L’utilisation du glucose exogène est un déterminant de la performance sportive, particulièrement lors d’épreuves de plus d’une heure. Les caractéristiques des sujets, les conditions d’exercice et d’ingestion du glucose sont tous des facteurs pouvant affecter l’oxydation de glucose exogène (OGE). De plus, la co-ingestion d’autres substrats et l’environnement dans lequel l’activité est pratiquée peuvent également avoir un impact sur l’OGE et sa contribution à la fourniture d’énergie. Il est souvent difficile, voire impossible, de comparer les résultats des études qui ont examiné l’OGE due au manque d’uniformité dans la méthodologie. Afin de clarifier l’effet de ces facteurs sur le taux d’OGE, ainsi que sa contribution à la fourniture d’énergie lors de l’exercice prolongé, une revue de littérature et une méta-analyse ont été effectuées. Le sexe, l’âge, la masse corporelle, le VO2max des participants, le moment d’ingestion, le taux d’ingestion, la concentration de la solution, la puissance absolue et relative de l’exercice, et la durée de l’exercice ont été utilisés comme modérateurs. Les facteurs pouvant influencer le taux d’OGE et sa contribution à la fourniture d’énergie pendant l’exercice prolongé rapportés dans cette méta-analyse confirment une relation dose-réponse curvilinéaire. D’autres facteurs, tels le VO2 et le %VO2max de l’exercice, ainsi que le moment d’ingestion, permettent également d’expliquer la relation observée dans le taux d’oxydation exogène et sa contribution à la fourniture d’énergie. La grande majorité des études ayant été effectuées sur une population restreinte (hommes sportifs ou en santé, âgés entre 20 et 30 ans), davantage de travaux sont nécessaires chez les femmes et les sujets d’âge et de masse corporelle différents afin d’éviter les biais d’interprétation dus à au sexe ou aux caractéristiques physiques. Les résultats de cette méta-analyse pourront aider à améliorer les recommandations sur l’ingestion de glucides au cours de l’exercice prolongé. / Exogenous glucose oxidation is a determinant of sports performance especially in activities lasting over 1 hour. Many factors concerning the subjects, the substrate and the exercise itself could influence the capacity of the human body to oxidize exogenous glucose. Furthermore, the co-ingestion of other substrates, as well as the environment in which the activity is performed, could also influence the rate of exogenous glucose oxidation (EGO) and its contribution to the energy yield. The lack of uniformity in methodologies used to investigate EGO makes it very difficult, and in some cases even impossible, to make direct comparisons between study results. In an attempt to shed some light on the impact of those various factors on the rate of EGO and its contribution to the energy yield, the literature was reviewed and a meta-analysis was done. The sex, age, body mass, VO2max, timing of ingestion, rate of ingestion, solution concentration, exercise’s absolute and relative intensity, and exercise duration were used as moderators. Many factors can contribute to EGO and its contribution to the energy yield and the results from this meta-analysis confirm a dose-response relationship. Additional factors, such as exercise VO2 or %VO2max, and ingestion timing also have a significant effect. Further studies might be needed with women and subjects with different age and body mass to avoid bias due to an unbalanced number of studies when comparing subject characteristics. These results should help improve nutritional recommendations for carbohydrate ingestion during prolonged exercise.

