Variabilité spatiale multiéchelle du zooplancton dans un lagoon récifal côtier (Multiscale spatial variability of zooplankton in a coastal reef lagoon)

Thèse de doctorat réalisée en cotutelle entre l'Univeristé Paris VI, l'Université de Montréal, Canada (directeur de thèse: Pr Pierre LEGENDRE) et l'Université des Antilles et de la Guyane, Guadeloupe (codirecteur de thèse: Pr Max LOUIS). Mention Très Honorable décernée par le jury composé de: M. G. BOUCHER, Directeur de Recherche, CNRS, Examinateur M. J. CLAVIER, Professeur, Université de Brest, Rapporteur M. F. IBANEZ, Maître de conférences, Université Paris 6, Rapporteur M. P. LEGENDRE, Professeur, Université de Montréal (Canada), Directeur de thèse M. M. LOUIS, Professeur, Université Antilles-Guyane (France), Directeur de thèse M. P. NIVAL, Professeur, Université Paris 6, Président du jury et ExaminateurMultiscale spatial variability of zooplankton in a coastal reef lagoon - The identification of changes in ecological patterns with scale, and the understanding of the processes that effect these changes are of considerable importance in modern oceanographic studies. In this context, understanding how a biological community responds to the environmental heterogeneity requires the knowledge of generating processes and the spatial scale at which they operate. The spatial relationships between zooplankton variability and environmental heterogeneity are still little known in coastal tropical ecosystems. Thus the objective of the present research has been to determine the scales of spatial dependency of the patterns of zooplankton associated with a coastal reef lagoon and of the underlying environmental processes. In this way, research interests consisted in quantifying patterns of zooplankton variability in space, understanding how patterns change with scale, and determining the physical and biological processes implicated in these spatial patterns. The sampling, carried out along one transect oriented from the coast to the open sea in the Grand Cul-de-Sac Marin lagoon (Guadeloupe, French West Indies) has been focused on two zooplankton size classes (190–600 µm and > 600 µm) for which biomass and abundance have been estimated. The multiscale analysis has been used to characterize the zooplankton patterns at different spatial scales (from the habitat scale to the lagoon scale) and to identify the processes responsible of these spatial structures. This study has shown that the zooplankton variability is a multiscale phenomenon of which the intensity and the spatial scale depend on the organism size, their motility and the response-variable considered (biomass or abundance). Biomass and abundance of the zooplankton associated with the coastal reef lagoon vary in response to the phytoplankton spatial distribution, the zooplankton behaviour, the habitat heterogeneity, the local hydrodynamics, and the meteorological events. The nature and the effects of these processes are dependent on the spatial scale. This work has also shown how the change of spatial scale underlines the different organisation levels in zooplankton community in response to the environmental heterogeneity.Variabilité spatiale multiéchelle du zooplancton dans un lagoon récifal côtier - L'identification des changements dans les patrons écologiques selon l'échelle spatiale et la compréhension des processus qui génèrent ces changements sont d'une importance considérable en océanographie. Dans ce contexte, comprendre comment une communauté biologique répond à l'hétérogénéité environnementale requiert la connaissance des processus impliqués et l'échelle spatiale à laquelle ils opèrent. Les relations spatiales entre la variabilité du zooplancton et l'hétérogénéité environnementale sont encore imprécises dans les écosystèmes tropicaux côtiers. L'objectif de ce travail de thèse a donc été de déterminer les échelles de dépendance spatiale des patrons du zooplancton associé à un lagon récifal côtier et des processus environnementaux sous-jacents. Dans ce contexte, les intérêts de cette recherche ont été de quantifier les patrons de la variabilité du zooplancton dans l'espace, de comprendre comment ces patrons changent avec l'échelle spatiale et de déterminer les processus physiques et biologiques responsables de ces patrons spatiaux. L'échantillonnage, effectué le long d'un transect de la côte vers le large dans le lagon du Grand-Cul-de-Sac Marin (Guadeloupe), a concerné deux classes de taille du zooplancton (190–600 µm et > 600 µm) pour lesquelles la biomasse et l'abondance ont été estimées. L'analyse multiéchelle a été utilisée pour caractériser les patrons du zooplancton aux différentes échelles spatiales (de l'échelle de l'habitat à celle du lagon tout entier) et pour identifier les processus responsables de ces structures spatiales. Cette étude a montré que la variabilité du zooplancton est un phénomène multiéchelle dont l'amplitude et la dépendance spatiale dépendent de la taille des organismes, de leur motilité et de la variable-réponse considérée (biomasse ou abondance). La biomasse et l'abondance du zooplancton varient en réponse à la distribution spatiale du phytoplancton, au comportement du zooplancton, à l'hétérogénéité de l'habitat, à l'hydrodynamique et aux évènements météorologiques. La nature et les effets de ces processus sont dépendants de l'échelle spatiale. Ce travail a montré comment le changement d'échelle spatiale met en évidence différents niveaux d'organisation de la communauté zooplanctonique en réponse à l'hétérogénéité environnementale

Concentrations of Nandrolone metabolites in urine after the therapeutic administration of an ophthalmic solution

