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This article focuses on the attitude of practicing teachers toward teaching science and technology (S&T). It reports the results of a study conducted with 110 late-elementary school teachers in ord...

Human adult muscle-type acetylcholine receptors are heteropentameric ion channels formed from two α-subunits, and one each of the β-, δ-, and ε-subunits. To form functional channels, the subunits must assemble with one another in a precise stoichiometry and arrangement. Despite being different, the four subunits share a common ancestor that is presumed to have formed homopentamers. The extent to which the properties of the modern-day receptor result from its subunit complexity is unknown. Here, we discover that a reconstructed ancestral muscle-type β-subunit can form homopentameric ion channels. These homopentamers open spontaneously and display single-channel hallmarks of muscle-type acetylcholine receptor activity. Our findings attest to the homopentameric origin of the muscle-type acetylcholine receptor, and demonstrate that signature features of its function are both independent of agonist and do not necessitate the complex heteropentameric architecture of the modern-day protein.

Studies show that training and assistance programs for primary teachers have an impact on their sense of self-efficacy in teaching science and technology. In line with this research perspective, we studied the participation of 105 primary teachers in a particular assistance program designed to improve their sense of efficacy. In this program, the teachers are accompanied by scientific experts for a period of two years and take workshops on selected themes, the content of which is then applied in the classroom with the help of students aged 17-19 years. The results—gathered using a mixed methodology of questionnaires, open-ended questions and discussion groups—show that these teachers feel a stronger sense of efficacy and confidence in their science teaching. They also demonstrate a better understanding of conceptual content, less reliance on the school environment to teach science and technology, and a willingness to give priority to a pedagogy that is geared toward scientific experimentation.

In this study, Hapke's radiative transfer model is used to verify the feasibility of retrieving the composition and grain-size of the ground in an open-pit mine, seen as a regolith. Such a tool could be useful for dust surveys and thus preventing potential environmental risks such as acid mine drainage. As the true compositional endmembers of the medium are not retrieved but rather chosen from spectral libraries and the range of grain sizes (a few to hundreds of micrometers) and porosities (0.22 to 0.52 for the filling factor) vary greatly in an open-pit mine, we show that the mineralogical unmixing results are not reliable. Too many combinations of different relative abundances, grain sizes and porosities lead to fits between modelled and measured spectra under 0.3% in reflectance. To tackle this issue, we explore a lithological unmixing approach. Considering lithologies as endmembers, as opposed to considering minerals, reduces the variability in the solutions as fewer endmembers are used. The results show that the studied samples with multi-component grains behave spectrally as expected for mono-mineral grains. With no root mean square errors higher than 5%, the relative abundances retrieved are sufficiently precise to consider mapping lithologies with this method.

We prove a quantitative version of the multi-colored Motzkin---Rabin theorem in the spirit of Barak et al. (Proceedings of the National Academy of Sciences, 2012): Let $$V_1,\ldots ,V_n \subset {\mathbb {R}}^d$$V1,?,Vn?Rd be $$n$$n disjoint sets of points (of $$n$$n `colors'). Suppose that for every $$V_i$$Vi and every point $$v \in V_i$$v?Vi there are at least $$\delta |V_i|$$?|Vi| other points $$u \in V_i$$u?Vi so that the line connecting $$v$$v and $$u$$u contains a third point of another color. Then the union of the points in all $$n$$n sets is contained in a subspace of dimension bounded by a function of $$n$$n and $$\delta $$? alone.

International audience; This paper aims at presenting the results of experimental and numerical investigation programs assessing the stress reduction in orthotropic steel bridge decks associated with ultra high performance fiber reinforced concrete (UHPFRC) topping layer. This RandD project was aimed at evaluating the effectiveness of the UHPFRC overlay, as an alternative to conventional bituminous concrete, to reduce the stress distribution and thereby improve the fatigue resistance of the complex deck plate. Loading tests were carried out on realistic samples of orthotropic deck equipped or not with a reference bituminous concrete or a new UHPFRC topping. The deflection, and strain and stress values on the top and the bottom of the orthotropic deck plate and more particularly at the weld joint between longitudinal stiffeners (troughs) and the deck plate were measured. A 3-D shell element model has been developed using a finite element code in order to obtain the stresses in details for the most representation and critical locations. The global and local behaviors have been analyzed in order to understand and to evaluate the beneficial effects of UHPFRC topping layer under static condition. The results obtained in terms of stress reduction factor demonstrate the beneficial effects for fatigue verification. © 2013 Elsevier Ltd.

We report the synthesis and characterization of tantalum-boronate trimetallic clusters of general formula {[Cp*Ta](3)(μ(2)-RB(O)(2))(3)(μ(2)-OH)(μ(2)-O)(2)(μ(3)-OH)} (R= 4-(C(6)H(5))(C(6)H(4)) (Ta(3)-4Ph), 4-(C(6)H(5)O)(C(6)H(4)) (Ta(3)-4OPh), 4-(C(7)H(7)O)(C(6)H(4)) (Ta(3)-4OBn), 4-(C(8)H(5))(C(6)H(4)) (Ta(3)-4PhEt), and 4-(C(12)H(7))(C(6)H(4)) (Ta(3)-4Napht)). All complexes have been characterized by NMR spectroscopy and X-ray diffraction. The trimetallic species feature a large Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. ΔH° and ΔS° values for association of acetone with the complexes vary between -2.0 and -4.1 kcal·mol(-1) and -3 and 2 cal·mol(-1)·K(-1), respectively, showing weaker binding than smaller cavitands of the same type. The barrier for acetone exchange at equilibrium is similar for all complexes, and ΔH(‡) values vary between 8.2 and 11.4 kcal·mol(-1).

Microsingle crystals of poly(para-phenylene terephthalamide), abbreviated PPTA, were obtained by water-vapor induced precipitation of PPTA rigid-flexible copolymers in sulfuric acid solution. Electron diffraction was performed and yielded hk0 patterns. The crystal structure of a model compound, N, N′ para (4-methoxycarbonyl) phenylene dibenzamide, abbreviated 3ARB-COOMe, is also reported. Its structure is compatible with that of the polymer, in which aromatic rings are all coplanar and form a 30° angle with amide groups. A reinvestigation of form II, based on electron diffraction data and molecular modeling simulations, is reported. The proposed space group is P112, and corresponds to a parallel chain arrangement, with terephthaloyl groups facing one another, and carbonyl groups pointing in opposite directions along the b -axis in adjacent hydrogen-bonded sheets. Chain conformation is the same as in form I, as previously established. The 3ARB-COOMe conformation is suggested as a possible polymorph or as defects in the crystal phase.