As mudanças no uso do solo, como por exemplo a remoção de áreas florestais para a implantação da agricultura e pecuária, promovem alterações no teor de matéria orgânica do solo. Em contrapartida, a regeneração natural surge como uma possibilidade do reestabelecimento parcial de funções ecológicas importantes, com destaque para o papel das florestas secundárias na redução do fluxo de gases atmosféricos, na influência da qualidade e quantidade da água, e no sequestro de carbono da atmosfera e estocagem no solo. O objetivo deste trabalho foi avaliar o comportamento do carbono e do nitrogênio no solo ao longo da sequência cronológica de florestas secundárias, comparando-as com floresta madura e pastagens no município de Rio Claro (SP). Com o auxílio de imagens aéreas (dos anos de 1978, 1995, 2000 e 2008) foram selecionadas 15 parcelas com 900 m2 cada, as quais consistiram em uma sequência temporal de florestas secundárias regeneradas sob pastagem (apresentando 8 a 16 anos (FS12), 21 a 38 anos (FS30) e 38 a 54 anos (FS46)), além de floresta \"fonte\" (floresta estacional semidecidual) com mais de 55 anos (FF) e pastagem em uso há mais de 50 anos (PA50). O solo da área de estudo é classificado como Argissolo de textura média. As concentrações e estoques de carbono (C) e nitrogênio (N) e os valores isotópicos de C (?13C) foram analisados na serapilheira e nas camadas de 0-10, 10-20 e 20-30 cm do solo. A análise de ?13C indicou presença do sinal isotópico oriundo de vegetação C3 já nos primeiros 12 anos de regeneração, representando 60% do C presente no solo (proveniente da FF e da FS12). Na área de pastagem foi constatada a presença de carbono remanescente da floresta nativa (C3), correspondendo por 30% do carbono total. A análise de componentes principais definiu os agrupamentos de acordo com as áreas de estudo, além de correlacionar negativamente os estoques de carbono e nitrogênio e os teores de areia. As florestas secundárias apresentaram estoques de carbono e nitrogênio na serapilheira próximos à floresta fonte (1,8 Mg C ha-1 e 0,10 Mg N ha-1). Os estoques de C e N no solo (0-30 cm) foram maiores na floresta fonte (74,1 Mg C ha-1 e 7,6 Mg N ha-1), ocorrendo brusca redução (40%) na conversão para pastagem (41,4 Mg C ha-1 e 4,7 Mg N ha-1). Além disso, as áreas de regeneração não diferiram da área de pastagem quanto aos estoques de carbono e nitrogênio no solo / Changes in soil use, such as the removal of forest areas for the implantation of agriculture and livestock, promote changes in soil organic matter content. Due to this imbalance between the inputs and outputs of plant material in the system the MOS dynamics will be changed, affecting the ecosystem as a whole. On the other hand, natural regeneration appears as a possibility for the partial reestablishment of important ecological functions, with emphasis on the role of secondary forests in the reduction of the flow of atmospheric gases, the influence of water quality and quantity, and sequestration of carbon from the atmosphere and storage in the soil. The objective of this work was to evaluate the behavior of carbon and nitrogen in the soil along the chronological sequence of secondary forests, comparing them with old growth forest and pastures in Rio Claro (SP). Fifteen plots with 900 m2 each were selected using aerial images (from 1978, 1995, 2000 and 2008), which consisted of a temporal sequence of regenerated secondary forests under pasture (8 to 16 years old (FS12) 21 to 38 years old (FS30) and 38 to 54 years old (FS46)), as well as an old growth forest (seasonal semideciduous forest) with more than 55 years (FF) and pasture in use for more than 50 years (PA50). The soil of the study area is classified as Argissolo. with medium texture. The concentrations and stocks of carbon (C) and nitrogen (N) and the isotopic values of C (?13C) were analyzed in the litter and in the layers of 0-10, 10-20 and 20-30 cm of the soil. The analysis of ?13C indicated the presence of the isotopic signal from C3 vegetation already in the first 12 years of regeneration, representing 60% of the C present in the soil (coming from FF and FS12). In the pasture area, the remaining carbon of the native forest (C3) was observed, corresponding to 30% of the total carbon. The principal components analysis defined the groupings according to the study areas, in addition to negatively correlating the carbon and nitrogen stocks and the sand contents. Secondary forests presented carbon and nitrogen stocks in the litter approximate to the old growth forest (1,8 Mg C ha-1 and 0,10 Mg N ha-1). C and N stocks in the soil (0-30 cm) were higher in the old growth forest (74,1 Mg C ha-1 and 7,6 Mg N ha-1), with an abrupt reduction (40%) in conversion to pasture (41,4 Mg C ha-1 and 4,7 Mg N ha-1). In addition, the regeneration areas did not differ from the pasture area for carbon and nitrogen stocks in the soil

North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.

