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Genomic imprinting is an epigenetic phenomenon whereby the expression of a gene, chromosomal region, or entire chromosome, depends on the sex of the transmitting parent. Imprinting results in an otherwise fully functional gene being transcriptionally silenced when transmitted by one parent, yet the same gene, with identical DNA sequence, is active when transmitted by the other. Thus, the gene retains an imprint or “memory” of its genetic history, which is reversible and reset each successive generation by passage through the germline. Within this thesis, I present my findings that show genomic imprinting in Drosophila is regulated by distinct epigenetic mechanisms at different stages of embryogenesis, suggesting the requirement of a transitional stage to stabilize the imprint between establishment in the germline and maintenance in the soma. I futher show that Drosophila utilize epigenetic mechanisms that are involved in regulating genomic imprinting in mammals and plants, such as DNA methylation, histone modification, antisense RNA, and chromatin insulators. These findings demonstrate convergence of the epigenetic mechanisms that regulate genomic imprinting in diverse organisms.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1974. / Typescript. Vita. Includes bibliographical references.

Thesis (Ph. D.)--Lehigh University, 2005. / Includes vita. Includes bibliographical references (leaves 121-124).

O comportamento materno é essencial para a sobrevivência e desenvolvimento do filhote mamífero. Durante a prenhez, as fêmeas recebem estímulos sensoriais e hormonais capazes de modificar e preparar o cérebro da mãe para o início dos padrões de comportamento materno (por exemplo, aumentando o número neurônios produtores de oxitocina no hipotálamo). Estudos têm identificado o hipotálamo como o principal responsável por estas mudanças, porém outras áreas do cérebro também estão envolvidas no processo do comportamento materno. Peg3, um gene marcado paternalmente expresso, é conhecido por controlar o comportamento materno em camundongos. Fêmeas nocautes para o gene Peg3 falham em aumentar a ingestão de alimentos, na ejeção de leite e em algumas atividades maternais, como placentofagia e construção do ninho. Este estudo teve como objetivo determinar os padrões de metilação da região diferencialmente metilada de Peg3 (Peg3DMR) de animais da raça Nelore de bovinos em diversas áreas do cérebro. Amostras foram coletadas das seguintes áreas: córtex frontal, occipital, temporal e parietal, hipocampo e hipotálamo, num total de 8 animais (4 machos e 4 fêmeas). O padrão de metilação destas amostras foi analisado pelo protocolo COBRA (do inglês, Combined Bisulfite-Restriction Analysis), que combina a modificação do DNA por bissulfito de sódio, amplificação por PCR e digestão por enzima de restrição. Foram encontrados diferentes padrões de metilação entre as amostras, ocorrendo uma predominância de hipometilação entre as amostras do sexo masculino, e padrões mais variados nas amostras do sexo feminino. As variações nos padrões de metilação ocorreram de maneira mais marcante entre as amostras de uma mesma região cerebral de diferentes animais, do que entre as amostras de várias regiões de um mesmo animal. Os resultados indicam que pode haver uma variação no status de imprinting em nível populacional, porém estudos com um número maior de amostras são necessários para a verificação da significância estatística destas variações. / The maternal behavior is essential to survival and development of mammalian offspring. Throughout pregnancy, females receive sensory and hormonal stimuli which promote modifications and prepare the mothers brain to the onset of maternal behavior patterns (for example, by increasing numbers of neurons producing oxytocin in the hypothalamus). Studies have identified the hypothalamus as the main responsible for these changes, but other areas of the brain are also involved in the maternal behavior process. Peg3, an imprinted paternally expressed gene, is known to control maternal behavior in mice. Peg3 knockout females failed in increasing food intake, milk ejection and some maternal activities as placentofagia and nest building. This study aimed to determine the methylation patterns of the differently methylated region of Peg3 (DMR-Peg3) of animals from Nellore cattle breed in several areas of the brain. Samples were collected from the following areas of cattle brain: the frontal, occipital, temporal and parietal cortices, hippocampus and hypothalamus, in a total of 8 animals (4 males and 4 females). The methylation pattern of these samples was analyzed by the protocol COBRA (Combined Bisulfite-Restriction Analysis), which combines DNA modification by sodium bisulfite, PCR amplification and digestion by restriction enzymes. It was found different methylation patterns among the samples. There was a predominance of hypomethylation among male samples, while different patterns were found among the female samples. Variation in the methylation patterns was more markedly observed among samples of the same cerebral region among different animals, then among samples of several regions within an animal. The results suggest that there may be a variation in the imprinting status at a population level, but further assays, with an increased number of samples are needed to verify the statistical significance of this variation.

