Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Yes / One-pot reaction between 8-hydroxyquinoline-2-carboxaldehyde (HQC) and tris(hydroxymethyl)aminomethane (TRIS) followed by in situ cyclization yielded an oxazolidine based ligand which produced four mononuclear complexes of MnII(1), CoII(2), NiII(3), ZnII(4), a tetranuclear iron (FeIII4) complex (5) and a trinuclear cobalt (CoIICoIII2) complex (6). Magnetic studies show dominant antiferromagnetic interaction in tetranuclear iron (FeIII4) complex 5 and presence of the slow relaxation of magnetisation in 6. The compounds were also studied for their antibacterial properties. The oxazolidine ligand (H3L2) of this study showed good antimicrobial activity not only against Gram-positive bacteria but against Gram-negative bacteria too. The antimicrobial efficacy of the metal complexes (1–6) is also reported. / The full-text of this article will be released for public view at the end of the publisher's embargo period on 11 Apr 2019.

La phospholipase D (PLD) hydrolyse les phospholipides membranaires en libérant leur tête polaire afin de générer l'acide phosphatidique (PA), impliqué dans la signalisation cellulaire. Pour comprendre les propriétés biochimiques des PLDs, les travaux présentés ont été réalisés autour de deux axes. Le premier axe concerne l'expression recombinante et la purification de la PLDa d'Arabidopsis thaliana (AtPLDa) dans la levure Pichia pastoris. La détermination de la séquence N-terminale a révélé que l'AtPLDa est amputée de ses 35 premiers résidus, suggérant ainsi la participation d'un mécanisme de maturation. Cependant, la région N-terminale des PLDs de plantes est homologue au domaine C2, impliqué dans leur interaction Ca2+-dépendante avec la membrane. Afin d'évaluer l'impact d'un tel clivage, les domaines C2 de l'AtPLDa mais également de l'AtPLDß, à titre de comparaison, ont été étudiés sous leur forme entière ou mature. Ainsi, la caractérisation de leur affinité pour les phospholipides, associée à leur modélisation tridimensionnelle, ont permis de démontrer que les différences de régulation par le Ca2+, observées entre les formes entières et mature, provenait de la présence d'une hélice a amphipathique, retirée lors du processus de maturation. Le second axe concerne le développement d'une nouvelle méthode de mesure des activités PLD via le dosage de manière direct, spécifique et continu du PA grâce à la propriété d'amplification de fluorescence par chélation de la 8-hydroxyquinoléine, en présence de Ca2+. Ainsi, ce test apparait adapté pour le suivi de l'inhibition des PLDs et pour l'étude de leur spécificité de substrat, en utilisant des phospholipides naturels avec différentes tête polaires, et à l'échelle d'une microplaque / Phospholipase D (PLD) hydrolyses membrane phospholipids, leading to the formation of free polar headgroup and phosphatidic acid releasing, involved in cell signaling. To understand the biochemical properties of PLDs, this work has been made around two axes. The one first concerns the recombinant expression and purification of the PLDa of Arabidopsis thaliana (AtPLDa) in the yeast Pichia pastoris. The N-terminal sequence of the recombinant AtPLDa has been determined and found to lack its first 35 amino acids, suggesting the involvement of a maturing mechanism. However, plant PLDs exhibit a C2-lipid binding domain at their N-terminal region, which is involved in their Ca2+-dependent membrane targeting. Thus, to assess the impact of such a cleavage, whole and mature-like C2 domains of AtPLDa, as well as of AtPLDß, for the sake of comparison were studied. Thus, the characterization of their affinity for phospholipids, combined with their three-dimensional modeling have demonstrated that the differences observed in their regulation by Ca2+, observed between whole and mature-like forms, originated from the presence of a N-terminus amphipathic a helix, removed during the maturation process. The second axis concerns the development of a novel PLD assay that measure PA in a direct, specific and continuous manner, using the chelation enhanced fluorescence property of 8-hydroxyquinoline in the presence of Ca2+. Thus, this assay appears suitable for monitoring both the inhibition of PLDs as well as their substrate specificity, using natural phospholipids with different polar headgroups, and at a microplate scale

The submitted thesis deals within the sensitive fluorimetric determination of scandium with a new reagent 8-Hydroxyquinoline-5-sulphonic acid. All important factors such as time, pH, reagent concentration, buffers, surfactants and selected interferents have been studied with respect to the selectivity, sensitivity, precision and detection limit on the determination by using classic fluorescence spectra and their first derivation. This reagent was also used for the determination of scandium in real waters. The new reagent was shortly compared to morin and lumogallion when used for scandium.

