase subunit 5 (ND5) gene sequences representing all 15 species and the majority of subspecies or races of theOhomopterus ground beetles from all over the Japanese archipelago have uncovered a remarkable evolutionary history. Clustering of the species in the molecular phylogenetic tree is linked to their geographic distribution and does not correlate with morphological characters. Taxonomically the same species or the members belonging to the same species-group fall out in more than two different places on the ND5 tree. Evidence has been presented against a possible participation of ancestral polymorphism and random lineage sorting or of hybrid individuals for the observed distribution of mitochondrial DNA haplotypes. The most plausible explanation of our results is that parallel evolution took place in different lineages. Most notably,O. dehaanii, O. yaconinus, andO. japonicus in a lineage reveal almost identical morphology with those of the same species (or subspecies) but belonging to the phylogenetically remote lineages.The nucleotide sequence data reported in this paper will appear in the DDBJ, EMBL, and GenBank nucleotide sequence databases with accession numbers D50711-DD-50733 and D87131-D87186. 相似文献
66.
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
67.
Details of Retropositional Genome Dynamics That Provide a Rationale for a Generic Division: The Distinct Branching of All the Pacific Salmon and Trout (Oncorhynchus) from the Atlantic Salmon and Trout (Salmo) 总被引:2,自引:2,他引:0
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Salmonid species contain numerous short interspersed repetitive elements (SINEs), known collectively as the HpaI family, in their genomes. Amplification and successive integration of individual SINEs into the genomes have occurred during the evolution of salmonids. We reported previously a strategy for determining the phylogenetic relationships among the Pacific salmonids in which these SINEs were used as temporal landmarks of evolution. Here, we provide evidence for extensive genomic rearrangements that involved retropositions and deletions in a common ancestor of all the Pacific salmon and trout. Our results provide genetic support for the recent phylogenetic reassignment of steelhead and related species from the genus Salmo to the genus Oncorhynchus. Several other informative loci identified by insertions of HpaI SINEs have been isolated, and previously proposed branching orders of the Oncorhynchus species have been confirmed. The authenticity of our phylogenetic tree is supported both by the isolation of more than two informative loci per branching point and by the congruence of all our data, which suggest that the period between succesive speciations was sufficiently long for each SINE that had been amplified in the original species to become fixed in all individuals of that species. 相似文献
68.
The action of branching enzyme (EC 2.4.l.l8) from Bacillus stearothermophilus on amylose was analyzed. The enzyme reduced the molecular size of amylose without increasing the reducing power. This result could not be explained by the normal branching reaction model. When the product was treated with glucoamylase (an exo++-type amylase), a resistant component remained. The glucoamylase-resistant component was easily digested by an endo-type alpha-amylase or by isoamylase plus glucoamylase. These results suggested that the glucoamylase-resistant component was a cyclic glucan composed of alpha-1,4- and alpha-l,6-glucosidic linkages. In other words, it was suggested that branching enzyme catalyzed cyclization of the alpha-l,4-glucan chain of the amylose molecule to form an alpha-l,6-glucosidic linkage, thereby forming two smaller molecules. Mass spectrometry also supported the cyclic nature of the product. 相似文献
69.
H. Furudate Y. Okada T. Yamaguchi 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,179(5):635-643
In the brain of the intact crayfish, three pairs of non-spiking giant interneurons (G1, G2, G3; NGIs) scarcely responded to substrate tilt about the longitudinal axis of the body either in the dark or in the presence of an overhead light. However, when the statolith was removed, these NGIs responded with depolarizing and hyperpolarizing potentials respectively to upward movements of the ipsilateral legs (2nd–5th pereiopods) and upward movements of the contralateral legs produced by substrate tilt. The relationships between the polarity of the potential and the direction of movement in the contralateral legs were opposite to those in the ipsilateral legs. The amplitude of the responses was proportional to the frequency (0.5-0.05 Hz) and amplitude of tilting. When the legs were moved unilaterally, the NGIs responded with depolarizing and hyperpolarizing potentials to upward movements of the ipsilateral legs and to upward movements of the contralateral legs, respectively. When the legs were moved bilaterally in the same direction by upward or downward movement of the substrate, the NGIs scarcely responded to the leg movements. A hypothetical model is presented to account for the pathways of sensory inputs to the NGIs and the role of NGIs in compensatory oculomotor system. 相似文献
70.
Repression by a differentiation-specific factor of the human cytomegalovirus enhancer. 总被引:5,自引:0,他引:5
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T H Huang T Oka T Asai T Okada B W Merrills P N Gertson R H Whitson K Itakura 《Nucleic acids research》1996,24(9):1695-1701
We detected a novel nuclear protein, MRF, that binds to multiple sites on the modulator which is located upstream of the human cytomegalovirus major immediate early gene enhancer. The expression of MRF is differentiation specific; the DNA binding activity is present in nuclear extracts from undifferentiated Tera-2 and THP-1 cells, but significantly reduced after these cells are induced to differentiate. In undifferentiated cells the enhancer activity is repressed by the modulator and upon differentiation the enhancer becomes active. Competitive binding assays demonstrate that MRF requires the presence of multiple A+T stretches for binding to DNA, rather than binding to a specific DNA sequence. Mutations of these stretches in the modulator reduce the binding activity of MRF, as well as the repressing activity on the enhancer. These results suggest that MRF may act as a repressor of enhancer function. We propose that MRF binds over the entire modulator and exerts repressor activity. 相似文献