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181.
Ibayashi S Nagao T Kitazono T Ooboshi H Kitayama J Sadoshima S Fujishima M 《Neurochemical research》2000,25(3):349-355
The present study was designed to examine the effect of a calcium antagonist isradipine (PN200-110: PN) on local cerebral blood flow and brain tissue metabolism after 1-hour supratentorial ischemia induced by bilateral carotid artery ligation (BCL) in spontaneously hypertensive rats (SHR). PN, dissolved in ethanol plus polyethylene glycol 400, diluted with saline to make the final concentration of 0.25mg/ml and 2.5mg/ml, was administered subcutaneously either 30 min prior to BCL or just after the induction of incomplete cerebral ischemia (n = 7 in each group). Vehicle injection was served as a control group (n = 7). Cerebral blood flow in the parietal cortex (CBF) and the cerebellar cortex (CeBF) was measured by hydrogen clearance technique, and the supra- and infratentorial metabolites of the brain frozen in situ were determined by the enzymatic method. Blood pressure was lowered, but CBF was increased by PN administration in pre-BCL treatment study. After 1 hour of BCL, CBF decreased to around 10% or less of the resting value, being insignificant among the groups. Brain adenosine triphosphate was better preserved in PN-administered groups. The increase in lactate level tended to reduce dose dependently by PN treatment. PN also reduced the metabolic alterations in brain tissue with significance, even when administered just after the induction of forebrain ischemia. It is considered that pre- as well as post-BCL administration of PN is beneficial to attenuate the metabolic alterations in incomplete forebrain ischemia in SHR. 相似文献
182.
183.
Christian Schobert Lucian Baker Judit Szederkényi Pia Großmann Ewald Komor Hiroaki Hayashi Mitsuo Chino William J. Lucas 《Planta》1998,206(2):245-252
The mature, functional sieve-tube system in higher plants is dependent upon protein import from the companion cells to maintain
a functional long-distance transport system. Soluble proteins present within the sieve-tube lumen were investigated by analysis
of sieve-tube exudates which revealed the presence of distinct sets of polypeptides in seven monocotyledonous and dicotyledonous
plant species. Antibodies directed against sieve-tube exudate proteins from Ricinus communis L. demonstrated the presence of shared antigens in the phloem sap collected from Triticum aestivum L., Oryza sativa L., Yucca filamentosa L., Cucurbita maxima Duch., Robinia pseudoacacia L. and Tilia platyphyllos L. Specific antibodies were employed to identify major polypeptides. Molecular chaperones related to Rubisco-subunit-binding
protein and cyclophilin, as well as ubiquitin and the redox proteins, thioredoxin h and glutaredoxin, were detected in the
sieve-tube exudate of all species examined. Actin and profilin, a modulator of actin polymerization, were also present in
all analyzed phloem exudates. However, some proteins were highly species-specific, e.g. cystatin, a protease-inhibitor was
present in R. communis but was not detected in exudates from other species, and orthologs of the well-known squash phloem lectin, phloem protein
2, were only identified in the sieve-tube exudate of R. communis and R. pseudoacacia. These findings are discussed in terms of the likely roles played by phloem proteins in the maintenance and function of the
enucleate sieve-tube system of higher plants.
Received: 12 February 1998 / Accepted: 16 March 1998 相似文献
184.
Yasuyuki Ishida Hiroaki Yokoi Shinichi Isomura Hajime Ohtani Shin Tsuge Tatsuki Sekino Masami Nakanishi Takashi Kimoto 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,716(1-2)
Pyrolysis–gas chromatography (Py–GC) combined with on-line methylation was applied to a correlation analysis between the distributions of fatty acid components in the lipids of zooplankter individuals and those of ingested algae using principal component analysis (PCA). Py–GC in the presence of organic alkali, tetramethylammonium hydroxide (TMAH), was used to estimate the apparent distributions of fatty acid components contained in a single individual zooplankter weighing several tens of micrograms and a small sample size of ingested algae samples in the order of 10 μg. The observed fatty acid compositions were used as a database for the PCA in order to discriminate the zooplankton and ingested algae samples. The result obtained indicated that the fatty acid compositions of zooplankton individuals used in this work were significantly reflected in those of their ingested food in spite of some contribution from isomerization and/or elongation of fatty acid components during digestion of the ingested algae phytoplankton in living zooplankters. 相似文献
185.
186.
Alessandra Gradi Hiroaki Imataka Yuri V. Svitkin Eran Rom Brian Raught Shigenobu Morino Nahum Sonenberg 《Molecular and cellular biology》1998,18(1):334-342
Mammalian eukaryotic translation initiation factor 4F (eIF4F) is a cap-binding protein complex consisting of three subunits: eIF4E, eIF4A, and eIF4G. In yeast and plants, two related eIF4G species are encoded by two different genes. To date, however, only one functional eIF4G polypeptide, referred to here as eIF4GI, has been identified in mammals. Here we describe the discovery and functional characterization of a closely related homolog, referred to as eIF4GII. eIF4GI and eIF4GII share 46% identity at the amino acid level and possess an overall similarity of 56%. The homology is particularly high in certain regions of the central and carboxy portions, while the amino-terminal regions are more divergent. Far-Western analysis and coimmunoprecipitation experiments were used to demonstrate that eIF4GII directly interacts with eIF4E, eIF4A, and eIF3. eIF4GII, like eIF4GI, is also cleaved upon picornavirus infection. eIF4GII restores cap-dependent translation in a reticulocyte lysate which had been pretreated with rhinovirus 2A to cleave endogenous eIF4G. Finally, eIF4GII exists as a complex with eIF4E in HeLa cells, because eIF4GII and eIF4E can be purified together by cap affinity chromatography. Taken together, our findings indicate that eIF4GII is a functional homolog of eIF4GI. These results may have important implications for the understanding of the mechanism of shutoff of host protein synthesis following picornavirus infection. 相似文献
187.