No description available.

The growth of ornamental plant market in Brazil is remarkable nowadays with strong participation of Northeast region, particularly in Alagoas State on the commercialization of tropical flowers. Taking into account this economic aspect, it is of great importance for the productive chain of ornamental species the study of aspects of post harvest activities. Alpinia purpurata (Viell) K. Schum (Zingiberaceae) which occupies the second place in economic importance amongst tropical flowers. It is the main flower for growing and harvesting. The main objective of this research programme is to study the different aspects of Alpinia post-harvesting: (1) time of harvesting and cut of the basis of the stems, and (2) the use of solutions of pulsing ; and/or maintenance of the floral stem by using: (2.1.) biocide compounds and pH of the solution; (2.2) carbohydrates and carbohydrates plus biocides; (2.3) anti-ethylene compounds and antiethylene compounds plus carbohydrates; (2.4) elements as calcium and silicon; and (2.5) senescence retarding growth regulators. It was evaluated the influence of these factors in the water relations, quality and longevity of the stems. Six experiments were carried out in the laboratory (CECA) of the Federal University of Alagoas. In the first experiment, the stems were harvested in three different times and they were cut periodically on their basis. In the second experiment different biocide substances were tested (8- hydroxyquinoline sulphate, aluminum sulphate, salicilic acid and sodium hipocloride) associated to pH variation of the maintenance solution. In the third experiment the stems received sucrose solutions pulsing from 2 to 20% for 12, 24 and 48 hours, following by maintenance in distilled water or in solution of 8- hidroxikinolin (HQS). The fourth experiment comprised three times of exposition (30, 60 and 120 min) with STS 1mM following by the presence or absence of pulsing in sucrose 20% for 12 hours. In the fifth experiment it was evaluated the effect of the addition of Ca (calcium sulphate 50 and 100mM), Si (sodium silicate 1,25 and 2,50 mM) and Ca+Si in maintenance solution. In the sixth experiment the stems were submitted to gibberellins, solutions (GA3), 10, 30 and 60 μm and cytokinin (benzyladenine 6-BA), 10, 20 and 100μm in 24 hours pulsing under continuous light. In all experiments the fresh biomass and the quality (scale of values) of the stems were determined daily or every two days until the end of the experiment. The amount of water was also determined for the floral bracts and dry biomass. The experiments were analised by completely randomized design and the data submitted to the variance analysis, test of averages and , when necessary, to the regression analysis. It was observed that the stems harvested at the end of the afternoon had shown greater commercial value; however, the regular cuts of the basis of the stems reduced their longevity. The use of HQS provided greater durability and humidity of the stems. On the other hand the other biocides did not improve the quality when compared to the control. The reduction of the pH by using citric acid did not interfere with the studied parameters. The use of sucrose in pulsing was only effective when the stems had been kept in distilled water. In this case the concentration sucrose of 20% for 12 hours showed better results. Silver thiosulphate when in pulsing for 30 minutes produced an increase of water contents and for 60 minutes or plus, or when addition of sucrose, caused dehydration of the stems. The only use of calcium sulphate or in association with sodium silicate in maintenance solution caused high improvement of the quality of the stems in comparison to the control and sodium silicate treatment. The use of cytokinin and gibberellins even considering it improved the water contents of the stems did not affect the commercial durability of them. / É notável o crescimento do