No sex-biased dispersal in a primate with an uncommon social system-cooperative polyandry.

An influential hypothesis proposed by Greenwood (1980) suggests that different mating systems result in female and male-biased dispersal, respectively, in birds and mammals. However, other aspects of social structure and behavior can also shape sex-biased dispersal. Although sex-specific patterns of kin cooperation are expected to affect the benefits of philopatry and dispersal patterns, empirical evidence is scarce. Unlike many mammals, Saguinus geoffroyi (Geoffroy's tamarin) has a breeding system in which typically multiple males mate with a single breeding female. Males typically form cooperative reproductive partnerships between relatives, whereas females generally compete for reproductive opportunities. This system of cooperative polyandry is predicted to result in female-biased dispersal, providing an opportunity to test the current hypotheses of sex-biased dispersal. Here we test for evidence of sex-biased dispersal in S. geoffroyi using demographic and genetic data from three populations. We find no sex bias in natal dispersal, contrary to the prediction based on the mating patterns. This pattern was consistent after controlling for the effects of historical population structure. Limited breeding opportunities within social groups likely drive both males and females to disperse, suggesting that dispersal is intimately related to the social context. The integration of genetic and field data revealed that tamarins are another exception to the presumed pattern of male-biased dispersal in mammals. A shift in focus from mating systems to social behavior, which plays a role in most all processes expected to influence sex-bias in dispersal, will be a fruitful target for research both within species and across taxa

Ecological and evolutionary processes in two southern African endemic birds

Includes abstract.Includes bibliographical references.In this dissertation, I propose a population-level framework that integrates ecology and population genetics to rethink the mechanisms that promote divergence. To accomplish that I studied two southern African endemic Cercotrichas scrub-robins: C. coryphaeus and C. signata. Despite its phylogenetic proximity the two study species occupy the two ends of the habitat spectrum available in southern Africa: semi-arid Karoo vs. Forest

Study of Pt/MCM-22 based catalysts in the transformation of n-hexane: effect of rare earth elements and mode of platinum introduction

The bifunctional transformation of n-hexane was carried out over Pt/MCM-22 based catalysts. MCM-22 was synthesized and submitted to ion exchange with rare earth nitrate solutions of La, Nd and Yb, followed by Pt introduction. Three different methods were used to introduce about 1 wt% of Pt in the zeolite: ion exchange, incipient wetness impregnation and mechanical mixture with Pt/Al(2)O(3). The bifunctional catalysts were characterized by transmission electron microscopy and by the model reaction of toluene hydrogenation. These experiments showed that, in the ion exchanged sample, Pt is located both within the inner micropores and on the outer surface, whereas in the impregnated one, the metal is essentially located on the outer surface under the form of large particles. The presence of RE elements increases the hydrogenating activity of Pt/MCM-22 since the location of these species at the vicinity of metal particles causes modification on its electronic properties. Whatever the mode of Pt introduction, a fast initial decrease in conversion is observed for n-hexane transformation, followed by a plateau related to the occurrence of the catalytic transformations at the hemicages located at the outer surface of the crystals. The effect of rare earth elements on the hydrogenating function leads to a lower selectivity in dibranched isomers and increased amounts of light products

Inhibition of brain energy metabolism by the α-keto acids accumulating in maple syrup urine disease

AbstractNeurological dysfunction is a common finding in patients with maple syrup urine disease (MSUD). However, the mechanisms underlying the neuropathology of brain damage in this disorder are poorly known. In the present study, we investigated the effect of the in vitro effect of the branched chain α-keto acids (BCKA) accumulating in MSUD on some parameters of energy metabolism in cerebral cortex of rats. [14CO2] production from [14C] acetate, glucose uptake and lactate release from glucose were evaluated by incubating cortical prisms from 30-day-old rats in Krebs–Ringer bicarbonate buffer, pH 7.4, in the absence (controls) or presence of 1–5 mM of α-ketoisocaproic acid (KIC), α-keto-β-methylvaleric acid (KMV) or α-ketoisovaleric acid (KIV). All keto acids significantly reduced 14CO2 production by around 40%, in contrast to lactate release and glucose utilization, which were significantly increased by the metabolites by around 42% in cortical prisms. Furthermore, the activity of the respiratory chain complex I–III was significantly inhibited by 60%, whereas the other activities of the electron transport chain, namely complexes II, II–III, III and IV, as well as succinate dehydrogenase were not affected by the keto acids. The results indicate that the major metabolites accumulating in MSUD compromise brain energy metabolism by blocking the respiratory chain. We presume that these findings may be of relevance to the understanding of the pathophysiology of the neurological dysfunction of MSUD patients

