Resumo: Considerando a importância da eubiota intestinal na saúde dos animais, o papel da dieta em sua composição e metabolismo tem sido estudado. Neste aspecto os prebióticos têm merecido destaque, incluindo-se a parede celular de leveduras (PCL), uma fonte natural de mananoligossacarídeos. Para o estudo de seu potencial prebiótico para cães, foram empregadas quatro dietas isonutrientes com inclusão de 0% (T0), 0,15% (T15), 0,30% (T30) e 0,45% (T45) de PCL. Foram utilizados oito Beagles adultos, divididos em dois quadrados latinos 4 X 4. Em cada período uma fase de adaptação de 15 dias precedeu 5 dias de coleta total de fezes para o ensaio de digestibilidade e 1 dia de coleta de fezes frescas para enumeração bacteriana, mensuração de pH e determinação das concentrações de ácidos graxos de cadeia curta e aminas bioativas. No dia 21 de cada período, amostra de sangue foi colhida para quantificação imunofenotípica por citometria de fluxo das subpopulações linfocitárias CD5+CD4+, CD5+, CD5+CD8+, CD45+ e CD45+CD21+. Os dados foram avaliados pelo Proc GLM do SAS, sendo as médias comparadas pelo teste de Tukey e por contraste polinomial e ortogonal (p<0,1). Os coeficientes de digestibilidade dos nutrientes não variaram com a inclusão de PCL (p>0,1). A inclusão de PCL não resultou em diferenças quanto às contagens de anaeróbios totais, aeróbios totais, bifidobactéria, lactobacilos, clostridios nas fezes dos cães (p>0.1). Verificou-se aumento linear na concentração fecal de butirato (p=0,055), redução linear das concentrações fecais de tiramina (P=0,1) e histamina (P=0,07) e redução quadrática de feniletilamina e triptamina (P=0,07). Os cães apresentaram, também, aumento linear na concentração de linfócitos CD5+ (P=0,10) e maior número de linfócitos CD45+CD21+ (P=0,053) mediante ingestão de PCL. Concluiu-se que a PCL apresenta efeito prebiótico... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Considering the importance of the intestinal microbiota to the animal health, the role of diet upon microbiota composition and metabolism have been studied. Prebiotics have been emphasized on this regard, including the yeasts cell walls (YCW), a natural source of mannanoligosaccharides. To study the prebiotic potential of this compound for dogs, four isonutrient diets were used with inclusion of 0% (T0), 0,15% (T15), 0,30% (T30) and 0,45% (T45) of YCW. Eight Beagles adults were used, arranged in two 4 X 4 Latin squares. In each replicate an adaptation phase of 15 days preceded a 5 days of total feces collection for digestibility trial and 1 day collection of fresh fecal samples for bacterial enumeration, pH measurement and determination of short chain fatty-acids and bioactive amines concentration. On day 21, a blood samples were collected for immunophenotypic quantification of lymphocyte subsets CD5+CD4+, CD5+, CD5+CD8+, CD45+ e CD45+CD21+ through flow cytometry. The data were evaluated using Proc GLM of SAS, means were compared by Tukey test and polinomial and orthogonal contrasts (p <0,1). The inclusion of YCW did not change the coefficient of total tract apparent digestibility of nutrients (p>0.1) nor the fecal bacterial enumeration (total aerobes and anaerobes, Bifidobacterium, Lactobacillus, Clostridium and Escherichia coli) in dog's feces (p>0.1). Fecal butirate concentration increased linearly with YCW addition (p=0,055), fecal concentrations of tyramine (P=0,1) and histamine (P=0,07) decreased linearly, and phenylethylamine (P=0,07) and tryptamine (P=0,07) concentrations showed a quadratic reduction with YCW consumption. Dogs also presented a linear increase in lymphocytes CD5+ concentration (P=0,10) and a greater CD45+CD21+ lymphocytes number (P=0,053) with YCW addition. In conclusion YCW presents a prebiotic (changing bacterial end product formation) and immunostimulating effect for dogs. / Orientador: Aulus Cavalieri Carciofi / Coorientador: Ruben Pablo Schocken-Iturrino / Banca: Áureo Evangelista Santana / Banca: Maria Beatriz Abreu Glória / Mestre

