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991.
992.
Sayuri Suzuki Jun Namiki Shinsuke Shibata Yumi Mastuzaki Hideyuki Okano 《The journal of histochemistry and cytochemistry》2010,58(8):721-730
Nestin is an intermediate filament protein that is known as a neural stem/progenitor cell marker. It is expressed in undifferentiated central nervous system (CNS) cells during development, but also in normal adult CNS and in CNS tumor cells. Additionally, nestin is expressed in endothelial cells (ECs) of CNS tumor tissues and of adult tissues that replenish by angiogenesis. However, the regulation of nestin expression in vascular endothelium has not been analyzed in detail. This study showed that nestin expression was observed in proliferating endothelial progenitor cells (EPCs), but not in mature ECs. In adherent cultured cells derived from bone marrow cells, EPCs that highly expressed nestin also expressed the endothelial marker CD31 and the proliferation marker Ki67. ECs cultured without growth factors showed attenuated nestin immunoreactivity as they matured. Transgenic mice that carried the enhanced green fluorescent protein under the control of the CNS-specific second intronic enhancer of the nestin gene showed no reporter gene expression in EPCs. This indicated that the mechanisms of nestin gene expression were different in EPCs and CNS cells. Immunohistochemistry showed nestin expression in neovascular cells from two distinct murine models. Our results demonstrate that nestin can be used as a marker protein for neovascularization. (J Histochem Cytochem 58:721–730, 2010) 相似文献
993.
994.
Extensive biochemical and structural analyses have been performed on the putative DNA repair proteins of hyperthermophilic archaea, in contrast to the few genetic analyses of the genes encoding these proteins. Accordingly, little is known about the repair pathways used by archaeal cells at high temperature. Here, we attempted to disrupt the genes encoding the potential repair proteins in the genome of the hyperthermophilic archaeon Thermococcus kodakaraensis. We succeeded in isolating null mutants of the hjc, hef, hjm, xpb, and xpd genes, but not the radA, rad50, mre11, herA, nurA, and xpg/fen1 genes. Phenotypic analyses of the gene-disrupted strains showed that the xpb and xpd null mutants are only slightly sensitive to ultraviolet (UV) irradiation, methyl methanesulfonate (MMS) and mitomycin C (MMC), as compared with the wild-type strain. The hjm null mutant showed sensitivity specifically to mitomycin C. On the other hand, the null mutants of the hjc gene lacked increasing sensitivity to any type of DNA damage. The Hef protein is particularly important for maintaining genome homeostasis, by functioning in the repair of a wide variety of DNA damage in T. kodakaraensis cells. Deletion of the entire hef gene or of the segments encoding either its nuclease or helicase domain produced similar phenotypes. The high sensitivity of the Δhef mutants to MMC suggests that Hef performs a critical function in the repair process of DNA interstrand cross-links. These damage-sensitivity profiles suggest that the archaeal DNA repair system has processes depending on repair-related proteins different from those of eukaryotic and bacterial DNA repair systems using homologous repair proteins analyzed here. 相似文献
995.
Shoya Yamada Fuminori Ohsawa Shuji Fujii Ryosuke Shinozaki Makoto Makishima Hirotaka Naitou Shuichi Enomoto Akihiro Tai Hiroki Kakuta 《Bioorganic & medicinal chemistry letters》2010,20(17):5143-5146
Retinoid X receptor (RXR) agonists are candidate agents for the treatment of metabolic syndrome and type 2 diabetes via activation of peroxisome proliferator-activated receptor (PPAR)/RXR or liver X receptor (LXR)/RXR-heterodimers, which control lipid and glucose metabolism. Reporter gene assays or binding assays with radiolabeled compounds are available for RXR ligand screening, but are unsuitable for high-throughput screening. Therefore, as a first step towards stabilizing a fluorescence polarization (FP) assay system for high-throughput RXR ligand screening, we synthesized fluorescent RXR ligands by modification of the lipophilic domain of RXR ligands with a carbostyril fluorophore, and selected the fluorescent RXR agonist 6-[ethyl(1-isobutyl-2-oxo-4-trifluoromethyl-1,2-dihydroquinolin-7-yl)amino]nicotinic acid 8d for further characterization. Compound 8d showed FP in the presence of RXR and the FP was decreased in the presence of the RXR agonist LGD1069 (2). This compound should be a lead compound for use in high-throughput assay systems for screening RXR ligands. 相似文献
996.
Shuji Fujii Fuminori Ohsawa Shoya Yamada Ryosuke Shinozaki Ryosuke Fukai Makoto Makishima Shuichi Enomoto Akihiro Tai Hiroki Kakuta 《Bioorganic & medicinal chemistry letters》2010,20(17):5139-5142
Retinoid X receptors (RXRs) function as homo- or heterodimers with other nuclear receptors, such as peroxisome proliferator-activated receptors (PPARs), which are targets for treatment of hyperlipidemia and type 2 diabetes, or liver X receptors (LXRs), which are involved in glucose/lipid metabolism. PPAR/RXR or LXR/RXR are known as permissive RXR-heterodimers because they are activated by RXR agonists alone. Interestingly, the pattern of RXR-heterodimer activation is different depending on the RXR agonist structure, but the structure–activity relationship has not been reported. Here we show that modification or replacement of the carboxyl group in the acidic domain of RXR agonists has little or no effect on permissive RXR-heterodimer activation. Phosphonic acid (9), tetrazole (10), and hydroxamic acid (12) analogues were synthesized from the common bromo intermediate 7. Except for 9, these compounds showed RXR full-agonistic activities in the concentration range of 1–10 μM. The order of agonistic activity toward both PPARγ/RXRα and LXRα/RXRα was the same as it was for RXR, that is, 11 > 10 > 12. These results should be useful for the development of RXR agonists with improved bioavailability. 相似文献
997.
