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81.
Understanding the mechanism of water infiltration through nanopores is essential for wide applications ranging from membrane separation to gene therapy. In this paper, the molecular dynamics simulation method is used to investigate the pressure-assisted water transport process through graphene nanopores. Various factors including the hydrophobicity of nanopore surface, nanopore dimension, temperature as well as external electric field that affect water in permeation into graphene nanopores are discussed. It is found that classic Laplace-Young equation fails and the relationship between pressure and diameter (D) does not follow the 1/D dependence as the characteristic dimension of a nanopore is sufficiently small (smaller than 1?nm). The critical pressure significantly depends on both the pore length and electric field as D is smaller than 5?nm. Besides, enhancing temperature and electric field intensity are obviously beneficial for water infiltration through those nanopores with a diameter smaller than 5?nm. 相似文献
82.
83.
84.
A 22-mer peptide, identical to the primary sequence of domain I segment 3 (IS3) of rat brain sodium channel I, was synthesized. With the patch clamp cell-attached technique, single channel currents could be recorded from the patches of cultured rat myotube membranes when the patches were held at hyperpolarized potentials and the electrode solution contained NaCl and 1 microM IS3, indicating that IS3 incorporated into the membranes and formed ion channels. The single channel conductances of IS3 channels were distributed heterogeneously, but mainly in the range of 10-25 pS. There was a tendency that the mean open time and open probability of IS3 channels increased and the mean close time decreased with the increasing of hyperpolarized membrane potentials. IS3 channels are highly selective for Na+ and Li+ but not for Cl- and K+, similar to the authentic Na+ channels. 相似文献
85.
The Holliday junction is a central intermediate in genetic recombination. It contains four strands of DNA that are paired into four double helical arms that flank a branch point. In the presence of Mg2+, the four arms are known to stack in pairs forming two helical domains whose orientations are antiparallel but twisted by about 60 degrees. The basis for the antiparallel orientation of the domains could be either junction structure or the effect of electrostatic repulsion between domains. To discriminate between these two possibilities, we have constructed and characterized an analogue, called a bowtie junction, in which one strand contains a 3',3' linkage at the branch point, the strand opposite it contains a 5',5' linkage, and the other two strands contain conventional 3',5' linkages. Electrostatic effects are expected to lead to an antiparallel structure in this system. We have characterized the molecule in comparison with a conventional immobile branched junction by Ferguson analysis and by observing its thermal transition profile; the two molecules behave virtually identically in these assays. Hydroxyl radical autofootprinting has been used to establish that the unusual linkages occur at the branch point and that the arms stack to form the same domains as the conventional junction. Cooper-Hagerman gel mobility analyses have been used to determine the relative orientations of the helical domains. Remarkably, we find them to be closer to parallel than to antiparallel, suggesting that the preferred structure of the branch point dominates over electrostatic repulsion. We have controlled for the number of available bonds in the branch point, for gel concentration, and for the role of divalent cations. This finding suggests that control of branch point structure alone can lead to parallel domains, which are generally consistent with recombination models derived from genetic data. 相似文献
86.
Shpynov SN Rydakov NV Samoĭlenko IE Reshetnikova TA Iastrebov VK Shaĭman MS Fournier PE Raoult D 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2004,(5):43-48
A total of 25 rickettsial cultures of the tick-borne spotted fever (TBSF) group from the collection of the Research Institute of Infections in Omsk, isolated from different sources in the territory of the Russian Federation (from the Urals to the Far East) during the period of 1954-2001) were studied by the methods of genetic analysis. The fragments of the gene coding the outer-membrane protein of 190 kD (ompA) and synthetase citrate (gltA) of the rickettsiae under the study were sequenced. 23 isolates were identified as R. sibirica, among them 3 isolates obtained from patients, 16 isolates obtained from Dermacentor ticks, 2 isolates from Haemaphysalis concinna and 2--from Ixodes persulcatus. The strain Primorye 32/84, isolated from D. silvarum ticks in the Far East and earlier identified as S. sibirica by the results of the PCR-RFLP analysis proved to be a genovariant Rickettsia spBJ-90, i.e. close to this species. Strain Karpunino 19/69, isolated in the Kurgan region, was identified as R. slovaca. The results obtained extended our notions of the spectrum of rickettsiae group TBSF in Russia as well as their vectors. 相似文献
87.