O objetivo do estudo foi avaliar os efeitos da suplementação de levedura autolisada de Saccharomyces cerevisiae fornecida em duas diferentes inclusões em dietas para frangos de corte como alternativa a um antimicrobiano sobre desempenho zootécnico e avaliação do sistema imune intestinal pela realização da enumeração bacteriana, citometria de fluxo e expressão intestinal de genes ligados à resposta imune intestinal. Neste estudo foram utilizados 1260 pintos de corte machos de um dia de idade da linhagem ROSS AP95&reg; em um experimento de 1 a 35 dias de idade alojados em galpão climatizado com cama de casa de arroz nova. O experimento foi realizado em delineamento inteiramente aleatorizado, com 4 tratamentos e 7 repetições, com 45 aves por boxe. Os tratamentos utilizados foram: T1: ração basal e sem aditivo - controle negativo; T2: ração basal suplementada com 55 ppm de bacitracina de zinco - controle positivo; T3: controle negativo + 2 kg/t de levedura autolisada; T4: controle negativo + 4 kg/t de levedura autolisada. As dietas foram à base de milho e farelo de soja, sendo adicionados às rações 5% de farelo de trigo e 5% de farinha de penas e vísceras (sem tratamento prévio) com objetivo de impor um desafio nutricional aos animais. Ainda visando estimular imunologicamente os animais, aos 7 dias de idade, todas as aves foram desafiadas via ocular com uma vacina viva contendo oocistos de Eimeria sp. na dose recomendada pelo fabricante. Aos 8 dias de idade e 21 dias de idade, uma ave de cada unidade experimental, sem jejum prévio, teve sangue coletado e foi sacrificada para coleta de conteúdo intestinal ileal e cecal para realização da emumeração bacteriana de Enterococus sp., Escherichia coli e Lactobacillus sp., e para a coleta do segmento ileal para avaliar a expressão gênica intestinal de Claudin-1, IL-1&beta;, IL-4, TLR4 e MUC-2 através da PCR em tempo real. Em relação ao desempenho das aves, o tratamento T3 propiciou melhor conversão alimentar em relação a T1 até os 21 dias de idade. Para o período cumulativo, o tratamento T4 propiciou conversão alimentar semelhante ao T2, sendo esta variável melhor para estes tratamentos em relação ao controle negativo. Na enumeração de bactérias no íleo, aos 8 dias de idade, os tratamentos T3 e T4 modularam de forma distinta a contagem de Enterococus sp., e para o gênero Lactobacillus sp., ambos os grupos de levedura apresentaram menor contagem em contraste com o controle positivo. No conteúdo do ceco foi encontrado um menor número de E. coli para os animais grupo T3, diferentemente para o T2 que propiciou maior contagem. Aos 21 dias de idade, foi encontrado diferença na enumeração do gênero Enterococus sp. ileal, cuja contagem foi menor para o T2 em relação ao T1. Na na análise de citometria de fluxo, tendências foram observadas aos 8 dias de idade para o percentual de linfócitos T auxiliares (P=0,16) e para o percentual de linfócitos B (P=0,12) havendo redução com a suplementação de levedura autolisada. A mesma tendência (P=0,19) foi observada aos 21 dias de idade para a contagem de células T citóxicos. Sobre a PCR em tempo real, não foram detectadas diferenças para a expressão de Claudin-1. T2 e T4 propiciaram aumento da expressão gênica de IL-1&beta; aos 21 dias de idade em relação ao controle negativo, sendo que T2 também promoveu aumento de TLR-4 aos 8 dias de idade. Tendências foram observadas com a maior expressão de IL-4 (P=0,06) aos 21 dias de idade pelo T2 e aumento na expressão de MUC-2 (P=0,09) pelo T4 aos 8 dias de idade. Os diferentes padrões de ativação ou não de citocinas revela uma estimulação da via Th2 pelo controle positivo (aumento de IL-1&beta; e IL-4) e da via Th17 pelo tratamento suplementado com 4 kg/t de levedura autolisada (aumento de IL-1&beta;). / The objective of this study was to evaluate the effects of a Saccharomyces cerevisiae autolyzed yeast supplementation in substitution of AGP in broiler diets on performance and immune system (on two different feed inclusions for broilers diets in replacing AGP on broiler performance and evaluation of immune system trough bacterial enumeration, flux citometry and intestinal gene expression. For that, 1260 one-day-old male Ross AP95 chicks were raised from 1 to 35 days of age in a poultry house with new rice husk as litter. The experiment was arranged in a completely randomized design with 4 treatments and 7 replications, with 45 birds per pen. The treatments were: T1: basal diet and no additive - negative control; T2: basal diet supplemented with 55 ppm of zinc bacitracin - positive control; T3: negative control + 2 kg/t of autolyzed yeast; T4: negative control + 4 kg/t of autolyzed yeast. The corn-soybean meal based diets contained 5% wheat bran and 5% poultry by-product meal (with no previous treatment) in order to impose a nutritional challenge to the animals. To impose a further immunological challenge, at 7 days of age, all the birds were eye drop-vaccinated with live vaccine containing Eimeira sp. oocysts at the manufacturer recommended dosis. At 8 and 21 days of age, one chick per experimental unit, with no fasting, had the blood collected and was sacrificed for sampling the ileal and cecal intestinal contents for enumeration of Enterococus sp., Escherichia coli and Lactobacillus sp. Also, the ileal segment was sampled for intestinal gene expression of Claudin-1, IL-1&beta;, IL-4, TLR4 e MUC-2 by RNA extraction through real time PCR. For the performance results at 21 days of age, T3 had the same feed conversion rate of T1. For the cumulative grow-out, T4 had the same feed conversion rate as T2, being this variable better for the aforementioned tretaments in comparison to negative control. For ileal bacterial enumeration, at 8 days of age, T3 and T4 modulated distinctly the enumeration of Enterococus sp., and reduced the counts of Lactobacillus sp. in comparison to the positive control. In the cecal contents, the enumeration for E. coli was the lowest for T3, differing from the positive control. At 21 days of age, there was a difference in ileal Enterococus sp., with higher counts for T2 relative to T1. In the flux citometry, tendencies were observed at 8 days of age for T helper cells (P=0,16) and for B cells (P=0,12), which were reduced in the autolyzed yeast treatments. The same tendency (p=0.19) was seen at 21 days of age for T activated cytotoxic cells. For the real time PCR, there was no difference in the expression of Claudin-1 (P<0,05). T2 and T4 promoted upregulation of IL-1&beta; at 21 days of age (P<0,05) in comparison to the negative control; additionally, the antibiotic tretatment also upregulated the expression of TLR-4 at 8 days of age (P<0,05). Tendencies were observed as upregulation of IL-4 (P=0,06) at 21 days of age by positive control and upregulation of MUC-2 (P=0,09) by the treatment with 4 kg/t of autolyzed yeast at 8 days of age. The different profiles in activating or not cytokines reveals a stimulation of Th2 pathway for the positive control (upregulation of IL-1&beta; and IL-4) and Th17 pathway for the treatment supplemented with 4 kg/t of autolyzed yeast (upregulation of IL-1&beta;).

