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1.
DNA damage is a common hazard that all cells have to combat. Saccharomyces cerevisiae HMO2 is a high mobility group protein (HMGB) that is a component of the chromatin-remodeling complex INO80, which is involved in double strand break (DSB) repair. We show here using DNA end-joining and exonuclease protection assays that HMO2 binds preferentially to DNA ends. While HMO2 binds DNA with both blunt and cohesive ends, the sequence of a single stranded overhang significantly affects binding, supporting the conclusion that HMO2 recognizes features at DNA ends. Analysis of the effect of duplex length on the ability of HMO2 to protect DNA from exonucleolytic cleavage suggests that more than one HMO2 must assemble at each DNA end. HMO2 binds supercoiled DNA with higher affinity than linear DNA and has a preference for DNA with lesions such as pairs of tandem mismatches; however, comparison of DNA constructs of increasing length suggests that HMO2 may not bind stably as a monomer to distorted DNA. The remarkable ability of HMO2 to protect DNA from exonucleolytic cleavage, combined with reports that HMO2 arrives early at DNA DSBs, suggests that HMO2 may play a role in DSB repair beyond INO80 recruitment. 相似文献
2.
N.m.r. studies of metabolism in perfused organs 总被引:1,自引:0,他引:1
J J Ackerman P J Bore D G Gadian T H Grove G K Radda 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1980,289(1037):425-436
Several metabolites and intracellular pH in intact organs can be studied in a non-destructive manner by phorphorus nuclear magnetic resonance (31P n.m.r.). This possibility was demonstrated by us nearly five years ago. Since then we have developed the appropriate physiological techniques and improved the n.m.r. method for the study of animal hearts and kidneys. Here we described measurements aimed at clarifying three problesm. (1) Having measured the enzyme-catalysed fluxes between phosphocreatine and ATP by the method of saturation transfer n.m.r., we examine the relations between energy supply and heart rate in the isolated perfused rat heart. (2) We describe experiments to establish the validity of the perfusion model. For the first time, we report 31P n.m.r. measurements of an in vivo rat heart and compare the results with those obtained for the perfused rat heart. (3) Ischaemia and metabolism in rabbit kidneys is investigated to establish the relation between functional and metabolic recovery after a renal transplant operation. 相似文献
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Neuronal precursor cells in the rat hippocampal formation contribute to more than one cytoarchitectonic area. 总被引:4,自引:0,他引:4
We have tested the hypothesis that cell lineage restriction boundaries define the borders between cytoarchitectonic areas in the cerebral cortex. Clonally related cells were identified using a retroviral marking technique, and the dispersion of neuronal clones was examined with respect to the transitions between cortical areas. We chose to study the hippocampal formation because we found that clones of hippocampal neurons, unlike those in neocortex, are compact and readily identifiable in the adult and that transitions between areas in the hippocampus are sharp relative to the spread of a typical clone. We conclude, contrary to the hypothesis, that clones of neurons transgress the boundaries between areas in the hippocampal formation, that border-crossing clones are observed as frequently as would be expected if clones spread freely over the hippocampus with no constraint imposed by area borders, and that different types of pyramidal neurons, characteristic of different areas, may appear to a single clone. different areas, may appear in a single clone. 相似文献
5.
G L Grove 《The journal of histochemistry and cytochemistry》1979,27(10):1375-1376
During recent years, the utilization of microspectrophotometry in biomedical research has increased at a rapid pace. This growth has been facilitated by both the advent of commercially available instruments which are reliable and manageable as well as improvements in histochemical techniques. This paper discusses the fundamental principles of visible light microspectrophotometry and important design criteria as well as briefly reviewing a wide range of applications. Special emphasis will be given to the Vickers M85 scanning integrating microspectrophotometer which is being routinely employed for both clinical and laboratory studies by a sizeable number of investigators. 相似文献
6.
