排序方式: 共有77条查询结果,搜索用时 15 毫秒
1.
The formation of textures in DNA films with LiCl, NaCl, KCl, RbCl, and CsCl salts has been studied. The films are prepared by evaporation of water solution with highly polymerized calf thymus DNA and excess salt of specific type. For DNA solution with 10 mM concentration of NaCl, KCl, and RbCl the films with dendritic textures have been obtained, whereas in case of CsCl the textures in the films appear only at 30 mM concentration of excess salt in the initial solution. In the solution with LiCl, the textures in DNA films have not been observed within the whole range of concentration of excess salt under consideration. The analysis of parameters of DNA films with different salts has showed that evaporation of solution leads to crystallization of salt ions on DNA macromolecule and formation of DNA‐salt complexes. Electrostatic energy of the system of crystalline ordered ions and charges of DNA chains has been estimated to study the stability of DNA‐salt complexes. The results obtained for different salts have been showed that the presence of DNA macromolecule enhances crystallization as compared with solution without DNA. The property of excess salt to form the crystalline structures has been found to decrease in the following order: KCl > NaCl > RbCl > CsCl > LiCl. The results of estimation are in good agreement with the experimentally observed dependence of texture formation on excess salt type. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 508–516, 2013. 相似文献
2.
Vera S. Bogdanova Olga O. Zaytseva Anatoliy V. Mglinets Natalia V. Shatskaya Oleg E. Kosterin Gennadiy V. Vasiliev 《PloS one》2015,10(3)
In crosses of wild and cultivated peas (Pisum sativum L.), nuclear-cytoplasmic incompatibility frequently occurs manifested as decreased pollen fertility, male gametophyte lethality, sporophyte lethality. High-throughput sequencing of plastid genomes of one cultivated and four wild pea accessions differing in cross-compatibility was performed. Candidate genes for involvement in the nuclear-plastid conflict were searched in the reconstructed plastid genomes. In the annotated Medicago truncatula genome, nuclear candidate genes were searched in the portion syntenic to the pea chromosome region known to harbor a locus involved in the conflict. In the plastid genomes, a substantial variability of the accD locus represented by nucleotide substitutions and indels was found to correspond to the pattern of cross-compatibility among the accessions analyzed. Amino acid substitutions in the polypeptides encoded by the alleles of a nuclear locus, designated as Bccp3, with a complementary function to accD, fitted the compatibility pattern. The accD locus in the plastid genome encoding beta subunit of the carboxyltransferase of acetyl-coA carboxylase and the nuclear locus Bccp3 encoding biotin carboxyl carrier protein of the same multi-subunit enzyme were nominated as candidate genes for main contribution to nuclear-cytoplasmic incompatibility in peas. Existence of another nuclear locus involved in the accD-mediated conflict is hypothesized. 相似文献
3.
Passive immunization against the MHC class I molecule Mamu-AG disrupts rhesus placental development and endometrial responses 总被引:2,自引:0,他引:2
Bondarenko GI Burleigh DW Durning M Breburda EE Grendell RL Golos TG 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(12):8042-8050
The unique MHC phenotype of the human and nonhuman primate placenta has suggested a potential role in maternal-fetal immune tolerance, pregnancy success, and maternal as well as fetal well-being. In the rhesus monkey (Macaca mulatta) a nonclassical MHC class I molecule, Mamu-AG, is a putative homologue of HLA-G and is hypothesized to play a role in maternal-fetal immune interactions during pregnancy. Rhesus monkeys were passively immunized during the second week after implantation with a mAb against Mamu-AG. Passive immunization altered the growth and vascularization of the fetal placenta, the placental modification of maternal endometrial vessels, the maternal leukocyte response to implantation, and the differentiation of epithelial and stromal cells in the endometrium. These data are the first to demonstrate in vivo the importance of MHC class I molecules expressed on primate trophoblasts in establishing an important environment for pregnancy success through coordinated interactions between endometrial and fetal tissues. 相似文献
4.