O paradigma de sistemas de moléculas auto-replicantes é o modelo de quase-espécies, no qual as moléculas são representadas por seqüências binárias de tamanho L e o mecanismo de replicação é suposto imperfeito. Em particular, cada seqüência é gerada corretamente com probabilidade Q = qL, onde q é a probabilidade de cópia exata por dígito. Um dos resultados mais intrigantes no modelo para o relevo de replicação de pico único, no qual há apenas um tipo de molécula com vantagem seletiva a em relação aos outros tipos, é a observação de um limiar de erro a partir do qual toda informação biológica relevante é perdida. A transição de limiar de erro verificada para Qc = l /a pode ser visualizada como uma transição de fase do tipo ordem-desordem. Verificamos que a largura dessa transição decresce com L de acordo com L-1. Concluímos também que as grandezas físicas de interesse são bem descritas por meio de funções de escala. Elaboramos ainda uma versão estocástica (isto é, tamanho de população N finito) para o modelo de quase-espécies, no qual a dinâmica é descrita por uma cadeia de Markov. Mostramos que o tempo característico &#964 para o desaparecimento de seqüências mestras na população obedece uma relação de escala bem definida. A transição em nosso modelo é constatada através da divergência de &#964 em Qc no limite de N &#8594 &#8734 ,sendo que a largura da transição decresce de acordo com N -1/2. Em nossa abordagem não utilizamos nenhuma definição arbitrária para o limiar de erro para população finita. Como solução para o problema da crise de informação associada ao limiar de erro estudamos o modelo de hiperciclos. Neste modelo, as macromoléculas se replicam com o auxílio de outros membros do hiperciclo por meio do mecanismo de catálise. Estudamos analiticamente a propagação de erro no hiperciclo e obtemos os diagramas de fases no espaço de parâmetros para vários tamanhos de hiperciclo n. Esses diagramas descrevem as regiões de estabilidade das diversas soluções de estado estacionário do sistema. Constatamos que para hiperciclos com n &#8804 4 existe um limiar de erro menor que aquele verificado no modelo de quase-espécies. Desde que o suporte catalítico realizado por uma molécula no hiperciclo pode ser considerado de fato um comportamento altruísta, modelos para evolução do altruísmo como, a teoria de seleção de grupos, têm sido utilizados no contexto de evolução pré-biótica. Aqui investigamos a evolução da produção de enzimas e os efeitos de sinergia utilizando esses conceitos. / The quasi-species model is the paradigm of systems composed of self-replicating molecules, which are represented by sequences of fixed length L. The replication machinery is assumed to be imperfect. Particularly, each sequence is copied exactly with probability Q=qL, where q denotes the probability of exact copy per digit. One of the most intriguing results of the model for the single-peak replication landscape, which considers the existence of a master sequence that has a selective advantage a in comparison to the other types, is the occurrence of an error threshold phenomenon beyond the biological information is completely lost. The error threshold transition can be viewed as an order-disorder phase-transition. We investigated the sharpness of the threshold and found that its characteristics persist across a range of Q of order L-1 about Qc. Other physical quantities of interest are also well described by universal functions. We formulate a stochastic version (i.e., finite population size N) for the quasispecies model, in which a Markov chain defines the dynamics. We show that the characteristic time r for the disappearance of master sequences in the population obeys a well defined scaling relation. The transition in this model is signalized by the divergente of t at Qc in the limit N &#8594 &#8734, and the sharpness of the transition decreases like N -1/2. In our approach we do not use any arbitrary definition of the error threshold for finite population. As a solution for the information crisis associated to the error threshold, here we considered the hypercycle model, where the macromolecules self-replicate with the catalytic support of the other members of the hypercycle. We study analytically the error propagation in the hypercycle and obtain the phases diagrams in the space of parameters for several hypercycle sizes n. These diagrams describe the stability regions of the steady state solutions of the system. We find that for hypercicle size n &#8804 4 the error threshold is smaller than that for the quasispecies model. Since the catalytic support developed by a molecule is in fact an altruistic behavior, some models for the evolution of altruism, for instance, the selection group theory, have been investigated in the context of pre-biotic evolution. Specifically, here we analyze the evolution of enzyme production and the effects of synergism.