mercado de plantas ornamentais no Brasil. Com participação efetiva da região Nordeste, destacando-se as exportações de flores tropicais, onde o Estado de Alagoas vem se firmando, com Alpinia purpurata (Viell) K. Schum (Zingiberaceae) como a principal flor de corte, e que ocupa o segundo lugar em importância econômica dentre as flores tropicais. Levando-se em conta esse aspecto econômico, verifica-se ser de grande importância para a cadeia produtiva desses cultivos, o estudo de aspectos relativos à da pós-colheita. Assim sendo, a presente pesquisa, objetivou estudar diferentes aspectos do manejo pós-colheita dessas flores, testando: (1) hora de colheita e corte da base das hastes, e (2) o uso de soluções de pulsing ; e/ou manutenção das hastes florais - neste caso ainda associado (2.1) a substâncias biocidas com o pH na solução sob controle; (2.2) a carboidratos e carboidratos mais biocidas; (2.3) a substâncias anti-etileno e substâncias anti-etileno mais carboidratos; (2.4) a elementos como cálcio e silício; e (2.5) a fitorreguladores retardantes da senescência. Avaliou-se a influência destes fatores nas relações hídricas, qualidade e longevidade das hastes cortadas, através de seis experimentos em laboratório no Centro de Ciências Agrárias da Universidade Federal de Alagoas (CECA/UFAL). No primeiro experimento, as hastes foram colhidas em três diferentes horários, recebendo durante o período pós-colheita cortes periódicos na base da haste. No segundo experimento, foram testadas substâncias biocidas (Sulfato de 8- hidroxiquinolina, Sulfato de alumínio, Ácido salicílico, Hipoclorito de sódio) associadas à redução ou não do pH. No terceiro experimento as hastes receberam tratamento de pulsing com soluções de sacarose entre 2 e 20%, por períodos de 12, 24 e 48 h, seguidas de manutenção em água destilada ou em solução de 8-hidroxiquinolina (HQS) comparando-se com duas testemunhas (água destilada ou solução de HQS). No quarto experimento, foram testados três tempos de exposição (30, 60 e 120 minutos) a STS 1mM, seguido ou não de pulsing em sacarose a 20%, por 12 horas. No quinto experimento, foram verificados os efeitos da adição de Ca (sulfato de cálcio a 50 e 100mM), Si ( silicato de sódio a 1,25 e 2,50 mM) e Ca+Si em solução de manutenção. No sexto experimento, as hastes foram submetidas a soluções de SILVA, A.T.C. 2006 Manejo pós-colheita de alpinia purpurata (Vieill) K. Schum (zingiberaceae)... xv giberelina (GA3), a 10, 30 e 60 μM e citocinina (benziladenina 6-BA), a 10, 20 e 100 μM em pulsing por 24 horas, sob luz contínua. Em todos os experimentos, a massa fresca e a qualidade (com base em notas) das hastes foram determinadas diariamente, ou a cada 2 dias; no final de cada experimento foram também determinados o conteúdo relativo de água das brácteas florais e a massa seca das hastes. O delineamento utilizado foi o inteiramente casualizado sendo os dados submetidos à análise de variância, teste de médias e, quando necessário, à análise de regressão. As hastes cortadas ao final da tarde tiveram maior durabilidade comercial, porém o corte periódico da base das hastes reduziu sua longevidade. O uso de HQS proporcionou maior durabilidade e hidratação das hastes, sendo que os demais biocidas testados não melhoraram a qualidade. A redução do pH, pelo uso do ácido cítrico, não influenciou nas variáveis estudadas. O uso de sacarose em pulsing só foi efetivo quando as hastes foram mantidas em água destilada, sendo melhor o resultado para a concentração de 20% por 12 horas. O tiossulfato de prata em pulsing por 30 minutos, promoveu um aumento de hidratação, mas desidratou as hastes a 60 minutos ou mais ou quando adicionado à sacarose. O uso de sulfato de cálcio em solução de manutenção e quando associado ao silicato de sódio promoveu elevada melhoria de qualidade das hastes. O uso de citocininas e giberelinas embora tenha melhorado as relações hídricas das hastes não afetou a durabilidade comercial das mesmas.