An efficient route for the synthesis of 1-iodo-5-octyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione as a key intermediate to build new electron-deficient monomers and related conjugated polymers is reported. Along these lines, two new low bandgap copolymers were synthesized from Stille or Suzuki coupling. These polymers were characterized and their properties compared to those of analogous conjugated polymers.

Pt(II) and Pd(II) compounds containing the free radical 4-aminoTEMPO (4amTEMPO) were synthesized and characterised by X-ray diffraction methods. The disubstituted complexes cis- and trans-Pt(4amTEMPO)2I2 were studied. The trans isomer was prepared from the isomerisation of the cis analogue. The two Pd(II) compounds trans-Pd(4amTEMPO)2X2 (X = Cl and I) were also characterised by crystallographic methods. A mixed-ligand complex cis-Pt(DMSO)(4amTEMPO)Cl2 was synthesized from the isomerisation of the trans isomer in hot water. Its crystal structure was also determined. In all the complexes, the 4amTEMPO ligand is bonded to the metal through the –NH2 group, since the nitroxide O atom is not a good donor atom for the soft Pt(II) and Pd(II) metals. The conformation of the 4-aminoTEMPO ligand was compared to those of the few reported structures in the literature.

Les câbles actuellement utilises en genie civil, notamment sur les ponts a haubans ou suspendus, sont constitues de fils d'acier cylindriques de diametre compris entre 3 et 7 mm. Ils sont en acier non ou peu allie de composition proche de l'eutectoide et sont obtenus par trefilage a froid. Ils ont une resistance a la traction elevee (superieure a 1900 MPa) et une faible ductilite. De par leur constitution, les câbles presentent une bonne robustesse en traction et une faible rigidite a la flexion. Cependant, les etudes conduites ces dernieres annees ont montre que les principales causes de deterioration des câbles sont liees a la corrosion et aux frottements interfilaires induits par la fatigue. Ces mecanismes de degradation des câbles sont decrits dans cet article. Les differents moyens de protection des câbles du genie civil ont ete initialement developpes pour lutter contre la corrosion. Ils se presentent sous la forme de revetements de type peinture, galvanisation, galfanisation, associees a une lubrification. Certains peuvent cependant avoir aussi des effets sur la fatigue. Les resultats experimentaux et numeriques obtenus sur fils unitaires, presentes dans cet article, montrent clairement l'effet benefique de la galvanisation et de la lubrification en termes de duree de vie en fretting fatigue. Cependant, les mecanismes de degradation dus au fretting fatigue en presence de corrosion ne sont pas totalement connus et font l'objet actuellement d'une etude approfondie.

The success of reintroduction programs greatly depends on the amount of mortality and dispersal of the released individuals. Although local environmental pressures are likely to play an important role in these processes, they have rarely been investigated because of the lack of spatial replicates of reintroduction. In the present study, we analyzed a 25-year data set encompassing 272 individuals released in five reintroduction programs of Griffon Vultures (Gyps fulvus) in France to examine the respective roles of survival and dispersal in program successes and failures. We use recent developments in multi-strata capture-recapture models to take into account tag loss in survival estimates and to consider and estimate dispersal among release areas. We also examined the effects of sex, age, time, area, and release status on survival, and we tested whether dispersal patterns among release areas were consistent with habitat selection theories. Results indicated that the survival of released adults was reduced during the first year after release, with no difference between sexes. Taking into account local observations only, we found that early survival rates varied across sites. However when we distinguished dispersal from mortality, early survival rates became equal across release sites. It thus appears that among reintroduction programs difference in failure and success was due to differential dispersal among release sites. We revealed asymmetrical patterns of dispersal due to conspecific attraction: dispersers selected the closest and the largest population. We showed that mortality can be homogeneous from one program to another while, on the contrary, dispersal is highly dependent on the matrix of established populations. Dispersal behavior is thus of major interest for metapopulation restoration and should be taken into account in planning reintroduction designs.

The crystal structures of several Pt(II) complexes containing sulfoxide ligands are described. The two iodo bridged dimers of the type I(R2SO)Pt(μ-I)2Pt(R2SO)I (where R is ethyl or n-butyl) are twinned structures. The dinuclear species are the trans isomers. Two compounds of the type trans-Pt(DMSO)(amine)X2 were studied by X-ray diffraction methods. The diiodo MeNH2 compound forms H-bonded chains, formed by maximizing the H-bonds between the amine group with the O atom of DMSO and one iodo ligand. The H-bonding pattern is quite different in the dichloro t-BuNH2 complex. In the latter crystal, there are two independent molecules which are H-bonded in pairs. The methyl groups of DMSO and the t-butyl group of the amine are oriented towards the outside of the pairs of molecules, while the H-bonds link the two independent molecules. Again, the amino group forms the maximum H-bonds with the O atom of DMSO and one chloro ligand. The crystal structures of trans-Pt(DMSO)(pyridine)I2 and of trans-Pt(MeBzSO)(pyrimidine)I2 (Bz = benzyl) were also studied. In the pyridine complex, the O atom of DMSO is in the Pt(II) plane by symmetry, while in the pyrimidine compound, the C atom of the –CH3 group is in the Pt(II) plane. The pyridine and the pyrimidine ligands are perpendicular to the Pt(II) square plane. The trans influence of the different ligands is discussed.

Synthesis, X-ray diffraction, and Fourier transform infrared spectroscopy of aliphatic–aromatic aramid oligomers are reported with the aim of shedding light on the effect of end-chain substituent on the morphology and structure of poly(para-phenylene terephthalamide) or PPTA. Three types of X-ray powder diffraction patterns were observed: one similar to that of PPTA form I, one similar to that of PPTA form II, and an additional form never reported. Some compounds, differing by their internal distribution of amide–aromatic rings, adopt two different crystal structures, whereas compounds having the same internal amide–aromatic arrangements, but differing by the nature of the end-groups, can adopt the same crystal structure. This clearly shows that both factors influence the packing adopted by the chains. Single-crystal structures of two polymorphs of a nitro-terminated model compound were resolved; both forms incorporate dimethyl formamide, and both show completely different packing. Infrared amide I and II band positions of most studied compounds match those observed for PPTA forms I or II, indicating that they exhibit planar hydrogen bonded sheets of molecules.Key words: aramid, crystal structure, poly(para-phenylene terephtalamide).