Since late 1990s, organocatalysis has been widely explored in many aspects and achieved various difficult transformations. In this field, carbonyl catalysis, which could be traced back to 1860 has been developed with impressive progress including asymmetric variants. Over the years, major activation modes were developed for carbonyl catalysis including exploiting temporary intramolecularity to form catalytic tethers and transient intramolecular nucleophiles, dioxirane formation and imine formation. On the other hand, electrophilic activation is also an important area of organocatalysis where impressive progress has been achieved. However, limited examples were reported to achieve the electrophilic activation via carbonyl catalysis. Organophosphorus compounds are crucially important in many aspects in organic chemistry. Many approaches were developed for asymmetric organophosphorus compounds. In this work, different types of organophosphorus compounds were used as the substances for aldehyde-catalyzed hydrolysis reactions. The first part of this thesis illustrated the strategy to combine carbonyl catalysis and electrophilic activation. The hydrolysis of organophosphorus compounds containing P(=O)-N bond were investigated based on Jencks and Gilchrist’s preliminary results with formaldehyde as the catalyst to promote the hydrolysis of one inorganic substance, phosphoramidate. This Chapter describes a systematic research to identify a superior catalyst, o-phthalaldehyde, and develop catalytic hydrolyses of various organophosphorus compounds containing P(=O)-NHR subunits. Gratifyingly, the reaction proved efficient with phosphinic amides and phosphoramidates. Moreover, chemoselectivity was also studied and selective hydrolysis of the P(=O)-N bonds in the presence of P(=O)-OR bonds could be accomplished. The second part of this thesis demonstrated the further development of one of the major modes of carbonyl catalysis. Formaldehyde was identified as the efficient catalyst to react with α-amino phosphonates to form the transient intramolecular nucleophile, which facilitated the subsequent hydrolysis reactions. In this Chapter, different primary and secondary α-amino phosphonates with phenol as the leaving group, were tested in the reaction conditions. As a result, a vast of mono esters of α-amino phosphoric acids could be formed as the products. Finally, the last portion of this thesis applied the methodologies developed in Chapter 2 to prebiotic chemistry. A prebiotic-related aldehyde, glycolaldehyde was studied as the catalyst for the hydrolysis of organophosphorus compounds containing P(=O)-N bond, including phosphinic amides and phosphoramidates. Additionally, other prebiotic important substances, diamidophosphate (DAP) and monoamidophosphate (MAP) were also investigated for potential glycolaldehyde-catalyzed phosphorylation reaction under aqueous conditions. In the presence of catalytic amount of glycolaldehyde, 1) when water was used as the nucleophile, the hydrolysis of DAP and MAP were significantly improved; 2) when other phosphate nucleophiles were added to compete with water, DAP could act as a phosphorylating reagent to phosphorylate other phosphate nucleophiles. Overall, the results presented in this thesis investigated two different activation modes, electrophilic activation and transient intramolecular nucleophiles, for carbonyl catalysis to hydrolyze different organophosphorus compounds, phosphinic amides, phosphoramidates and α-amino phosphonates. The application of carbonyl catalysis to prebiotic chemistry was also achieved especially with the phosphorylation reaction with DAP.

A indústria de pet food cresce juntamente com as pesquisas nessa área com os objetivos não apenas de atender as necessidades nutricionais, mas também, com o propósito de promover saúde, bem estar e longevidade aos animais de companhia. Portanto, objetivou-se avaliar os efeitos de suplementos promotores de saúde intestinal sobre a digestibilidade dos nutrientes, produtos fermentativos e parâmetros imunológicos em cães adultos. Foram utilizados 24 cães adultos de diferentes pesos e portes, divididos em seis blocos casualizados e, distribuídos aleatoriamente nos tratamentos [(CO) controle, sem adição de prebiótico; (GOS) inclusão de 1,0% de galactooligossacarídeos; (B1) inclusão de 0,5% de um blend de prebióticos; (B2) inclusão de 1,0% de um blend de prebióticos\"]. O experimento foi constituído de 30 dias, sendo os 20 primeiros de adaptação aos tratamentos e os últimos 10 dias de coletas de fezes e sangue. Os dados obtidos foram analisados no programa SAS. Foram previamente verificadas normalidade dos resíduos e homogeneidade das variancias, em seguida os dados foram submetidos a teste de ANOVA, por fim as médias foram comparadas pelo teste de Tukey ao nível de significância de 5%. A suplementação dos prebióticos não alterou os coeficientes de digestibilidade aparente testados, produção e escore fecal (p&gt;0,05). Em relação aos produtos de fermentação avaliados, a adição dos promotores de saúde intestinal não alterou o pH fecal, nem as concentrações de amônia, ácido lático, ácido acético, ácido propiônico e ácido butiríco, ácidos graxos de cadeia curta (AGCC) totais, ácido valérico, ácido