Nandrolone, an anabolic steroid, is used for the treatment of several diseases and is available in various pharmaceutical formulations. The most widely used pharmaceutical formulation is Deca-Durabolin (R), but other products, such as Keratyl (R) eye drops solution, are also currently administered. Nandrolone is one of the most abused anabolic steroid in sports. Analyses for this anabolic steroid according to the World Anti-Doping Agency (WADA) protocol are based on the identification of the nandrolone two main urinary metabolites which, in humans, are glucuronides of 19-norandrosterone and 19-noretiocholanolone. A positive cut off limit of 2ng/mL has been set by the anti-doping code for the first metabolite, 19-norandrosterone. In this preliminary study, an eye drops solution (Keratyl (R)) containing a therapeutic dose of a nandrolone sodium sulphate was administered to several male volunteers during 3 days and urines were collected during 3 weeks. Surprisingly, contrary to all expectations, the urinary concentrations measured in urines reached 450 ng/mL and 70 ng/mL for norandrosterone and noretiocholanolone, respectively. Moreover, concentration levels near to 2 ng/mL were found, more than 2 weeks after the last administration, depending on individual metabolism. Inter-variability as well as intra-variability of nandrolone excretion kinetic, regarding this particular administration mode, were also evaluated. Quantification of nandrolone metabolites was performed by GC-MS. The method was previously validated in terms of specificity, precision, linearity, LOD, LOQ, robustness, accuracy and the expanded uncertainty was also evaluated

Use of ion trap gas chromatography-multiple mass spectrometry for the detection and confirmation of 3 ' hydroxystanozolol at trace levels in urine for doping control

Stanozolol, a synthetic anabolic androgenic steroid, is often abused in sports to enhance performance. Consequently, the anti-doping laboratories daily screen for its metabolites (3'hydroxystanozolol and 4beta hydroxystanozolol) in all urines, mainly by GC-MS, after enzymatic hydrolysis and TMS derivatization. A sensitive and specific method by GC-MS3 has been developed for the identification in urine of 3'hydroxystanozolol at trace levels. Full mass spectra and diagnostic ions are presented and a case report is commented. In this case, it was possible to attest the presence of a low concentration of stanozolol metabolite in a sample obtained from a competition test. This would have not been possible with other analytical techniques used in the laboratory. Through this case report, it was also possible to demonstrate the importance of sampling and the difficulties that has to face the laboratory when the pre-analytical step is not correctly performed

Development and validation of a capillary zone electrophoresis method for the determination of ephedrine and related compounds in urine without extraction

A capillary zone electrophoresis (CZE) method, with UV detection and in the presence of dimethyl-beta-CD, was optimized by means of an experimental design for the separation and the simultaneous quantitation of ephedrine, pseudoephedrine, norephedrine (phenylpropanolamine) and norpseudoephedrine (cathine) in urine without any extraction. In this application, the optimization of the analytical conditions with an experimental design was preferred to a univariate study. Therefore, a central composite design was used and the following factors were investigated and varied simultaneously: buffer concentration, buffer pH and dimethyl-beta-CD concentration. In order to evaluate the influence of each experimental parameter on the analytical separation, the resolutions between the four compounds, as well as the separation time and generated current were observed and established as responses of the experimental design. A model was obtained for each response by linear multiple regression of a second-degree mathematical expression. After acceptance of the mathematical models, the most favorable conditions were determined by maximizing the resolutions between the four compounds and by setting the other responses at threshold values. Successful results were obtained with a 260 mM Tris-phosphate buffer at pH 3.5 in the presence of 13.3 mM dimethyl-beta-CD at 25degreesC and with an applied voltage of 30 W Under these optimized conditions, a baseline separation of the four compounds was achieved in less than 6 min. The method was validated in terms of precision, linearity, accuracy and successfully applied for the determination of these compounds in urine samples without any extraction as well as in nutritional supplements

Variabilité spatiale multiéchelle du zooplancton dans un lagon récifal côtier

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceCanadaFRC

Development and validation of a capillary zone electrophoresis method for the determination of atropine, homatropine and scopolamine in ophthalmic solutions

A capillary zone electrophoresis method is described for the simultaneous determination of atropine, homatropine and scopolamine. Successful results were obtained after optimization of the electrophoretic parameters such as buffer composition and pH. The best separation was achived using a 100 mM Tris-phosphate running buffer at pH 7. The validation data proved that the method had the requisite selectivity, sensitivity, reproducibility and linearity to be used for the assay of these compounds in pharmaceutical formulations. Dosage of the separate drugs in ophtalmic preparations is also presented

Application of micellar electrokinetic chromatography to the determination of some tropane alkaloids in various plant extracts

A micellar electrokinetic chromatography method is described for the simultaneous determination of hyoscyamine, scopolamine and littorine. The separation buffer consisted of a 30 mM borate-phosphate buffer at pH 8.7, in the presence of 40 mM sodium dodecyl sulfate and 16.5 % acetonitrile. The method is applied to the determination of these alkaloids in various hairy root and plant extracts