Ryosuke Yamada Tsutomu Tanaka Chiaki Ogino Hideki Fukuda Akihiko Kondo 《Applied microbiology and biotechnology》2010,85(5):1491-1498
We developed a novel strategy for constructing yeast to improve levels of amylase gene expression and the practical potential
of yeast by combining δ-integration and polyploidization through cell fusion. Streptococcus bovis α-amylase and Rhizopus oryzae glucoamylase/α-agglutinin fusion protein genes were integrated into haploid yeast strains. Diploid strains were constructed
from these haploid strains by mating, and then a tetraploid strain was constructed by cell fusion. The α-amylase and glucoamylase
activities of the tetraploid strain were increased up to 1.5- and tenfold, respectively, compared with the parental strain.
The diploid and tetraploid strains proliferated faster, yielded more cells, and fermented glucose more effectively than the
haploid strain. Ethanol productivity from raw starch was improved with increased ploidy; the tetraploid strain consumed 150 g/l
of raw starch and produced 70 g/l of ethanol after 72 h of fermentation. Our strategy for constructing yeasts resulted in
the simultaneous overexpression of genes integrated into the genome and improvements in the practical potential of yeasts. 相似文献
998.
Kenji Okano Qiao Zhang Shogo Yoshida Tsutomu Tanaka Chiaki Ogino Hideki Fukuda Akihiko Kondo 《Applied microbiology and biotechnology》2010,85(3):643-650
In order to achieve direct fermentation of an optically pure d-lactic acid from cellulosic materials, an endoglucanase from a Clostridium thermocellum (CelA)-secreting plasmid was introduced into an l-lactate dehydrogenase gene (ldhL1)-deficient Lactobacillus plantarum (∆ldhL1) bacterial strain. CelA expression and its degradation of β-glucan was confirmed by western blot analysis and enzyme assay,
respectively. Although the CelA-secreting ∆ldhL1 assimilated cellooligosaccharides up to cellohexaose (although not cellotetraose), the main end product was acetic acid,
not lactic acid, due to the conversion of lactic acid to acetic acid. Cultivation under anaerobic conditions partially suppressed
this conversion resulting in the production of 1.27 g/l of D-lactic acid with a high optical purity of 99.5% from a medium containing 2 g/l of cellohexaose. Subsequently, D-lactic acid fermentation from barley β-glucan was carried out with the addition of Aspergillus aculeatus β-glucosidase produced by recombinant Aspergillus oryzae and 1.47 g/l of D-lactic was produced with a high optical purity of 99.7%. This is the first report of direct lactic acid fermentation from
β-glucan and a cellooligosaccharide that is a more highly polymerized sugar than cellotriose. 相似文献
999.
Shuhei Yanase Tomohisa Hasunuma Ryosuke Yamada Tsutomu Tanaka Chiaki Ogino Hideki Fukuda Akihiko Kondo 《Applied microbiology and biotechnology》2010,88(1):381-388
To exploit cellulosic materials for fuel ethanol production, a microorganism capable of high temperature and simultaneous
saccharification–fermentation has been required. However, a major drawback is the optimum temperature for the saccharification
and fermentation. Most ethanol-fermenting microbes have an optimum temperature for ethanol fermentation ranging between 28 °C
and 37 °C, while the activity of cellulolytic enzymes is highest at around 50 °C and significantly decreases with a decrease
in temperature. Therefore, in the present study, a thermotolerant yeast, Kluyveromyces marxianus, which has high growth and fermentation at elevated temperatures, was used as a producer of ethanol from cellulose. The strain
was genetically engineered to display Trichoderma reesei endoglucanase and Aspergillus aculeatus β-glucosidase on the cell surface, which successfully converts a cellulosic β-glucan to ethanol directly at 48 °C with a
yield of 4.24 g/l from 10 g/l within 12 h. The yield (in grams of ethanol produced per gram of β-glucan consumed) was 0.47 g/g,
which corresponds to 92.2% of the theoretical yield. This indicates that high-temperature cellulose fermentation to ethanol
can be efficiently accomplished using a recombinant K. marxianus strain displaying thermostable cellulolytic enzymes on the cell surface. 相似文献
1000.
Kaoru Washio Takanori Iwata Manabu Mizutani Tomohiro Ando Masayuki Yamato Teruo Okano Isao Ishikawa 《Cell and tissue research》2010,341(3):397-404
Periodontal-ligament-derived cells (PDL cells) have stem-cell-like properties and, when implanted into periodontal defects
in vivo, can induce periodontal regeneration including the formation of new bone, cementum, and periodontal ligament. We have
previously demonstrated that PDL cell sheets, harvested from temperature-responsive cell culture dishes, have a great potential
for periodontal regeneration. The purpose of this study has been to validate the safety and efficacy of human PDL (hPDL) cell
sheets for use in clinical trials. hPDL tissues from three donors were enzymatically digested, and the obtained cells were
cultured with media containing autologous serum in a cell-processing center (CPC). The safety and efficacy of hPDL cell sheets
were evaluated both in vitro and in vivo. In vitro studies showed that the hPDL cell sheets had high alkaline phosphatase
activity and periostin expression (known PDL markers) and no contamination with microorganisms. In vivo studies revealed that
hPDL cell sheets, implanted with dentin blocks, induced the formation of cementum and PDL-like tissue in immunodeficient mice.
The hPDL cells presented no evidence of malignant transformation. Thus, hPDL cell sheets created in CPCs are safe products
and possess the potential to regenerate periodontal tissues. 相似文献