Explicit kinetic heterogeneity: mechanistic models for interpretation of labeling data of heterogeneous cell populations

Estimation of division and death rates of lymphocytes in different conditions is vital for quantitative understanding of the immune system. Deuterium, in the form of deuterated glucose or heavy water, can be used to measure rates of proliferation and death of lymphocytes in vivo. Inferring these rates from labeling and delabeling curves has been subject to considerable debate with different groups suggesting different mathematical models for that purpose. We show that the three models that are most commonly used are in fact mathematically identical and differ only in their interpretation of the estimated parameters. By extending these previous models, we here propose a more mechanistic approach for the analysis of data from deuterium labeling experiments. We construct a model of "kinetic heterogeneity" in which the total cell population consists of many sub-populations with different rates of cell turnover. In this model, for a given distribution of the rates of turnover, the predicted fraction of labeled DNA accumulated and lost can be calculated. Our model reproduces several previously made experimental observations, such as a negative correlation between the length of the labeling period and the rate at which labeled DNA is lost after label cessation. We demonstrate the reliability of the new explicit kinetic heterogeneity model by applying it to artificially generated datasets, and illustrate its usefulness by fitting experimental data. In contrast to previous models, the explicit kinetic heterogeneity model 1) provides a mechanistic way of interpreting labeling data; 2) allows for a non-exponential loss of labeled cells during delabeling, and 3) can be used to describe data with variable labeling length

Ingestão dietética de pacientes bariátricas femininas após gastroplastia anti-obesidade

PURPOSE: Roux-en-Y gastric bypass is a popular and successful operation for the treatment of morbid obesity. However, it greatly restricts ingestion and moderately interferes with absorption of food, thus potentially paving the way for undernutrition, especially during the first year before patients adapt to the new condition. Aiming to document actual dietary intake during this period, a prospective observational study was performed. METHODS: Forty consecutive patients were investigated using a 24-hour dietary recall technique every 3 months after surgery for 1 year. Females only were accepted for greater homogeneity of the sample. All received a vitamin and mineral supplement on a daily basis as a postoperative routine. A questionnaire was employed regarding general, nutritional, and gastrointestinal changes as well as consumption of medications. Dietary intake was analyzed after data processing using the Virtual Nutri software package (São Paulo, SP, Brazil). RESULTS: The surgical response was within the expected range, with about 67% excess weight loss at the end of the 1st year, and the same occurred with gastrointestinal symptoms and drug requirements. Daily energy intake on the 4 analyzed occasions was 529.4 ± 47.4, 710.9 ± 47.6, 833.2 ± 72.0, and 866.2 ± 95,1 kcal/day (mean ± SEM); protein intake was increased in the same proportion at 6 and 9 months, but reduced at 12 months. Thus, patients did not meet standard recommendations regarding calories and proteins, even at the end of the 1st year; iron and zinc intake were also inadequate, although deficiencies were probably staved off by the prescribed supplement preparation. CONCLUSIONS: 1) The risk for postoperative undernutrition was evidenced up to 1 year, while spontaneous improvement in food intake was slow and inefficient; 2) Specific protocols should be devised to improve nutrition and health during the postoperative phase until successful dietary adaptation is achieved.OBJETIVO: A gastroplastia com anastomose gastrojejunal em Y de Roux é uma operação popular e bem sucedida no tratamento da obesidade grave. Ela restringe seriamente a ingestão e moderadamente a absorção do alimento, potencialmente abrindo caminho para desnutrição especialmente no primeiro ano, antes que o paciente se adapte à nova condição. Com o propósito de documentar a real ingestão neste período, um estudo prospectivo observacional foi executado. MÉTODO: Quarenta pacientes consecutivos foram investigados por recordatório de 24 horas a cada três meses após a operação, até um ano. Apenas mulheres foram arroladas para maior homogeneidade da amostra. Todas receberam diariamente um suplemento vitamínico-mineral, como rotina pós-operatória. Um questionário foi empregado abordando alterações gerais, nutricionais e gastrointestinais assim como consumo de medicamentos. Os ganhos dietéticos foram analisados mediante o programa Virtual Nutri (São Paulo, SP, Brasil). RESULTADOS: A resposta cirúrgica situou-se dentro da faixa esperada, com perda de cerca de 67% do excesso de peso após um ano, e o mesmo ocorreu com sintomas gastrointestinais e necessidades medicamentosas. A quantidade de energia diária nas quatro ocasiões foi de 529,4±47,5, 710,9± 47,7, 833,2± 72,0 e 866,2± 95,1 kcal/dia (média ± erro padrão da média), e o aumento do consumo de proteína foi da mesma proporção nos 6 e 9 meses e com redução em 12 meses. Consequentemente mesmo após um ano as pacientes estavam abaixo das recomendações usuais de calorias e proteínas. A contribuição da dieta no tocante a ferro e zinco também mostrou-se inadequada, embora quadros deficitários tenham provavelmente sido abortados pelo suplemento utilizado. CONCLUSÕES: 1) O risco para desnutrição pos-operatória ficou demonstrado até um ano, e a melhora espontânea da ingestão de alimentos revelou-se lenta e ineficiente; 2) Protocolos específicos deveriam ser elaborados visando melhorar a nutrição e a saúde na fase pós-operatória, até que se verifique uma adaptação dietética satisfatória