Energy demands can be particularly high in arctic-nesting birds that face harsh, unpredictable conditions during the breeding season. Consequences of these demands, particularly energy-partitioning during egg laying and incubation, are fundamentally important for arctic nesters. This study investigated differences in breeding strategies between Long-tailed Duck (<i>Clangula hyemalis</i>) and King Eider (<i>Somateria spectabilis</i>) in the central Canadian arctic. The focus was on ecological variables and influences of variation in nutrient resources used during incubation and egg production. Research was done at Karrak Lake, Nunavut, where both species nest sympatrically at relatively high densities, permitting comparative research about breeding strategies.<p>This study used stable-carbon (d13C) and nitrogen (d15N) isotope analysis to investigate origins and allocation of endogenous (stored) and exogenous (external) nutrients used in egg production. Remote temperature sensors were placed in nests to estimate and compare incubation rhythms and gain insight into capital and income incubating strategies of both species. Results suggest that breeding Long-tailed Ducks and King Eiders used a mixed breeding strategy, that is they relied on both exogenous and endogenous resources for reproduction. Close correspondence between d13C and d15N values of egg components and potential diet items indicated that King Eiders allocated exogenous nutrients for egg production (albumen 98.1%, yolk protein 96.8%, whole yolk 98.4%, and yolk lipids 84%). Female King Eiders relied on endogenous nutrients for incubation, as evidenced by high incubation constancy (96%). Conversely, the range of d13C values in components of Long-tailed Duck eggs and d13C values of diet items suggested that although some females allocated endogenous reserves for egg production, most females allocated exogenous resources for egg production (albumen 98.5%, yolk protein 78.3%, whole yolk 84.9%, and yolk lipids 38.3%). Long-tailed Duck females had an 84% incubation constancy, suggesting less reliance on endogenous nutrients for incubation than was estimated for female King Eiders. Knowledge about the relative importance of endogenous reserves and exogenous nutrients for egg production and incubation may help direct management decisions to specific winter/staging and or breeding areas used by King Eiders and Long-tailed Ducks.

Energy demands can be particularly high in arctic-nesting birds that face harsh, unpredictable conditions during the breeding season. Consequences of these demands, particularly energy-partitioning during egg laying and incubation, are fundamentally important for arctic nesters. This study investigated differences in breeding strategies between Long-tailed Duck (<i>Clangula hyemalis</i>) and King Eider (<i>Somateria spectabilis</i>) in the central Canadian arctic. The focus was on ecological variables and influences of variation in nutrient resources used during incubation and egg production. Research was done at Karrak Lake, Nunavut, where both species nest sympatrically at relatively high densities, permitting comparative research about breeding strategies.<p>This study used stable-carbon (d13C) and nitrogen (d15N) isotope analysis to investigate origins and allocation of endogenous (stored) and exogenous (external) nutrients used in egg production. Remote temperature sensors were placed in nests to estimate and compare incubation rhythms and gain insight into capital and income incubating strategies of both species. Results suggest that breeding Long-tailed Ducks and King Eiders used a mixed breeding strategy, that is they relied on both exogenous and endogenous resources for reproduction. Close correspondence between d13C and d15N values of egg components and potential diet items indicated that King Eiders allocated exogenous nutrients for egg production (albumen 98.1%, yolk protein 96.8%, whole yolk 98.4%, and yolk lipids 84%). Female King Eiders relied on endogenous nutrients for incubation, as evidenced by high incubation constancy (96%). Conversely, the range of d13C values in components of Long-tailed Duck eggs and d13C values of diet items suggested that although some females allocated endogenous reserves for egg production, most females allocated exogenous resources for egg production (albumen 98.5%, yolk protein 78.3%, whole yolk 84.9%, and yolk lipids 38.3%). Long-tailed Duck females had an 84% incubation constancy, suggesting less reliance on endogenous nutrients for incubation than was estimated for female King Eiders. Knowledge about the relative importance of endogenous reserves and exogenous nutrients for egg production and incubation may help direct management decisions to specific winter/staging and or breeding areas used by King Eiders and Long-tailed Ducks.