Anaerobic bacteria have been used to produce 2,4-dihydroxylamino-nitrotoluene (2,4DHANT), a reductive metabolite of 2,4,6-trinitrotoluene
(TNT). Here, an aerobic TNT biodegrader Pseudomonas sp. strain TM15 produced 2,4DHANT as evidenced by the molecular ion with m/z of 199 identified from LC-TOFMS analyses. TNT
biodegradation with a high cell concentration (109 cells/ml) led to a significant accumulation of 2,4DHANT in the culture medium, as well as hydroxylamino-dinitrotoluenes (HADNTs),
although these products were not accumulated when a low cell concentration was used; also, the accumulation of diamino-nitrotoluene
and of an unidentified metabolite were observed in the culture medium with the high cell concentration (1010 cells/ml). 2,4DHANT overproduction was a function of the aeration speed since cultures with low aeration speeds (30 rpm)
had a 19-fold higher DHANT productivity than those aerated with high speeds (180 rpm); this indicates that molecular oxygen
was related to the formation of 2,4DHANT. The quantification of dissolved oxygen (DO) in the media demonstrated that the productivity
of 2,4DHANT was increased at low DO values. Moreover, supplying oxygen to the culture media produced a remarkable decrease
of 2,4DHANT accumulation; these results clearly indicate that high 2,4DHANT production was a consequence of the oxygen deficit
in the culture medium. This finding is useful for understanding the TNT biodegradation (bioremediation technology) in an anoxic
environment.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
188.
Opi S Takeuchi H Kao S Khan MA Miyagi E Goila-Gaur R Iwatani Y Levin JG Strebel K 《Journal of virology》2006,80(10):4673-4682
APOBEC3G (APO3G) is a cytidine deaminase that restricts replication of vif-defective human immunodeficiency virus type 1 (HIV-1). Like other members of the cellular deaminase family, APO3G has the propensity to form homo-multimers. In the current study, we investigated the functional determinants for multimerization of human APO3G and studied the role of APO3G multimerization for catalytic activity, virus encapsidation, and antiviral activity. We found that human APO3G is capable of forming multimeric complexes in transfected HeLa cells. Interestingly, multimerization of APO3G was exquisitely sensitive to RNase treatment, suggesting that interaction of APO3G subunits is facilitated or stabilized by an RNA bridge. Mutation of a conserved cysteine residue (C97) that is part of an N-terminal zinc-finger motif in APO3G abolished multimerization of APO3G; however, the C97 mutation inhibited neither in vitro deaminase activity nor antiviral function of APO3G. These results suggest that monomeric APO3G is both catalytically active and has antiviral activity. Interference studies employing either catalytically inactive or packaging-incompetent APO3G variants suggest that wild-type APO3G is packaged into HIV-1 particles in monomeric form. These results provide novel insights into the catalytic function and antiviral property of APO3G and demonstrate an important role for C97 in the RNA-dependent multimerization of this protein. 相似文献
189.
Homma Yuri Mita Kazuei Nakamura Yuki Namiki Toshiki Noda Hiroaki Shinoda Tetsuro Togawa Toru 《Applied Entomology and Zoology》2020,55(1):45-54
Applied Entomology and Zoology - Juvenile hormone (JH) has crucial roles in insect physiology, including development, reproduction, and polyphenism. JH is synthesized in the corpora allata (CA)... 相似文献
190.
Takahashi Y Daitoku H Yokoyama A Nakayama K Kim JD Fukamizu A 《Journal of receptor and signal transduction research》2011,31(2):168-172
Protein arginine methylation is a common post-translational modification in eukaryotes that is catalyzed by a family of the protein arginine methyltransferases (PRMTs). PRMTs are classified into three types: type I and type II add asymmetrically and symmetrically dimethyl groups to arginine, respectively, while type III adds solely monomethyl group to arginine. However, although the enzymatic activity of type I and type II PRMTs have been reported, the substrate specificity and the methylation activity of type III PRMTs still remains unknown. Here, we report the characterization of Caenorhabditis elegans PRMT-2 and PRMT-3, both of which are highly homologous to human PRMT7. We find that these two PRMTs can bind to S-adenosyl methionine (SAM), but only PRMT-3 has methyltransferase activity for histone H2A depending on its SAM-binding domain. Importantly, thin-layer chromatographic analysis demonstrates that PRMT-3 catalyzes the formation of monomethylated, but not dimethylated arginine. Our study thus identifies the first type III PRMT in C. elegans and provides a means to elucidate the physiological significance of arginine monomethylation in multicellular organisms. 相似文献