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排序方式: 共有313条查询结果,搜索用时 46 毫秒
1.
Jef D. Boeke Francois La Croute Gerald R. Fink 《Molecular & general genetics : MGG》1984,197(2):345-346
Summary Mutations at the URA3 locus of Saccharomyces cerevisiae can be obtained by a positive selection. Wild-type strains of yeast (or ura3 mutant strains containing a plasmid-borne URA3
+ gene) are unable to grow on medium containing the pyrimidine analog 5-fluoro-orotic acid, whereas ura3
– mutants grow normally. This selection, based on the loss of orotidine-5-phosphate decarboxylase activity seems applicable to a variety of eucaryotic and procaryotic cells. 相似文献
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5.
Willem Nieuwenhuizen Jef J. Emeis Anton Vermond 《Biochemical and biophysical research communications》1982,105(3):1122-1127
Solubilization of fibrin monomers (Fm's) is usually performed with dilute acetic acid, urea or sodium bromide. These solvents can affect the biological properties of Fm's. Therefore we describe a new method to keep Fm's in solution, under milder conditions i.e. by generating them in Dcate solutions and avoiding non-physiological conditions. The in vivo behaviour of iodinated rat Fm's injected in rats and prepared by this new method was compared with that of Fm's dissolved in acetic acid, urea or sodium bromide.Fm's prepared in Dcate solutions accumulate rapidly, within 10 minutes after injection, in all organs tested, predominantly in kidney, liver and lung, probably by interaction with endothelial cells. The blood radioactivity remains nearly constant during the first 90 minutes and decreases thereafter exponentially. Fm's dissolved in sodium bromide behave similarly. However, Fm's dissolved in acetic acid or urea behave differently and do not accumulate in organs. This suggests that Fm's loose their capability to accumulate in organs and probably to interact with endothelial cells when they have been dissolved in acetic acid or urea.The slow exponential clearance phase does not differ significantly between the various Fm's and their are estimated to lie between 5 and 7 hours. 相似文献
6.
Marc Mercken† Mark Vandermeeren† Ursula Lübke‡ Jan Six Jef Boons† Eugène Vanmechelen re Van De Voorde Jan Gheuens† 《Journal of neurochemistry》1992,58(2):548-553
Immunoaffinity chromatography with a monoclonal antibody produced against bovine tau protein was used to purify tau proteins from human brain. Fifty grams of brain tissue yielded approximately 2 mg of pure tau proteins. The affinity-purified human tau was used to produce a high-titered rabbit anti-human tau serum. The monoclonal anti-tau antibody and the polyclonal rabbit anti-tau serum were then used to construct a sandwich enzyme-linked immunosorbent assay for detection of human tau proteins, with a sensitivity of 1 ng/ml. 相似文献
7.
Suppressor T cell (Ts) lines specific for myelin basic protein (MBP)-reactive helper T cell (Th) clones were generated from two patients with multiple sclerosis (MS) following a primary culture of peripheral blood mononuclear cells (PBMC) with MBP and cyclosporine A (CsA). These suppressor T cell lines were maintained in culture by alternate stimulation with MBP and antigen-presenting cells (APC). The Ts lines expressed preferentially the CD4 phenotype (5/6 Ts lines tested) and exhibited potent antigen-specific suppressor activity on the proliferation of MBP-specific Th clones and not on the T cell lines with other antigen specificity. For some Ts lines, a Ts-to-Th ratio of 1 was sufficient to inhibit the proliferation of MBP-specific T cells by 90%. The suppressor T cells obtained were weakly responsive to MBP and required the presence of the autologous PBMC for proliferation. Furthermore, proliferation of these suppressor T cell lines was restricted by HLA-DR molecules (for CD4+ Ts lines) and HLA class I (for a CD8+ Ts line). The suppressor T cell lines generated and the techniques described in this study may be helpful in our understanding of the events involved in the immune regulation in MS and other autoimmune diseases. 相似文献
8.
A panel of 17 myelin basic protein (MBP)-specific T lymphocyte clones were generated from four multiple sclerosis (MS) patients. All T cell clones expressed CD4 phenotype and 14 clones exhibited substantial cytotoxic activity on MBP-coated target cells. T cell recognition sites of the clones on human MBP were identified by using MBP fragments and synthetic peptides. Despite the fact that at least three epitopes were defined, these T cell clones displayed a striking bias to the C-terminal peptide 149-171 independent of differences in HLA-DR and DQ expression. In addition, the T cell responses of the clones appeared to be restricted by HLA-DR molecules irrespective of peptide specificities. The present study suggests an immunodominant property of the C-terminal peptide for HLA-DR-restricted T cell responses to MBP. However, its association with encephalitogenicity in humans and its potential pathologic importance in MS await further clarification. 相似文献
9.
Four genes in two diverged subfamilies encode the ribulose-1,5-bisphosphate carboxylase small subunit polypeptides of Arabidopsis thaliana 总被引:5,自引:0,他引:5
Enno Krebbers Jef Seurinck Lydia Herdies Anthony R. Cashmore Michael P. Timko 《Plant molecular biology》1988,11(6):745-759
The multigene family encoding the small subunit polypeptides of ribulose-1,5-bisphosphate carboxylase/oxygenase in the crucifer Arabidopsis thaliana has been isolated and the organization and structure of the individual members determined. The family consists of four genes which have been divided into two subfamilies on the basis of linkage and DNA and amino acid sequence similarities. Three of the genes, designated ats1B, ats2B, and ats3B, reside in tandem on an 8 kb stretch of the chromosome. These genes share greater than 95% similarity in DNA sequence and encode polypeptides identical in length and 96.7% similar in amino acid sequence. The fourth gene, ats1A, is at least 10 kb removed from, or completely unlinked to the B subfamily. The B subfamily genes are more similar to each other than to ats1A in nucleotide and amino acid sequence. All four genes are interupted by two introns whose placement within the coding region of the genes is conserved. The introns of the B subfamily genes are similar in length and nucleotide sequence, but show no similarity to the introns of ats1A. Comparison of the DNA sequences within the immediate 5 and 3 flanking sequences among the genes revealed only limited regions of homology. S1 analysis shows that all four genes are expressed. 相似文献
10.
Xu J Reumers J Couceiro JR De Smet F Gallardo R Rudyak S Cornelis A Rozenski J Zwolinska A Marine JC Lambrechts D Suh YA Rousseau F Schymkowitz J 《Nature chemical biology》2011,7(5):285-295
Many p53 missense mutations possess dominant-negative activity and oncogenic gain of function. We report that for structurally destabilized p53 mutants, these effects result from mutant-induced coaggregation of wild-type p53 and its paralogs p63 and p73, thereby also inducing a heat-shock response. Aggregation of mutant p53 resulted from self-assembly of a conserved aggregation-nucleating sequence within the hydrophobic core of the DNA-binding domain, which becomes exposed after mutation. Suppressing the aggregation propensity of this sequence by mutagenesis abrogated gain of function and restored activity of wild-type p53 and its paralogs. In the p53 germline mutation database, tumors carrying aggregation-prone p53 mutations have a significantly lower frequency of wild-type allele loss as compared to tumors harboring nonaggregating mutations, suggesting a difference in clonal selection of aggregating mutants. Overall, our study reveals a novel disease mechanism for mutant p53 gain of function and suggests that, at least in some respects, cancer could be considered an aggregation-associated disease. 相似文献