O comportamento materno é essencial para a sobrevivência e desenvolvimento do filhote mamífero. Durante a prenhez, as fêmeas recebem estímulos sensoriais e hormonais capazes de modificar e preparar o cérebro da mãe para o início dos padrões de comportamento materno (por exemplo, aumentando o número neurônios produtores de oxitocina no hipotálamo). Estudos têm identificado o hipotálamo como o principal responsável por estas mudanças, porém outras áreas do cérebro também estão envolvidas no processo do comportamento materno. Peg3, um gene marcado paternalmente expresso, é conhecido por controlar o comportamento materno em camundongos. Fêmeas nocautes para o gene Peg3 falham em aumentar a ingestão de alimentos, na ejeção de leite e em algumas atividades maternais, como placentofagia e construção do ninho. Este estudo teve como objetivo determinar os padrões de metilação da região diferencialmente metilada de Peg3 (Peg3DMR) de animais da raça Nelore de bovinos em diversas áreas do cérebro. Amostras foram coletadas das seguintes áreas: córtex frontal, occipital, temporal e parietal, hipocampo e hipotálamo, num total de 8 animais (4 machos e 4 fêmeas). O padrão de metilação destas amostras foi analisado pelo protocolo COBRA (do inglês, Combined Bisulfite-Restriction Analysis), que combina a modificação do DNA por bissulfito de sódio, amplificação por PCR e digestão por enzima de restrição. Foram encontrados diferentes padrões de metilação entre as amostras, ocorrendo uma predominância de hipometilação entre as amostras do sexo masculino, e padrões mais variados nas amostras do sexo feminino. As variações nos padrões de metilação ocorreram de maneira mais marcante entre as amostras de uma mesma região cerebral de diferentes animais, do que entre as amostras de várias regiões de um mesmo animal. Os resultados indicam que pode haver uma variação no status de imprinting em nível populacional, porém estudos com um número maior de amostras são necessários para a verificação da significância estatística destas variações. / The maternal behavior is essential to survival and development of mammalian offspring. Throughout pregnancy, females receive sensory and hormonal stimuli which promote modifications and prepare the mothers brain to the onset of maternal behavior patterns (for example, by increasing numbers of neurons producing oxytocin in the hypothalamus). Studies have identified the hypothalamus as the main responsible for these changes, but other areas of the brain are also involved in the maternal behavior process. Peg3, an imprinted paternally expressed gene, is known to control maternal behavior in mice. Peg3 knockout females failed in increasing food intake, milk ejection and some maternal activities as placentofagia and nest building. This study aimed to determine the methylation patterns of the differently methylated region of Peg3 (DMR-Peg3) of animals from Nellore cattle breed in several areas of the brain. Samples were collected from the following areas of cattle brain: the frontal, occipital, temporal and parietal cortices, hippocampus and hypothalamus, in a total of 8 animals (4 males and 4 females). The methylation pattern of these samples was analyzed by the protocol COBRA (Combined Bisulfite-Restriction Analysis), which combines DNA modification by sodium bisulfite, PCR amplification and digestion by restriction enzymes. It was found different methylation patterns among the samples. There was a predominance of hypomethylation among male samples, while different patterns were found among the female samples. Variation in the methylation patterns was more markedly observed among samples of the same cerebral region among different animals, then among samples of several regions within an animal. The results suggest that there may be a variation in the imprinting status at a population level, but further assays, with an increased number of samples are needed to verify the statistical significance of this variation.

The main aim of this study is to contribute to understanding of family influence on mate choice and satisfaction in long-term relationship. Studies suggest that family has significant influence on mate choice. According to the theory of sexual imprinting, individual create an image of the opposite sex parent during early childhood, which is in adulthood used as a template for partner choice (Bereczkei et al., 2002). However, in accordance with phenotype matching theory, the preference for similar traits like parents have, could be preferences for self-similarity, because they share with parents a half of genom. So it could means, that they prefer self-similar traits more than parent-similar traits (Rushton, 1989). Fourty nine couples participated in our research and also partner and parents of our respondents filled a set of standardized questionnaires. In the second study women evaluated male somatotypes and completed a questionnaire on the relationship with their father during childhood. The study showed many interesting results. Studyies aimed on sexual imprinting have focused only on the influence of the opposite sex parent (Wiszewska et al., 2007), however, we found that the parent of same sex influences partner choice of their offspring too. These findings support more the phenotypic matching...