Cytoplasmic Incompatibility as a Means of Controlling Culex pipiens quinquefasciatus Mosquito in the Islands of the South-Western Indian Ocean

The use of the bacterium Wolbachia is an attractive alternative method to control vector populations. In mosquitoes, as in members of the Culex pipiens complex, Wolbachia induces a form of embryonic lethality called cytoplasmic incompatibility, a sperm-egg incompatibility occurring when infected males mate either with uninfected females or with females infected with incompatible Wolbachia strain(s). Here we explore the feasibility of the Incompatible Insect Technique (IIT), a species-specific control approach in which field females are sterilized by inundative releases of incompatible males. We show that the Wolbachia wPip(Is) strain, naturally infecting Cx. p. pipiens mosquitoes from Turkey, is a good candidate to control Cx. p. quinquefasciatus populations on four islands of the south-western Indian Ocean (La Réunion, Mauritius, Grande Glorieuse and Mayotte). The wPip(Is) strain was introduced into the nuclear background of Cx. p. quinquefasciatus mosquitoes from La Réunion, leading to the LR[wPip(Is)] line. Total embryonic lethality was observed in crosses between LR[wPip(Is)] males and all tested field females from the four islands. Interestingly, most crosses involving LR[wPip(Is)] females and field males were also incompatible, which is expected to reduce the impact of any accidental release of LR[wPip(Is)] females. Cage experiments demonstrate that LR[wPip(Is)] males are equally competitive with La Réunion males resulting in demographic crash when LR[wPip(Is)] males were introduced into La Réunion laboratory cages. These results, together with the geographic isolation of the four south-western Indian Ocean islands and their limited land area, support the feasibility of an IIT program using LR[wPip(Is)] males and stimulate the implementation of field tests for a Cx. p. quinquefasciatus control strategy on these islands

Rôle de l'activité hydrolytique bactérienne dans le cycle de la matière organique en milieu marin (focus sur les enzymes lipase)

Après une étude bibliographique rappelant l'importance de l'activité ectoenzymatique bactérienne dans le cycle du carbone organique en milieu marin, ce manuscrit, ciblé sur l'étude du modèle lipides - lipases, présente les étapes qui ont permis de mettre au point un protocole fournissant des mesures réalistes de l'activité lipase des bactéries marines en suivant la dégradation d'un substrat triglycéride radioactif : la [3H]-trioléine. Au cours d'une étude dans le lagon de Nouvelle-Calédonie, cette nouvelle technique a été comparée avec la technique traditionnelle qui utilise des analogues fluorescents, et s'est révélée être plus spécifique, sensible et reproductible. Puis, comparée aux mesures chimiques de l'hydrolyse d'un triglycéride au cours d'une expérience de biodégradation in vitro, elle s'est avérée refléter de manière significative l'activité lipase s'exerçant in situ. Suite à ces deux étapes de validation, ce protocole a été utilisé au cours d'une étude environnementale en Méditerranée nord-occidentale dans le cadre du projet PROOF-PROPECHE, notamment pour mettre en évidence le rôle joué par l'hydrolyse ectoenzymatique dans l'accumulation de carbone organique dissous au cours de la transition printanière du milieu vers l'oligotrophieAIX-MARSEILLE1-BU Sci.St Charles (130552104) / SudocSudocFranceF

A Pre-Sizing Method for Salient Pole Synchronous Reluctance Machines with Loss Minimization Control for a Small Urban Electrical Vehicle Considering the Driving Cycle

In this paper, a design methodology for synchronous reluctance machines (SynRM) working with variable torque and speed profiles was presented. Unlike conventional solutions which size the machine considering a reduced number of working points in order to reduce the computation time, the solution proposed in this paper takes into account all the points which allow for better management of the constraints along the cycle to avoid an oversizing of the machine. To solve this problem with a reduced computation time, the geometry of the motor as well as the control strategy were optimized in two steps. In the first step, the d-q axis stator currents were analytically expressed. In the second step, the geometry was optimized with the use of a genetic algorithm. As an application of this method, the case of a small and low-cost electric vehicle (EV) was chosen with the objective of minimizing both the mass and the energy lost for the standardized urban dynamometer driving schedule (UDDS). The method was based on the use of a 1-D analytical model which was validated by a 2D finite element analysis (FEA)

Rétif de La Bretonne, "Les Revies" (essai d'archéologie littéraire, édition critique avec introd., notes et variantes d'après des manuscrits autographes inédits)

