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101.
Escherichia coli was transformed with a recombinant plasmid (pEGFP) containing the genes for ampicillin resistance and Green Fluorescent Protein (GFP). Escherichia coli expressing GFP (E. coli/GFP+) was then fed to workers of the termite Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). The transformed bacteria in the termite guts were detected by growing the gut flora under selective conditions and then checking the cultures for fluorescence. Recombinant plasmids in the termite gut were detected by plasmid extraction with subsequent restriction enzyme digest. The presence of the GFP gene in the gut of termites fed with E. coli/GFP+ was verified by PCR amplification. Transformed E. coli were ingested rapidly when workers fed on filter paper inoculated with E. coli/GFP+. After 1 day, 42% of termite guts harbored E. coli/GFP+. Transfer of E. coli/GFP+ from donor termites (fed with E. coli/GFP+) to recipients (fed with moist filter paper) occurred within 1 day. However, without continuous inoculation, termites lost the transformed bacteria within 1 week. 相似文献
102.
Ohmori K Umeda M Tanaka N Takagi H Yoshimura I Sasaki K Asasda S Sakai A Araki H Asakura M Baba H Fushiwaki Y Hamada S Kitou N Nakamura T Nakamura Y Oishi H Sasaki S Shimada S Tsuchiya T Uno Y Washizuka M Yajima S Yamamoto Y Yamamura E Yatsushiro T;Non-Genotoxic Carcinogen Study Group in the Environmental Mutagen Society of Japan 《Alternatives to laboratory animals : ATLA》2005,33(6):619-639
The Bhas promotion assay is a cell culture transformation assay designed as a sensitive and economical method for detecting the tumour-promoting activities of chemicals. In order to validate the transferability and applicability of this assay, an inter-laboratory collaborative study was conducted with the participation of 14 laboratories. After confirmation that these laboratories could obtain positive results with two tumour promoters, 12-O-tetradecanoylphorbol-13-acetate (TPA) and lithocholic acid (LCA), 12 coded chemicals were assayed. Each chemical was tested in four laboratories. For eight chemicals, all four laboratories obtained consistent results, and for two of the other four chemicals, only one of the four laboratories showed inconsistent results. Thus, the rate of consistency was high. During the study, several issues were raised, each of which were analysed step-by-step, leading to revision of the protocol of the original assay. Among these issues were the importance of careful maintenance of mother cultures and the adoption of test concentrations for toxic chemicals. In addition, it is suggested that three different types of chemicals show positive promoting activity in the assay. Those designated as T-type induced extreme growth enhancement, and included TPA, mezerein, PDD and insulin. LCA and okadaic acid belonged to the L-type category, in which transformed foci were induced at concentrations showing growth-inhibition. In contrast, M-type chemicals, progesterone, catechol and sodium saccharin, induced foci at concentrations with little or slight growth inhibition. The fact that different types of chemicals similarly induce transformed foci in the Bhas promotion assay may provide clues for elucidating mechanisms of tumour promotion. 相似文献
103.
Oishi S Karki RG Shi ZD Worthy KM Bindu L Chertov O Esposito D Frank P Gillette WK Maderia M Hartley J Nicklaus MC Barchi JJ Fisher RJ Burke TR 《Bioorganic & medicinal chemistry》2005,13(7):2431-2438
Preferential binding of ligands to Grb2 SH2 domains in beta-bend conformations has made peptide cyclization a logical means of effecting affinity enhancement. This is based on the concept that constraint of open-chain sequences to bend geometries may reduce entropy penalties of binding. The current study extends this approach by undertaking ring-closing metathesis (RCM) macrocyclization between i and i+3 residues through a process involving allylglycines and beta-vinyl-functionalized residues. Ring closure in this fashion results in minimal macrocyclic tetrapeptide mimetics. The predominant effects of such macrocyclization on Grb2 SH2 domain binding affinity were increases in rates of association (from 7- to 16-fold) relative to an open-chain congener, while decreases in dissociation rates were less pronounced (approximately 2-fold). The significant increases in association rates were consistent with pre-ordering of solution conformations to near those required for binding. Data from NMR experiments and molecular modeling simulations were used to interpret the binding results. An understanding of the conformational consequences of such i to i+3 ring closure may facilitate its application to other systems where bend geometries are desired. 相似文献
104.