Pt(II) complexes of the types K[Pt(R2SO)X3], NR4[Pt(R2SO)X3] and Pt(R2SO)2Cl2 (where X = Cl or Br) were characterized by multinuclear magnetic resonance spectroscopy (195Pt, 1H and 13C). In 195Pt NMR, the chloro ionic compounds have shown signals between −2979 and −3106 ppm, while the cis disubstituted complexes were observed at higher fields, between −3450 and −3546 ppm. The signal of the compound trans-Pt(DPrSO)2Cl2 was found at higher field (−3666 ppm) than its cis analogue (−3517 ppm), since π-back-donation is considerably less effective in the trans geometry. In 1H NMR, a single signal was observed for the sulfoxide in [Pt(DMSO)Cl3]−, but for the other more sterically hindered ligands, two series of resonances were observed for the protons in α and β positions. The coupling constant 3J(195Pt–1H) are between 15 and 33 Hz. The 13C NMR results were interpreted in relation to the concept of inversed polarization of the π sulfoxide bond. The 2J(195Pt–13C) values vary between 35 and 66 Hz, while a few 3J(195Pt–13C) couplings were observed (13–26 Hz). The crystal structures of five monosubstituted ionic compounds N(n-Bu)4[Pt(TMSO)Cl3], N(Me)4[Pt(DPrSO)Cl3], K[Pt(EMSO)Cl3], K[Pt(TMSO)Br3] · H2O and N(Et)4[Pt(DPrSO)Br3] and one disubstituted complex cis-Pt(DBuSO)2Cl2 were determined. The trans influence of the different ligands is discussed.

The crystal structures of two Pt(II) amine–alkyne complexes cis -Pt(cyclobutylNH 2 )(DHMD)Cl 2 ( I ) and cis -Pt(2,5-lutidine)(DMHD)Cl 2 ( II ) were determined (DMHD = (CH 3 ) 2 (OH)C–C C–C(OH)(CH 3 ) 2 ). The DMHD ligand in I is perpendicular to the Pt(II) plane and the mid-point of the C C bond occupies the fourth corner of the square plane. This geometry of the DMHD ligand in I is similar to the few other Pt(R–C C–R)Cl 2 L (L = amine or Cl) complexes, where the two acetylenic carbon atoms are roughly equally located on both sides of the Pt plane. The Pt–C bonds are 2.161(13) and 2.100(14) A, while the Pt–Cl bond distances are 2.298(4) and 2.332(5) A. The Pt–MP (midpoint of the C C bond) is 2.044 A. In II , the steric hinderance of the 2,5-lutidine ligand located in cis position is very important and the geometry of bonded DMHD is quite different. The alkyne ligand is pushed away from 2,5-lutidine, so that one of the C atoms of the triple bond lies in the Pt(II) plane. A linear trans Cl–Pt–C angle (175.2(3) A), a lengthening of the Pt–Cl bond (2.433(4) A) located trans to the Pt–C bond and a shortening of the latter (2.021(14) A) are observed in complex II . There results are without precedent in the literature. The two structures are disordered over two positions, but the low R factors (respectively 3.61% and 3.44% for I and II ) confirm the reliability of the results. A complete description of the disordered arrangement is provided for both complexes. Crystal I crystallized with a molecule of H 2 O and the two structures are stabilized by an extensive H-bonding system.

It is generally considered that limiting the loss of genetic diversity in reintroduced populations is essential to optimize the chances of success of population restoration. Indeed, to counter founder effect in a reintroduced population we should maximize the genetic variability within the founding group but also take into account networks of natural populations in the choice of the reintroduction area. However, assessment of relevant reintroduction strategies requires long-term post-release genetic monitoring. In this study, we analyzed genetic data from a network of native and reintroduced Griffon vulture (Gyps fulvus) populations successfully restored in Southern Europe. Using microsatellite markers, we characterized the level of genetic diversity and degree of genetic structure within and among three native colonies, four captive founding groups and one long-term monitored reintroduced population. We also used Bayesian assignment analysis to examine recent genetic connections between the reintroduced population and the other populations. We aimed to assess the level of fragmentation among native populations, the effectiveness of random choice of founders to retain genetic variability of the species, the loss of genetic diversity in the reintroduced population and the effect of gene flow on this founder effect. Our results indicate that genetic diversity was similar in all populations but we detected signs of recent isolation for one native population. The reintroduced population showed a high immigration rate that limited loss of genetic diversity. Genetic investigations performed in native populations and post-released genetic monitoring have direct implications for founder choice and release design.

Complexes of the type [Pt(amine)4]I2 were synthesized and characterized mainly by multinuclear (195Pt, 1H and 13C) magnetic resonance spectroscopy. The compounds were prepared with different primary amines, but not with bulky amines, due to steric hindrance. In 195Pt NMR, the signals were observed between −2715 and −2769 ppm in D2O. The coupling constant 3J(195Pt–1H) for the MeNH2 complex is 42 Hz. In 13C NMR, the average values of the coupling constants 2J(195Pt–13C) and 3J(195Pt–13C) are 18 and 30 Hz, respectively. The crystal structure of [Pt(EtNH2)4]I2 was determined by X-ray diffraction methods. The Pt atom is located on an inversion center. The structure is stabilized by H-bonding between the amines and the iodide ions. The compound with n-BuNH2 was found by crystallographic methods to be [Pt(n-BuNH2)4]2I3(n-BuNHCOO). The crystal contains two independent [Pt(CH3NH2)4]2+ cations, three iodide ions and a carbamate ion formed from the reaction of butylamine with CO2 from the air. When the compound [Pt(CH3NH2)4]I2 was dissolved in acetone, crystals identified as trans-[Pt(CH3NH2)2(H3C N C(CH3)2)2]I2 were isolated and characterized by crystallographic methods. Two trans bonded MeNH2 ligands had reacted with acetone to produce the two N-bonded Schiff base Pt(II) compound.

DIOGEN1 is an open access database from AFGC2, providing impacts of production materials used in France for civil engineering works. DIOGEN is designed to provide reliable and representative environmental data, established according to standard EN 15804. Based on values provided by the industry or scientific studies, the working group determines a scoring reflecting the level of reliability and representativeness of the data, according to the Ecoinvent methodology.Based on the database DIOGEN and developed in web format, the tool CIOGEN3, in its current version, offers an assessment of the stages of production and construction of road bridges according to EN 15804. To preserve the representativeness and reliability of the calculations, several representative worksites were used to measure inventory flows and then calculate standard values of processes for different types of structures. A second version is being developed to perform an LCA assessment on the full life cycle of different bridges structures.

The ReOX(2)(met) compounds (X = Cl, Br) adopt a distorted octahedral structure in which a carboxylato oxygen lies trans to the Re=O bond, whereas the equatorial plane is occupied by two cis halides, an NH(2), and an SCH(3) group. Coordination of the SCH(3) unit creates an asymmetric center, leading to two diastereoisomers. X-ray diffraction studies reveal that the crystals of ReOBr(2)(d,l-met).1/2H(2)O and ReOBr(2)(d,l-met).1/2CH(3)OH contain only the syn isomer (S-CH(3) bond on the side of the Re=O bond), whereas ReOCl(2)(d-met) and ReOCl(2)(d,l-met) consist of the pure anti isomer. (1)H NMR spectroscopy shows that both isomers coexist in equilibrium in acetone (anti/syn ratio = 1:1 for X = Br, 3:1 for X = Cl). Exchange between these two isomers is fast above room temperature, but it slows down below 0 degrees C, and the sharp second-order spectra of both isomers at -20 degrees C were fully assigned. The coupling constants are consistent with the solid-state conformations being retained in solution. Complexes of the type [ReOX(2)(His-aa)]X (X = Cl, Br) are isolated with the dipeptides His-aa (aa = Gly, Ala, Leu, and Phe). X-ray diffraction work on [ReOBr(2)(His-Ala)]Br reveals the presence of distorted octahedral cations containing the Re=O(3+) core and a dipeptide coordinated through the histidine residue via the imidazole nitrogen, the terminal amino group, and the amide oxygen, the site trans to the Re=O bond being occupied by the oxygen. The alanine residue is ended by a protonated carboxylic group that does not participate in the coordination. The constant pattern of the(1)H NMR signals for the protons in the histidine residue confirms that the various dipeptides adopt a similar binding mode, consistent with the solid-state structure being retained in CD(3)OD solution.

Nous avons étudié les effets de l’association des pathologies hypertensive et diabétiques sur la conversion des acides linoléique et alpha-linolénique en acides gras plus longs et plus insaturés. Pour cela, nous avons mis en place deux modèles de rats : le premier combinant hypertension artérielle (HTA) et diabète de type 2, grâce à l’administration d’un régime enrichi en fructose à des rats SHR (Spontaneously Hypertensive Rat) adultes \; le deuxième combinant HTA et diabète de type 1, induit par une injection de streptozotocine à des rats SHR adultes, traités (STZI) ou non (STZ) à l’insuline. Après mesure de la pression artérielle et de la glycémie au sacrifice des animaux, nous avons déterminé la composition des lipides totaux hépatiques en acides gras, les activités de delta-6 désaturation microsomales hépatiques ainsi que l’expression du gène codant la delta-6 désaturase. Les résultats de l’expérience 1 mettent en évidence une diminution des teneurs en 18 : 2 n-6 et en produits de désaturation à longue chaîne, chez les animaux du lot fructose. L’activité de delta-6 n-3 désaturation est augmentée significativement, alors que l’expression génique a tendance à diminuer. Dans l’expérience 2, une augmentation de la teneur en 18 : 2 n-6 est observée dans le lot STZ, alors que le lot STZI présente des teneurs semblables à celles des témoins. De plus, les teneurs en 20 : 4 n-6 et 22 : 6 n-3 sont augmentées dans le lot STZI. L’activité delta-6 n-3 désaturante est partiellement inhibée dans le lot STZI, et l’expression génique de la delta-6 désaturase est diminuée dans les deux lots traités. Ces résultats mettent en évidence que l’association de l’HTA et des différentes formes de diabète entraîne des perturbations de la biosynthèse des acides gras polyinsaturés qui sont différentes, voire opposées, selon le type de diabète. Leurs répercussions sur les fonctions biologiques des acides gras polyinsaturés restent à élucider.

Successful pregnancy requires profound differentiation and reorganization of the uterine tissues including, as pregnancy progresses, extensive apoptosis of decidual tissue to accommodate the developing conceptus. We have previously shown a positive correlation between expression of activin A and apoptosis in the decidua and have also shown that expression of activin A occurs at the time when prolactin (PRL) receptors disappear from decidual cells. The goals of this study were to examine whether activin A plays a role in decidual apoptosis and whether expression of activin A in the decidua is regulated by PRL and placental lactogens. Studies were carried out using primary rat decidual cells, a decidual cell line (GG-AD), and PRL null mice. Treatment of decidual cells with activin A significantly increased DNA degradation, caspase 3 activity, and caspase 3 mRNA expression. However, this effect was observed only in the absence of endogenous activin production by these cells. Addition of follistatin to decidual cells that were producing activin A decreased both caspase 3 activity and mRNA expression. Similarly, addition of activin-blocking antibodies to cultures of GG-AD cells, which also produce activin A, caused a reduction in both DNA degradation and caspase 3 activity. PRL and placental lactogens caused an inhibition of activin A mRNA expression in primary decidual cells. Even more convincingly, decidua of PRL null mice expressed abundant activin A at a time when no expression of this hormone is detected in wild-type mice and treatment of PRL null mice with PRL caused a profound inhibition of activin A mRNA expression. In summary, our investigations into the role and regulation of decidual activin have revealed that activin A can induce cell death in the decidua and that its expression is under tight regulation by PRL and placental lactogens. activin, apoptosis, decidua, prolactin

Equivalent amounts of ReOX(3)(OPPh(3))(Me(2)S) (where X = Cl, Br) and L-histidine (L-hisH) in acetonitrile yield ReOX(2)(L-his), in which the amino acid monoanion is N,N,O-tridentate. X-ray diffraction work on both compounds shows that the three donors occupy a face in a distorted octahedron and the carboxylate oxygen is coordinated trans to the Re=O bond. The 2:1 complex [ReO(L-his)(2)]I is obtained by reacting 2 equiv of L-histidine with ReO(2)I(PPh(3))(2) in methanol in the presence of NaOCH(3). (1)H NMR spectroscopy indicates that these complexes contain one N,N,O-tridentate histidine anion coordinated as above and one N,N-bidentate histidine anion, whose carboxylate group is free. By refluxing ReOX(2)(L-his) in methanol, the carboxylic groups esterify and two octahedral units condense into an oxo-bridged dinuclear complex [ReOX(2)(L-hisMe)](2)O containing N,N-bidentate histidine methyl ester. The O=Re-O-Re=O backbone is approximately linear, and the two ReOX(2)(L-hisMe) units are related by a 2-fold axis through the central oxygen. Crystals of [ReOBr(2)(L-hisMe)](2)O consist of an ordered phase containing two of the possible diastereoisomers in a 1:1 ratio. (1)H NMR spectra of these crystals include two sets of signals, consistent with the presence of two isomers with C(2) symmetry, and the spectra of the nonrecrystallized material confirm that these are the only two isomers formed.

We observed that human (Jurkat) T-cells constitutively expressed the mRNA, encoding for the four isoforms of phospholipase A(2) (PLA(2)), i.e. two secretory (type IB and type V), and two cytosolic (type IV, Ca(2+)-dependent and type VI, Ca(2+)-independent). In order to assess whether these PLA(2) isoforms are active, we labeled Jurkat T-cells with [(3)H]arachidonic acid ([(3)H]AA) and determined its release into the extracellular medium in the presence of phorbol 12-myristate 13-acetate (PMA) and ionomycin. The three PLA(2) isoforms seem functional as aristolochic acid and bromoenol lactone (BEL), the respective inhibitors of type IB/type V and type VI PLA(2)s, significantly inhibited the release of free [(3)H]AA. On the other hand, arachidonyl trifluoromethyl ketone (AACOCF(3)), an inhibitor of type IV PLA(2), failed to curtail significantly the release of free [(3)H]AA into the extracellular medium. We assessed the implication of these PLA(2) isoforms in transcription of the interleukin-2 (IL-2) gene, involved in T-cell proliferation. Hence, aristolochic acid and BEL, but not AACOCF(3), significantly inhibited the PMA and ionomycin-induced induction of mRNA of IL-2. Similarly, aristolochic acid and BEL, but not AACOCF(3), significantly inhibited the PMA and ionomycin-induced secretion of IL-2 in the culture supernatants. Together these results suggest that human Jurkat T-cells possess two secretory and two cytosolic PLA(2) isoforms and only three of them (type IB, type V and type VI) are implicated in T-cell proliferation.

The hydrolyis or the aquation reactions of compounds of the types cis- and trans-Pt(Ypy)2(NO3)2 (Ypy = pyridine derivative) were studied in D2O and characterized by multinuclear (195Pt, 13C, and 1H) NMR spectroscopy. In acidic pD, the product of the cis complexes is cis-[Pt(Ypy)2(D2O)2]2+, whereas in basic medium cis-Pt(Ypy)2(OD)2 is formed. The 195Pt NMR resonances of the products containing ligands with an ortho substituent were observed at lower fields than the other complexes. The average coupling constant (3J(195Pt–1H) and 3J(195Pt–13C)) is 44 Hz for the diaqua species and 42 Hz for the dihydroxo compounds. At neutral pD, several hydrolyzed species were observed, except for the 2-picoline and 2,4-lutidine complexes, which contained only one compound, cis-[Pt(Ypy)2(D2O)(OD)]+. The other hydrolyzed products for the ligands with no ortho substituent were identified as the dihydroxo-bridged dimer, the monohydroxo-bridged dimer, the trimer, and possibly the tetramer. The trans analogues have shown two signals in acidic pD corresponding to the diaqua monomer and the monohydroxo-bridged aqua dimer. Two species (the dihydroxo compound and the monohydroxo-bridged hydroxo dimer) were also observed in basic pD. In neutral medium, a third signal assigned to a longer chain hydroxo-bridged oligomer or polymer was detected.Key words: platinum, pyridine derivative, nitrato, hydrolysis, NMR, aquation.

Compounds of the type cis- and trans-Pt(Ypy)2(NO3)2 (Ypy=pyridine or its methyl derivatives) have been synthesized and characterized by IR and multinuclear (195Pt, 13C and 1H) NMR spectroscopies. The 195Pt NMR resonances of the trans complexes were observed at lower fields (ave. −1450 ppm) than the cis analogs (ave. −1509 ppm). The complexes containing a methyl substituent in ortho position on the pyridine ligand were observed at lower fields than the others. The coupling constants 3J(195Pt–1H) and 3J(195Pt–13C) are larger in the cis configuration (ave. 44 and 46 Hz, respectively) than in the trans analogs (ave. 33 and 35 Hz, respectively). The covalent character of the PtO bond seems greater in the trans complexes than in the cis compounds. The crystal structures of cis-Pt(3,5-lut)2(NO3)2, cis-Pt(2-pic)2(NO3)2, cis-Pt(py)2(NO3)2·1/2CH2Cl2, trans-Pt(3,5-lut)2(NO3)2 and trans-Pt(py)2(NO3)2 were determined. Except for the cis pyridine complex, which contains some molecules of solvent, the two nitrato groups are on opposite sides of the coordination plane. The trans influence of the different ligands is compared.

During gestation, the uterus undergoes severe changes to accommodate and protect the developing conceptus. In particular, stromal endometrial cells proliferate and differentiate to form the decidual tissue, which produces PRL. Once the conceptus begins to grow, extensive regression by apoptosis take place in the decidua coincident with the loss of the PRL receptor in this tissue. In this report we have established for the first time that PRL, acting through the long form of the PRL receptor and the PI3K pathway, exerts an antiapoptotic effect in rat decidua. We have also shown that protein kinase B phosphorylation on serine 473 as well as its nuclear translocation are stimulated by PRL in decidual cells. Moreover, we have found that caspase-3, a well known effector of apoptosis, becomes expressed and active in the rat decidua just at a time when this tissue undergoes extensive apoptosis. PRL was able to down-regulate both caspase-3 mRNA levels as well as activity. Furthermore, using a protein kinase B dominant-negative expression vector, we provide evidence that PRL inhibition of caspase-3 requires an intact protein kinase B pathway. Finally, we have also found that rat placental lactogen I and II dose-dependently inhibit caspase-3 mRNA, suggesting multiple sources of PRL in the hormonal control of rat decidual regression. In summary, the results of this study have defined an important role for decidual PRL in the normal progress of pregnancy, specifically in the regression and reorganization of the decidua.

Estradiol is known to play an important role in the growth and differentiation of rat uterine stromal cells into decidual cells. In particular, this hormone with progesterone is necessary for blastocyst implantation and subsequent decidualization in the rat. Although binding experiments have demonstrated the presence of estrogenbinding sites, no evidence exists as to whether the rat decidua expresses both isoforms of the estrogen receptor (ER), a and b. In this investigation, we analyzed the expression of decidual ERa and ERb, studied their regulation by PRL and steroid hormones and examined the ability of decidual ERb to transduce the estradiol signal to the progesterone receptor. Immunocytochemistry, RT-PCR, and Northern blot analysis showed that both ER species are coexpressed in the decidua during pseudopregnancy. Interestingly, these genes were preferentially found in a cell population localized in the antimesometrial site of the uterus where blastocyst implantation takes place. Using decidual cells in primary culture obtained from pseudopregnant rats and a decidua-derived cell line (GG-AD), we show a differential regulation of ERa and ERb by PRL and ovarian steroid hormones. Whereas PRL, estradiol, and progesterone all increased ERb messenger RNA (mRNA) expression in a dose-dependent manner, only PRL up-regulated the mRNA levels of ERa. Estradiol had no effect on ERa expression, whereas progesterone markedly decreased its mRNA levels. Interestingly, progesterone, which up-regulates the ability of PRL to signal to a PRL-regulated gene in mammary-gland derived cells, prevented PRL stimulation of decidual ERa and had no synergistic effect on ERb expression. The use of GG-AD cells, which express only ERb, allowed us to demonstrate that this receptor subtype is functional and transduces estradiol signal to the progesterone receptor. In summary, the results of this investigation have revealed that ERb is expressed in addition to ERa in the rat decidua, and that the expression of both ERs are cell specific and differentially regulated by PRL and steroids. One salient finding of this investigation is that progesterone down-regulates ERa, but concomitantly increases the expression of a functional ERb that mediates estradiol up-regulation of the decidual progesterone receptor. (Endocrinology 141: 3842‐3851, 2000)

Establishment and maintenance of pregnancy require the activity of a highly specialized maternal tissue, the decidua. It is well established that the human decidua synthesizes and releases prolactin. However, in the rat, no study has been able to demonstrate the production of prolactin by the decidua. In this report, we established for the first time using Northern blot analysis and reverse transcription-polymerase chain reaction, Western blot analysis, immunocytochemistry, and enzyme-linked immunosorbent assay, that a defined cell population located in the rat antimesometrial decidua expresses prolactin mRNA, as well as synthesizes and secretes this hormone. By reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends, we cloned a full-length cDNA for rat decidua prolactin, whose sequence was identical to that of pituitary prolactin. Our results also showed that pituitary prolactin appeared to down-regulate decidual prolactin levels. Under these circumstances, inhibition of pituitary prolactin secretion led to a rise in both decidual prolactin mRNA and protein expression. Moreover, addition of exogenous prolactin to primary decidual cells in culture also caused a marked decrease in decidual prolactin mRNA expression. Finally, treatment of primary decidual cells with steroid hormones or 8-bromo-cAMP revealed a differential regulation of decidual prolactin expression from that of pituitary suggesting a tissue-specific regulation of prolactin gene expression, possibly through the use of an alternative promoter in rat decidua.

Complexes of the types cis- and trans-Pt(Ypy)2X2 where Ypy is a methyl derivative of pyridine and X=Cl or I were studied by spectroscopic methods, especially by multinuclear NMR spectroscopy. In 195Pt MNR, the cis-dichloro compounds were observed between −1998 and −2021 ppm in CDCl3, while the trans compounds were found at slightly lower field, between −1948 and −1973 ppm. The diiodo species were observed at much higher field, between −3199 and −3288 ppm for the cis isomers and between −3122 and −3264 ppm for the trans isomers. In 1H NMR, the 3J(195Pt1H) coupling constants are larger for the cis compounds (about 42 ppm) than for the trans isomers (about 33 ppm). In 13C NMR, the values of 3J(195Pt13C) were also found to be larger for the cis complexes. There seems to be a slight dependence of the pKa values of the protonated ligands on the δ(Pt) chemical shifts. The presence of π-bonding between Pt and the pyridine ligands do not seem very important. The crystal structures of three dichloro and five diiodo complexes were determined, in an attempt to obtain information on the trans influence of the three ligands. The results have shown that the iodo ligand has the greatest trans influence. Chloro and pyridine ligands seem to have similar trans influence, although, the chloro ligand seems to have a slightly larger influence than pyridine derivatives. One structure, trans-Pt(2-pic)2I2, has shown a syn conformation of the two 2-picoline ligands.

The cytokine interleukin 6 (IL-6), a major mediator of immune and acute phase responses of the liver, has been implicated in the termination of pregnancy once expressed in the uterus. This study was undertaken to investigate the expression and regulation of genes encoding IL-6 and IL-6 receptor (IL-6R) in rat decidual tissue. Total RNA obtained from rat decidual tissue on different days of pseudopregnancy was analyzed by RT-PCR using specific primers for IL-6, IL-6R, and 130-kDa glycoprotein (gp130). Ribosomal L19 primers served as an internal control. IL-6R and gp130 were found to be expressed in the decidua throughout development, while no messenger RNA (mRNA) for IL-6 was detected. Interestingly, within several hours of culture, decidual explants acquired the ability to express IL-6. The apparent ability of decidual cells to express IL-6 and its lack of expression in vivo led us to examine whether the IL-6 gene is actively inhibited. Primary decidual cells were cultured in the presence of estradiol, pr...

The International Journal of Life Cycle Assessment, 18 (5), ISSN:0948-3349, ISSN:1614-7502

Sixteen batches of eggs collected immediately after spawning from five atipa (Hoplosternum littorale, (Hancock, 1828), Siluriformes, Callichthyidae) nests have been incubated at temperatures ranging from 22.5 to 32 °C. After a growing period of 8 months allowing all the fishes to express totally all secondary sexual characteristics, the sex of 9756 fishes was determined. The sexing criteria based on the color and length of the first ray of the pectoral fins are very reliable, and may lead to an error for only 0.3% of the fishes. For the 16 batches, the male sex ratio (ratio between the number of males and the total number of fishes) varies from 46.4 to 98.5% and is always greater than 50% with one exception. An overall analysis of the results shows no marked correlation (r2 = 0.312) between the proportions of males and the thermic conditions during incubation of eggs. But within each set of eggs from the same nest, this ratio systematically increases with increasing temperatures. The very low probability (0.0015) of such an event in the 15 batches of eggs from four independent nests suggests both a strong influence of the incubation temperature on the final proportion of males, and an important parental effect on the thermosensitivity of the offspring. The analysis shows clearly that a differential mortality between the sexes cannot account for the shifts towards such high proportions of males in the sex ratios. Thermosensitivity would be expressed early in this species, in the 3 days following spawning. The validity of these experimental results with regard to the natural environment as well as the potential adaptative advantage of such a mechanism for the species are discussed.

The synthesis and characterization of new heterofluorene derivatives based on germanium are described. These germafluorene monomers have been polymerized with different aromatic comonomers. The resulting homopolymers and alternating copolymers have been characterized by size exclusion chromatography, thermal analyses (TGA and DSC), UV-vis-NIR absorption spectroscopy, X-ray diffraction, and cyclic voltammetry. These homopolymers and copolymers are air-stable and present bandgaps ranging from 3.0 to 1.6 eV. Some copolymers were tested in field-effect transistors (FETs) and bulk heterojunction photovoltaic cells (PCs). Best results in FETs were obtained with poly[2,7-(9,9-di-n-butylgermafluorene)-alt 3,6-bis(thiophen-5-yl)-2,5-dioctylpyrrolo[3,4-]pyrrole-1,4-dione], which shows a hole mobility up to 0.04 cm2 (V 3 s)-1 with an Ion/Ioff ratio of 1.0_106. For photovoltaic applications, the best results were obtained with poly[2,7-(9,9-di-n-octylgermafluorene)-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] with a power conversion efficiency (PCE) of 2.8%.

To investigate further the mechanisms of developmental programming, we analysed the effects of maternal overnutrition and of postnatal high-fat feeding on adipose tissue metabolism in the offspring. Postnatal changes in serum adiponectin, leptin and TAG [triacylglycerol (triglyceride)] levels, adipose tissue TAGs, fatty acids and enzyme activities were determined in offspring of cafeteria-diet-fed dams during gestation and lactation, weaned on to standard chow or on to cafeteria diet. Obese rats showed higher adiposity (+35% to 85%) as well as a significant increase in serum glucose, insulin, leptin, adiponectin and TAG levels (P

The Griffon Vulture (Gyps fulvus) is considered to be socially monogamous. However, extra-pair fertilizations are suspected due to observations of extra-pair copulations in some populations. We performed parentage studies based on ten polymorphic microsatellite markers in two reintroduced colonies of Griffon Vulture. Out of 40 genotyped chicks, we found eight chicks whose genotypes mismatched those of their observed parents. Two could be explained by the occurrence of a null allele at one locus. The six remaining mismatches detected relied on mismatches at one locus, and they were not detected when we increased the potential genotyping error rate. We thus conclude that the Griffon Vulture is genetically monogamous, at least in low-density populations.

Metabolic syndrome characterized by insulin resistance and obesity is accompanied by severe lipid metabolism perturbations and chronic low-grade inflammation. However, many unresolved questions remained regarding the regulation that underlie dyslipidemia, particularly the regulation of the metabolic cascade (synthesis and release) leading to eicosanoid precursors release. This study was undertaken to investigate the regulation of desaturases/elongases and phospholipases A2 during the establishment of metabolic syndrome. Our results showed that delta-6 desaturase as well as elongase-6 expressions were upregulated in 3-month-old Zucker fatty rats as compared to lean littermates, independently of SREBP-1c activation. We also demonstrated for the first time an increase of liver group VII phospholipase A2 gene expression in the obese animals together with a strong specific inhibition of type IVA and VIA phospholipases A2. These results suggest that the regulation of unsaturated fatty acids biosynthesis and signalling cascade could contribute to the development of liver lipid dysregulation related to metabolic syndrome and may be considered as new potential targets in such pathological conditions.

It is recognised that no single machine smoking regime can represent the different behaviours of individual human smokers. It has been argued that the current ISO standard regime provides machine yields that are somewhat low for certain cigarette designs compared to human intake. Various cigarette machine smoking regimes have been proposed as options for regulatory use to provide data that reflect "average" or "maximum" yields as related to human intake. Some public health representatives have proposed that the intense regime mandated for testing in Canada with 100% of the ventilation holes in the cigarette filter blocked, should be used for product characterisation and that it is not necessary that it should reflect general human smoking behaviour. We believe that this is a flawed approach because our studies and those of other workers demonstrate that the conditions generated in the cigarette when using this intense machine smoking regime are extreme in comparison to the conditions found for regimes based more realistically on human smoking. In this paper, we provide data to show that smokers modify their smoking intensity over the course of smoking in response to changes in draw resistance, smoke concentrations and smoke temperatures. We compare changes in and interactions between these parameters during puffing when smoking cigarettes of different designs. Cigarettes were smoked using various machine smoking regimes previously proposed for smoke testing as well as a regime based on human smoking data from an 'in-house' study. Puffing parameters were derived from this study to represent the 'average smoker' under laboratory conditions and equivalent to the 90th percentile when the studied smokers smoked under natural conditions. Biomarker data from human uptake studies have shown that ventilation is an effective cigarette design tool to reduce total smoke constituent uptake in humans so demonstrating that any blocking of filter ventilation is far from 100%. Likewise, this current work also shows how smokers modify their smoking behaviour in ways not well reflected by the 100% ventilation blocking regime. It seems logical that any machine smoking regime chosen for future product regulation should reflect these findings for it to have valid public health relevance. In addition, it seems misguided to discourage product design features, such as ventilation, which clearly can provide products with reduced human smoke exposure, just to maintain the dogma, counter to the scientific evidence, that there must be a regulatory regime with 100% ventilation blocking.

cited By 38; International audience; In this study, hydrogen embrittlement is simulated in an accelerated way with an ammonium thiocyanate media test. Damage evolution of prestressing strand is monitored with electrochemical measurements and with acoustic emission (AE). Three stages of the damage mechanism are identified with different acoustic activities. For each stage, three pattern parameters coming from AE analyse are highlighted to distinguish each emitting stage. To have a precise description of damage evolution of prestressing cables during the hydrogen embrittlement test, some interrupted tests have been used. For each interruption, metallographic observations enable to characterize degradation mechanisms. Finally, each acoustic stage has been correlated to a degradation mechanism. © 2010 Elsevier Ltd. All rights reserved.

Background Cancer cells present a sustained de novo fatty acid synthesis with an increase of saturated and monounsaturated fatty acid (MUFA) production. This change in fatty acid metabolism is associated with overexpression of stearoyl-CoA desaturase 1 (Scd1), which catalyses the transformation of saturated fatty acids into monounsaturated fatty acids (e.g., oleic acid). Several reports demonstrated that inhibition of Scd1 led to the blocking of proliferation and induction of apoptosis in cancer cells. Nevertheless, mechanisms of cell death activation remain to be better understood. Principal Findings In this study, we demonstrated that Scd1 extinction by siRNA triggered abolition of de novo MUFA synthesis in cancer and non-cancer cells. Scd1 inhibition-activated cell death was only observed in cancer cells with induction of caspase 3 activity and PARP-cleavage. Exogenous supplementation with oleic acid did not reverse the Scd1 ablation-mediated cell death. In addition, Scd1 depletion induced unfolded protein response (UPR) hallmarks such as Xbp1 mRNA splicing, phosphorylation of eIF2α and increase of CHOP expression. However, the chaperone GRP78 expression, another UPR hallmark, was not affected by Scd1 knockdown in these cancer cells indicating a peculiar UPR activation. Finally, we showed that CHOP induction participated to cell death activation by Scd1 extinction. Indeed, overexpression of dominant negative CHOP construct and extinction of CHOP partially restored viability in Scd1-depleted cancer cells. Conclusion These results suggest that inhibition of de novo MUFA synthesis by Scd1 extinction could be a promising anti-cancer target by inducing cell death through UPR and CHOP activation.