iso-butírico e ácidos graxos de cadeia ramificada (AGCR) totais das fezes (p&gt;0,05). No entanto, a adição de GOS diminuiu a concentração do AGCR isovalérico (p=0,0423) em relação a B1. Quanto aos parâmetros imunológicos avaliados, a adição de GOS e B2 aumentou o número total de células polimorfonucleares, assim como o burst oxidadivo em relação aos tratamentos B1 e CO (p&lt;0,0001). O tratamento B2 melhorou o índice de fagocitose de S. aureus em relação ao CO, porém não diferiu dos demais (p=0,011). No teste de fagocitose de E.coli, os tratamentos GOS e B2 apresentaram melhor índice do que o tratamento CO, o qual não diferiu de B1 (p=0,0067). Pode-se concluir que os tratamentos GOS e Blend Yes Golf, quando incluídos a 1,0% na formulação do alimento, aumentaram a atividade fagocitária e o burst oxidativo de cães saudáveis. / The pet food industry grows along with research in this area with the goals not only of meeting nutritional needs but also with the purpose of promoting health, well-being and longevity to companion animals. The objective of this study was to evaluate the effects of intestinal health promoting supplements on nutrient digestibility, fermentative products and immunological parameters in adult dogs. Twenty-four adult dogs were divided into six blocks and randomly assigned to the treatments [ a control treatments, without prebiotics (CO); inclusion of 0.5% a prebiotic blend Yes Golf (B1); inclusion of 1.0.% galactooligosaccharide (GOS); inclusion of 1.0% a prebiotic blend Yes Golf (B2)], following a randomized block design. The experiment consisted of 30 days, being the first 20 of adaptation to the treatments and the last 10 days of collections of feces and blood. The results were analyzed for their normality and the means were compared by the Tukey test at the significance level of 5.0%. Prebiotic supplementation had no effect on the apparent digestibility coefficients tested, yield and fecal score (p&gt; 0.05). For the fermentation products evaluated, the addition of the intestinal health promoters did not alter the fecal pH, nor the concentrations of ammonia, lactic acid, short chain fatty acids (SCFA) and most faecal branched chain fatty acids (BCFA) (p&gt; 0.05). The addition of GOS decreased the concentration of iso-valeric fatty acid (p = 0.0423). Regarding the immunological parameters evaluated, the addition of GOS and B2 increased the total number of polymorphonuclear cells, as well as the oxidative burst in relation to the treatments B1 and CO (p &lt;0.0001). Treatment B2 improved the rate of S. aureus phagocytosis in relation to CO, but did not differ from the others, and treatments B1 and GOS did not differ from CO (p = 0.0111). For E.coli phagocytosis, the GOS and B2 treatments had a better index than the CO treatment, which did not differ from B1 (p = 0.0067). It can be concluded that GOS and B2, when included 1.0% in the formulation of the food, seem to present prebiotic potential regarding the immunity of healthy dogs.

he influence of two levels of yeast cell wall on phase one laying hen performance was investigated in this study. A total of 75 Lohmann W-36 replacement pullets, 17-weeks-old, were distributed among 75 laying hen cages (1 bird per pen). A total of 3 treatments were sequentially assigned to pens and each treatment had 25 replicates. Feeds were prepared according to the management guide for those birds and a single basal diet was divided into three treatments. First was the control basal diet only with no feed additives. The second was the basal diet supplemented with 250 ppm of yeast cell wall (YCW 250) and the third treatment was the basal diet supplemented with 500 ppm of yeast cell wall (YCW 500). Individual birds per cage served as the experimental unit for this study. Feed and water were offered ad libitum. Data were collected when birds were 21 weeks old and hen day egg production was > 90%. Treatment YCW 250 resulted in significantly higher egg weight than the control and YCW 500 treatment in the first and second production period and was higher than YCW 500 in the third and fourth production period. Feed consumed per dozen eggs was significantly lower in treatment YCW 500 versus treatment YCW 250, but not significantly lower than the control for the first production period and all treatments were not different from each other for the rest of the study. Average feed consumed per bird per day, and monthly cumulative egg production was not different between treatments. Period feed conversion ratios were lower for the second and fourth period (P = 0.15 and 0.18 respectively). There was no treatment effect on interior egg quality except for yolk color for the YCW 500 treatment in the fourth period which had significantly higher Roche color scores than the YCW 250 treatment. Specific gravity, egg shell thickness, egg shell weight, and percent shell weight were significantly higher in hens fed YCW 500 versus YCW 250. Egg shell breaking force was significantly higher in hens fed YCW 250 versus the control group. Overall, feeding a diet supplemented with yeast cell wall improved laying hen performance and 250 ppm YCW had the most significant influences, particularly with respect to increasing egg weight in early production laying hens.

