排序方式: 共有38条查询结果,搜索用时 31 毫秒
21.
Biological functions of proline in morphogenesis and osmotolerance revealed in antisense transgenic Arabidopsis thaliana 总被引:10,自引:0,他引:10
Tokihiko Nanjo Masatomo Kobayashi Yoshu Yoshiba Yukika Sanada Keishiro Wada Hirokazu Tsukaya Yoshitaka Kakubari Kazuko Yamaguchi-Shinozaki Kazuo Shinozaki 《The Plant journal : for cell and molecular biology》1999,18(2):185-193
Many organisms, including higher plants, accumulate free proline (Pro) in response to osmotic stress. Although various studies have focused on the ability of Pro as a compatible osmolyte involved in osmotolerance, its specific role throughout plant growth is still unclear. It has been reported that Pro is synthesized from Glu catalyzed by a key enzyme, delta 1-pyrroline-5-carboxylate synthetase (P5CS), in plants. To elucidate essential roles of Pro, we generated antisense transgenic Arabidopsis plants with a P5CS cDNA. Several transgenics accumulated Pro at a significantly lower level than wild-type plants, providing direct evidence for a key role of P5CS in Pro production in Arabidopsis. These antisense transgenics showed morphological alterations in leaves and a defect in elongation of inflorescences. Furthermore, transgenic leaves were hypersensitive to osmotic stress. Microscopic analysis of transgenic leaves, in which the mutated phenotype clearly occurred, showed morphological abnormalities of epidermal and parenchymatous cells and retardation of differentiation of vascular systems. These phenotypes were suppressed by exogenous L-Pro but not by D-Pro or other Pro analogues. In addition, Pro deficiency did not broadly affect all proteins but specifically affected structural proteins of cell walls in the antisense transgenic plants. These results indicate that Pro is not just an osmoregulator in stressed plants but has a unique function involved in osmotolerance as well as in morphogenesis as a major constituent of cell wall structural proteins in plants. 相似文献
22.
Arima H Horiguchi N Takaichi S Kofuji R Ishida K Wada K Sakamoto T 《FEMS microbiology ecology》2012,79(1):34-45
The phylogeny of the terrestrial cyanobacterium Nostoc commune and its neighboring Nostoc species was studied using molecular genetic and chemotaxonomic approaches. At least eight genotypes of N. commune were characterized by the differences among 16S rRNA gene sequences and the petH gene encoding ferredoxin-NADP? oxidoreductase and by random amplified polymorphic DNA analysis. The genotypes of N. commune were distributed in Japan without regional specificity. The nrtP gene encoding NrtP-type nitrate/nitrite permease was widely distributed in the genus Nostoc, suggesting that the occurrence of the nrtP gene can be one of the characteristic features that separate cyanobacteria into two groups. The wspA gene encoding a 36-kDa water stress protein was only found in N. commune and Nostoc verrucosum, suggesting that these Nostoc species that form massive colonies with extracellular polysaccharides can be exclusively characterized by the occurrence of the wspA gene. Fifteen species of Nostoc and Anabaena were investigated by comparing their carotenoid composition. Three groups with distinct patterns of carotenoids were related to the phylogenic tree constructed on the basis of 16S rRNA sequences. Nostoc commune and Nostoc punctiforme were clustered in one monophyletic group and characterized by the occurrence of nostoxanthin, canthaxanthin, and myxol glycosides. 相似文献
23.
Drug combinations are common in cancer treatment and are rapidly evolving, moving beyond chemotherapy combinations to combinations of signal transduction inhibitors. For the delivery of drug combinations, i.e., multi-drug delivery, major considerations are synergy, dose regimen (concurrent versus sequential), pharmacokinetics, toxicity, and safety. In this contribution, we review recent research on polymeric micelles for multi-drug delivery in cancer. In concurrent drug delivery, polymeric micelles deliver multi-poorly water-soluble anticancer agents, satisfying strict requirements in solubility, stability, and safety. In sequential drug delivery, polymeric micelles participate in pretreatment strategies that “prime” solid tumors and enhance the penetration of secondarily administered anticancer agent or nanocarrier. The improved delivery of multiple poorly water-soluble anticancer agents by polymeric micelles via concurrent or sequential regimens offers novel and interesting strategies for drug combinations in cancer treatment.KEY WORDS: controlled release, drug combination, drug delivery, drug solubilization, polymeric micelles 相似文献
24.
Alterations in pumpkin seed globulin during germination wereexamined mainly by sodium dodecyl sulfate-polyacrylamide gelelectrophoresis. The total protein content of etiolated cotyledonsdecreased to 32% of the initial content 14 days after germination,and the globulin was rapidly degraded to produce new componentswith molecular weights of about 40,000 (major component) and30,000 daltons, which were soluble in a solution with relativelylow concentrations of salt at neutral pHs in contrast to insolublecrystalline globulin. The proportion of these soluble proteinsto the total amount of protein extracted in 2 M NaCl solutionincreased rapidly during the period of 2 to 4 days after planting.During this period, the globulin was rapidly degraded with progressiveincrease of the component of 40,000 daltons. This species wasseparated into two polypeptide chains with molecular weightof about 20,000 daltons by treatment with sulfhydryl reducingreagent. The soluble fraction preserved oxaloacetate decarboxylaseactivity. These changes in solubility and subunit structure,and the preservation of the decarboxylase activity of heat stableproteins obtained from etiolated cotyledons are discussed. (Received April 9, 1976; ) 相似文献
25.