Schweitzer BA Neumann WL Rahman HK Kusturin CL Sample KR Poda GI Kurumbail RG Stevens AM Stegeman RA Stallings WC South MS 《Bioorganic & medicinal chemistry letters》2005,15(12):3006-3011
We describe the structure-based design, synthesis, and enzymatic activity of a series of substituted pyrazinones as inhibitors of the TF/VIIa complex. These inhibitors contain substituents meta to the P(1) amidine designed to explore additional interactions with the VIIa residues in the so-called 'S(1) side pocket'. A crystal structure of the designed inhibitors demonstrates the ability of the P(1) side pocket moiety to engage Lys192 and main chain of Gly216 via hydrogen bond interactions, thus, providing additional possibility for chemical modification to improve selectivity and/or physical properties of inhibitors. 相似文献
5.
We explored the possibility that, in the regulation of an effector enzyme by a Ca(2+)-sensor protein, the actual Ca(2+) sensitivity of the effector enzyme can be determined not only by the affinity of the Ca(2+)-sensor protein for Ca(2+) but also by the relative affinities of its Ca(2+)-bound versus Ca(2+)-free form for the effector enzyme. As a model, we used Ca(2+)-sensitive activation of photoreceptor guanylyl cyclase (RetGC-1) by guanylyl cyclase activating proteins (GCAPs). A substitution Arg(838)Ser in RetGC-1 found in human patients with cone-rod dystrophy is known to shift the Ca(2+) sensitivity of RetGC-1 regulation by GCAP-1 to a higher Ca(2+) range. We find that at physiological concentrations of Mg(2+) this mutation increases the free Ca(2+) concentration required for half-maximal inhibition of the cyclase from 0.27 to 0.61 microM. Similar to rod outer segment cyclase, Ca(2+) sensitivity of recombinant RetGC-1 is strongly affected by Mg(2+), but the shift in Ca(2+) sensitivity for the R838S mutant relative to the wild type is Mg(2+)-independent. We determined the apparent affinity of the wild-type and the mutant RetGC-1 for both Ca(2+)-bound and Ca(2+)-free GCAP-1 and found that the net shift in Ca(2+) sensitivity of the R838S RetGC-1 observed in vitro can arise predominantly from the change in the affinity of the mutant cyclase for the Ca(2+)-free versus Ca(2+)-loaded GCAP-1. Our findings confirm that the dynamic range for RetGC regulation by Ca(2+)/GCAP is determined by both the affinity of GCAP for Ca(2+) and relative affinities of the effector enzyme for the Ca(2+)-free versus Ca(2+)-loaded GCAP. 相似文献
6.
Dolganiuc A Chang S Kodys K Mandrekar P Bakis G Cormier M Szabo G 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(10):6758-6768
IFN-alpha production by plasmacytoid dendritic cells (PDCs) is critical in antiviral immunity. In the present study, we evaluated the IFN-alpha-producing capacity of PDCs of patients with chronic hepatitis C virus (HCV) infection in treatment-naive, sustained responder, and nonresponder patients. IFN-alpha production was tested in PBMCs or isolated PDCs after TLR9 stimulation. Treatment-naive patients with chronic HCV infection had reduced frequency of circulating PDCs due to increased apoptosis and showed diminished IFN-alpha production after stimulation with TLR9 ligands. These PDC defects correlated with the presence of HCV and were in contrast with normal PDC functions of sustained responders. HCV core protein, which was detectable in the plasma of infected patients, reduced TLR9-triggered IFN-alpha and increased TNF-alpha and IL-10 production in PBMCs but not in isolated PDCs, suggesting HCV core induced PDC defects. Indeed, addition of rTNF-alpha and IL-10 induced apoptosis and inhibited IFN-alpha production in PDCs. Neutralization of TNF-alpha and/or IL-10 prevented HCV core-induced inhibition of IFN-alpha production. We identified CD14+ monocytes as the source of TNF-alpha and IL-10 in the HCV core-induced inhibition of PDC IFN-alpha production. Anti-TLR2-, not anti-TLR4-, blocking Ab prevented the HCV core-induced inhibition of IFN-alpha production. In conclusion, our results suggest that HCV interferes with antiviral immunity through TLR2-mediated monocyte activation triggered by the HCV core protein to induce cytokines that in turn lead to PDC apoptosis and inhibit IFN-alpha production. These mechanisms are likely to contribute to HCV viral escape from immune responses. 相似文献
7.