The problem of forming a glycosidic bond between ribose and the free nucleoside bases to produce beta-nucleosides under plausible prebiotic conditions is commonly referred to in origin of life research as The Nucleoside Problem. The lack of a general solution to this problem currently represents one of the largest stumbling blocks to the RNA world hypothesis and many other theories regarding the origin of life. Over thirty years ago the purine nucleosides were successfully synthesized by drying the fully-formed bases and ribose together in the presence of divalent metal ion salts. However, glycosidic bond formation by the pyrimidine bases has never been achieved under similar reaction conditions. This thesis describes the first plausible prebiotic synthesis of a pyrimidine nucleoside, demonstrated with the pyrimidine base analogue 2-pyrimidinone. Information provided by nucleoside-formation reaction involving 2-pyrimidinone and related pyrimidine bases should provide valuable insights into the possible mechanism by which glycosidic bond formation was accomplished on the prebiotic Earth.

Modeling chemical environments is an important step to understanding the diversity of prebiotic systems that may have formed on the early earth or potentially can occur on other worlds. By using the modern Earth as a test case, these models predict scenarios with systems more conducive to the formation of the organic molecules that are important to life. Here we use the equilibrium thermodynamic modeling program HSC Chem to investigate prebiotic environments. This program uses the raw material that the user inputs into the system in order to calculate the change in amounts of chemical species forming as a function of temperature and pressure using equilibrium (batch reactor) chemistry. Our results show that that ferrous ion (Fe2+), which may be important in the early formation of organic molecules on Earth, is most abundant in the aqueous phase where the atmosphere contains carbon dioxide as a major constituent. A pure methane atmosphere exhibits the lowest concentrations of this ion, and mixtures tend to end up in between the two extremes. Additionally, we have determined the pH of early oceans, which has implications for biomineralization, chemical reactions, and mineral chemistry. We see that the CO2 atmosphere, and to some extent, the mixtures and CH4 atmospheres, exhibit near neutral pHs. These results allow prediction of processes that might have taken place and could have impacted the development of life on the early earth.

Two different feeding trials were conducted to evaluate the effects of dietary supplementation with the dairy/yeast prebiotic GroBiotic-A (GBA) to Nile tilapia diets. A nutritionally complete basal diet was supplemented with GBA at either 1 or 2% of dry weight, and all three diets were fed to triplicate groups of juvenile fish in two consecutive trials. Trial 1 continued for 8 weeks, while Trial 2 was conducted for 5 weeks to more specifically assess immunological responses, intestinal characteristics and disease resistance of tilapia. At the conclusion of Trial 1, there were no differences in weight gain (WG) or feed efficiency (FE) among fish fed the three diets. However, fish fed the diet with GBA at 2% had significantly increased survival and noticeably elevated levels of plasma lysozyme compared to fish fed the basal diet or the diet with GBA at 1%. Similarly, at the conclusion of Trial 2, WG and FE were unaffected by GBA supplementation; however, fish fed the diet with GBA at 2% also exhibited elevated plasma lysozyme as well as significantly (P < 0.05) increased levels of extracellular superoxide anion production (EX-SOAP) by macrophages. Dendrogram analysis of denaturing gradient gel electrophoresis (DGGE) images detected a significantly different microbial community within the intestine of fish fed the diet with GBA at 2% compared to fish fed the basal diet and diet with GBA at 1%. None of the experimental diets resulted in significant improvements to survival after exposure to Streptococcus iniae due to within treatment variability. However, fish fed the diet with GBA at 2% did tend to experience reduced mortality (12.5%) as compared to fish fed the basal diet (35%). Thus, supplementation of GBA at 2% of diet did alter the gut microbiota of tilapia and enhanced immunological responses and disease resistance to S. iniae.