North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.

Submitted by BARBARA CRISTINA DA SILVA FERNANDES null (barbarafernandes_zootecnista@yahoo.com) on 2016-01-28T13:35:27Z No. of bitstreams: 1 Tese Final Barbara Fernandes com ficha.pdf: 597431 bytes, checksum: d9fc240064bb0f75de1ddcb65bb3ba45 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-02-02T11:38:50Z (GMT) No. of bitstreams: 1 fernandes_bcs_dr_bot.pdf: 597431 bytes, checksum: d9fc240064bb0f75de1ddcb65bb3ba45 (MD5) / Made available in DSpace on 2016-02-02T11:38:50Z (GMT). No. of bitstreams: 1 fernandes_bcs_dr_bot.pdf: 597431 bytes, checksum: d9fc240064bb0f75de1ddcb65bb3ba45 (MD5) Previous issue date: 2016-01-19 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se rastrear a presença de subprodutos de origem animal na alimentação de frangos de corte de granjas comerciais por meio da metodologia dos isótopos estáveis de carbono e nitrogênio (δ13C e δ15N), no músculo peitoral e mucosa intestinal, assim como iniciar um banco de dados de valores bromatológicos e isotópicos dos ingredientes da ração de maior interesse na avicultura de corte. Foram amostradas aleatoriamente oito aves (machos) semanalmente de sete granjas de diferentes empresas avícolas dentro do Estado de São Paulo para obtenção das amostras de músculo peitoral e mucosa intestinal. Nos mesmos dias de coletas foram retiradas três amostras aleatórias de ração, adquiridas dos comedouros de cada granja. Para o banco de dados foram amostrados os ingredientes milho, soja, farelo de soja e farinhas de origem animal dos departamentos de recepção e controle de qualidade dos ingredientes das fabricas de ração visitadas. Todas as amostras foram submetidas à análise de espectrometria de massa de razão isotópica, sendo que a ração também foi avaliada quanto à presença de DNA de origem animal por PCR. Os dados isotópicos das amostras foram submetidos à análise de variância em cada idade de coleta, sendo complementados pelo teste de Tukey, e o conjunto de todos os dados foram avaliados pelas análises multivariadas de componentes principais e discriminante linear. Foi possível verificar pela análise de PCR na ração que somente as empresas D e F utilizaram ração estritamente vegetal ao longo do período de criação das aves. Houve diferença entre os valores isotópicos da ração, músculo peitoral e mucosa intestinal das aves das empresas D e F em relação às demais, sendo esta mais definida para o δ15N dos sete aos 42 dias de idade. Esse mesmo resultado foi obtido pelas análises multivariadas. Portanto, foi possível diferenciar as empresas que utilizaram alimentação estritamente vegetal em relação às demais, demonstrando a possibilidade de rastrear a presença de subprodutos de origem animal na alimentação dos frangos de corte de granjas comerciais pela metodologia dos isótopos estáveis. / The aim of this study was to trace the presence of animal by-products in commercial broiler farms feed using the methodology of stable isotope ratios of carbon and nitrogen (δ13C and δ15N) in the pectoral muscle and intestinal mucosa, and start a database of bromatological and isotopic values of feed ingredients with greatest interest in poultry production. Eight male birds were sampled randomly week-by-week in seven broiler farms of different poultry companies in the São Paulo State to obtain samples of pectoral muscle and intestinal mucosa. Were taken on the same day of sampling three random samples of feed, acquired from feeders of each commercial broiler unit. For the database were sampled corn, soybean, soybean meal and animal by-products obtained from reception and quality control departments of visited feed factories. All samples were analyzed using isotope ratio mass spectrometry, and feed was also evaluated for the presence of animal DNA by PCR analysis. The isotopic data of the samples were submitted to analysis of variance in each age collection, complemented by Tukey test, and the set of all data were