POITIERS-BU Droit Lettres (861942101) / SudocSudocFranceF

Functional analyses of phosphatidylserine/PI(4)P exchangers with diverse lipid species and membrane contexts reveal unanticipated rules on lipid transfer

International audienceBackground: Lipid species are accurately distributed in the eukaryotic cell so that organelle and plasma membranes have an adequate lipid composition to support numerous cellular functions. In the plasma membrane, a precise regulation of the level of lipids such as phosphatidylserine, PI(4)P, and PI(4,5)P 2 , is critical for maintaining the signaling competence of the cell. Several lipid transfer proteins of the ORP/Osh family contribute to this fine-tuning by delivering PS, synthesized in the endoplasmic reticulum, to the plasma membrane in exchange for PI(4)P. To get insights into the role of these PS/PI(4)P exchangers in regulating plasma membrane features, we question how they selectively recognize and transfer lipid ligands with different acyl chains, whether these proteins exchange PS exclusively for PI(4)P or additionally for PI(4,5)P 2 , and how sterol abundance in the plasma membrane impacts their activity. Results: We measured in vitro how the yeast Osh6p and human ORP8 transported PS and PI(4)P subspecies of diverse length and unsaturation degree between membranes by fluorescence-based assays. We established that the exchange activity of Osh6p and ORP8 strongly depends on whether these ligands are saturated or not, and is high with representative cellular PS and PI(4)P subspecies. Unexpectedly, we found that the speed at which these proteins individually transfer lipid ligands between membranes is inversely related to their affinity for them and that high-affinity ligands must be exchanged to be transferred more rapidly. Next we determined that Osh6p and ORP8 cannot use PI(4,5)P 2 for exchange processes, because it is a low-affinity ligand, and do not transfer more PS into sterol-rich membranes. Conclusions: Our study provides new insights into PS/PI(4)P exchangers by indicating the degree to which they can regulate the acyl chain composition of the PM, and how they control PM phosphoinositide levels. Moreover, we establish general rules on how the activity of lipid transfer proteins relates to their affinity for ligands

Can evolutionary biology help better predict the risks associated with population control using gene drives?

National audienc

Techno-economic Optimization of Flywheel Storage System in transportation

Energy storage technologies in transport applications are continuously improved and updated to ensure energy demand, to decrease the fuel consumption and in order to make systems more reliable. Flywheel kinetic energy storage offers very good features such as power and energy density. Moreover, with some short-range vehicles such as buses or small ferries, this technology can be enough to supply all the energy to the power train.The challenges to be met to integrate such technology in vehicles are the mass, the efficiency and especially the cost. Then, in this paper, a techno-economic optimization of a flywheel energy storage system is presented. It is made up of a flywheel, a permanent magnet synchronous machine and a power converter. For each part of the system, physical and economical models are proposed. Finally, an economic optimization is done on a short-range ship profil, currently using supercapacitors

Can evolutionary biology help better predict the risks associated with population control using gene drives?

National audienc

Application of a Specific and Sensitive Radiometric Assay for Microbial Lipase Activities in Marine Water Samples from the Lagoon of Nouméa

Marine microbiologists commonly assay lipase activities by using a synthetic fluorescent analog, 4-methylumbelliferyl (MUF)-oleate. The technique is convenient, but it is considered to be unspecific because of the structure of this analog. This study reports the design of a new specific and sensitive lipase assay based on the use of a radiolabeled triglyceride, [(3)H]triolein. Free fatty acids (FFA) resulting from its hydrolysis are isolated as a function of time in a one-step liquid-liquid extraction and then radioassayed. MUF-oleate and [(3)H]triolein techniques were compared by measuring lipase activities at similar substrate concentrations along a trophic gradient in the Southwest Lagoon of New Caledonia, near Nouméa. Hydrolysis rates decreased from the nearshore station to the offshore station and showed similar trends regardless of the technique used. Rates decreased from 5.83 to 0.88 nmol of FFA · liter(−1) · h(−1) and from 0.76 to 0.23 nmol of (3)H-FFA · liter(−1) · h(−1), respectively. These results appeared to be consistent with bacterial production results, which also decreased similarly (from 0.59 to 0.26 μg of C · liter(−1) · h(−1)). However, the ratio of MUF-oleate activities to [(3)H]triolein activities, which was constant at the offshore stations (3.8 ± 0.1), gradually increased at the nearshore stations (from 4.1 to 7.6). This result shows that the two assays respond in different ways to changes in environmental conditions and validates the need to set up more specific enzymatic assays