Fenofibrate induces apoptotic injury in cultured human hepatocytes by inhibiting phosphorylation of Akt 总被引:2,自引:0,他引:2
Kubota T Yano T Fujisaki K Itoh Y Oishi R 《Apoptosis : an international journal on programmed cell death》2005,10(2):349-358
Fibric acid derivatives have a potent and effective lipid-lowering action, however, the use of these compounds is sometimes limited due to the occurrence of hepatic injury. In the present study, we characterized cell injury induced by fenofibrate in cultured human hepatocytes. Fenofibrate caused a loss of cell viability and nuclear damage as assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling or by DNA electrophoresis, in which caspase activation is involved. The cell injury was accompanied by the shrinkage and the translocation of phosphatidyl serine from inner membrane to the outer membrane as determined by annexin V stain. The mRNA expression for bcl-2 was reduced by fenofibrate. An immunofluorescent stain with antiserum raised against phosphorylated Akt revealed that fenofibrate inhibited insulin-stimulated phosphorylation of Akt. Like fenofibrate, several compounds that inhibit the phosphorylation of Akt, including wortmannin, SH-6 and a high concentration (100 M) of SB203580, reduced the viability of cultured human hepatocytes. Both nuclear damage and cell injury induced by fenofibrate were reversed by insulin in a concentration-dependent manner. In contrast, bezafibrate or 8(S)-hydroxyeicosatetraenoic acid had no hepatotoxic action. These findings suggest that fenofibrate causes caspase-dependent apoptosis in human hepatocytes by inhibiting phosphorylation of Akt, in which PPAR is not involved. 相似文献
105.
Unnatural amino acids are effective as building blocks to design functional peptides from the following two points: (1) utilization of rigid unnatural amino acids for the incorporated peptides to control the conformation to appear the function, and (2) incorporation of functional and unnatural amino acids into peptides resulting in appearance of the inherent functions. As a combined strategy, molecular design of artificial metalloproteins utilizing 5'-amino-2,2'-bipyridine-5-carboxilic acid (H-5Bpy-OH) as an unnatural amino acid is proposed. The peptide containing three residues of the unnatural amino acid would fold through coordination to a metal ion. In particular, ruthenium(II) ion would yield a ruthenium tris(bipyridine) derivative as the core complex of the artificial protein, which would appear the similar photochemical functions as that of ruthenium(II) tris(bipyridine) complex. The central complex could form two isomers, fac and mer. For selective synthesis of the mer complex, which is expected as the core complex in the artificial protein, dicyclohexylamide as a bulky group is introduced at the C-terminal of the unnatural amino acid to destabilize the fac complex due to steric hindrance. Furthermore, in order to know the photochemical properties and function of the protein mimics, ruthenium(II) tris(2,2'-bipyridine) complexes bearing amide groups at 5,5' positions have been synthesized as the model complexes. As a result, the direction of amide groups (RNHCO-or RCONH-) in ruthenium complexes is found to significantly affect the emission efficiency: the former reduces the quantum yield and the latter enhances it, respectively. The ruthenium(II) tris(5,5'-diamide-2,2'-bipyridine) complexes are also found to strongly bind with various anions [e.g., halogen ions (Cl-, Br-) and acetate anion] in acetonitrile and to detect these anions through the emission spectral changes under air. The molecular design of artificial protein is expected to develop new fields among peptide, organic, inorganic, and physical chemistry. 相似文献
106.
Shimura K Nameki D Kajiwara K Watanabe K Sakagami Y Oishi S Fujii N Matsuoka M Sarafianos SG Kodama EN 《The Journal of biological chemistry》2010,285(50):39471-39480
Human immunodeficiency virus (HIV) gp41 plays a key role in viral fusion; the N- and C-terminal heptad repeats (N-HR and C-HR) of gp41 form a stable 6-helical conformation for fusion. Therefore, HR-derived peptides, such as enfuvirtide (T-20), inhibit HIV-1 fusion by acting as decoys, and have been used for the treatment of HIV-1 infection. However, the efficacy of T-20 is attenuated by resistance mutations in gp41, including V38A and N43D. To suppress the resistant variants, we previously developed electrostatically constrained peptides, SC34 and SC34EK, and showed that both exhibited potent anti-HIV-1 activity against wild-type and T-20-resistant variants. In this study, to clarify the resistance mechanism to this next generation of fusion inhibitors, we selected variants with resistance to SC34 and SC34EK in vitro. The resistant variants had multiple mutations in gp41. All of these mutations individually caused less than 6-fold resistance to SC34 and SC34EK, indicating that there is a significant genetic barrier for high-level resistance. Cross-resistance to SC34 and SC34EK was reduced by a simple difference in the polarity of two intramolecular electrostatic pairs. Furthermore, the selected mutations enhanced the physicochemical interactions with N-HR variants and restored activities of the parental peptide, C34, even to resistant variants. These results demonstrate that our approach of designing gp41-binding inhibitors using electrostatic constraints and information derived from resistance studies produces inhibitors with enhanced activity, high genetic barrier, and distinct resistance profile from T-20 and other inhibitors. Hence, this is a promising approach for the design of future generation peptide fusion inhibitors. 相似文献
107.
