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81.
Weller GR Kysela B Roy R Tonkin LM Scanlan E Della M Devine SK Day JP Wilkinson A d'Adda di Fagagna F Devine KM Bowater RP Jeggo PA Jackson SP Doherty AJ 《Science (New York, N.Y.)》2002,297(5587):1686-1689
In eukaryotic cells, double-strand breaks (DSBs) in DNA are generally repaired by the pathway of homologous recombination or by DNA nonhomologous end joining (NHEJ). Both pathways have been highly conserved throughout eukaryotic evolution, but no equivalent NHEJ system has been identified in prokaryotes. The NHEJ pathway requires a DNA end-binding component called Ku. We have identified bacterial Ku homologs and show that these proteins retain the biochemical characteristics of the eukaryotic Ku heterodimer. Furthermore, we show that bacterial Ku specifically recruits DNA ligase to DNA ends and stimulates DNA ligation. Loss of these proteins leads to hypersensitivity to ionizing radiation in Bacillus subtilis. These data provide evidence that many bacteria possess a DNA DSB repair apparatus that shares many features with the NHEJ system of eukarya and suggest that this DNA repair pathway arose before the prokaryotic and eukaryotic lineages diverged. 相似文献
82.
Partridge EA Le Roy C Di Guglielmo GM Pawling J Cheung P Granovsky M Nabi IR Wrana JL Dennis JW 《Science (New York, N.Y.)》2004,306(5693):120-124
The Golgi enzyme beta1,6 N-acetylglucosaminyltransferase V (Mgat5) is up-regulated in carcinomas and promotes the substitution of N-glycan with poly N-acetyllactosamine, the preferred ligand for galectin-3 (Gal-3). Here, we report that expression of Mgat5 sensitized mouse cells to multiple cytokines. Gal-3 cross-linked Mgat5-modified N-glycans on epidermal growth factor and transforming growth factor-beta receptors at the cell surface and delayed their removal by constitutive endocytosis. Mgat5 expression in mammary carcinoma was rate limiting for cytokine signaling and consequently for epithelial-mesenchymal transition, cell motility, and tumor metastasis. Mgat5 also promoted cytokine-mediated leukocyte signaling, phagocytosis, and extravasation in vivo. Thus, conditional regulation of N-glycan processing drives synchronous modification of cytokine receptors, which balances their surface retention against loss via endocytosis. 相似文献
83.
84.
T A Roy J R Meeks C R Mackerer 《Journal of the Association of Official Analytical Chemists》1983,66(6):1319-1321
Ion-pair reverse phase liquid chromatography (LC) and UV detection at 280 nm have been used to determine sodium acifluorfen (sodium-5-[2-chloro-4-(trifluoromethyl)-phenoxy]-2-nitrobenzoate), an experimental diphenyl ether herbicide, in dog feed. Sodium-5-(2,4-dichlorophenoxy)-2-nitrobenzoate is used as the internal standard. The feed is homogenized in 0.01N HCl, followed by ethyl acetate extraction, and centrifugation. The organic layer is removed and evaporated and the residue is reconstituted in methanol and filtered before LC analysis (mobile phase methanol-water (58 + 42), 0.005M in tetrabutylammonium phosphate and 0.045M in (NH4)2HPO4, at pH 7.4). The ion-pair technique offers a high degree of control over the retention characteristics of the herbicide and internal standard. The use of the internal standard permits precise and accurate quantitation and substantially reduces analysis time compared with the external standard method. 相似文献
85.
86.
Abha Jain A. K. Roy P. Kaushal D. R. Malaviya S. N. Zadoo 《Genetic Resources and Crop Evolution》2006,53(2):339-347
Isozyme banding pattern was studied in Guinea grass (Panicum maximum Jacq.), a widely cultivated grass having good fodder value. Similarity among 63 accessions collected from diverse sources
was worked out using five enzyme systems (SOD, GOT, ACP, Esterase and Peroxidase) following horizontal starch gel electrophoresis.
Biochemical markers such as isozymes are useful supplements in identifying the genetic variation present in any crop. A total
of 35 clear and unambiguous bands were used for analysis of which 8 bands were monomorphic. Polymorphism exhibited by 27 bands
from all five enzyme systems indicate presence of considerable diversity in this species. The dendrogram generated after UPGMA
and SAHN cluster analysis using Jaccard genetic distance showed that 63 accessions from diverse geographical locations could
be grouped in three main clusters, of which two could further be divided into sub-clusters. Although the clusters comprised
members from different locations, most of the accessions from similar geographical locations tended to cluster in same group. 相似文献
87.
This paper describes a pilot investigation dealing with changes in chemical composition of wood in pollution-stressed white pine trees, taken from two forested ecosystems of Southern Ontario, Canada. The implications of this research lie in a much needed search for a potential bloindicator of a pre-decline, incipient-stress induced (and/or contributed by) the air-pollutants. 相似文献
88.
Sulphur isotope abundances demonstrate that natural emissions of biogenic H2S and its oxidation products from springs near Paige Mountain, N.W.T., Canada, can be incorporated into surrounding soil and vegetation. δ34S values as low as ? 33‰ for soil and vegetation are the result of dominant uptake of biogenic atmospheric compounds. In contrast, vegetation on a gypsum outcrop remote from the springs, has δ34S values as high as + 26‰ indicating nearly exclusive derivation of S from the soil. Near the springs, soil with vegetative cover is less depleted in 34S than soil lacking cover. Lower needles on a Black Spruce were found to be less depleted in 34S than the upper needles. These observations suggest that upper foliage exerts a canopy effect on lower foliage and in turn, interception by vegetation reduces the flux of atmospheric S compounds to the soil. Clearly, natural emissions of S compounds can interfere in studies of long range transport of industrial emissions; S isotope analyses might identify such interferences and reduce the chance of misinterpretation. 相似文献
89.
Sarah C. Roode Heather R. Shive Willemijn Hoorntje Jennifer Bernard Devorah M. Stowe Roy R. Pool Carol B. Grindem 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2018,47(3):484-488
A 20‐month‐old female spayed Staffordshire Terrier (22.3 kg) presented to the Orthopedic Surgery Service at North Carolina State University Veterinary Teaching Hospital for evaluation of a 6‐week history of toe‐touching to nonweight‐bearing lameness in the right hind limb. Radiographs of the right stifle revealed a multiloculated lytic lesion of the distal femur, with a large open lytic zone centrally, numerous osseous septations peripherally, and focal areas of cortical thinning and loss. An aspirate of the right distal femoral lesion yielded mildly cloudy serosanguineous fluid. Cytologic examination of the fluid revealed a pleomorphic population of discrete cells that exhibited marked anisocytosis and anisokaryosis and a variable nuclear‐to‐cytoplasmic (N:C) ratio, which were interpreted as probable neoplastic cells, with few macrophages, and evidence of hemorrhage. Given the clinical signs of pain, lesion size, and concern for malignant neoplasia, amputation of the right hind limb was performed. Histologically, the lesion had undulating walls 1‐3 mm thick with a continuous outer layer of dense fibrous tissue and an inner layer composed of reactive cancellous bone with no cortical compacta remaining. Remnants of thin fibrous or fibro‐osseous septa projected from the bony wall into the cyst lumen. The final histologic diagnosis was a benign multiloculated solitary (unicameral) bone cyst of the distal right femur. Based on the histopathologic findings, it was speculated that the cells identified on cytology were a mixture of developing osteoclasts, osteoblasts, endothelial, and stromal cells. This is the first report describing the cytologic examination of a solitary bone cyst in veterinary medicine. 相似文献
90.