8.
Effects of retinoic acid on the development of liver fibrosis produced by carbon tetrachloride in mice 总被引:4,自引:0,他引:4
Wang L Potter JJ Rennie-Tankersley L Novitskiy G Sipes J Mezey E 《Biochimica et biophysica acta》2007,1772(1):66-71
The role of retinoic acid (RA) in liver fibrogenesis was previously studied in cultured hepatic stellate cells (HSCs). RA suppresses the expression of alpha2(I) collagen by means of the activities of specific nuclear receptors RARalpha, RXRbeta and their coregulators. In this study, the effects of RA in fibrogenesis were examined in carbon tetrachloride (CCl4) induced liver fibrosis in mice. Mice were treated with CCl4 or RA and CCl4, along side control groups, for 12weeks. RA reduced the amount of histologically detectable fibrosis produced by CCl4. This was accompanied by a attenuation of the CCl4 induced increase in alpha2(I) collagen mRNA and a lower (2-fold versus 3-fold) increase in liver hydroxyproline. Furthermore, RA reduced the levels of 3-nitrotyrosine (3-NT) protein adducts and thiobarbituric acid (TBA) reactive substance (TBARS) in the liver, which are formed as results of oxidative stress induced by CCl4 treatment. These in vivo findings support our previous in vitro studies in cultured HSC of the inhibitory effect of RA on type I collagen expression. The data also provide evidence that RA reduces CCl4 induced oxidative stress in liver, suggesting that the anti-fibrotic role of RA is not limited to the inhibition of type I collagen expression. 相似文献
9.
Bosse TD Larson DP Wagner R Hutchinson DK Rockway TW Kati WM Liu Y Masse S Middleton T Mo H Montgomery D Jiang W Koev G Kempf DJ Molla A 《Bioorganic & medicinal chemistry letters》2008,18(2):568-570
A series of gem-dialkyl naphthalenone derivatives with varied alkyl substitutions were synthesized and evaluated according to their structure-activity relationship. This investigation led to the discovery of potent inhibitors of the hepatitis C virus at low nanomolar concentrations in both enzymatic and cell-based HCV genotype 1a assays. 相似文献
10.
Mandal MN Moiseyev GP Elliott MH Kasus-Jacobi A Li X Chen H Zheng L Nikolaeva O Floyd RA Ma JX Anderson RE 《The Journal of biological chemistry》2011,286(37):32491-32501
α-Phenyl-N-tert-butylnitrone (PBN), a free radical spin trap, has been shown previously to protect retinas against light-induced neurodegeneration, but the mechanism of protection is not known. Here we report that PBN-mediated retinal protection probably occurs by slowing down the rate of rhodopsin regeneration by inhibiting RPE65 activity. PBN (50 mg/kg) protected albino Sprague-Dawley rat retinas when injected 0.5-12 h before exposure to damaging light at 2,700 lux intensity for 6 h but had no effect when administered after the exposure. PBN injection significantly inhibited in vivo recovery of rod photoresponses and the rate of recovery of functional rhodopsin photopigment. Assays for visual cycle enzyme activities indicated that PBN inhibited one of the key enzymes of the visual cycle, RPE65, with an IC(50) = 0.1 mm. The inhibition type for RPE65 was found to be uncompetitive with K(i) = 53 μm. PBN had no effect on the activity of other visual cycle enzymes, lecithin retinol acyltransferase and retinol dehydrogenases. Interestingly, a more soluble form of PBN, N-tert-butyl-α-(2-sulfophenyl) nitrone, which has similar free radical trapping activity, did not protect the retina or inhibit RPE65 activity, providing some insight into the mechanism of PBN specificity and action. Slowing down the visual cycle is considered a treatment strategy for retinal diseases, such as Stargardt disease and dry age-related macular degeneration, in which toxic byproducts of the visual cycle accumulate in retinal cells. Thus, PBN inhibition of RPE65 catalytic action may provide therapeutic benefit for such retinal diseases. 相似文献