The aim of this thesis was to evaluate the level of feeding habits of a selected human population segment in order to assess their understanding of issues related to nutrition and to basic components in their diet. For this purpose, a measuring instrument (a questionnaire) was designed. The first part contained questions related to respondent´s eating habits preferences, while the second part of questionnaire included questions examining the level of respondent?s nutritional awareness. In total 389 questionnaires were personally administered and completed by the respondents, under supervision of teachers. On the basis of the recorded answers it was found that, when purchasing food, the interviewed persons are governed mostly by the quality of it (37%). It was also discovered that, 40% of people preferred local foods to foods from abroad. Only 13% of respondents indicated their ?always or almost always? preference for ?bio foods?. It may also be said that, the three most popular dairy products are yoghurts (80%), milk (72%) and cheeses (72%), as opposed to fermented drinks (43%), which are the least consumed dairy products. Among the most popular meats the respondents included these three categories: chicken (83%), pork (73%) and beef (47%). The least favourite meat selected by respondents was mutton and lamb (35%). It was found that, 27% of the respondents follow information presented on food packaging but also that, 16% of the respondents do not follow packaging data, at all. According to the recorded frequency of occurrence the sum of correct answers can be said that most students answer 4 questions correctly. The recorded answer frequency counts show that most respondents answered correctly the following question: "What is bio food?" (94% of respondents). The worst answered individual question had to do with choosing foods with the highest ?Vitamin C? content, with only 7% being correct. On the basis of recorded answers it may be concluded that; the food consumption was influenced by the type of school which the respondents attended; as it appears related to the respondents´ age and their individual ability to decide on their food money spending. The questions that examined the level of information have shown that, the overall percentage of correct answers was increasing depending on the age of a respondent. The total percentage of correct answers kept increasing in relation to increasing age of respondents. No influence of gender on percentage totals of correct responses was demonstrated.

Made available in DSpace on 2014-10-09T12:33:01Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:11Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Background: The mosquito Aedes aegypti has long been a vector for human illness in the Southeastern United States. In the past, it has been responsible for outbreaks of dengue, chikungunya, and yellow fever and, very recently, the Zika virus that has been introduced to the region. Multiple studies have modeled the geographic distribution of Ae. aegypti as a function of climate factors; however, this ignores the importance of humans to the anthropophilic biter. Furthermore, Ae. aegypti thrives in areas where humans have created standing water sites, such as water storage containers and trash. As models are developed to examine the potential impact of climate change, it becomes increasingly important to include the most comprehensive set of predictors possible. Results: This study uses Maxent, a species distribution model, to evaluate the effects of adding poverty and population density to climate-only models. Performance was evaluated through model fit statistics, such as AUC, omission, and commission, as well as individual variable contributions and response curves. Models which included both population density and poverty exhibited better predictive power and produced more precise distribution maps. Furthermore, the two human population characteristics accounted for much of the model contribution-more so than climate variables. Conclusions: Modeling mosquito distributions without accounting for their dependence on local human populations may miss factors that are very important to niche realization and subsequent risk of infection for humans. Further research is needed to determine if additional human characteristics should be evaluated for model inclusion.

