Partenaires

CNRS


Rechercher


Accueil > Publications > Recherche par années > Années 1990 > 1994

1994

Page(s) : < | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |

A fluorescence high-performance liquid-chromatography assay for enzymes acting on the di-n-acetylchitobiosyl part of asparagine-linked glycans

The glycoasparagine, Man(7)GlcNAc(2)Asn (’Man(7)’) was labelled with resorufin and used as a specific substrate for the detection and quantification of endo-beta-N-acetyl glucosaminidases (Endos) acting on the di-N-acetylchitobiosyl part of asparagine-linked glycans. Peptide-N-4-(N-acetyl-beta-glucosaminyl) asparagine amidases (PNGases) cannot transform this substrate but they can be detected by the procedure described earlier using the resorufin-labelled N-glycopeptide [Glycoconjugate J., 9 (1992) 162-167]. These two substrates can be used in a simple, reproducible and very sensitive fluorescence HPLC assay in order to monitor Endo and PNGase activities during isolation and purification processes, or studies of the evolution of such activities during cultivation of the producing cells.

Lire la suite

A monoclonal-antibody inhibits adhesion to fibronectin and vitronectin of a colon-carcinoma cell-line and recognizes the integrins a ;(v)ß(3), a ;(v)ß(5), and a ;(v)ß(6)

Using whole viable human colon carcinoma HT29 cells as immunogen, we produced a monoclonal antibody (mAb) termed 69-6-5. The antibody was functionally selected on its anti-cell-spreading activity. By immunoprecipitation of surface radiolabeled cell lysates from HT29-D4 cells (an HT29 cell clone), mAb 69-6-5 recognized a molecular complex resembling integrin heterodimers.

Lire la suite

A Moon-based laboratory for extraterrestrial sample analysis

If organic molecules were safely delivered to the early Moon, they may still be present beneath the currently gardened lunar regolith at a depth of 10 m or more. A Moon based laboratory would be helpful to search for organic matter below the surface layers since the problem of terrestrial contamination, which has been a major concern in the past analysis of returned lunar samples, will be overcome. The moon provides also a sterile platform for collection and analysis of individual cosmic dust particles assuming special devices to slowly decelerate the particles allowing a nondestructive capture.

Lire la suite

A negative regulatory element of the macrophage-specific human mannose receptor gene represses its expression in nonmyeloid cells

We have cloned the putative promoter of the human mannose receptor gene using the ligation-mediated polymerase chain reaction. This modified polymerase chain reaction method depends upon the ligation of restricted genomic DNA fragments to a sequence of DNA containing a generic primer site. Approximately 400 bp of genomic DNA sequence immediately upstream from the 5’ end of the lectin gene was amplified with this strategy. Primer-extended reverse transcription identified several 5’ ends of the mannose receptor mRNA corresponding to differential use of initiation transcription sites.

Lire la suite

A SV40 immortalized murine endothelial-cell line from peripheral lymph-node high endothelium expresses a new a-L-fucose binding-protein

Endothelial cells from mouse peripheral lymph nodes were immortalized by cationic liposome-mediated transfection using a plasmid construct containing both the gene coding for the large T antigen of simian virus 40 and a geneticin resistance gene suitable for selection. A cell line (HECa10) was isolated on the basis of its capacity to specifically bind fucoside carrying glycoconjugates ; these cells present the main characteristics of endothelial cells : production of angiotensin converting enzyme and of factor VIII-related antigen.

Lire la suite

An EBV based vector allowing high level of LTRHIV-directed expression in human cells

We have developed a vector that allows high and transactivable expression of inserted genes. The vector contains a transcription unit in which the LTR from HN flanks a multicloning site. The plasmid is based on the EBV p205 plasmid, which allows stable replication in human cells. The ability of the vector to express an exogenous DNA in human cells has been tested using the firefly luciferase gene. (C) 1994 Academic Press. Inc.

Lire la suite

An inhibitor of cytotoxic functions produced by cd8(+)cd57(+) t-lymphocytes from patients suffering from aids and immunosuppressed bone-marrow recipients

An inhibitor of the cytotoxic functions (ICF) mediated by human immunodeficiency virus (HIV)- or HLA-specific cytotoxic T lymphocytes, natural killer and lymphokine-activated killer (LAK) cells is secreted by CD8(+)CD57(+) T lymphocytes, a subset expanded during infection with HIV and after bone marrow transplantation. We previously showed an apparent molecular mass of 20-30 kDa for this soluble glycosylated concanavalin A-binding inhibitor which is distinct from known cytokines. Here, we report a characterization of the mechanism of action of this CD8(+)CD57(+) ICF. We show that the ICF-induced inhibition of LAK cell cytolytic activity is transient, with a spontaneous recovery of cytolytic potential after 18 h.

Lire la suite

Archaebacterial histone-like protein mc1 can exhibit a sequence-specific binding to DNA

The binding of MC1 protein, the major chromosomal protein of the archaebacterium Methanosarcina sp. CHTI 55, to the region preceding the strongly expressed genes encoding methyl coenzyme reductase in a closely related micro-organism has been investigated. By gel retardation and DNAase I footprinting assays, we identified a preferential binding sequence in an open reading frame of unknown function. The large area of DNA protected against DNAase I is interrupted by a strong cleavage enhancement site on each strand. By circular permutation assays, we showed that the DNA bends upon MC1 binding. Furthermore we observed that the presence of a sequence outside the binding site can induce an unusual electrophoretic behaviour in some complexes.

Lire la suite

Archaebacterial histone-like protein MC1 can exhibit a sequence-specific binding toDNA

The binding of MC1 protein, the major chromosomal protein of the archaebacterium Methanosarcina sp. CHTI 55, to the region preceding the strongly expressed genes encoding methyl coenzyme reductase in a closely related micro-organism has been investigated. By gel retardation and DNAase I footprinting assays, we identified a preferential binding sequence in an open reading frame of unknown function. The large area of DNA protected against DNAase I is interrupted by a strong cleavage enhancement site on each strand. By circular permutation assays, we showed that the DNA bends upon MC1 binding. Furthermore we observed that the presence of a sequence outside the binding site can induce an unusual electrophoretic behaviour in some complexes.

Lire la suite

Page(s) : < | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |