50 research outputs found

    Identification and characterization of a triacylglycerol lipase in Arabidopsis homologous to mammalian acid lipases

    Get PDF
    AbstractTriacylglycerol (TAG) lipases have been thoroughly characterized in mammals and microorganisms. By contrast, very little is known on plant TAG lipases. An Arabidopsis cDNA called AtLip1 (At2g15230), which exhibits strong homology to lysosomal acid lipase, was found to drive the synthesis of an active TAG lipase when expressed in the baculovirus system. The lipase had a maximal activity at pH 6 and the specific activity was estimated to be about 45ÎŒmolmin−1mg−1 protein using triolein as a substrate. Knock-out mutant analysis showed no phenotype during germination indicating that this enzyme is fully dispensable for TAG storage breakdown during germination. Northern blot analyses indicated that the transcript is present in all tissues tested

    Présentation

    No full text
    En juillet 2001, s’est tenu Ă  Strasbourg un colloque de recherche sur les lipides des plantes. Nous prĂ©sentons ici des articles correspondant Ă  cinq des confĂ©rences qui y ont Ă©tĂ© donnĂ©es. Un point dĂ©terminant la qualitĂ© des huiles de plantes rĂ©side dans leur degrĂ© d’insaturation. Cette caractĂ©ristique est dĂ©terminĂ©e par des enzymes appelĂ©es dĂ©saturases et les gĂšnes codant pour ces enzymes peuvent ĂȘtre utilisĂ©s comme marqueurs molĂ©culaires


    Les proteines de transfert de lipides chez les vegetaux superieurs : purification, biosynthese, caracterisation d'ADN complementaire

    No full text
    SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

    Identification et caractérisation d'une lipase chez Arabidopsis thaliana

    No full text
    AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

    Characterization and heterologous expression of three DGATs from oil palm (Elaeis guineensis) mesocarp in Saccharomyces cerevisiae

    No full text
    International audienceOil palm (Elaeis guineensis) can accumulate up to 88% oil in fruit mesocarp. A previous transcriptome study of oil palm fruits indicated that genes coding for three diacylglycerol acyltransferases (DGATs), designated as EgDGAT1_3, EgDGAT2_2 and EgWS/DGAT_1 (according to Rosli et al., 2018) were highly expressed in mesocarp during oil accumulation. In the present study, the corresponding open reading frames were isolated, and characterized by heterologous expression in the mutant yeast H1246, which is devoid of neutral lipid synthesis. Expression of EgDGAT1_3 or EgDGAT2_2 could restore TAG synthesis, confirming that both proteins are true DGAT. In contrast, expression of EgWS/DGAT_1 resulted in the synthesis of fatty acid isoamyl esters (FAIEs) with saturated long-chain and very-long-chain fatty acids. In the presence of exogenously supplied fatty alcohols, EgWS/DGAT_1 was able to produce wax esters, indicating that EgWS/DGAT_1 codes for an acyltransferase with wax ester synthase but no DGAT activity. Finally, the complete wax ester biosynthetic pathway was reconstituted in yeast by coexpressing EgWS/ DGAT_1 with a fatty acyl reductase from Tetrahymena thermophila. Altogether, our results characterized two novel DGATs from oil palm as well as a putative wax ester synthase that preferentially using medium chain fatty alcohols and saturated very-long chain fatty acids as substrates

    LIPIDES DES PLANTES Symposium « Lipides des plantes et oxylipines » : compte rendu et mise en place d’un rĂ©seau lipides des plantes

    No full text
    Un colloque sur les lipides de plantes et les oxylipines s’est tenu Ă  Strasbourg les 10 et 11 juillet 2001, dans le cadre des JournĂ©es de la SociĂ©tĂ© Française de Physiologie VĂ©gĂ©tale. Plus de 85 chercheurs ont participĂ© Ă  ce colloque et 45 communications ont Ă©tĂ© faites. La plupart ont portĂ© sur la synthĂšse des stĂ©rols et des isoprĂ©noĂŻdes, le mĂ©tabolisme des lipides, les relations entre le stress thermique et les lipides membranaires ainsi que sur les oxylipines. Les confĂ©rences plĂ©niĂšres ont Ă©tĂ© donnĂ©es par le Pr Heinz sur les cĂ©rĂ©brosides et les stĂ©rols glucosides, le Dr R. Verger sur les lipases et le Dr I. Feussner sur les oxylipines. Une table ronde s’est tenue pour discuter de la constitution d’un rĂ©seau rĂ©unissant les spĂ©cialistes des lipides des plantes en France. L’idĂ©e a Ă©tĂ© accueillie favorablement par tous les participants et il a Ă©tĂ© envisagĂ© de crĂ©er un site « web » contenant un annuaire des chercheurs, des cahiers de protocoles et une base de donnĂ©es bibliographiques. Ceci se fera en collaboration Ă©troite avec les chercheurs europĂ©ens et amĂ©ricains de la spĂ©cialitĂ©

    LIPIDES DES PLANTES Symposium « Lipides des plantes et oxylipines » : compte rendu et mise en place d’un rĂ©seau lipides des plantes

    No full text
    Un colloque sur les lipides de plantes et les oxylipines s’est tenu Ă  Strasbourg les 10 et 11 juillet 2001, dans le cadre des JournĂ©es de la SociĂ©tĂ© Française de Physiologie VĂ©gĂ©tale. Plus de 85 chercheurs ont participĂ© Ă  ce colloque et 45 communications ont Ă©tĂ© faites. La plupart ont portĂ© sur la synthĂšse des stĂ©rols et des isoprĂ©noĂŻdes, le mĂ©tabolisme des lipides, les relations entre le stress thermique et les lipides membranaires ainsi que sur les oxylipines. Les confĂ©rences plĂ©niĂšres ont Ă©tĂ© donnĂ©es par le Pr Heinz sur les cĂ©rĂ©brosides et les stĂ©rols glucosides, le Dr R. Verger sur les lipases et le Dr I. Feussner sur les oxylipines. Une table ronde s’est tenue pour discuter de la constitution d’un rĂ©seau rĂ©unissant les spĂ©cialistes des lipides des plantes en France. L’idĂ©e a Ă©tĂ© accueillie favorablement par tous les participants et il a Ă©tĂ© envisagĂ© de crĂ©er un site « web » contenant un annuaire des chercheurs, des cahiers de protocoles et une base de donnĂ©es bibliographiques. Ceci se fera en collaboration Ă©troite avec les chercheurs europĂ©ens et amĂ©ricains de la spĂ©cialitĂ©

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

    No full text
    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 NoumĂ©a. 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 ÎŒg 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
    corecore