The tensiometric properties of expanded guinea pig skin 总被引:12,自引:0,他引:12
M S Schneider J E Borkow I T Cruz R D Marangoni J Shaffer D Grove 《Plastic and reconstructive surgery》1988,81(3):398-405
Our purpose in this study was to evaluate the tensile properties of expanded skin. In five guinea pigs, 29-cc ovoid tissue expanders were placed and sequentially expanded every 4 days until maximum volume was achieved. Five control and five expanded skins were harvested. Using an Instron tensile testing apparatus, skins were evaluated for stress-strain, maximum stiffness, and tensile strength, and the results were statistically compared. Centrally located expanded specimens demonstrated significantly weaker stress-strain values: 9.51 in.lb/in3 for expanded versus 30.11 in.lb/in3 for control (p less than 0.001). Maximum stiffness was similarly reduced: 4.56 lb/mm2 for expanded vs. 12.98 lb/mm2 for control (p less than 0.001). This is a 67.4 and 64.9 percent reduction, respectively, for the stress-strain and maximum stiffness. No statistically significant difference was seen in peripherally located expanded specimens relative to the controls: stress-strain expanded, 28.7 in.lb/in3 (p greater than 0.5); maximum stiffness expanded, 12.84 lb/mm2 (p greater than 0.5). Expanded skin demonstrated an average 35 percent reduction in tensile strength. We conclude that the tensile properties of expanded skin are significantly less than unexpanded skin and are a function of the degree of expansion. 相似文献
7.
Emptying rates of single and double meals of different food quality from the stomach of the dab, Limanda limanda (L.) 总被引:1,自引:0,他引:1
In previous studies on gastric emptying time in Limanda , data were obtained which predict that food will empty from the stomach according to: after a temperature sensitive delay. This curve gives an excellent prediction of the emptying of both artificial and natural food items given as single meals when stomachs are sampled directly. However, when two meals are given 3 h apart, emptying rate depends on whether the two meals remain separate or are allowed to mix by omitting the binding agent. In the absence of a binder, both meals are slowed so that the overall emptying rate is as predicted by the equation. When binder is present, the first meal is not delayed and the overall gastric emptying rate is increased 35%. 相似文献
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Design of a functional calcium channel protein: inferences about an ion channel-forming motif derived from the primary structure of voltage-gated calcium channels. 总被引:1,自引:1,他引:0 下载免费PDF全文
A. Grove J. M. Tomich T. Iwamoto M. Montal 《Protein science : a publication of the Protein Society》1993,2(11):1918-1930
To identify sequence-specific motifs associated with the formation of an ionic pore, we systematically evaluated the channel-forming activity of synthetic peptides with sequence of predicted transmembrane segments of the voltage-gated calcium channel. The amino acid sequence of voltage-gated, dihydropyridine (DHP)-sensitive calcium channels suggests the presence in each of four homologous repeats (I-IV) of six segments (S1-S6) predicted to form membrane-spanning, alpha-helical structures. Only peptides representing amphipathic segments S2 or S3 form channels in lipid bilayers. To generate a functional calcium channel based on a four-helix bundle motif, four-helix bundle proteins representing IVS2 (T4CaIVS2) or IVS3 (T4CaIVS3) were synthesized. Both proteins form cation-selective channels, but with distinct characteristics: the single-channel conductance in 50 mM BaCl2 is 3 pS and 10 pS. For T4CaIVS3, the conductance saturates with increasing concentration of divalent cation. The dissociation constants for Ba2+, Ca2+, and Sr2+ are 13.6 mM, 17.7 mM, and 15.0 mM, respectively. The conductance of T4CaIVS2 does not saturate up to 150 mM salt. Whereas T4CaIVS3 is blocked by microM Ca2+ and Cd2+, T4CaIVS2 is not blocked by divalent cations. Only T4CaIVS3 is modulated by enantiomers of the DHP derivative BayK 8644, demonstrating sequence requirement for specific drug action. Thus, only T4CaIVS3 exhibits pore properties characteristic also of authentic calcium channels. The designed functional calcium channel may provide insights into fundamental mechanisms of ionic permeation and drug action, information that may in turn further our understanding of molecular determinants underlying authentic pore structures. 相似文献
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