Establishment of a continuous embryonic cell line from Japanese flounder Paralichthys olivaceus for virus isolation 总被引:6,自引:0,他引:6
A continuous cell line, the flounder embryonic cell line (FEC), was established from gastrula-stage embryos of a marine cultured fish, the Japanese flounder Paralichthys olivaceus and cultured for more than 200 d with more than 60 passages. FEC cells were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with antibiotics, fetal bovine serum (FBS), sea perch serum (SPS), and basic fibroblast growth factor (bFGF). The cells were small and round, and grew actively and stably in culture. The effect of temperature, FBS concentration and bFGF on FEC cell growth was examined. Cells grew well between 24 and 30 degrees C, but had a reduced growth rate below 18 degrees C. The growth rate of FEC cells in medium containing 15% FBS was higher than that in medium containing 7.5% FBS. Addition of bFGF to the medium also significantly increased the growth rate. Chromosome analysis revealed that FEC cells have a normal diploid karyotype with 2n = 48. High survival rate was obtained after cryopreservation of cell cultures. The susceptibility of the cell line to piscine viruses was examined. Two viruses tested were shown to induce CPE (cytopathic effect) on FEC cells. FEC cell culture infected with fish iridovirus was further elucidated by electron microscopy. Many virus particles were found in the cytoplasm of the virus-infected FEC cells. These results indicated that the FEC cell line could be potentially used to isolate and study fish viruses. 相似文献
88.
Meegalla SK Doller D Sha D Soll R Wisnewski N Silver GM Dhanoa D 《Bioorganic & medicinal chemistry letters》2004,14(19):4949-4953
A convenient synthetic route to novel 4-arylpyrazoles is described. The potential for insecticidal activity through GABA channel blockage by this series of compounds, as well as their selectivity for insect versus mammalian receptors, are explored through in vitro and in vivo assays. 相似文献
89.
Zhu H Zhou ZM Huo R Huang XY Lu L Lin M Wang LR Zhou YD Li JM Sha JH 《Acta biochimica et biophysica Sinica》2004,36(3):227-234
A gene, presumably involved in spermatogenesis, was identified and characterized by using cDNA microarray. Hybridization intensity was 2.13 fold higher in adult testis than that in fetal testis.The full length of this gene was 4288bp and it encoded a 578 amino acid protein. Conserved structure and amino acid sequence analysis revealed that the protein contained 1 Thif-domain, 2 UBACT-domains,and a functional active site cysteine lay upstream of UBACT domain, all of them also existed in ubiquitin-activating enzyme E1 and E1 like proteins. So we named this gene as a novel ubiquitin-activating enzyme E1 like gene (nUBE1L). Expression profile showed that nUBE1L was predominantly expressed in testis.Comparison of the expression of nUBE1L in different developmental stages of testis indicated that it was highly expressed in adult testis. In conclusion, nUBE1L is a novel human E1 like gene highly expressed inadult testis, which plays key role in ubiquitin system, and accordingly influences spermatogenesis and male fertility. 相似文献
90.
Actinomycin D (ACTD) has been shown to bind weakly to the sequence -GGCC-, despite the presence of a GpC site. It was subsequently found, however, that d(CATGGCCATG) binds relatively well to ACTD but exhibits unusually slow association kinetics, contrary to the strong-binding -XGCY- sites. In an effort to elucidate the nature of such binding and to delineate the origin of its interesting kinetic behavior, studies have now been extended to include oligomers with the general sequence motifs of d(CXYGGCCY′X′G)2. It was found that analogous binding characteristics are observed for these self-duplex decamers and comparative studies with progressively base-truncated oligomers from the 5′-end led to the finding that d(GGCCY′X′G) oligomers bind ACTD considerably stronger than their parent decamers and exhibit 1:1 drug/strand binding stoichiometry. Melting profiles monitored at the drug spectral region indicated additional drug binding prior to the onset of eventual complex disruptions with near identical melting temperatures for all the oligomers studied. These results are consistent with the notion that the related oligomers share a common strong binding mode of a hairpin-type, with the 3′-terminus G folding back to base-pair with the C base of GGC. A binding scheme is proposed in which the oligomers d(CXYGGCCY′X′G) exist predominantly in the duplex form and bind ACTD initially at the central GGCC weak site but subsequently disrupt to accommodate the stronger hairpin binding and thus the slow association kinetics. Such a mechanism is supported by the observation of distinct biphasic fluorescence kinetic traces in the binding of 7-amino-ACTD to these duplexes. 相似文献