Search results for "MST"
showing 10 items of 363 documents
Diverse cell surface protein ectodomains are shed by a system sensitive to metalloprotease inhibitors.
1996
The extracellular domains of a diverse group of membrane proteins are shed in response to protein kinase C activators such as phorbol 12-myristate 13-acetate (PMA). The lack of sequence similarity in the cleavage sites suggests the involvement of many proteases of diverse specificity in this process. However, a mutant Chinese hamster ovary cell line recently isolated for being defective in PMA-activated shedding of the membrane-anchored growth factor transforming growth factor alpha precursor (proTGF-alpha) is concomitantly defective in the shedding of many other unrelated membrane proteins. Here we show that independent mutagenesis and selection experiments yield shedding mutants having th…
Oxidative DNA damage and mutations induced by a polar photosensitizer, Ro19-8022.
1999
The oxidative DNA damage induced by the polar photosensitizer Ro19-8022 in the presence of light was studied and correlated with the associated mutagenicity. Both in isolated DNA and AS52 Chinese hamster ovary cells, photoexcited Ro19-8022 gave rise to a DNA damage profile that was similar to that caused by singlet oxygen: base modifications sensitive to the repair endonuclease Fpg protein, which according to high-performance liquid chromatography (HPLC) analysis were predominantly 8-hydroxyguanine (8-oxoG) residues, were generated in much higher yield than single-strand breaks, sites of base loss (AP sites) and oxidative pyrimidine modifications sensitive to endonuclease III. Fifty percent…
Powder diffraction analysis of gemstone inclusions
2011
Gemstones are pieces of materials that once cut and polished are used as jewels or adornments. Gemstones may be single crystal (such as diamonds), polycrystalline (such as lapis lazuli), or amorphous (such as amber). In any case, gems may have inclusions that may yield a variety of optic effects. It is also important to unravel the crystal structure of the inclusion(s) in order to determine the origin of the gem and to help to understand their formation mechanism. Here, we expand the use of powder diffraction to identify crystalline inclusions in bulk gemstones highlighting Mo Kα radiation to penetrate within compact gems. Initially, rock crystal quartz with rutile needles was investigated …
Hamster Bcl-2 Protein Is Cleaved in Vitro and in Cells by Caspase-9 and Caspase-3
2001
Full-length cDNA of hamster bcl-2 (771 nt) was cloned by RT-PCR and inserted into pGEX-4T-1 to produce the recombinant hamster Bcl-2 protein. The purified recombinant Bcl-2 protein (26.4 kDa) was used as a substrate for the active human caspase-3 and caspase-9 in vitro. It is shown here that Bcl-2 is efficiently cleaved by caspase-3 to a 23 kDa fragment. Although not possessing a putative caspase-9 cleavage site in its sequence, hamster Bcl-2 was also cleaved by caspase-9 into exactly the same 23 kDa cleavage product, indicating that cleavage occurred at the same site. Caspase-3- and caspase-9-mediated cleavage of Bcl-2 was efficiently blocked by caspase-3 (zDEVD) and caspase-9 (zLEHD) inhi…
Expression and trafficking of fluorescent viral membrane proteins in baculovirus-transduced BHK cells
2004
Baculovirus vectors show promise as a novel tool for gene delivery into mammalian cells and gene transfer with wild-type baculovirus has been demonstrated both in vitro and in vivo. To study expression and intracellular trafficking of foreign viral membrane proteins in baculovirus-transduced mammalian cells, the envelope proteins, E1 and E2, of rubella virus (RV) were chosen as a model. The enhanced green fluorescent protein (EGFP) and a red fluorescent protein (RFP) were fused to the C-terminus of E1 and E2, respectively. The proteins were cloned under a cytomegalovirus (CMV) promoter and expressed as fluorescent fusion proteins in baculovirus-transduced baby hamster kidney (BHK) cells. Ex…
Neoclassical Convergence Versus Technological Catch-Up : A Contribution for Reaching a Consensus.