The combined effects of developmental programming and high-fat feeding at weaning on fatty acid metabolism of the offspring are not well known. In the present study, we aim at characterizing the influence of maternal and offspring's own diets on liver and very low-density lipoprotein (VLDL) lipids; fatty acid profiles of VLDL and liver phospholipids, triglycerides, and cholesteryl esters; and hepatic enzyme activities. Twenty obese male rats born to cafeteria diet-fed dams and 20 control rats born to control diet-fed dams were selected. At weaning, 10 rats of each group were fed control or cafeteria diet. Obese rats had a significant increase in serum glucose, insulin, leptin, VLDL apolipoprotein B100 and lipid levels, and hepatic fatty acid synthase and a reduction in acyl-coenzyme A oxidase and dehydrogenase activities compared with control pups at day 21 and day 90. Hepatic steatosis was apparent only at day 90. The proportions of saturated fatty acids and monounsaturated fatty acids and the oleic to stearic acid ratio were significantly increased, whereas polyunsaturated fatty acids and the arachidonic to linoleic acid ratio were decreased, in liver and VLDL lipids of obese pups compared with controls. The cafeteria diet at weaning induced more severe abnormalities in obese rats. In conclusion, maternal cafeteria diet induced a permanent reduction in hepatic β-oxidation and an increase in hepatic lipogenesis that caused liver steatosis and VLDL and fatty acid alterations in adult offspring. These preexisting alterations in offspring were worsened under a high-fat diet from weaning to adulthood. Nutritional recommendations in obesity must then target maternal and postnatal nutrition, especially fatty acid composition. METABOLISM-CLINICAL AND EXPERIMENTAL, ISSN : 0026-0495, DOI : 10.1016/j.metabol.2010.04.003, Issue : 12, Volume : 59, pp. 1701-1709, December 2010.

The asymmetric unit of the title compound {systematic name: cis-dichloridobis[(3,7-dimethylbicyclo-[3.3.1]non-1-ylmeth-yl)-amine-κN]platinum(II) N,N-dimethyl-formamide solvate}, [PtCl(2)(C(11)H(19)N)(2)]·C(3)H(7)NO, consists of two metrically similar Pt complexes and two dimethyl-formamide solvent mol-ecules. Each Pt(II) center is coordinated by the amine groups of two (1-adamantylmeth-yl)amine ligands and two Cl atoms in a cis-square-planar arrangement. The Pt(II) centers lie slightly outside [0.031 (4) and 0.038 (4) Å] the coordination planes. The N-Pt-N and Cl-Pt-Cl angles [92.1 (4)-92.30 (11)°] are slightly more open than the N-Pt-Cl angles [87.3 (3)-88.3 (3)°]. N-H⋯O and N-H⋯Cl inter-molecular hydrogen bonds are observed, forming two discrete pairs of complexes and solvent mol-ecules.

In this study, plasma lipids, lipoproteins and markers of oxidant/antioxidant status were investigated in young (n = 45) and older (n = 40) obese men and compared to those in young (n = 65) and older (n = 55) normal weight controls. The purpose was to determine whether obesity exacerbates or not lipid, lipoprotein abnormalities and oxidative stress in older men. Our findings showed that all obese patients had increased plasma triglyceride, cholesterol, LDL-cholesterol, -triglyceride and HDL-triglyceride levels concentrations compared to controls (P < 0.01). However, the younger obese men had relatively larger and accentuated changes in plasma lipids and lipoproteins than the older patients. Additionally, total antioxidant capacity (ORAC), vitamins C and E were lower while hydroperoxides and carbonyl proteins were higher in young and older obese patients compared to their respective controls (P < 0.001). Erythrocyte antioxidant SOD and catalase activities were enhanced in obese young patients, but reduced in obese older men. Glutathione peroxidase activity was low in obesity irrespective of age. In multiple regression analysis, BMI significantly predicted total cholesterol, LDL-C, LDL-TG and HDL-TG (P < 0.0001). These relationships were not modified by age. BMI alone was a not a significant predictor for ORAC, vitamins C, E, catalase and Glutathione peroxidase. However, the interaction BMI-age significantly predicted these parameters and explained 28-45% of their changes. BMI was a significant predictor of SOD, carbonyl proteins and hydroperoxides. This effect became more significant (P < 0.0001) and worsened with BMI-age interaction. In conclusion, lipoprotein metabolism and oxidant/antioxidant status are altered in obesity irrespective of age. However, obesity-related lipid and lipoprotein alterations were attenuated while oxidative stress was aggravated in older adults. NUTRITION METABOLISM AND CARDIOVASCULAR DISEASES, ISSN : 0939-4753, DOI: 10.1016/j.numecd.2010.02.007, Issue : 10, Volume : 21, pp. 792-799, OCT 2011.

Dietary polyunsaturated fatty acids (PUFA) play a key role in regulating delta-6 desaturase (D6D), the key enzyme for long-chain PUFA biosynthesis. Nevertheless, the extent of their effects on this enzyme remains controversial and difficult to assess. It has been generally admitted that C18 unsaturated fatty acids (UFAs) regulate negatively delta-6 desaturase (D6D). This inhibition has been evidenced in regard to a high glucose/fat free (HG/FF) diet used in reference. However, several nutritional investigations did not evidence any inhibition of desaturases when feeding fatty acids. Because the choice of the basal diet appeared to be of primary importance in such experiments, our goal was to reconsider the specific role of dietary UFAs on D6D regulation, depending on nutritional conditions. For that, sixteen adult Wistar rats were fed purified linoleic acid, alpha-linolenic acid or oleic acid, included in one of two diets at 4% by weight: an HG/FF or a high starch base (HS) where the pure UFAs replaced a mixed vegetable oil. Our results showed first that D6D specific activity was significantly greater when measured in presence of an HG/FF than with an HS/4% vegetable oil diet. Secondly, we found that linoleic and alpha-linolenic acids added to HG/FF reduced the specific activity of D6D. In contrast, when pure UFAs were added to an HS base, D6D specific activities remained unchanged or increased. Concordant results were obtained on D6D mRNA expression. Altogether, this study evidenced the importance of the nutritional status in D6D regulation by C18 UFAs: when used as control, HG/FF diet stimulates D6D compared with a standard control diet containing starch and 4% fats, leading to an overestimation of the D6D regulation by UFAs. Then, UFAs should be considered as repressors for unsaturated fatty acid biosynthesis only in very specific nutritional conditions.