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Reconstructing the origins and evolutionary journey of humans is a central piece of biology. Complementary to archeology, population genetics studying genetic variation among individuals in extant populations has made considerable progress in understanding the evolution of our species. Particularly, studies in indigenous humans provide valuable insights on the prehistory of humans because their life history closely resembles that of our ancestors. Despite these efforts, it can be difficult to disentangle population genetic inferences because of the interplay among evolutionary forces, including mutation, recombination, selection, and demographic processes. To date, few studies have adopted a comprehensive framework to jointly account for these confounding effects. The shortage of such an approach inspired this dissertation work, which centered on the development of model-based analysis and demonstrated its importance in population genetic inferences. Indigenous African Pygmy hunter-gatherers have been long studied because of interest in their short stature, foraging subsistence strategy in rainforests, and long-term socio-economic relationship with nearby farmers. I proposed detailed demographic models using genomes from seven Western African Pygmies and nine Western African farmers (Appendix A). Statistical evidence was shown for a much deeper divergence than previously thought and for asymmetric migrations with a larger contribution from the farmers to Pygmies. The model-based analyses revealed significant adaption signals in the Pygmies for genes involved in muscle development, bone synthesis, immunity, reproduction, etc. I also showed that the proposed model-based approach is robust to the confounding effects of evolutionary forces (Appendix A). Contrary to the low-latitude African homeland of humans, the indigenous Siberians are long-term survivors inhabiting one of the coldest places on Earth. Leveraging whole exome sequencing data from two Siberian populations, I presented demographic models for these North Asian dwellers that include divergence, isolation, and gene flow (Appendix B). The best-fit models suggested a closer genetic affinity of these Siberians to East Asians than to Europeans. Using the model-based framework, seven NCBI BioSystems gene sets showed significance for polygenic selection in these Siberians. Interestingly, many of these candidate gene sets are heavily related to diet, indicating possible adaptations to special dietary requirements in these populations in cold, resource-limited environments. Finally, I moved beyond studying the history of extant humans to explore the origins of our species in Africa (Appendix C). Specifically, with statistical analyses using genomes only from extant Africans, I rejected the null model of no archaic admixture in Africa and in turn gave the first whole-genome evidence for interbreeding among human species in Africa. Using extensive simulation analyses under various archaic admixture models, the results suggest recurrent admixture between the ancestors of archaic and modern Africans, with evidence that at least one such event occurred in the last 30,000 years in Africa.

El trabajo realizado trata de estudiar la diversidad del genoma mitocondrial humano en poblaciones humanas de diferentes áreas geográficas que habían sido hasta ahora poco o nada estudiadas. Los grupos de poblaciones humanos estudiados en este trabajo esta formado por las poblaciones del oeste del Mediterráneo, de l'África sub-Sahariana, de la Isla de La Reunión, y de l'Asia. Cada una de estas poblaciones pertenecen a un entorno geográfico diferente y han padecido diferentes y numerosos movimientos de poblaciones que han modulado su composición genética. El análisis de diferentes polimorfismos del genoma mitocondrial han permitido entender los factores poblacionales, tal como la migración, la mezcla genética, la deriva genética, los efectos fundadores, y inferir la historia d la poblaciones bajo estudio, La metodología utilizada incluye diferentes tipos de técnicas adaptadas a los diferentes tipos de polimorfismos estudiados. La técnica aplicadas fueron la secuenciación, el análisis de fragmentos y la técnica de SNaPshot. Los resultados obtenidos han aportado un conocimiento nuevo de las poblaciones que han modulado la diversidad genética de los grandes grupos humanos a nivel continental pero también a un nivel mas regional.

Natural selection has played an important role in shaping human genetic variation, thus, finding variants that have been targeted by positive selection can provide insights about which genes influence human phenotypic variability. In this work we conduct a genome-wide survey of protein-coding genes comparing humans, chimpanzees, and closely related species in order to detect the fraction of genes undergoing positive selection on the human lineage, and further investigate intraspecific variation in a subset of candidate genes in the search of recent selective events in worldwide human populations. Our results suggest that most of the genes implicated in selective events during early human evolution differ from those involved in recent human adaptations, implying distinct selective pressures during varying stages of human evolutionary history. We also found three genome regions with evidence of recent positive selection, which were dissected to propose targets of selection and discuss on the possible underlying selective pressures in each case. / La selección natural ha moldeado de forma importante la variación genética humana, por lo que encontrar variantes que hayan sido seleccionadas positivamente puede dar indicios acerca de los genes que determinan la diversidad fenotípica humana. En este trabajo comparamos los genes del genoma humano, del chimpancé y de varias especies cercanamente emparentadas para detectar aquellos genes bajo selección positiva en el linaje humano, y posteriormente evaluar la variación intraespecífica en un subconjunto de genes con la intención de buscar eventos de selección reciente en poblaciones humanas de todo el mundo. Nuestros resultados sugieren que la mayoría de genes implicados en eventos selectivos durante la evolución temprana del hombre no son los mismos que aquellos involucrados en adaptaciones humanas recientes, lo que implica la existencia de diferentes presiones selectivas a lo largo de las distintas etapas de la historia evolutiva humana. También encontramos tres regiones genómicas con evidencias de selección positiva reciente, las cuales fueron analizadas en profundidad para proponer posibles dianas de selección y discutir las presiones selectivas subyacentes en cada caso.