2004
http://www.businessperspectives.org/files/ppm/PPM_EN_2004_03pp15_42.pdf; International audience; New macro empirical evidence is provided to assess the relative importance of object andidea gaps in explaining the world income distribution dynamics over a benchmark period of 1960-1985. Results are then extended through 1995. Formal statistical hypothesis tests allow us to discriminatebetween two competing growth models: (i) the standard neoclassical growth model similarto that employed by Mankiw, Romer, and Weil (1992), and (ii) an endogenous growth modelclosely related to the Nelson and Phelps' approach (1966) that emphasizes the importance of technologytransfer in addition to factor accumu…
HADES RV Programme with HARPS-N at TNG. IV. Time resolved analysis of the Ca II H&K and Hα chromospheric emission of low-activity early-type M dwarfs
2016
Context. M dwarfs are prime targets for current and future planet search programs, particularly those focused on the detection and characterization of rocky planets in the habitable zone. In this context, understanding their magnetic activity is important for two main reasons: it affects our ability to detect small planets and it plays a key role in the characterization of the stellar environment. Aims: We analyze observations of the Ca II H&K and Hα lines as diagnostics of chromospheric activity for low-activity early-type M dwarfs. Methods: We analyze the time series of spectra of 71 early-type M dwarfs collected in the framework of the HADES project for planet search purposes. The HARPS-…
Some substrates and inhibitors of cytosolic epoxide hydrolase induce sister-chromatid exchanges in mammalian cells, but do not induce gene mutations …
1993
Abstract Trans -stilbene oxide, trans -β-methylstyrene, 7,8-oxide, trans -β-ethylstyrene, 7,8-oxide, trans -β-propylstyrene 7,8-oxide and 4-fluorochalcone oxide were investigated for genotoxic activity in bacterial and mammalian cells, in the absence of external xenobiotic-metabolising systems. All compounds strongly enhanced the frequency of sister-chromatid exchanges (SCE) in cultured human lymphocytes. None of them was mutagenic in Salmonella typhimurium (reversion of the his − strains TA98, TA100 and TA104). The limit of detection was 1 20,000 to 1 10 6 of the activity of the positive control, benzo[ a ]pyrene 4,5-oxide, depending on the compound and the bacterial strain. Trans -β-methy…
Squaraine Dyes for Photodynamic Therapy: Study of Their Cytotoxicity and Genotoxicity in Bacteria and Mammalian Cells¶‡
2007
Halogenated squaraine dyes are characterized by long wavelength absorption (>600 nm) and high triplet yields and therefore represent new types of photosensitizers that could be useful for photodynamic therapy. We have analyzed the cytotoxicity and genotoxicity of the bromo derivative 1, the iodo derivative 2 and the corresponding nonhalogenated dye 3 in the absence and presence of visible light. At concentrations of 1-2 microM, 1 and 2 reduced the cloning efficiency of AS52 Chinese hamster ovary cells to less than 1% under conditions that were well tolerated in the dark. Similarly, the proliferation of L5178Y mouse lymphoma cells was inhibited by photoexcited 1 and 2 with high selectivity. …
Mutagenicity of N-substituted phenanthrene 9,10-imines in Salmonella typhimurium and Chinese hamster V79 cells.
1986
We previously showed that some (nonsubstituted) aziridines derived from polycyclic aromatic hydrocarbons (arene imines) elicit various mutagenic and genotoxic effects in bacteria and mammalian cells and that these arene imines are active at much lower concentrations than the corresponding epoxide analogues. In the present study, N-substituted derivatives of phenanthrene 9,10-imine were investigated. All 10 derivatives studied showed direct mutagenicity in Salmonella typhimurium TA100. Some of the compounds additionally exhibited weak effects in the strains TA98 and TA1537. Most N-substituted derivatives were weaker mutagens than unsubstituted phenanthrene 9,10-imine but stronger mutagens th…