Combined engineering of disaccharide transport and phosphorolysis for enhanced ATP yield from sucrose fermentation in Saccharomyces cerevisiae

Anaerobic industrial fermentation processes do not require aeration and intensive mixing and the accompanying cost savings are beneficial for production of chemicals and fuels. However, the free-energy conservation of fermentative pathways is often insufficient for the production and export of the desired compounds and/or for cellular growth and maintenance. To increase free-energy conservation during fermentation of the industrially relevant disaccharide sucrose by Saccharomyces cerevisiae, we first replaced the native yeast α-glucosidases by an intracellular sucrose phosphorylase from Leuconostoc mesenteroides (LmSPase) (Figure 1). Subsequently, we replaced the native proton-coupled sucrose uptake system by a putative sucrose facilitator from Phaseolus vulgaris (PvSUF1). The resulting strains grew anaerobically on sucrose at specific growth rates of 0.09 ± 0.02 h-1 (LmSPase) and 0.06 ± 0.01 h-1 (PvSUF1, LmSPase). Overexpression of the yeast PGM2 gene, which encodes phosphoglucomutase, increased anaerobic growth rates on sucrose of these strains to 0.23 ± 0.01 h-1 and 0.08 ± 0.00 h-1, respectively. Determination of the biomass yield in anaerobic sucrose-limited chemostat cultures was used to assess the free-energy conservation of the engineered strains. Replacement of intracellular hydrolase with a phosphorylase increased the biomass yield on sucrose by 31%. Additional replacement of the native proton-coupled sucrose uptake system by PvSUF1 increased the anaerobic biomass yield by a further 8%, resulting in an overall increase of 41%. By experimentally demonstrating an energetic benefit of the combined engineering of disaccharide uptake and cleavage, this study represents a first step towards anaerobic production of compounds whose metabolic pathways currently do not conserve sufficient free-energy. Please click Additional Files below to see the full abstract

The HOXB4 Homeoprotein Promotes the Ex Vivo Enrichment of Functional Human Embryonic Stem Cell-Derived NK Cells

Human embryonic stem cells (hESCs) can be induced to differentiate into blood cells using either co-culture with stromal cells or following human embryoid bodies (hEBs) formation. It is now well established that the HOXB4 homeoprotein promotes the expansion of human adult hematopoietic stem cells (HSCs) but also myeloid and lymphoid progenitors. However, the role of HOXB4 in the development of hematopoietic cells from hESCs and particularly in the generation of hESC-derived NK-progenitor cells remains elusive. Based on the ability of HOXB4 to passively enter hematopoietic cells in a system that comprises a co-culture with the MS-5/SP-HOXB4 stromal cells, we provide evidence that HOXB4 delivery promotes the enrichment of hEB-derived precursors that could differentiate into fully mature and functional NK. These hEB-derived NK cells enriched by HOXB4 were characterized according to their CMH class I receptor expression, their cytotoxic arsenal, their expression of IFNγ and CD107a after stimulation and their lytic activity. Furthermore our study provides new insights into the gene expression profile of hEB-derived cells exposed to HOXB4 and shows the emergence of CD34+CD45RA+ precursors from hEBs indicating the lymphoid specification of hESC-derived hematopoietic precursors. Altogether, our results outline the effects of HOXB4 in combination with stromal cells in the development of NK cells from hESCs and suggest the potential use of HOXB4 protein for NK-cell enrichment from pluripotent stem cells

Etude de l'expression conjonctivale de MICA au cours du Syndrome de Gougerot-Sjögren

POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Contribution à l'étude des lymphocytes T NK murins et humains

NANCY1-SCD Medecine (545472101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Etude des interactions entre les lymphocytes iNKT et les cellules dendritiques chez l'homme (implication dans la réponse immunitaire anti-tumorale au cours de la leucémie myéloïde chronique)

POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Geomechanical response of an abandoned chalk mine to multi-annual water table fluctuations

International audienceThe Paris basin contains 35,000–40,000 mines, most of which are abandoned, having mined chalk, a rock very sensitive to water. Although they have been excavated above the groundwater level, some of the mines can be temporarily or permanently flooded, due to (some) exceptional rainfall events. We have thus instrumented the chalk mine of Estreux (Nord department) to measure the impact of the oscillations of the water table on the stability of one of its pillars. It is a mine dug around 20 m deep by the chambers and pillars method. Now abandoned, it is temporarily flooded when the water table, located a few meters below the mine floor, rises due to heavy precipitation, which occurs on average every 8 years. From 2004 to 2012, a pillar was equipped with a convergence rod and two extensometers. There is a correlation between the vertical and horizontal deformation rates of the pillar and the periodic rise in the water table. Chalk samples were also taken in situ and their geomechanical properties characterized in the laboratory. On this basis, a first 3D mechanical simulation of the behavior of this pillar has been carried out taking into account elasticity, plasticity and creep. The calculated mean values of deformation generally match the measurements, and the model succeeds in reproducing the annual fluctuations of these parameters in relation to those of the level of the water table. However, compared to the measurements carried out in situ, the current model exaggerates the vertical deformations compared to the horizontal deformations. However, with this first model, we can observe that the variations in the water table induce elastic and reversible deformations of the pillar, given the absence of plastification of the chalk. These deformations are complementary to those due to the creep induced by the weight of the overlying grounds. If we want to model the long-term behavior of the pillar, particularly under the effect of the fluctuations of the water table induced by the climate change in progress, it is necessary to improve this model, taking into account the hydromechanical couplings and the flows in unsaturated condition. In conclusion, it is proposed to use these data later in a complete mechanical model, still under development at INERIS

Les fonctions innées des lymphocytes T CD8 dans la lutte contre le cancer

International audienceno abstrac

Etude des effecteurs immunorégulateurs chez des patients atteints de cGVHD traités ou non par la PCE

POITIERS-BU Médecine pharmacie (861942103) / SudocSudocFranceF

Identification des effecteurs de l'immunosurveillance au cours de la leucémie myéloïde chronique (du patient à la modélisation chez l'animal)

POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF