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21.
Iben B. Bentsen Ida Nielsen Michael Lisby Helena B. Nielsen Souvik Sen Gupta Kamilla Mundbjerg Anni H. Andersen Lotte Bjergbaek 《Nucleic acids research》2013,41(5):3173-3189
To address how eukaryotic replication forks respond to fork stalling caused by strong non-covalent protein–DNA barriers, we engineered the controllable Fob-block system in Saccharomyces cerevisiae. This system allows us to strongly induce and control replication fork barriers (RFB) at their natural location within the rDNA. We discover a pivotal role for the MRX (Mre11, Rad50, Xrs2) complex for fork integrity at RFBs, which differs from its acknowledged function in double-strand break processing. Consequently, in the absence of the MRX complex, single-stranded DNA (ssDNA) accumulates at the rDNA. Based on this, we propose a model where the MRX complex specifically protects stalled forks at protein–DNA barriers, and its absence leads to processing resulting in ssDNA. To our surprise, this ssDNA does not trigger a checkpoint response. Intriguingly, however, placing RFBs ectopically on chromosome VI provokes a strong Rad53 checkpoint activation in the absence of Mre11. We demonstrate that proper checkpoint signalling within the rDNA is restored on deletion of SIR2. This suggests the surprising and novel concept that chromatin is an important player in checkpoint signalling. 相似文献
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In situ ellipsometry was employed to study adsorption from human palatal saliva (HPalS) in terms of dependence on surface wettability and saliva concentration ( ? 1%). Adsorbed amounts, kinetics, and elutability with buffer and sodium dodecyl sulphate (SDS) were determined. The low-molecular weight protein content of bulk HPalS was also investigated using two-dimensional gel electrophoresis, and this revealed the presence of a large group of proteins < 100 kDa in size. Adsorption to pure (hydrophilic) and methylated (hydrophobized) silica surfaces revealed that the total adsorbed amounts were greater on hydrophobized silica. Below concentrations of 0.5 and 0.25% saliva, adsorption was concentration dependent on hydrophobized and hydrophilic surfaces, respectively. The initial adsorption ( ? 30 min) was faster on hydrophobized surfaces. Addition of SDS removed more material than buffer rinsing on both surfaces. Analysis of the adsorption kinetics indicated that the presence of low-molecular weight proteins plays a role in adsorption from HPalS. 相似文献
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Maja Martic Ida Noémi Jakab-Simon Lærke Tvedebrink Haahr Wilfred Raymond Hagen Hans Erik Mølager Christensen 《Journal of biological inorganic chemistry》2013,18(2):261-276
Heterometallic [AgFe3S4] iron–sulfur clusters assembled in wild-type Pyrococcus furiosus ferredoxin and two variants, D14C and D14H, are characterized. The crystal structure of the [AgFe3S4] D14C variant shows that the silver(I) ion is indeed part of the cluster and is coordinated to the thiolate group of residue 14. Cyclic voltammetry shows one redox pair with a reduction potential of +220 mV versus the standard hydrogen electrode which is assigned to the [AgFe3S4]2+/+ couple. The oxidized form of the [AgFe3S4] D14C variant is stable in the presence of dioxygen, whereas the oxidized forms of the [AgFe3S4] wild type and D14H variants convert to the [Fe3S4] ferredoxin form. The monovalent d 10 silver(I) ion stabilizes the [Fe3S4]+/0 cluster fragment, as opposed to divalent d 10 metal ions, resulting in more than 0.4 V difference in reduction potentials between the silver(I) and, e.g., zinc(II) heterometallic [MFe3S4] ferredoxins. The trend in reduction potentials for the variants containing the [AgFe3S4] cluster is wild type ≤ D14C < D14H and shows the same trend as reported for the variants containing the [Fe3S4] cluster, but is different from the D14C < D14H < wild type trend reported for the [Fe4S4] ferredoxin. The similarity in the reduction potential trend for the variants containing the heterometallic [AgFe3S4] cluster and the [Fe3S4] cluster can be rationalized in terms of the electrostatic influence of the residue 14 side chains, rather than the dissociation constant of this residue, as is the case for [Fe4S4] ferredoxins. The trends in reduction potentials are in line with there being no electronic coupling between the silver(I) ion and the Fe3S4 fragment. 相似文献
26.
Shoji Ida Ikuo Kitamura Yuhei Morita 《Bioscience, biotechnology, and biochemistry》2013,77(5):715-723
Rice embryo peroxidase 556 was purified to the extent as indicated by the absorbance ratio, RZ greater than 4.0. The enzyme was found to be major basic component among isoenzymes of rice embryo. The preparation was homogeneous as examined by sedimentation analysis, and the sedimentation coefficient, s°20,w, was 3.76 S. The prosthetic group of the enzyme was identified as protohematin and its content was 1.36%. The minimum molecular weight was calculated to be 46,700. From the typical spectra of ligand-enzyme compounds, peroxidase 556 was found to react with carbon monoxide, cyanide, fluoride, and azide. However, at neutral pH, neither fluoride nor azide reacted with the enzyme. The high affinity of the enzyme to ammonia was one of the most remarkable characteristics of the enzyme. The hydrogen peroxide compounds I and II have been observed in the enzymic reaction, and therefore rice embryo peroxidase 556 is also concluded to follow the common reaction mechanism of plant peroxidases. Overall results show the close resemblance of rice embryo peroxidase 556 with wheat germ peroxidase 556 and hemoprotein 550. 相似文献
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Yasuo Noda Yoshiki Ida Shinichi Tanaka Taku Toyama Murilo Felix Roggia Yasuhiro Tamaki Naohiko Sugita Mamoru Mitsuishi Takashi Ueta 《PloS one》2013,8(1)
Purpose
To elucidate the merits of robotic application for vitreoretinal maneuver in comparison to conventional manual performance using an in-vitro eye model constructed for the present study.Methods
Capability to accurately approach the target on the fundus, to stabilize the manipulator tip just above the fundus, and to perceive the contact of the manipulator tip with the fundus were tested. The accuracies were compared between the robotic and manual control, as well as between ophthalmologists and engineering students.Results
In case of manual control, ophthalmologists were superior to engineering students in all the 3 test procedures. Robotic assistance significantly improved accuracy of all the test procedures performed by engineering students. For the ophthalmologists including a specialist of vitreoretinal surgery, robotic assistance enhanced the accuracy in the stabilization of manipulator tip (from 90.9 µm to 14.9 µm, P = 0.0006) and the perception of contact with the fundus (from 20.0 mN to 7.84 mN, P = 0.046), while robotic assistance did not improve pointing accuracy.Conclusions
It was confirmed that telerobotic assistance has a potential to significantly improve precision in vitreoretinal procedures in both experienced and inexperienced hands. 相似文献30.
Tor Paaske Utheim Rakibul Islam Ida G. Fostad Jon R. Eidet Amer Sehic Ole K. Olstad Darlene A. Dartt Edward B. Messelt May Griffith Lara Pasovic 《PloS one》2016,11(3)