analyzed by multivariate analysis of major and linear discriminant components. It was verified by PCR analysis in feed that only D and F companies used strictly vegetable diet throughout the period of raising birds. There was difference between isotopic values of feed, pectoral muscle, and intestinal mucosa of birds from D and F companies compared with others, which is most definitely for the δ15N from seven to 42 days old. The same result was obtained by multivariate analysis. Therefore, it was possible to differentiate the companies that used strictly vegetable diet from the others, demonstrating the ability to trace the presence of animal by-products in commercial broiler farms feed using the methodology of stable isotopes. / FAPESP: 13/04339-2

Orientador: Carlos Ducatti / Banca: Cyntia Ludovico Martins / Banca: Antonio Celso Pezzato / Banca: Marcos Macari / Banca: Marcelo Zacarias Moreira / Resumo: O objetivo deste trabalho foi identificar a inclusão de níveis crescentes de farinha de vísceras (FV) na alimentação de frangos de corte, usando os isótopos estáveis de carbono e nitrogênio na análise do sangue e músculo peitoral das aves coletados semanalmente. Foram utilizados 560 pintos machos (Cobb), com um dia de idade, distribuídos aleatoriamente em tratamentos: controle (dieta vegetal), os demais tratamentos tiveram a inclusão de 0,5; 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0 e 8,0% de FV na dieta. A cada 7 dias foram separadas ao acaso oito aves (n = 8) por tratamento e coletados sangue e músculo peitoral para análise da razão isotópica do carbono e nitrogênio. Tanto no sangue quanto no músculo peitoral das aves aos 7 dias de idade a FV foi detectada a partir de 3,5%, valor que é mantido para o sangue aos 14 dias de idade. No músculo peitoral aos 14 dias a detecção foi a partir de 4,0%. Com 21 dias de idade no sangue a FV foi detectada a partir 2,0% e no músculo peitoral acima de 0,5% de inclusão. Aos 28, 35 e 42 dias no sangue foi detectado a partir de 4,0; 2,5 e 3,0%; respectivamente. No músculo peitoral aos 28 e 35 dias de idade foi identificada a FV em nível a partir de 2,0% e oas 42 dias a partir de 1,5%. A coleta de amostras ao longo do período de criação é necessária para acompanhar a variação do nível de inclusão de FV na alimentação de frangos de corte, devido as mudanças de dieta de acordo com as fase de criação de aves. O músculo peitoral comparado ao sangue das aves identifica a FV na alimentação de frangos de corte em menores níveis. A análise estatística linear discriminante é boa ferramenta para identificação de menores níveis de inclusão de FV na alimentação de frangos de corte comparada a análise estatística manova / Abstract: The aim of this paper was to identify the increasing levels of poultry offal meal (POM) in feed for broiler chickens using stable isotopes of carbon and nitrogen in the blood analysis and breast muscle of birds at each week. They were used 560 male chicks (Cobb), one day age. They were randomly assigned to treatments: control (vegetable diet), all other treatments had the inclusion of 0.5, 1.0; 1.5; 2.0; 2.5; 3.0; 3.5; 4.0 and 8.0% of POM in the diet. For analysis of the isotope ratio carbon and nitrogen at every 7 days were separated at random eight birds (n = 8) per treatment and collected blood and breast muscle. Both in blood as in breast muscle at 7 days old POM was detected at 3.5%, which is maintained for the blood at 14 days old. In the breast muscle at 14 days the detection was from 4.0%. Within 21 days of age in the POM blood was detected from 2.0% in the breast muscle and above the 0.5% inclusion. At 28, 35 and 42 days in the blood was detected from 4.0, 2.5 and 3.0%, respectively. In the breast muscle at 28 and 35 days of age was identified in the POM level from 2.0% and 42 days from 1.5%. The collection of samples throughout the growing period is needed to monitor the level of inclusion variação POM in feed for broiler chickens, because of changes in diet according to the phase of poultry. The breast muscle compared to the blood of birds identified the POM in the supply of broilers at lower levels. Statistical analysis of linear discriminant is a good tool for identification of lower levels of inclusion of POM in feed for broiler chickens compared to Manova statistical analysis / Doutor

