No description available.

The motivation of this work was to produce novel analytical techniques capable of probing the physical properties of the cell surface. Many researchers have used supported lipid bilayers (SLBs) as models to study the structure and function of the cell membrane. The complexity of these models is consistently increasing in order to better understand the myriad of physiologically relevant processes regulated by this surface. In order to aid researchers in studying such phenomenon, the following contributions were made. To manipulate components within the cell membrane, an electrophoretic flow cell was designed which can be used as a probe to study the effect of electrical fields on charged membrane components and for the separation of these components. This devise allows for the strict control of pH and ionic strength as species are observed in real-time using fluorescence microscopy. Additionally, advancements have been made to the production of patterned heterogeneous SLBs for use in separations and to probe the interactions of membrane components. The methodology to couple SLB separations and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) imaging was devised. This technology allows for the label-free mapping of the SLB surface post electrophoresis in order to observe naturally occurring species unperturbed by the addition of extrinsic tags. The final contribution, and perhaps the greatest, is the development of a procedure to create highly mobile SLBs from native membranes. These surfaces have vast potential in that they are no longer simple models of the cell surface, they are in fact the actual cell surface made planar. This advancement will be of great use to biophysicists and biochemists interested in using surface specific analytical methods to better understand physiological processes. These highly mobile native membrane surfaces have been coupled with the SLB electrophoresis technology to separate discrete bands of lipids and proteins, a proof of principle that will hopefully be further developed into a standard method for membrane proteomic studies. Collectively the tools and methodologies described herein show great potential in allowing researchers to further add to mankind’s understanding of the cellular membrane.

La qualité des lipides des préparations pour nourrissons est primordiale, notamment en termes d’acides gras polyinsaturés (AGPI) comme l’acide arachidonique (ARA) et docosahexaénoïque (DHA). Ces derniers pourraient favoriser le développement neurosensoriel de l’enfant. Nous avons ainsi évalué 4 standards commerciaux contenant des lipides végétaux ou laitiers et supplémentés ou non en ARA/DHA, sur le développement neurosensoriel au travers d’un modèle d’allaitement artificiel « pups in the cups ». En TEP-cs, nous observons que la supplémentation en ARA/DHA permet de normaliser le fonctionnement cérébral.L’exploration des lipides tissulaires indique des différences en DHA particulièrement bas avec l’allaitement en lipides végétaux purs. Nous proposons un algorithme de prédiction du DHA cérébrale et oculaire via les profils en acides gras érythrocytaires. Dans ces tissus un tiers des espèces à DHA sont affectées et corrélées à l’activité cérébrale. Les neuromédiateurs issus de l’AL, ARA, DHA par la voie LOX sont impactés ainsi que la distribution spatiale en DHA en IMS. Les autres données omiques soulignaient l’impact des interactions fond lipidique x ajout DHA/ARA (transcriptomique) ou fond lipidique (métabolomique) sur la régulation du métabolisme cérébral impactant le métabolisme neuronal et le métabolisme cérébral du microbiote probablement via l’axe de signalisation intestin-cerveau. Nous identifions alors un métagénome sensible à l’ajout DHA/ARA corrélé à la fonction cérébrale. Enfin, des modifications épigénétiques (méthylation du génome et miARN) touchant le groupe FC suggèrent potentiellement un impact à long terme. / The quality of lipids in infant formula is essential, especially in terms of polyunsaturated fatty acids (PUFAs) such as arachidonic acid (ARA) and docosahexaenoic acid (DHA). These could promote the neurosensory development of the child. We thus evaluated 4 commercial standards containing plant or dairy lipids and supplemented or not with ARA / DHA, on the neurosensory development through an artificially feeding model "pups in the cups". In PET-cs, we observe that the supplementation in ARA / DHA makes it possible to normalize the cerebral functioning. The exploration of tissue lipids indicates differences in DHA which are particularly low with pure plant lipids intake. We propose an algorithm for predicting cerebral and ocular DHA via erythrocyte fatty acids profiles. In these tissues one-third of the DHA species are affected and correlated with brain activity. The neuromediators resulting from AL, ARA, DHA by the LOX pathway are impacted as well as the spatial distribution of DHA in IMS imaging. Other omics data underlined the impact of lipid background x combination DHA / ARA (transcriptomics) or lipid background (metabolomics) on the regulation of cerebral metabolism impacting neuronal metabolism and brain metabolism of the microbiota probably through the signalling of gut-brain axis. We then identify a metagenome sensitive to the addition of DHA / ARA correlated to brain function. Finally, epigenetic modifications (methylation of the genome and miRNA) affecting the FC group potentially suggest a long-term impact.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-07-25T12:53:59Z No. of bitstreams: 2 Tese - Aline Pereira Moraes - 2017.pdf: 5958230 bytes, checksum: 799ef005b7ec97bfd8fd06e0e7f3a36b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-07-26T11:58:55Z (GMT) No. of bitstreams: 2 Tese - Aline Pereira Moraes - 2017.pdf: 5958230 bytes, checksum: 799ef005b7ec97bfd8fd06e0e7f3a36b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-07-26T11:58:55Z (GMT). No. of bitstreams: 2 Tese - Aline Pereira Moraes - 2017.pdf: 5958230 bytes, checksum: 799ef005b7ec97bfd8fd06e0e7f3a36b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-04-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Palicourea and Psychotria (Rubiaceae) are known for the presence of compounds with potential biological activity, such as the indole alkaloids, flavonoids and norisoprenoids. In order to increase the chemical knowledge of Palicourea species, the phytochemical study of the aerial parts of Palicourea officinalis was carried out for the first time, through the isolation by chromatography and structural elucidation of the compounds by NMR and mass spectrometry. The following secondary metabolites were identified: the novel alkaloid 18-epi-brachycerine; the norisoprenoids: guettardionoside, 3-oxo--ionol 9-O--D-apiofuranosyl-(1®6)--D-glucopyranoside, vomifoliol 9-O--D - apiofuranosyl-(1®6)--D-glucopyranoside and 7,8-dihydro-vomifolol 9-O--D-apiofuranosyl-(1®6)--D-glucopyranoside; the lignan syringaresinol--D-glucoside; the pyrazines 2,5-deoxyfructosazine, 2,6-deoxyfructosazine and fructosazine; the flavonoids quercetin 3-O-sophoroside and kampferol 3-O-sophoroside; 3-caffeoyl and 4-caffeoylquinic acids; feruloylquinic acids; salicylic acid; coumarin scopoletin; besides ursolic and oleanolic triterpenes acids and glycosylated sitesterol and stigmasterol steroids. In addition, for the first time, the indirect and direct DESI-MSI techniques were applied in the study of the spatial distribution of alkaloids in the leaves of Palicourea coriacea and Psychotria prunifolia. The indirect approach was applied successfully and showed distinct distribution patterns of the alkaloids detected. The image data were confirmed by LC-MS. / Palicourea e Psychotria (Rubiaceae) são gêneros conhecidos pela presença de compostos com potencial atividade biológica, tais como os alcaloides indólicos, flavonoides e norisoprenoides. Com o objetivo de ampliar o conhecimento químico de espécies de Palicourea, foi realizado pela primeira vez o estudo fitoquímico das partes aéreas de P. officinalis, através do isolamento por cromatografia e elucidação estrutural dos compostos por RMN e espectrometria de massas. Os seguintes metabólitos secundários foram isolados e identificados: o alcaloide inédito 18-epi-braquicerina; os norisoprenoides: guettardionosídeo e 3-oxo--ionol 9-O--D-apiofuranosil(1”®6’)- -D-glicopiranosídeo e a mistura vomifoliol 9-glicopiranosídeo, vomifoliol 9-O--D-glucopiranosil-(1®6)--D-apiofuranosídeo e 7,8-diidro-vomifoliol 9-O--D-glucopiranosil-(1®6)--D-apiofuranosídeo; a lignana siringaresinol-4’--D-glicosídeo; a mistura de pirazinas 2,5-desoxifructosazina, 2,6-desoxifructosazina e fructosazina; os flavonoides quercetina 3-O-soforosídeo e canferol 3-O-soforosídeo; os ácidos clorogênicos 3-cafeoil e 4-cafeoil-quínicos; uma mistura de ácidos feruloil-quínicos; ácido salicílico; a cumarina escopoletina; além das misturas dos triterpenos ácidos ursólico e oleanólico e dos esteroides sitosterol e estigmasterol glicosilados. Além disso, pela primeira vez, as técnicas de produção de imagem química por DESI-MS direto e indireto foram aplicadas no estudo da distribuição espacial dos alcaloides nas folhas de Palicourea coriacea e Psychotria prunifolia. O método indireto apresentou melhores resultados, com distintos padrões de distribuição dos alcaloides detectados. Os dados da imagem foram confirmados por LC-MS.