Made available in DSpace on 2014-06-11T19:23:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-18Bitstream added on 2014-06-13T20:51:05Z : No. of bitstreams: 1 gomes_mos_me_jabo.pdf: 622478 bytes, checksum: be8b00fa47ea963d66d4d14490453d61 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Considerando a importância da eubiota intestinal na saúde dos animais, o papel da dieta em sua composição e metabolismo tem sido estudado. Neste aspecto os prebióticos têm merecido destaque, incluindo-se a parede celular de leveduras (PCL), uma fonte natural de mananoligossacarídeos. Para o estudo de seu potencial prebiótico para cães, foram empregadas quatro dietas isonutrientes com inclusão de 0% (T0), 0,15% (T15), 0,30% (T30) e 0,45% (T45) de PCL. Foram utilizados oito Beagles adultos, divididos em dois quadrados latinos 4 X 4. Em cada período uma fase de adaptação de 15 dias precedeu 5 dias de coleta total de fezes para o ensaio de digestibilidade e 1 dia de coleta de fezes frescas para enumeração bacteriana, mensuração de pH e determinação das concentrações de ácidos graxos de cadeia curta e aminas bioativas. No dia 21 de cada período, amostra de sangue foi colhida para quantificação imunofenotípica por citometria de fluxo das subpopulações linfocitárias CD5+CD4+, CD5+, CD5+CD8+, CD45+ e CD45+CD21+. Os dados foram avaliados pelo Proc GLM do SAS, sendo as médias comparadas pelo teste de Tukey e por contraste polinomial e ortogonal (p<0,1). Os coeficientes de digestibilidade dos nutrientes não variaram com a inclusão de PCL (p>0,1). A inclusão de PCL não resultou em diferenças quanto às contagens de anaeróbios totais, aeróbios totais, bifidobactéria, lactobacilos, clostridios nas fezes dos cães (p>0.1). Verificou-se aumento linear na concentração fecal de butirato (p=0,055), redução linear das concentrações fecais de tiramina (P=0,1) e histamina (P=0,07) e redução quadrática de feniletilamina e triptamina (P=0,07). Os cães apresentaram, também, aumento linear na concentração de linfócitos CD5+ (P=0,10) e maior número de linfócitos CD45+CD21+ (P=0,053) mediante ingestão de PCL. Concluiu-se que a PCL apresenta efeito prebiótico... / Considering the importance of the intestinal microbiota to the animal health, the role of diet upon microbiota composition and metabolism have been studied. Prebiotics have been emphasized on this regard, including the yeasts cell walls (YCW), a natural source of mannanoligosaccharides. To study the prebiotic potential of this compound for dogs, four isonutrient diets were used with inclusion of 0% (T0), 0,15% (T15), 0,30% (T30) and 0,45% (T45) of YCW. Eight Beagles adults were used, arranged in two 4 X 4 Latin squares. In each replicate an adaptation phase of 15 days preceded a 5 days of total feces collection for digestibility trial and 1 day collection of fresh fecal samples for bacterial enumeration, pH measurement and determination of short chain fatty-acids and bioactive amines concentration. On day 21, a blood samples were collected for immunophenotypic quantification of lymphocyte subsets CD5+CD4+, CD5+, CD5+CD8+, CD45+ e CD45+CD21+ through flow cytometry. The data were evaluated using Proc GLM of SAS, means were compared by Tukey test and polinomial and orthogonal contrasts (p <0,1). The inclusion of YCW did not change the coefficient of total tract apparent digestibility of nutrients (p>0.1) nor the fecal bacterial enumeration (total aerobes and anaerobes, Bifidobacterium, Lactobacillus, Clostridium and Escherichia coli) in dog’s feces (p>0.1). Fecal butirate concentration increased linearly with YCW addition (p=0,055), fecal concentrations of tyramine (P=0,1) and histamine (P=0,07) decreased linearly, and phenylethylamine (P=0,07) and tryptamine (P=0,07) concentrations showed a quadratic reduction with YCW consumption. Dogs also presented a linear increase in lymphocytes CD5+ concentration (P=0,10) and a greater CD45+CD21+ lymphocytes number (P=0,053) with YCW addition. In conclusion YCW presents a prebiotic (changing bacterial end product formation) and immunostimulating effect for dogs.