As mudanças no uso do solo, como por exemplo a remoção de áreas florestais para a implantação da agricultura e pecuária, promovem alterações no teor de matéria orgânica do solo. Em contrapartida, a regeneração natural surge como uma possibilidade do reestabelecimento parcial de funções ecológicas importantes, com destaque para o papel das florestas secundárias na redução do fluxo de gases atmosféricos, na influência da qualidade e quantidade da água, e no sequestro de carbono da atmosfera e estocagem no solo. O objetivo deste trabalho foi avaliar o comportamento do carbono e do nitrogênio no solo ao longo da sequência cronológica de florestas secundárias, comparando-as com floresta madura e pastagens no município de Rio Claro (SP). Com o auxílio de imagens aéreas (dos anos de 1978, 1995, 2000 e 2008) foram selecionadas 15 parcelas com 900 m2 cada, as quais consistiram em uma sequência temporal de florestas secundárias regeneradas sob pastagem (apresentando 8 a 16 anos (FS12), 21 a 38 anos (FS30) e 38 a 54 anos (FS46)), além de floresta \"fonte\" (floresta estacional semidecidual) com mais de 55 anos (FF) e pastagem em uso há mais de 50 anos (PA50). O solo da área de estudo é classificado como Argissolo de textura média. As concentrações e estoques de carbono (C) e nitrogênio (N) e os valores isotópicos de C (?13C) foram analisados na serapilheira e nas camadas de 0-10, 10-20 e 20-30 cm do solo. A análise de ?13C indicou presença do sinal isotópico oriundo de vegetação C3 já nos primeiros 12 anos de regeneração, representando 60% do C presente no solo (proveniente da FF e da FS12). Na área de pastagem foi constatada a presença de carbono remanescente da floresta nativa (C3), correspondendo por 30% do carbono total. A análise de componentes principais definiu os agrupamentos de acordo com as áreas de estudo, além de correlacionar negativamente os estoques de carbono e nitrogênio e os teores de areia. As florestas secundárias apresentaram estoques de carbono e nitrogênio na serapilheira próximos à floresta fonte (1,8 Mg C ha-1 e 0,10 Mg N ha-1). Os estoques de C e N no solo (0-30 cm) foram maiores na floresta fonte (74,1 Mg C ha-1 e 7,6 Mg N ha-1), ocorrendo brusca redução (40%) na conversão para pastagem (41,4 Mg C ha-1 e 4,7 Mg N ha-1). Além disso, as áreas de regeneração não diferiram da área de pastagem quanto aos estoques de carbono e nitrogênio no solo / Changes in soil use, such as the removal of forest areas for the implantation of agriculture and livestock, promote changes in soil organic matter content. Due to this imbalance between the inputs and outputs of plant material in the system the MOS dynamics will be changed, affecting the ecosystem as a whole. On the other hand, natural regeneration appears as a possibility for the partial reestablishment of important ecological functions, with emphasis on the role of secondary forests in the reduction of the flow of atmospheric gases, the influence of water quality and quantity, and sequestration of carbon from the atmosphere and storage in the soil. The objective of this work was to evaluate the behavior of carbon and nitrogen in the soil along the chronological sequence of secondary forests, comparing them with old growth forest and pastures in Rio Claro (SP). Fifteen plots with 900 m2 each were selected using aerial images (from 1978, 1995, 2000 and 2008), which consisted of a temporal sequence of regenerated secondary forests under pasture (8 to 16 years old (FS12) 21 to 38 years old (FS30) and 38 to 54 years old (FS46)), as well as an old growth forest (seasonal semideciduous forest) with more than 55 