No description available.

Symbiotic nitrogen (N) fixation (SNF) occurs in specialized organs called nodules after successful interactions between legume hosts and rhizobia. Within nodule cells, N-fixing rhizobia are surrounded by plant-derived symbiosome membranes, through which the exchange of nutrients and ammonium occurs between bacteria and the host legume. Phosphorus (P) is an essential macronutrient, and N2-fixing legumes have a higher requirement for P than legumes grown on mineral N. First, I investigated the impact of P deprivation on wild-type Medicago truncatula plants. My observations that plants had impaired SNF activity, reduced growth, and accumulated less phosphate in P-deficient tissues (leaves, roots and nodules) is consistent with those of similar previous studies. Galactolipids decreased with increase in phospholipids in all P-starved organs. Matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI-MSI) of phosphatidylcholine (PC) species in nodules showed that under low P environments distributions of some PC species changed, indicating that membrane lipid remodeling during P stress is not uniform across the nodule. Secondly, a metabolomics study was carried out to test the alterations in the metabolic profile of the nodules in P-stress. GC-MS based untargeted metabolomics showed increased levels of amino acids and sugars and decline in amounts of organic acids in P deprived nodules. Subsequently, LC-MS/MS was used to quantify these compounds including phosphorylated metabolites in whole plant. My findings showed strong drop in levels of organic acids and phosphorylated compounds in P deprived leaves with moderate reduction in P deprived roots and nodules. Moreover, sugars and amino acids were elevated in whole plant under P deprivation. Finally, the last project of my thesis involved studying the response of PDIL3 (Phosphate Deficiency-Induced LncRNA-3) a long non-coding RNA (lncRNA) mutant under severe P stress. PDIL3 is known to regulate Pi-deficiency signaling and transport in M. truncatula (Wang et al., 2017). My results confirmed that in P starvation, pdil3 plants showed better shoot growth, accumulated more phosphate in shoots, had impaired SNF and less rhizobial occupancy in nodules than WT. Subsequently, MALDI–MS imaging was used to spatially map and compare the distribution of phosphatidylcholine (PC) species in nodules of pdil3 and WT in P-replete and P-depleted conditions. Several PC species showed changes in distributions in pdil3 nodules compared to WT in both P sufficient and P deprived conditions. These data suggest that PDIL3's role is not just suppression of the Pi transporter, but it may also influence P partitioning between shoots and nodulated roots, meriting further investigation.