Inoue H Kobayashi-Hattori K Horiuchi Y Oishi Y Arai S Takita T 《Bioscience, biotechnology, and biochemistry》2006,70(5):1134-1139
We investigated the regulatory effects of structural differences among methylxanthine derivatives on the elevation of body fat percentage in developmental-stage rats. Caffeine, theophylline and theobromine were used as the methylxanthines. High-fat diets (20% lard) containing each methylxanthine (0.025%) were administered to male Sprague-Dawley rats for 12 weeks, with the result that the body fat percentage was generally reduced in each methylxanthine-fed group. The abdominal adipose tissue weight in the caffeine group was also significantly lower than that in the control group, the serum cholesterol and triglyceride levels in the caffeine group also being significantly lower than the levels in the control group. The study results suggest that caffeine could contribute most to preventing arteriosclerotic diseases. 相似文献
108.
Molecular cloning and characterization of novel splicing variants of human decay-accelerating factor
Osuka F Endo Y Higuchi M Suzuki H Shio Y Fujiu K Kanno R Oishi A Terashima M Fujita T Gotoh M 《Genomics》2006,88(3):316-322
Decay-accelerating factor (DAF) is one of the complement regulatory proteins. Two isoforms of DAF have been identified in humans. In this study, we isolated novel cDNAs encoding five isoforms of DAF from the human lung, which were generated by insertion of new exonic sequences. RT-PCR revealed that all isoforms were expressed in almost all tissues tested, although the expression patterns and levels differed among the tissues. Transfection of isoform vDAF1, 2, and 3 cDNAs into CHO cells showed that these molecules are soluble forms secreted after glycosylation. Isoform vDAF4 and vDAF5 cDNAs included a part of and the entire intron 7 sequence, respectively, and the transfection of vDAF4 cDNA produced a large, glycosylated, membrane-bound form. These results suggest that more than seven isoforms of human DAF are involved in the regulation of complement activation under physiological conditions through their specific structures and localization. 相似文献
109.
110.
Kamei N Tobe K Suzuki R Ohsugi M Watanabe T Kubota N Ohtsuka-Kowatari N Kumagai K Sakamoto K Kobayashi M Yamauchi T Ueki K Oishi Y Nishimura S Manabe I Hashimoto H Ohnishi Y Ogata H Tokuyama K Tsunoda M Ide T Murakami K Nagai R Kadowaki T 《The Journal of biological chemistry》2006,281(36):26602-26614
Adipose tissue expression and circulating concentrations of monocyte chemoattractant protein-1 (MCP-1) correlate positively with adiposity. To ascertain the roles of MCP-1 overexpression in adipose, we generated transgenic mice by utilizing the adipocyte P2 (aP2) promoter (aP2-MCP-1 mice). These mice had higher plasma MCP-1 concentrations and increased macrophage accumulation in adipose tissues, as confirmed by immunochemical, flow cytometric, and gene expression analyses. Tumor necrosis factor-alpha and interleukin-6 mRNA levels in white adipose tissue and plasma non-esterified fatty acid levels were increased in transgenic mice. aP2-MCP-1 mice showed insulin resistance, suggesting that inflammatory changes in adipose tissues may be involved in the development of insulin resistance. Insulin resistance in aP2-MCP-1 mice was confirmed by hyperinsulinemic euglycemic clamp studies showing that transgenic mice had lower rates of glucose disappearance and higher endogenous glucose production than wild-type mice. Consistent with this, insulin-induced phosphorylations of Akt were significantly decreased in both skeletal muscles and livers of aP2-MCP-1 mice. MCP-1 pretreatment of isolated skeletal muscle blunted insulin-stimulated glucose uptake, which was partially restored by treatment with the MEK inhibitor U0126, suggesting that circulating MCP-1 may contribute to insulin resistance in aP2-MCP-1 mice. We concluded that both paracrine and endocrine effects of MCP-1 may contribute to the development of insulin resistance in aP2-MCP-1 mice. 相似文献