years (FF) and pasture in use for more than 50 years (PA50). The soil of the study area is classified as Argissolo. with medium texture. The concentrations and stocks of carbon (C) and nitrogen (N) and the isotopic values of C (?13C) were analyzed in the litter and in the layers of 0-10, 10-20 and 20-30 cm of the soil. The analysis of ?13C indicated the presence of the isotopic signal from C3 vegetation already in the first 12 years of regeneration, representing 60% of the C present in the soil (coming from FF and FS12). In the pasture area, the remaining carbon of the native forest (C3) was observed, corresponding to 30% of the total carbon. The principal components analysis defined the groupings according to the study areas, in addition to negatively correlating the carbon and nitrogen stocks and the sand contents. Secondary forests presented carbon and nitrogen stocks in the litter approximate to the old growth forest (1,8 Mg C ha-1 and 0,10 Mg N ha-1). C and N stocks in the soil (0-30 cm) were higher in the old growth forest (74,1 Mg C ha-1 and 7,6 Mg N ha-1), with an abrupt reduction (40%) in conversion to pasture (41,4 Mg C ha-1 and 4,7 Mg N ha-1). In addition, the regeneration areas did not differ from the pasture area for carbon and nitrogen stocks in the soil

L’imagerie par résonance magnétique du 13C (13C-IRM) hyperpolarisée est une technique émergente pour le suivi métabolique in vivo en vue de la détection précoce de cancers. L’optimisation de la sensibilité de la mesure IRM nécessite l’injection de molécules endogènes marquées au carbone-13 et deutérium. Dans ce contexte, le sodium L-[1-13C,U-D] lactate est un agent prometteur pour le diagnostic et le suivi thérapeutique des patients atteints du cancer de la prostate. Pendant cette thèse, la synthèse de cette molécule a été réalisée à partir de la L-[1-13C] alanine. Pour réaliser cette synthèse, deux méthodes pour la deutération des positions C2 et C3 de l’alanine ont été développées. La deutération en position C2, basée sur la technique de l’échange hydrogène-deutérium metallo-catalysé, a permis de préparer différents acides-aminés marqués en cette position à l’échelle du gramme. La deutération en position C3 est réalisée via fonctionnalisation C-H pallado-catalysée. Cette technique permet d’obtenir un marquage sélectif de certains des 20 acides-aminés naturels en position C3. Un procédé pour le marquage sélectif de la position C1 de l’alanine avec du carbone-13 a été établi à partir de l’acétaldéhyde et du K13CN selon une modification de la procédure de Strecker. L’utilisation de l’acétaldéhyde perdeutéré rend ainsi possible une synthèse à large échelle du sodium L-[1-13C,U-D] lactate. / Hyperpolarized 13C magnetic resonance imaging (13C-MRI) is a promising emerging tool to follow the metabolic routes in vivo in view of early stage detection of cancer. Optimization of the sensitivity of the MRI measurement requires injection of carbon-13 or deuterium labelled endogenous molecules. In this context, sodium L-[1-13C,U-D] lactate was individuated as a promising probe for the detection and prediction of treatment-response in patients with prostate cancer. We realized the first chemical synthesis of such probe starting from L-[1-13C] alanine by developing two distinct strategies for the selective deuteration of the position C2 and C3. The method of C2 deuteration relies on the technique of the metal-catalyzed hydrogen-deuterium exchange and can be applied to the synthesis of several deuterated amino-acids to an industrial-scale. The method of C3 deuteration was realised by Pd(OAc)2 catalyzed C-H activation. It provides a unique route to obtain amino-acids selectively deuterated in position C3. We also developed a robust route for the 13C labelling of the C1 position of L-alanine from acetaldehyde and K13CN by a modification of the Strecker’s synthesis. By using deuterated acetaldehyde, a scalable synthesis of L-[1-13C,U-D] lactate could now be possible.