The catalytic methyl-transfer reaction from methyl tosylate to 1-octanethiol was carried out in the presence of a simple vitamin B12 model complex, [Co(III){(C2C3)(DO)(DOH)pn}Br2], with zinc powder as the reducing reagent at 50 °C. Such a catalytic reaction proceeded via the formation and dissociation of a cobalt-carbon bond in the simple vitamin B12 model complex under non-enzymatic conditions. The mechanism for the methyl-transfer reaction was investigated by electronic and mass spectroscopies. The Co(I) species, which is generated from the reduction of the catalyst by the zinc powder, and its methylated CH3-Co complex were found to be indispensable intermediates. 相似文献
26.
Keishiro Yoshida Kazuo Furihata Hiroshi Habe Hisakazu Yamane Toshio Omori 《Biotechnology letters》2001,23(11):873-879
Transposon Tn5 mutagenesis was carried out to clarify the metabolism of 18-glycyrrhetinic acid (18-GRA) in Sphingomonas paucimobilis G5. A Tn5-induced mutant strain, named TM9638 that was affected in its metabolism of 18-GRA, was isolated. This mutant accumulated three metabolites, designated as M-A, M-B and M-C, from 18-GRA in the culture broth. M-A was accumulated in the culture broth of wild type strain, but M-B and M-C were not accumulated in the culture broth of wild type strain. M-B and M-C were isolated from the culture broth of TM9638 and the chemical structures were elucidated by NMR and GC-MS. 相似文献
27.
Keishiro Yoshida Kazuo Furihata Hisakazu Yamane Toshio Omori 《Biotechnology letters》2001,23(4):253-258
Seven strains capable of utilizing 18-glycyrrhetinic acid (18-GRA) as a sole carbon and energy source were isolated from soil samples by enrichment culture technique. One of these strains, named strain G5, was identified as Sphingomonas paucimobilis. When this strain grew on 18-GRA, several metabolites were detected in the culture broth. A major metabolite, tentatively named M-A, was isolated and its chemical structure was determined by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). 相似文献
28.
Hiroshi Terada Satoru Goto Kazuko Yamamoto Isao Takeuchi Yoshiki Hamada Keishiro Miyake 《BBA》1988,936(3):504-512
The uncoupling activities of more than 20 salicylanilides were measured in rat liver mitochondria. The activities, expressed as the minimum concentrations required for full release of state-4 respiration, ranged over three orders of magnitude. The acid dissociation constant, pKA, and the partition coefficient between octanol and water (Poct) of some of the salicylanilides were determined. These two parameters were found to be well expressed in terms of the Hammett constant, σ, and the hydrophobic substituent coefficient, Π, respectively. The pKA and log Poct values of all the salicylanilides were predicted according to these relationships. Furthermore, the capacity factor, k′, on high-performance liquid chromatography was determined on glyceryl-coated-controlled pore glass (gly-CPG). Values of log k′ correlated well with those of log Poct. The uncoupling activities of the salicylanilides were analyzed in terms of these three parameters. Both hydrophobic and electron-withdrawing properties were found to be essential for induction of potent uncoupling activity. The correlations using log k′ were better than those using log Poct. 相似文献
29.
Kaeko Kamide Harumi Sakai Koh Aoki Yukika Sanada Keishiro Wada Laura S. Green Boihon C. Yee Bob B. Buchanan 《Photosynthesis research》1995,46(1-2):301-308
Several forms (isoproteins) of ferredoxin in roots, leaves, and green and red pericarps in tomato plants (Lycopersicon esculentum Mill.) were earlier identified on the basis of N-terminal amino acid sequence and chromatographic behavior (Green et al. 1991). In the present study, a large scale preparation made possible determination of the full length amino acid sequence of the two ferredoxins from leaves. The ferredoxins characteristic of fruit and root were sequenced from the amino terminus to the 30th residue or beyond. The leaf ferredoxins were confirmed to be expressed in pericarp of both green and red fruit. The ferredoxins characteristic of fruit and root appeared to be restricted to those tissue. The results extend earlier findings in demonstrating that ferredoxin occurs in the major organs of the tomato plant where it appears to function irrespective of photosynthetic competence.Abbreviations CBB
Coomassie brilliant blue R-250
- Cm
Carboxymethylated
- Fd
Ferredoxin
- FNR
ferredoxin-NADP+ oxidoreductase
- FPLC
Fast protein liquid chromatography
- HPLC
High performance liquid chromatography
- rt
root 相似文献
30.
The leaves, steins and ears of tetraploidal wheat, Triticumdurum (genomes AABB) harvested two weeks after heading wereanalyzed for purothionins. There were considerable amounts oftwo iso-purothionins (Pu-1 and Pu-2) in the young kernels ofthe ears, but not in the leaves and stems. The amino acid compositionsof Pu-1 and Pu-2 were in good agreement with those of Pu I andPu II from hexaploidal wheat. As diploidal wheat, T. monococcum(genome AA) is known to produce only Pu I [Fernandez de Caleyaet al. (1976) Genetics 83: 687], we conclude that the threeiso-purothionins, Pu I, Pu II and Pu III in hexaploidal wheat,T. aestivum (genomes AABBDD), are encoded by the genes of genomesA, B and D, respectively. (Received June 28, 1982; Accepted September 24, 1982) 相似文献