Mostrando 25-36 de 82 artigos, teses e dissertações.
25. Properties of the Bacillus subtilis chemotaxis protein CheF, a homolog of the Salmonella typhimurium flagellar protein FliJ.
The nucleotide sequence of Bacillus subtilis cheF was corrected. It encodes an 18-kDa protein that is homologous to FliJ, a protein required for formation of basal bodies in Escherichia coli and Salmonella typhimurium. Methanol release is abnormal in cheF mutants, suggesting that the morphology and functioning of the motor affects methanol formation.
26. Gene amplification: an example of accelerated evolution in tumorigenic cells.
During selection for methotrexate resistance, tumorigenic CHEF/16 cells and derivatives from CHEF/16 tumors underwent amplification of the dihydrofolate reductase gene (DHFR) at accelerated rates compared with closely related nontumorigenic CHEF/18 cells. "Dot blot" analysis showed that the CHEF/16 cells contained many more copies of the DHFR gene than did t
27. Intracellular pH is increased after transformation of Chinese hamster embryo fibroblasts.
These studies reveal that a series of tumorigenic Chinese hamster embryo fibroblast (CHEF) cell lines maintain an internal pH (pHi) that is 0.12 +/- 0.04 pH unit above that of the nontumorigenic CHEF/18 parental line. This increase of pHi in the tumorigenic CHEF cells is not due to autocrine growth factor production or to the persistent activation of pathway
28. DNA transfer of focus- and tumor-forming ability into nontumorigenic CHEF cells.
CHEF/18 fibroblastic cells derived from a Chinese hamster embryo are diploid and nontumorigenic and require multiple steps of chemical treatment and selection to produce tumorigenic derivatives. In this report, CHEF/18 cells and a mutant capable of growing in medium with a low concentration of serum, LS1-1, were recipients in DNA transfer experiments using t
29. Lysis of Chinese hamster embryo fibroblast mutants by human natural cytotoxic (NK) cells.
The nontransformed, nontumorigenic CHEF/18 Chinese hamster embryo fibroblast line, as well as nontumorigenic CHEF/18 mutants that had become anchorage independent or acquired a reduced serum requirement for growth, and fully transformed, tumorigenic CHEF cell lines were analyzed for their sensitivity to killing in vitro by human natural killer (NK) cells. No
30. Azacytidine-induced tumorigenesis of CHEF/18 cells: correlated DNA methylation and chromosome changes.
5-Azacytidine (azaC), a drug that induces decreased methylation of DNA in mammalian cells, was shown previously to induce differentiation of mesenchymal cell types in CHEF/18 cells (Chinese hamster embryo fibroblasts). This paper describes the effectiveness of azaC in inducing tumorigenicity in CHEF/18 cells, previously shown to be nontumorigenic stable dipl
31. Comparison of restriction enzyme analysis and pulsed-field gradient gel electrophoresis as typing systems for Candida albicans.
Candida species are an important cause of infection in immunocompromised hosts and the leading cause of nosocomial fungal infections. Study of the epidemiology of Candida infection has been difficult because of lack of a reliable typing system. We describe a typing system utilizing contour-clamped homogeneous electric fields (CHEF), which is a modified versi
32. Comparison of field inversion gel electrophoresis with contour-clamped homogeneous electric field electrophoresis as a typing method for Enterococcus faecium.
Direct comparisons between contour-clamped homogeneous electric field (CHEF) electrophoresis and field inversion gel electrophoresis (FIGE) to determine the epidemiology of antibiotic-resistant enterococci have not been previously published. Fifty non-beta-lactamase-producing, ampicillin-resistant Enterococcus faecium isolates and 10 vancomycin-resistant E.
33. Tumorigenicity and its suppression in cybrids of mouse and Chinese hamster cell lines.
The effect of cytoplasm upon the expression of tumorigenicity was examined with a pair of mouse and a pair of Chinese hamster cell lines, in intraspecies cybrids formed by reciprocal fusions between either tumorigenic or nontumorigenic cells and cytoplasms derived from them. With the mouse cells, 3T3 and the simian virus 40-transformed line SVT2, the cybrid
34. Comparison of restriction enzyme analysis versus pulsed-field gradient gel electrophoresis as a typing system for Torulopsis glabrata and Candida species other than C. albicans.
Candida species have recently emerged as important nosocomial pathogens. Because of the lack of a reliable system for detecting differences within the same species, little is known about the epidemiology of infection with Candida species. We describe a typing system for Torulopsis glabrata and the non-C. albicans Candida species that uses contour-clamped hom
35. Transfection with plasmid pSV2gptEJ induces chromosome rearrangements in CHEF cells.
In previous cytogenetic studies, trisomy for 3q was found to be the most frequent chromosome change associated with induced tumorigenicity by a variety of agents in Chinese hamster cells. Here we describe similar chromosome changes in 11 lines of CHEF/18 cells transfected with the mutant c-Ha-ras containing plasmid pSV2gptEJ. All 11 lines contained the trans
36. Suppression of tumorigenicity in hybrids of normal and oncogene-transformed CHEF cells.
Somatic cell hybridization experiments were carried out to determine whether normal cells have the ability to suppress the transforming effects of a defined oncogene. A nontransformed Chinese hamster embryo fibroblast cell line (CHEF/18-dm2) was used as the normal parent, and a CHEF/18 transfectant carrying the human mutant c-Ha-ras (EJ) oncogene was used as