Cell responses to xenobiotics: comparison of MCF7 multi-drug- and mussel blood cell multi-xenobiotic-defense mechanisms     

Marin M  Legros H  Poret A  Leboulenger F  Le Foll F 《Marine environmental research》2004,58(2-5):209-213

Multi-drug resistance (MDR) in MCF7 breast cancer cells and multi-xenobiotic resistance (MXR) in mussel (Mytilus edulis) blood cells (MBC) are well known mechanisms that contribute to the decrease in intracellular concentrations of many unrelated but cytotoxic compounds. In the present work, we have carried out comparative investigations of the MDR/MXR protective mechanisms using a rapid colorimetric assay for cell viability and calcein accumulation for MDR/MXR activities. These studies were performed using cultured MCF7 and MBC before and after in vitro exposure to xenobiotics. Our results indicate that a 5-day exposure to doxorubicin or vincristine decreased calcein accumulation in MBC which is consistent with an induction of multi-xenobiotic resistance. The increase in calcein accumulation provoked by 1-h treatment with 50 microM verapamil was much lower in MBC when compared to the P-glycoprotein overexpressing MCF7 cell line. We conclude that such microplate assays could be used in primary cultures of MBC to estimate the effects of various chemicals on MXR activity.  相似文献   

Rhodamine exclusion activity in primary cultured turbot (Scophthalmus maximus) hepatocytes     

Tutundjian R  Minier C  Le Foll F  Leboulenger F 《Marine environmental research》2002,54(3-5):443-447

Cellular detoxification by direct processes has been investigated in fish by studying the ability of hepatocytes prepared from juvenile aquarium-reared turbot (Scophthalmus maximus) to actively exclude the fluorescent dye rhodamine B (RB). Cell viability was studied by measurements of non-specific esterase activity using fluorescein diacetate. This revealed that turbot hepatocytes can be cultured for a few days with a viability decreasing to 38% after 24 h. The 24-h cultured cells have been used to study the rhodamine B exclusion activity using confocal laser microscopy. Hepatocytes accumulated the dye in a competitive manner with verapamil, thus suggesting that they express a transport system similar to the P-glycoprotein-mediated multixenobiotic resistance process. Incubation of cells with 1 microM RB and 20 microM verapamil led to a 26% increase of cellular fluorescence as compared to the accumulation in absence of competitor. Rhodamine B accumulated in the whole cytoplasm, with more concentrated areas that might correspond to the lysosomal compartment and the cell membrane.  相似文献   

Emplacement of Semail–Emirates ophiolite at ridge–trench collision          下载免费PDF全文

Adolphe Nicolas  Françoise Boudier 《地学学报》2017,29(2):127-134

The Oman‐Emirates is the largest and best‐exposed ophiolite; consequently, it has attracted significant interest among scientists, together with serious conflicts. Most geologists regard this ophiolite as having formed in an intra‐oceanic subduction zone before being accreted to the Arabian continent. Here, we propose an alternative scenario, supported by detailed field observations and integrated geophysics. The smaller Emirates part of the ophiolite was forced into a nearby continent, in the pre‐collision stage of Tethyan closure. The contraction led to the exhumation of the mantle floor of segmented basins accreted in a rifted system similar to the present‐day Gulf of California. The implied high temperature–high pressure metamorphism and the range of geochemical signatures were introduced during the process of rifting, whereas the larger Oman ophiolite was emplaced by obduction onto and along the subducting continental shore. This Ridge–Trench–Transform system might call for a new process to obduct over continents in particular Tethyan ophiolites.  相似文献   

Polyphase seismic faulting in the Ivrea zone (Italian Alps) revealed by 40Ar/39Ar dating of pseudotachylytes     

François Souquière  Patrick Monié  Olivier Fabbri  Alain Chauvet 《地学学报》2011,23(3):162-170

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2017 Leonard Medal for Mark Thiemens          下载免费PDF全文

François Robert 《Meteoritics & planetary science》2017,52(8):1754-1755

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Second‐order work analysis for granular materials using a multiscale approach     

François Nicot  Nejib Hadda  Félix Darve 《国际地质力学数值与分析法杂志》2013,37(17):2987-3007

It has been established that the second‐order work criterion is a general necessary condition for all instabilities by divergence in rate‐independent granular materials. The relation between the values of discrete second‐order work at the intergranular contact point level and its global macroscopic value is recalled at the beginning of this paper. Then, the basic purpose of the paper is tackled by an analysis of the main features of second‐order work criterion in relation with the granular microstructure. For that, it is considered a novel micromechanical model (the so‐called ‘H‐microdirectional model’), which has the property to involve three scales: grain scale, mesoscale with a specific granular configuration and continuum mechanics macroscale. Eventually, these exhibited features (a bifurcation stress domain and some instability cones) are qualitatively compared with the ones provided by direct numerical simulations issued from a discrete element model. The ultimate goal is to analyse what happens at the granular scale, when the macrosecond‐order work is vanishing at the macrolevel. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

River flux uncertainties predicted by hydrological variability and riverine material behaviour     

Florentina Moatar  Michel Meybeck  Sébastien Raymond  François Birgand  Florence Curie 《水文研究》2013,27(25):3535-3546

Data on riverine fluxes are essential for calculating element cycles (carbon, nutrients, pollutants) and erosion rates from regional to global scales. At most water‐quality stations throughout the world, riverine fluxes are calculated from continuous flow data (q) and discrete concentration data (C), the latter being the main cause of sometimes large uncertainties. This article offers a comprehensive approach for predicting the magnitude of these uncertainties for water‐quality stations in medium to large basins (drainage basin area > 1000 km²) based on the commonly used discharge‐weighted method. Uncertainty levels – biases and imprecisions – for sampling intervals of 3 to 60 days are correlated first through a nomograph with a flux variability indicator, the quantity of riverine material discharged in 2% of time (M_2%). In turn, M_2% is estimated from the combination of a hydrological reactivity index, W_2% (the cumulative flow volume discharged during the upper 2% of highest daily flow) and the truncated b_50sup exponent, quantifying the concentration versus discharge relationship for the upper half of flow values (C = a q ^b50sup, for q > q₅₀, where q₅₀ is the median flow): M_2% = W_2% + 27.6b_50sup. W_2% can be calculated from continuous flow measurements, and the b_50sup indicator can be calculated from infrequent sampling, which makes it possible to predict a priori the level of uncertainty at any station, for any type of riverine material either concentrated (b_50sup > 0) or diluted (b_50sup > 0) with flow. A large data base of daily surveys, 125 station variables of suspended particulate matter (SPM), total dissolved solids (TDS) and dissolved and particulate nutrients, was used to determine uncertainties from simulated discrete surveys and to establish relationships between indicators. Results show, for example, that for the same relatively reactive basin (W_2% > 25%), calculated fluxes from monthly sampling would yield uncertainties approaching ±100% for SPM (b_50sup > 1.4) fluxes and ±10% for TDS (b_50sup = ?0.2). The application to the nitrate survey of the river Seine shows significant trends for the 1972–2009 records. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Nonlinear homogenization approach to the friction coefficient of a quartz‐clay fault gouge     

Jean‐François Barthélémy  Christine Souque  Jean‐Marc Daniel 《国际地质力学数值与分析法杂志》2013,37(13):1948-1968

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Origin of components in Chilean thermal waters     

François Risacher  Bertrand Fritz  Arturo Hauser 《Journal of South American Earth Sciences》2011,31(1):153-170