Neuroprotection And Immunomodulation By Xenografted Human Mesenchymal Stem Cells Following Spinal Cord Ventral Root Avulsion.

The present study investigates the effects of xenotransplantation of Adipose Tissue Mesenchymal Stem Cells (AT-MSCs) in animals after ventral root avulsion. AT-MSC has similar characteristics to bone marrow mesenchymal stem cells (BM-MSCs), such as immunomodulatory properties and expression of neurotrophic factors. In this study, Lewis rats were submitted to surgery for unilateral avulsion of the lumbar ventral roots and received 5 × 10(5) AT-MSCs via the lateral funiculus. Two weeks after cell administration, the animals were sacrificed and the moto neurons, T lymphocytes and cell defense nervous system were analyzed. An increased neuronal survival and partial preservation of synaptophysin-positive nerve terminals, related to GDNF and BDNF expression of AT-MSCs, and reduction of pro-inflammatory reaction were observed. In conclusion, AT-MSCs prevent second phase neuronal injury, since they suppressed lymphocyte, astroglia and microglia effects, which finally contributed to rat motor-neuron survival and synaptic stability of the lesioned motor-neuron. Moreover, the survival of the injected AT- MSCs lasted for at least 14 days. These results indicate that neuronal survival after lesion, followed by mesenchymal stem cell (MSC) administration, might occur through cytokine release and immunomodulation, thus suggesting that AT-MSCs are promising cells for the therapy of neuronal lesions.51616

Quantitative and Qualitative Characteristics of the Loin of Grazing Lambs From Different Production Systems

The international sheep market is supplied mainly from New Zealand and Australia, where there are advanced production systems and marketing organisations, and where the product is exported mainly in the form of carcasses and cuts. In Brazil, the farmers should aim to produce a younger animal, with an adequate fat level at an optimum stage of muscle development, in order to gain market share The proportions of muscle, bone and fat largely determine the value of the carcass, and the breed and age of animal, in addition to other factors such as feeding systems, cause variation in the proportions (Purchas et al., 1991). Grazing systems may be considered in Brazil due to reduced production costs. Measuring M. longissimus (the loin muscle) traits is a way of evaluating carcass quality because this muscle is one of the most important commercial cuts and represents total carcass characteristics. The objective of this study was to determine qualitative and quantitative characteristics of the loin of lambs on different production systems