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by Chen Li. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 136-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Orientador: Dalton José Carneiro / Coorientador: Elisabete Maria Macedo Viegas / Banca: João Donato Scorvo Filho / Banca: Léa Silvia Sant'Ana / Banca: Nilva Kazue Sakomura / Banca: Maria Cristina Thomaz / Resumo: Este trabalho foi realizado com o objetivo de avaliar a composição em aminoácidos de vários tipos de silagens produzidas a partir de três matérias-primas, oriundas do descarte da comercialização de peixes marinhos, de água doce; e resíduos da filetagem de tilápias. As silagens foram produzidas por dois processos: por digestão ácida (com 2% de ácido fórmico e 2% de ácido sulfúrico) e por fermentação anaeróbica (com 5% de Lactobacillus plantarum e 15% de melaço de cana). Após um período de estocagem, de 30 a 45 dias, as silagens foram secas conjuntamente com dois subprodutos agrícolas, farelo de soja (protéico) ou quirera de arroz (energético), originando, dessa forma, 12 produtos secos. Foram realizadas análises do teor protéico e do perfil de aminoácidos das matérias primas, das silagens e das silagens co-secas. Observou-se que os descartes da comercialização de peixes marinhos apresentaram maiores teores de proteína bruta (77,67%) que os de água doce (49,62%) e os resíduos da filetagem de tilápia (42,99%). Quanto aos aminoácidos essenciais, em relação ao padrão da FAO, observou-se que todos os produtos de silagens e silagens co-secas apresentaram deficiência em, no máximo três aminoácidos para cada produto. No entanto, considerando-se como aminoácidos limitantes apenas os que estiverem 30% abaixo das exigências mínimas dos peixes em geral, esses produtos não foram deficientes em aminoácidos essenciais, mostrando que todos foram potencialmente viáveis para a utilização em dietas balanceadas para peixes / Abstract: Three types of raw materials (commercial waste from salt water (SW) and freshwater fish (FW); and tilapia filleting residue) were used to produce fish silage by acid digestion (2% formic acid and 2% sulfuric acid), and anaerobic fermentation, (5% of Lactobacillus plantarum and 15% sugar cane molasses). Six test diets were prepared for digestibility trials as follows: 70% reference diet and 30% silage. These diets were fed to juvenile pacu (146 g average weight) in triplicate. Fish were kept in 500-l tanks and feces collected by manual extrusion. It was observed for both processes that saltwater fish waste always presented the highest moisture content and lowest fat and ash. Highest crude protein levels were displayed in silages from commercial fish waste (SW and FW), made from whole fish unfit for human consumption. However, apparent digestibility coefficients did not vary among diets (P>0.05). Although values did not differ statistically, fermented silage consistently displayed higher digestibility coefficients compared to acid silage. The silages exhibited good protein digestibility (72,5 - 80,0%), thus suggesting the feasibility of using fish industry by-products in aquaculture feeds / Doutor

Thyroid hormones (TH) exert their multitude of effects on body development, growth and metabolism largely via transcriptional regulatory pathways. TH-induced transcription is controlled by receptors present in the cell nucleus, therefore extracellular TH must first cross the plasma membrane to gain entry into the cell. The exact mechanisms of TH transport across the plasma membrane are only beginning to be clarified, but it is likely that transport may be an important control step for the effects of TH on transcription. Members of the recently cloned organic anion transporting polypeptide (OATP) family have been shown to transport TH. Inhibitor studies indicate that both the aromatic amino acid System T-type transporter, and the broad scope neutral amino acid transporter System L are mediators of TH uptake into various cell types. However cloned amino acid transporters have not been studied to demonstrate directly whether they can accept TH as substrates.

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Chiral alpha-branched amines are common substructures of bioactive synthetic targets such as alkaloids and amino acids. Direct asymmetric amine synthesis by addition to the C=N bond of carbonyl imino derivatives is promising and efficient to introduce the stereogenic center and carbon-carbon bond in one step. Furthermore, disconnection of either C-C bond at the amine stereogenic center would be the most versatile method to achieve this objective; we could make the choice depending on the different synthetic strategies, such as the availability of precursors and the presence of complicating structural features. In our group, we disclosed that manganese carbonyl mediates stereoselective photolytic radical addition of alkyl iodides to chiral imino acceptors, which is a powerful tool to form a new C-C bond and generate a chiral center. Qualitative mechanistic studies confirm the importance of free radicals, imply that this is a nonchain (or short chain length) free-radical process, and reveal that organomanganese compounds are not a viable source of alkyl radical for the addition reactions under the conditions in our lab. In my thesis, we have extended the application of our methodology. At the beginning of my research, our Mn-mediated addition methodology was first applied to accomplish the couplings of iodides and ketone N-acylhydrazones, generating quaternary carbon stereocenters and offering access to a variety of alpha-alkylated alanine analogs. These radical additions complement enolate alkylation methodologies, as they occur under nonbasic conditions and permit introduction of both primary and secondary alkyl groups with relative ease. The versatility with respect to the iodide is a distinguishing feature of the Mn-mediated coupling that foreshadows application to more complex targets. Secondly, a Mn-mediated radical-ionic annulation strategy was validated as a synthetic route to quinine. Intermolecular radical addition to C=N bonds has rarely been applied as a strategic bond construction in natural product synthesis; this synthesis of quinine offers the strongest demonstration yet of the utility of such reactions in application toward complex multifunctional targets.

Uranyl hybrid materials attract interest owing to promise of synthesizing functional materials, but typically experience limitations in extending dimensionality. This is due to the tendency of the uranyl cation to oligomerize along its equatorial plane, leading to the formation of flat secondary building units. One way to overcome these limitations is to utilize weak interactions to hold a structure together. This can be achieved through using ligands to build secondary building units through strong coordinative bonds that simultaneously provide supramolecular interactions as a means to extend dimensionality in the structure. We examined amino acids as a ligand choice because of its dual features of having a carboxyl group for coordination to the uranyl cation and an amino group that can be protonated to provide charge-assisted hydrogen bonding between to secondary building units in the structure. Aqueous benchtop chemistry in ambient conditions were used to synthesize and crystallize thirteen uranyl-glycine coordination compounds whose structures were elucidated with single crystal X-ray diffraction. Under these conditions, 1D coordination polymers form. The structural features in these compounds were varied to investigate their effects on the hydrogen bonding, including the presence/absence of metal center hydrolysis, the presence of other H-bond accepting carboxylate ligands, the use of dicarboxylic acid ligands to connect uranyl centers, and the addition of a secondary metal. The compounds provide insight into how the charge-assisted hydrogen bonding provided by zwitterionic amino acids is a viable means to extending the dimensionality of uranyl hybrid materials in a variety of chemical systems.

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