Paul Sabatier University

About: Paul Sabatier University is a education organization based out in Toulouse, France. It is known for research contribution in the topics: Population & Catalysis. The organization has 15431 authors who have published 23386 publications receiving 858364 citations.

Ecology of spring-migrating Anatidae: a review

Abstract: Spring migration is generally considered as a crucial period of the year for many birds, not the least due to its supposed importance for subsequent breeding success. By reviewing the existing literature for Anatidae (ducks, geese, and swans), we show that little is known about their ecology in spring, although some goose species are exceptions. Another general pattern is that the ecology of Anatidae at staging sites is particularly neglected. Existing studies tend to focus on questions dealing with acquisition of nutrient reserves, whereas almost nothing has been published about stopover habitats, time use, microhabitat use, foraging behaviour, food availability, food limitation, diet selection, and interspecific relationships. Besides summarising present knowledge, we identify taxonomic groups and topics for which gaps of knowledge appear the most evident, thereby also highlighting research needs for the future.

Adrenergic regulation of adipocyte metabolism

Abstract: Five adrenoceptor (AR) subtypes (beta 1, beta 2, beta 3, alpha 2 and alpha 1), are involved in the control of white and brown fat cell function. A number of metabolic events are controlled by the adrenergic system in fat cells. The stimulatory effect of catecholamines on lipolysis and metabolism is mainly connected to increments in cAMP levels, cAMP protein kinase activation and phosphorylation of various target proteins. Norepinephrine and epinephrine operate through differential recruitment of alpha 2- and beta-AR subtypes on the basis of their relative affinity for the different subtypes (the relative order of affinity is alpha 2 > beta 1 > or = beta 2 > beta 3 for norepinephrine). Antagonistic actions at the level of cAMP production exist between alpha 2- and beta 1-, beta 2- and beta 3-AR-mediated lipolytic effects in human white fat cells. The role of fat cell alpha 2-ARs, which largely outnumber beta-ARs in fat cells of certain fat deposits, in human and primate has never been clearly understood. The other AR type which is not linked to lipolysis regulation, the alpha 1-AR, is involved in the control of glycogenolysis and lactate production. Pharmacological approaches using in-situ microdialysis and selective alpha 2- and beta-AR agonists and antagonists have revealed sex- and tissue-specific differences in the adrenergic control of fat cell function and nutritive blood flow in the tissue surrounding the microdialysis probe.

Adipocyte hormone-sensitive lipase: a major regulator of lipid metabolism.

Abstract: Le tissu adipeux joue un r81e important dans le contrde de la balance CnergCtique. La mobilisation des triacylglycCrols par la lipase hormono-sensible (EC 3.1.1.3; LHS) est soumis a un contrBle direct par les hormones et neurotransmetteurs qui modulent les concentrations intracellulaires d’AMP cyclique (AMPc). L’hydrolyse des triacylglycCrols par la LHS constitue l’etape limitante de la lipolyse. La LHS est phosphorylCe sur le site rkgulateur (Ser552 dans la LHS humaine) par la p r o t h e kinase dependante de 1’AMPc (EC 2.7.1.37) lorsque les concentrations intracellulaires d’ AMPc augmentent. Cette phosphorylation conduit B l’activation de l’enzyme. Une deuxikme site de phosphorylation (Ser5.54 dans la LHS humaine) dCnommC site basal est la cible de la protCine kinase activCe par I’AMP. La phosphorylation du site basal ne conduit pas B l’activation de la LHS et empkche la phosphorylation sur le site regulateur. La phosphorylation et I’activation de la protCine kinase activke par 1’AMP constitue donc un mecanisme antilipolytique qui est fonctionnel sur cellules isolCes mais dont l’importance physiologique n’est pas connue. Les ADN complkmentaires de la LHS de plusieurs espkces ont CtC clones et la structure des gbnes de LHS de l’homme et de la souris sont connus. Differents domaines fonctionnels de la protCine ont CtC proposes. Une rCgion d’homologie de sequences en amont de la serine 424 du site catalytique avec cinq enzymes d’organismes procaryotes et une enzyme humaine a ete decrite. La localisation chromosomique du gbne de la LHS est connue chez l’homme (chromosome 19, region q13-1+13.2), le porc et la souris. La mise en evidence de marqueurs polymorphiques dans le g&ne devrait permettre de tester l’hypothkse d’une implication de la LHS dans certaines maladies hereditaires du metabolisme lipidique. L’expression de la LHS varie selon la localisation anatomique du tissu adipeux chez le rat. Cette expression subit Cgalement des variations durant la gestation chez le rat et le cycle annuel chez les mammifbres hibernants. Chez l’homme, les taux d’ARN messagers de la LHS sont diminuCs dans le tissu adipeux de certains patients atteints de cancer. L‘activitC enzymatique totale est diminuee chez les patients atteints d’hyperlipidemie familiale combinCe mais pas chez les patients atteints du syndrome metabolique bien que, dans les deux cas, la lipolyse adipocytaire maximale soit diminuke. Les mkcanismes molCculaires de contr6le de l’expression de la LHS sont pratiquement inconnus.

Structure and Electrochemical Performance of Carbide‐Derived Carbon Nanopowders

Abstract: Microporous carbon materials are widely used in gas storage, sorbents, supercapacitor electrodes, water desalination, and catalyst supports. While these microporous carbons usually have a particle size in the 1–100 μm range, here the synthesis of porous carbide‐derived carbon (CDC) with particle diameters around 30 nm by extraction of titanium from nanometer‐sized titanium carbide (TiC) powder at temperatures of 200 °C and above is reported. Nanometer‐sized CDCs prepared at 200–400 °C show a disordered structure and the presence of CN sp1 bonds. Above 400 °C, the CN bond disappears with the structure transition to disordered carbon similar to that observed after synthesis from carbide micropowders. Compared to CDCs produced from micrometer‐sized TiC, nano‐CDC has a broader pore size distribution due to interparticle porosity and a large contribution from the surface layers. The material shows excellent electrochemical performance due to its easily accessible pores and a large specific surface area.