Troisième conférence internationale sur les ravageurs en agriculture

La contribution des techniques de la biologie moléculaire en Acarologie est présentée sur la base de résultats obtenus chez les acariens phytophages et prédateurs de phytophages. Différentes situations biologiques sont abordées : identification précise des espèces, élaboration de phylogénies, estimation de la variabilité génétique d'une espèce de prédateur utilisé en lutte biologique. (Résumé d'auteur

Mitochondrial COI sequences in mites : evidence for variations in base composition

Studies of mitochondrial DNA sequences in a variety of animals have shown important differences between phyla, including differences in the genetic codes used, and varying constraints on base composition. In that respect, little is known of mites, an important and diversified group. We sequenced a portion (340 nt) of the cytochrome oxidase subunit I (COI) encoding gene in twenty species of phytophagous mites belonging to nine genera of the two families #Tetranychidae and #Tenuipalpidae. The mitochondrial genetic code used in mites appeared to be the same as in insects. As is generally also the case in insects, the mite sequences were very rich in A + T (75% on average), especially at the third codon position (94%). However, important variations of base composition were observed among mite species, one of them showing as little as 69% A + T. Variations of base composition occur mostly through synonymous transitions, and do not have detectable effects on polypeptide evolution in this group. (Résumé d'auteur

Mitochondrial cytochrome oxidase I in tetranychid mites : a comparison between molecular phylogeny and changes of morphological and life history traits

Spider mites, #Tetranychidae, represent one of the most cosmopolitan and economically important groups of terrestrial arthropods ; however, many aspects of their evolutionary relationships remain uncertain. We sequenced part of the mitochondrial cytochrome oxidase subunit I (COI) gene in 20 species of phytophagous mites belonging to nine genera and two families (#Tetranychidae and #Tenuipalpidae$), including several agricultural pests. As reported in insects, the sequences were extremely rich in A+T (75$ there seems to have been convergent evolution of these morphological characters together with independent development of a common adaptation to this mode of life in different genera. (Résumé d'auteur

Polarized cortical tension drives zebrafish epiboly movements

The principles underlying the biomechanics of morphogenesis are largely unknown. Epiboly is an essential embryonic event in which three tissues coordinate to direct the expansion of the blastoderm. How and where forces are generated during epiboly, and how these are globally coupled remains elusive. Here we developed a method, hydrodynamic regression (HR), to infer 3D pressure fields, mechanical power, and cortical surface tension profiles. HR is based on velocity measurements retrieved from 2D+T microscopy and their hydrodynamic modeling. We applied HR to identify biomechanically active structures and changes in cortex local tension during epiboly in zebrafish. Based on our results, we propose a novel physical description for epiboly, where tissue movements are directed by a polarized gradient of cortical tension. We found that this gradient relies on local contractile forces at the cortex, differences in elastic properties between cortex components and the passive transmission of forces within the yolk cell. All in all, our work identifies a novel way to physically regulate concerted cellular movements that might be instrumental for the mechanical control of many morphogenetic processes.Peer ReviewedPostprint (author's final draft

Genetic variability in Tetranychus urticae (Acari : Tetranychidae) from Greece : insecticide resistance and isozymes

Etude de la résistance au méthyl-parathion, au méthidathion et au méthomyl chez une population de #Tetranychus urticae$ Koch originaire de Grèce. A la CL 50 le taux de résistance est hautement variable avec le méthidathion (5 à 63 fois) et avec le méthomyl (6 à 34 fois). Les courbes de mortalité avec le méthyl-parathion présentent un plateau net à une mortalité d'environ 20% et le taux de résistance est d'environ 50 fois à CL 50, dans tous les échantillons. Par utilisation de la focalisation isoélectrique sur des membranes d'acétate de cellulose, les études électrophorétiques de 5 loci codant les estérases (Est-1 et Est-2), l'isomérase gluco-phosphate (Gpi), l'enzyme malique (Me) et la phosphoglucomutase (Pgm), indiquent les différences génétiques importantes parmi les échantillons. (Résumé d'auteur

Análisis simultáneo de aflatoxinas y ocratoxina A en compost por HPLC-MS

Las aflatoxinas y ocratoxina A son las micotoxinas más estudiadas debido a su elevada toxicidad y amplia distribución. En este trabajo se describe un método de análisis simultáneo de las aflatoxinas B1, B2, G1, G2 y la ocratoxina A en compost por HPLC-MS. El método consiste en una extracción de las toxinas con MeOH:H 2O, posterior purificación de la muestra con cartuchos de extracción en fase sólida y posterior análisis cromatográfico en 18 minutos utilizando una columna XTerra (2.1x100mm, 3.5mm). En este trabajo se demuestra que no hay presencia de las toxinas de interes a concentraciones superiores a 0,2mg/kg

Plasma Proteomics: optimized experimental design in cardiovascular disease

Comunicaciones a congreso