ELEMENTS AGISSANT EN CIS DANS LA TRANSFORMATION CELLULAIRE PAR LES ADENOVIRUS

International audienc

Hydrothermal treatment of spent contaminated Ion Exchange Resins in sub and supercritical water.

International audienceSome water treatment systems in nuclear industry involve Ion Exchange Resins (IER) to control water chemistry, minimize equipment corrosion and remove radioactive contaminants. Typically, the volume of contaminated IER from a nuclear power plant is around 5-7 m3 per reactor and per year. The different issues studied for these IER solid waste is either the immobilization in an inert matrix (cement, bitumen, polymer) or the mineralization, so as to obtain inorganic residues before solidification [1]. Among mineralization processes, hydrothermal treatment in sub or supercritical water may be a promising alternative to leach resins and recover radionuclides such as 137Cs, 90Sr, 60Co or transuranic in an aqueous solution. Thus, the secondary waste would be solid waste of lower radioactivity, which may be incinerated or immobilized, and liquid wastewater containing radionuclides, which can be managed simply by the liquid treatment facility. Previous studies carried out using continuous supercritical water oxidation setup allow to reach 99.9% degradation yields on crushed IER [2]. Unfortunately, owing to IER radiolytical and thermal deterioration and high radioactivity, a grinding preprocessing step is not easy to manage. This is the reason why batch and semi-dynamic process have been considered on millimeter size resins. This study deals with the feasibility of leaching IER by hydrolysis and/or oxidation (by H2O2) runs carried out with temperature and pressure respectively ranging from 100 and 450°C and from 20 and 300 bar. Considered IER are strong cationic Amberlite IRN77 and anionic Amberlite IRN78. Contamination of each species of interest (Cs, Sr, Co and Eu) is 10 mg/g IER. The setup used to carry out runs under subcritical and supercritical hydrothermal conditions is described Figure 1. A titanium jacket allows to confine aggressive species and protect reactor outer walls from corrosion. Furthermore, this jacket is flexible to compensate any difference of pressure with the reactor. During batch experimental runs, {IER/ water or water + H2O2 with stoichiometric ratio equal to 1.3} mixture is introduced into the jacket while the reactor is filled with water, with equivalent volume ratios. This ratio has been set to reach targeted autogenous pressure (between 60 and 290 bar) according to operating temperature (300 or 450°C). The duration of runs is about 4h. Then, the experimental setup has been modified to be used in semi-dynamic mode. IER samples are introduced into a basket, inside the reactor, which is then fed continuously with a {water or water + H2O2} stream at a 5 mL/min flow rate. The reactor is heated until the working temperature is reached (set between 100 and 290°C). Pressure (from 5 to 50 bar) is controlled by a back pressure regulator. The aqueous effluents are then recovered downstream, in a collector, after cooling and depressurization. The treatment capacity of this setup is 50 g of IER per batch.Solid residues as well as generated effluents are gravimetrically analyzed. TOC-metry is used to measure carbon degradation yields. ICP-AES and AAS analyzers are used to measure ions release (Sr, Co, Eu and Cs). Experimental runs in batch mode allow to highlight following trends. Whatever operating conditions, carbon degradation yields higher than 86% are obtained, with especially yield around 99.7% for hydrothermal oxidation of IRN77 IER at 450°C/290 bar. Cs, Sr and Eu leaching yields close to 100% are noticeable not only for supercritical water treatment of IRN77 or {IRN77/IRN78} mixtures but also for subcritical water treatment at 300°C/for 70 bar. On the contrary, Co leaching yield is lower than 10% for each experimental run, because of “CoS type compounds” precipitation. Speciation study in hydrothermal medium is in progress to predict and explain these results.Semi-dynamic device allows to entirely decontaminate 50g of exchanged IER in 3h with softer operating conditions (200°C/50 bar/oxidation with H2O2). Furthermore, significant cobalt extraction capacity, around 460 mg/kg of water, has been obtained. Such results will be considered both for the process scale-up and for the compatibility with the downstream wastewater treatment plant

Non-heparan sulfate GAG-dependent infection of cells using an adenoviral vector with a chimeric fiber conserving its KKTK motif

AbstractRecently, the potential involvement of the putative heparan sulfate proteoglycans (HSPG) binding motif, KKTK, in mediating HAdV-5 liver cell infection following intravascular virus delivery has been debated. In the present study, we demonstrated that HSPGs were not involved in the in vitro infection process of an adenoviral vector harboring chimeric fibers without mutation in the KKTK motif, HAdV-5-F2/BAdV-4. The entry of HAdV-5-F2/BAdV-4 into cells occurs by two mechanisms 1) the attachment of HAdV-5-F2/BAdV-4 to the surface of cells requires N-glycosylation, 2) the uptake of the virus is effective after interaction with a co-receptor, putatively the chondroitin sulfate C. Together, these results contribute to improving our understanding of the molecular mechanisms determining HAdV's infectivity in vitro and may aid in designing novel HAdV-based vectors for gene therapy applications

Rapid production of transgenic wheat plants by direct bombardment of cultured immature embryos

6 Pags.We have developed an improved protocol for the rapid and efficient production of transgenic wheat. Three plasmids, each containing the selectable bar gene for resistance to the herbicide Basta and the beta-glucuronidase (GUS) reporter gene, were delivered via particle bombardment, directly into immature embryos of two spring and one winter cultivar of wheat four days to two months after culture. Resistant calli were selected on phosphinothricin (PPT) media and screened for histochemical GUS activity. Twelve independent callus lines showing phosphinothricin acetyltransferase (PAT) activity were recovered from the bombardment of 544 explants (374 immature embryos and 170 one or two month old calli). R0 plants were regenerated from seven of these lines, of which so far five have produced R1 progeny, and two of the latter have produced R2 progeny. PAT activity was detected in each of the plants tested from the seven R0 lines, as well as in a 1:1 or 3:1 ratio in R1 plants following cross or self pollination, respectively. Resistance to topical application of Basta was seen in PAT positive plants and transgenic progeny. Molecular analysis by Southern hybridization showed the presence of the bar gene in all PAT positive R0 and R1 plants analyzed. Hybridization of the bar gene probe with high molecular weight DNA further confirmed integration into nuclear DNA. Both male and female transmission of the bar gene, and its segregation as a dominant Mendelian trait in R1 and R2 plants, were demonstrated. Flowering transgenic R0 plants could be obtained in 7–9 months following excision and culture of immature embryos.Peer reviewe