271 research outputs found
Fréthun – Les Acqus des Alleux (site O)
Date de l'opération : 1988 (SU) Inventeur(s) : Demarez D La villa gallo-romaine de Fréthun [ (Fig. n°1 : Localisation des zones fouillées), site O], fouillée dans le cadre de l’opération archéologique préliminaire aux travaux du lien fixe Transmanche, fait figure de petite exploitation agricole dont on ne découvrit que deux bâtiments. Le bâtiment d’habitation (A), édifié à l’époque flavienne sur un site déjà occupé,est l’exemple type de la villa à galerie façade. Si les bains, ajoutés au IIe..
Localization of protein aggregation in Escherichia coli is governed by diffusion and nucleoid macromolecular crowding effect
Aggregates of misfolded proteins are a hallmark of many age-related diseases.
Recently, they have been linked to aging of Escherichia coli (E. coli) where
protein aggregates accumulate at the old pole region of the aging bacterium.
Because of the potential of E. coli as a model organism, elucidating aging and
protein aggregation in this bacterium may pave the way to significant advances
in our global understanding of aging. A first obstacle along this path is to
decipher the mechanisms by which protein aggregates are targeted to specific
intercellular locations. Here, using an integrated approach based on
individual-based modeling, time-lapse fluorescence microscopy and automated
image analysis, we show that the movement of aging-related protein aggregates
in E. coli is purely diffusive (Brownian). Using single-particle tracking of
protein aggregates in live E. coli cells, we estimated the average size and
diffusion constant of the aggregates. Our results evidence that the aggregates
passively diffuse within the cell, with diffusion constants that depend on
their size in agreement with the Stokes-Einstein law. However, the aggregate
displacements along the cell long axis are confined to a region that roughly
corresponds to the nucleoid-free space in the cell pole, thus confirming the
importance of increased macromolecular crowding in the nucleoids. We thus used
3d individual-based modeling to show that these three ingredients (diffusion,
aggregation and diffusion hindrance in the nucleoids) are sufficient and
necessary to reproduce the available experimental data on aggregate
localization in the cells. Taken together, our results strongly support the
hypothesis that the localization of aging-related protein aggregates in the
poles of E. coli results from the coupling of passive diffusion- aggregation
with spatially non-homogeneous macromolecular crowding. They further support
the importance of "soft" intracellular structuring (based on macromolecular
crowding) in diffusion-based protein localization in E. coli.Comment: PLoS Computational Biology (2013
The trophoblast clock controls transport across placenta in mice
In mammals, 24-h rhythms of physiology and behavior are organized by a body-wide network of clock genes and proteins. Despite the well-known function of the adult circadian system, the roles of maternal, fetal and placental clocks during pregnancy are poorly defined. In the mature mouse placenta, the labyrinth zone (LZ) is of fetal origin and key for selective nutrient and waste exchange. Recently, clock gene expression has been detected in LZ and other fetal tissues; however, there is no evidence of a placental function controlled by the LZ clock. Here, we demonstrate that specifically the trophoblast layer of the LZ harbors an already functional clock by late gestation, able to regulate in a circadian manner the expression and activity of the xenobiotic efflux pump, ATP-binding cassette sub-family B member 1 (ABCB1), likely gating the fetal exposure to drugs from the maternal circulation to certain times of the day. As more than 300 endogenous and exogenous compounds are substrates of ABCB1, our results might have implications in choosing the maternal treatment time when aiming either maximal/minimal drug availability to the fetus/mother.Fil: Demarez, CĂ©cile. Universität Zu LĂĽbeck; AlemaniaFil: de Assis, Leonardo Vinicius Monteiro. Universität Zu LĂĽbeck; AlemaniaFil: Krohn, Markus. Universität Zu LĂĽbeck; AlemaniaFil: Ramella, Nahuel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - La Plata. Instituto de Investigaciones BioquĂmicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias MĂ©dicas. Instituto de Investigaciones BioquĂmicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Schwaninger, Markus. Universität Zu LĂĽbeck; AlemaniaFil: Oster, Henrik. Universität Zu LĂĽbeck; AlemaniaFil: Astiz, Mariana. Universität Zu LĂĽbeck; Alemania. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
How to account for irrigation withdrawals in a watershed model
In agricultural areas, the downstream flow can be highly influenced by human activities during low-flow periods, especially during dam releases and irrigation withdrawals. Irrigation is indeed the major use of freshwater in the world. This study aims at precisely taking these factors into account in a watershed model. The Soil and Water Assessment Tool (SWAT+) agro-hydrological model was chosen for its capacity to model crop dynamics and management. Two different crop models were compared in terms of their ability to estimate water needs and actual irrigation. The first crop model is based on air temperature as the main determining factor for growth, whereas the second relies on high-resolution data from the Sentinel-2 satellite to monitor plant growth. Both are applied at the plot scale in a watershed of 800 km2 that is characterized by irrigation withdrawals. Results show that including remote sensing data leads to more realistic modeled emergence dates for summer crops. However, both approaches have proven to be able to reproduce the evolution of daily irrigation withdrawals throughout the year. As a result, both approaches allowed us to simulate the downstream flow with a good daily accuracy, especially during low-flow periods.</p
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