Thermal waters of northern (18°–27°S) and southern (37°–45°S) Chile occur in two very different climatic, geologic and hydrologic environments: arid closed basins with abundant evaporites in the north; humid climate and well drained valleys in the south. The origin and behavior of the main components of the two groups of waters are examined and compared to each other. The modeling of the alteration of volcanic rocks leads to water compositions very different from those observed both in the north and south. In addition to hydrothermal alteration and deep emanations, the Cl/Br ratio reveals a major contribution of saline waters to the two groups: infiltrating brines from salt lakes in the north; seawater in the south.In the north, concentrations of Cl, Br, Na, K, Ca, SO₄, Li, B, Si result from the mixing of alteration waters with recycled brines. Hydrothermal alteration is obscured by this massive saline input, except for Mg. δ³⁴S values are consistent with an origin of sulfate from salar brines, which are themselves derived from deep Tertiary gypsum. In the south, two processes account for the composition of thermal waters: mixing of alteration waters with seawater and deep magmatic contribution. The mixing process controls the concentration of Cl, Br, Na, Alk, Si, K, Ca, Mg. Magmatic inputs are detectable for SO₄, Li and B. δ³⁴S suggests that sulfate stems from the mixing of alteration waters with either marine SO₄ in coastal waters or with deep SO₂ in inland waters. In both the north and south, the Mg concentration is drastically lowered (<1 μmol/L) by the probable formation of a chlorite-type mineral. In the south, very small amounts of seawater (<1% in volume) are sufficient to imprint a clear signature on thermal waters. Not only coastal springs are affected by seawater mixing, but also remote inland springs, as far as 150 km from the sea. Subduction of marine sediments in the accretive margin could be the source of the marine imprint in thermal waters of southern Chile. Seawater may be expelled from the subducted lithosphere and incorporated into the mantle source.  相似文献   

Deep crustal source of gneiss dome revealed by eclogite in migmatite (Montagne Noire,French Massif Central)     

Donna L. Whitney  Clémentine Hamelin  Christian Teyssier  Natalie H. Raia  Megan S. Korchinski  Nicholas C. A. Seaton  Brian C. Bagley  Anette von der Handt  Françoise Roger  Patrice F. Rey 《Journal of Metamorphic Geology》2020,38(3):297-327

In orogens worldwide and throughout geologic time, large volumes of deep continental crust have been exhumed in domal structures. Extension-driven ascent of bodies of deep, hot crust is a very efficient mechanism for rapid heat and mass transfer from deep to shallow crustal levels and is therefore an important mechanism in the evolution of continents. The dominant rock type in exhumed domes is quartzofeldspathic gneiss (typically migmatitic) that does not record its former high-pressure (HP) conditions in its equilibrium mineral assemblage; rather, it records the conditions of emplacement and cooling in the mid/shallow crust. Mafic rocks included in gneiss may, however, contain a fragmentary record of a HP history, and are evidence that their host rocks were also deeply sourced. An excellent example of exhumed deep crust that retains a partial HP record is in the Montagne Noire dome, French Massif Central, which contains well-preserved eclogite (garnet+omphacite+rutile+quartz) in migmatite in two locations: one in the dome core and the other at the dome margin. Both eclogites record P ~ 1.5 ± 0.2 GPa at T  ~  700 ± 20°C, but differ from each other in whole-rock and mineral composition, deformation features (shape and crystallographic preferred orientation, CPO), extent of record of prograde metamorphism in garnet and zircon, and degree of preservation of inherited zircon. Rim ages of zircon in both eclogites overlap with the oldest crystallization ages of host gneiss at c. 310 Ma, interpreted based on zircon rare earth element abundance in eclogite zircon as the age of HP metamorphism. Dome-margin eclogite zircon retains a widespread record of protolith age (c. 470–450 Ma, the same as host gneiss protolith age), whereas dome-core eclogite zircon has more scarce preservation of inherited zircon. Possible explanations for differences in the two eclogites relate to differences in the protolith mafic magma composition and history and/or the duration of metamorphic heating and extent of interaction with aqueous fluid, affecting zircon crystallization. Differences in HP deformation fabrics may relate to the position of the eclogite facies rocks relative to zones of transpression and transtension at an early stage of dome development. Regardless of differences, both eclogites experienced HP metamorphism and deformation in the deep crust at c. 310 Ma and were exhumed by lithospheric extension—with their host migmatite—near the end of the Variscan orogeny. The deep crust in this region was rapidly exhumed from ~50 to <10 km, where it equilibrated under low-P/high-T conditions, leaving a sparse but compelling record of the deep origin of most of the crust now exposed in the dome.  相似文献