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71.
There is considerable interest in identifying and characterizing block-like patterns of linkage disequilibrium (LD; haplotype blocks) in the human genome as these may facilitate the identification of complex disease genes via genome-wide association studies. Although recombination hot-spots have been suggested as the primary mechanism to explain the block-like pattern of LD, other forces, such as genetic drift, may also be important. To this end, we have studied the effect of various recombination models on patterns of LD by using extensive simulations. As expected, haplotype blocks were observed under a model allowing recombination hot-spots. However, we also observed similar block-like patterns in the models where recombination crossovers are randomly and uniformly distributed, and we demonstrate that these blocks are generated by genetic drift. We caution that genetic drift may be an alternative mechanism (in addition to recombination hot-spots) that can lead to block-like patterns of LD. Our findings highlight the necessity of characterizing haplotype blocks in world-wide populations. 相似文献
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73.
Pathogenicity test ofFusarium oxysporum on ten cultivars of soybean revealed Soymax and Punjab-1 to be most resistant while JS-2 and UPSM-19 were most susceptible.
Antigens were prepared from the roots of all the ten varieties of soybean and the mycelium ofF. oxysporum. Polyclonal antisera were raised against the mycelial suspension ofF. oxysporum and the root antigen of the susceptible cultivar UPSM-19. Cross reactive antigens shared by the host and the pathogen were
detected first by immunodiffusion. The immunoglobulin fraction of the antiserum was purified by ammonium sulfate precipitation
and DEAE-Sephadex column chromatography. The immunoglobulin fractions were used for detection of cross-reactive antigens by
enzyme-linked immunosorbent assay. In enzyme-linked immunosorbent assay, antigens of susceptible cultivars showed higher absorbance
values when tested against the purified anti-F. oxysporum antiserum. Antiserum produced against UPSM-19 showed cross-reactivity with the antigens of other cultivars. Indirect staining
of antibodies using fluorescein isothiocyanate indicated that in cross-sections of roots of susceptible cultivar (UPSM-19)
cross-reactive antigens were concentrated around xylem elements, endodermis and epidermal cells, while in the resistant variety,
fluorescence was concentrated mainly around epidermal cells and distributed in the cortical tissues. CRAs were also present
in microconidia, macroconidia and chlamydospores of the fungus. 相似文献
74.
Dynein light chain (DLC8) is the smallest subunit of the dynein motor complex, which is known to act as a cargo adaptor in intracellular trafficking. The protein exists as a pure dimer at physiological pH and a completely folded monomer below pH 4. Here, we have determined the energy landscape of the dimeric protein using a combination of optical techniques and native-state hydrogen exchange of amide groups, the former giving the global features and the latter yielding the residue level details. The data indicated the presence of intermediates along the equilibrium unfolding transition. The hydrogen exchange data suggested that the molecule has differential stability in its various segments. We deduce from the free energy data that the antiparallel beta-sheets (beta4 and beta5) that form the hydrophobic core of the protein and the alpha2 helix, all of which are highly protected with regard to hydrogen exchange, contribute significantly to the initial step of the protein folding mechanism. Denaturant-dependent hydrogen exchange indicated further that some amides exchange via local fluctuations, whereas there are others which exchange via global unfolding events. Implications of these to cargo adaptability of the dimer are discussed. 相似文献
75.
Chandraditya Chakraborty Sudip Samadder Anirban Roychowdhury Anup Roy Pradip Das Ranajit Kumar Mandal Susanta Roychoudhury Chinmay Kumar Panda 《Molecular and cellular biochemistry》2018,443(1-2):121-130
In this study, importance of Wnt-β-catenin pathway in the development of uterine cervical carcinoma was evaluated. For this purpose, the profiles (expression/methylation/deletion) of β-catenin, p-β-catenin (Y654), Wnt3a, and APC were studied in disease free normal cervical epithelium (n = 9), adjacent normal cervical epithelium of primary tumors (n = 70), CIN (n = 28), CACX (n = 102) samples, and two CACX cell lines (HeLa and SiHa). Immunohistochemical analysis revealed high/medium (74–95%) expression of β-catenin/p-β-catenin (Y654) and Wnt3a and low expression (23–26%) of APC in proliferating basal–parabasal layers contrary to differentiated spinous layer in normal cervix irrespective of HPV16 infection. The expression profile of the genes in the basal–parabasal layers did not change significantly during development of CACX. High (66%) promoter methylation of APC was seen in basal–parabasal layers and the cervical lesions (42–69%), unlike in spinous layers (25%). The promoter methylation status of APC was validated by in vitro demethylation experiments using 5-aza-dC in CACX cell lines. However, additional deletion of APC was significantly increased from CIN (12%) to stage I/II (40%) and became comparable in stage III/IV (48%) of the tumor. Patients with alterations (deletion/methylation) of APC and high/medium expression of Wnt3a/β-catenin/p-β-catenin (Y654) showed significantly poor survival. Thus our data indicate that cumulative effect of Wnt3a overexpression and APC inactivation are needed for overexpression of β-catenin during the development of CACX. 相似文献
76.
77.
The primary structure of Klebsiella serotype K10 capsular polysaccharide has been investigated using mainly the techniques of methylation, partial hydrolysis, and 1H and 13C NMR spectroscopy. The polysaccharide was found to consist of hexasaccharide repeating units having the following structure: (formula; see text) 相似文献
78.
E. P. Storey R. Boghozian James L. Little Douglas W. Lowman R. Chakraborty 《Biometals》2006,19(6):637-649
The Rhizobia comprise one of the most important groups of beneficial bacteria, which form nodules on the roots (rarely on the stems) of leguminous plants. They live within the nodules and reduce atmospheric nitrogen to ammonia, which is further assimilated by plants into required nitrogenous compounds. The Rhizobia in return obtain nutrition from the plant. Rhizobia are free-living soil bacteria and have to compete with other microorganisms for the limited available iron in the rhizosphere. In order to acquire iron Rhizobia have been shown to express siderophore-mediated iron transport systems. Rhizobium leguminosarum IARI 917 was investigated for its ability to produce siderophore. It was found to produce a dihydroxamate type siderophore under iron restricted conditions. The siderophore was purified and chemically characterized. The ESMS, MS/MS and NMR analysis indicate the dihydroxamate siderophore to be ‘schizokinen’, a siderophore reported to be produced by Bacillus megaterium that shares a similar structure to ‘rhizobactin 1021’ produced by Sinorhizobium meliloti 1021. This is the first report of production of schizokinen by a strain of R. leguminosarum, therefore it was carefully investigated to confirm that it is indeed ‘schizokinen’ and not a degradation product of ‘rhizobactin 1021’. Since ferric–siderophore complexes are transported across the outer membrane (OM) into the periplasm via an OM receptor protein, R. leguminosarum IARI 917 was investigated for the presence of an OM receptor for ‘ferric–schizokinen’. SDS PAGE analysis of whole cell pellet and extracted OM fractions indicate the presence of a possible iron-repressible OM receptor protein with the molecular weight (MW) of approximately 74 kDa. 相似文献
79.
80.
Zhang G Karns R Sun G Indugula SR Cheng H Havas-Augustin D Novokmet N Rudan D Durakovic Z Missoni S Chakraborty R Rudan P Deka R 《PloS one》2011,6(12):e29475