Uma análise comparativa dos tempos de divergência dos eventos de cladogênese dentro dos gêneros Proechimys, Thrychomys e Trinomys de equimiídeos, baseada em seqüências do gene mitocondrial citocromo b, revelou distintos padrões de diversificação para esses três gêneros. Em geral houve pouca sobreposição entre os eventos de diversificação dos três gêneros comparados. Tanto Proechimys quanto Trinomys comportam diversas linhagens antigas, que vêm se diferenciando desde o Mioceno Médio. Thrichomys apresentou indício de uma perda de linhagens entre o final do Mioceno e o início do Plioceno, que pode estar associada ao Grande Intercâmbio Biótico Americano. Esses dados sugerem que as oscilações climáticas podem ter afetado de maneira diversa, com distintas respostas, os diferentes biomas ocupados por esses três gêneros. Nossos dados sugerem que apenas um modelo de diversificação não pode explicar a diversidade neotropical, enfatizando a necessidade de abordagens com modelos mais complexos. Este estudo demonstra a importância de associar uma estrutura temporal às análises filogenéticas. Associar tempo a eventos de cladogênese permite inferir modelos de especiação e extinção, comparar taxas de evolução entre táxons e correlacionar esses eventos com processos geológicos, paleoclimáticos e biogeográficos. / Comparative analysis of divergence times for cladogenic events within the echimyid genera Proechimys, Thrychomys, and Trinomys, based on sequences of the mitochondrial cytochrome-b gene, revealed distinct patterns of diversification for these three genera. In general there was little overlap between the events of diversification of the three genera, when compared. Both Proechimys and Trinomys consist of several lineages which have become differentiated since the Middle Miocene. Thrichomys seems to have undergone a severe bottleneck, with the survival of a single lineage, which may be associated with the Great American Biotic Interchange. These data suggest that fluctuations in past climate may have affected differently, the different biomes occupied by these three genera. Our data suggest that a single speciation mode fails to explain Neotropical biodiversity, emphasizing the need for approaches using complex models. This study demonstrates the importance of associating a temporal framework to phylogenetic analyses. Relating cladogenesis and time allows testing of hypotheses about the mode of speciation and extinction, comparison of rates of evolution across taxa, and correlation of such events with important geological, paleoclimatic, and biogeographic processes.

Uma análise comparativa dos tempos de divergência dos eventos de cladogênese dentro dos gêneros Proechimys, Thrychomys e Trinomys de equimiídeos, baseada em seqüências do gene mitocondrial citocromo b, revelou distintos padrões de diversificação para esses três gêneros. Em geral houve pouca sobreposição entre os eventos de diversificação dos três gêneros comparados. Tanto Proechimys quanto Trinomys comportam diversas linhagens antigas, que vêm se diferenciando desde o Mioceno Médio. Thrichomys apresentou indício de uma perda de linhagens entre o final do Mioceno e o início do Plioceno, que pode estar associada ao Grande Intercâmbio Biótico Americano. Esses dados sugerem que as oscilações climáticas podem ter afetado de maneira diversa, com distintas respostas, os diferentes biomas ocupados por esses três gêneros. Nossos dados sugerem que apenas um modelo de diversificação não pode explicar a diversidade neotropical, enfatizando a necessidade de abordagens com modelos mais complexos. Este estudo demonstra a importância de associar uma estrutura temporal às análises filogenéticas. Associar tempo a eventos de cladogênese permite inferir modelos de especiação e extinção, comparar taxas de evolução entre táxons e correlacionar esses eventos com processos geológicos, paleoclimáticos e biogeográficos. / Comparative analysis of divergence times for cladogenic events within the echimyid genera Proechimys, Thrychomys, and Trinomys, based on sequences of the mitochondrial cytochrome-b gene, revealed distinct patterns of diversification for these three genera. In general there was little overlap between the events of diversification of the three genera, when compared. Both Proechimys and Trinomys consist of several lineages which have become differentiated since the Middle Miocene. Thrichomys seems to have undergone a severe bottleneck, with the survival of a single lineage, which may be associated with the Great American Biotic Interchange. These data suggest that fluctuations in past climate may have affected differently, the different biomes occupied by these three genera. Our data suggest that a single speciation mode fails to explain Neotropical biodiversity, emphasizing the need for approaches using complex models. This study demonstrates the importance of associating a temporal framework to phylogenetic analyses. Relating cladogenesis and time allows testing of hypotheses about the mode of speciation and extinction, comparison of rates of evolution across taxa, and correlation of such events with important geological, paleoclimatic, and biogeographic processes.

I studied the social behaviour of the Vancouver Island marmot, Marmota vancouverensis, during the summers of 1973 and 1974. Virtually nothing was known about the behaviour of this species at the outset of this study, Barash (1973b, 1974a) suggested that the social behaviour and social organization of marmot species was determined by the severity of the environment (the vegetative growing season) and its effect on the growth rate of marmots. He predicted that marmot species living in short growing season environments would be highly social but that social tolerance would decrease as the growing season increased. The objective of this study was to test this hypothesis by observing the social behaviour of Vancouver Island marmots and comparing this to the length of the vegetative growing season. M. vancouverensis is endemic to Vancouver Island, British Columbia. The original colonizers of this species probably crossed to Vancouver Island via land connections that existed during the Illinoian glacial period, approximately 100,000 years ago, and survived subsequent glacial maxima on nunataks and coastal refugia or both. Vancouver Island marmots have been isolated from mainland forms for a length of time (10,000 to 100,000 years) sufficient to show specific evolutionary adaptations to their Vancouver Island environment. Vancouver Island marmots live in small colonies in the subalpine parkland. Social groups consisted of one adult male, one adult female, and variable numbers of two-year-olds, yearlings, and infants. Social groups were highly integrated with a large amount of communication occurring among colony members. Alarm calls were given in response to potential predators and could be heard over the whole colony. Short whistles were given in response to aerial predators (e.g. eagles) and long whistles were given in response to terrestrial predators (e.g. black bears). Both calls are narrow bandwidth sounds, a characteristic that makes them difficult to locate. The most common social behaviour that occurred among colony members was a nose touching behaviour termed greeting. All age-sex classes of Vancouver Island marmots engaged in greetings as well as other social behaviour patterns in about the same proportions. The vegetative growing season experienced by Vancouver Island marmots was approximately the same as that of M. flaviventris but the social behaviour of Vancouver Island marmots most closely resembled M. olympus, a species living where the growing season is much shorter. On this basis I rejected Barash's hypothesis that the length of the vegetative growing season is sufficient to account for the variability that Barash observed among marmot species. I suggest that vegetative growing season not be used as an index of growth rate but that the time taken to reach adult size be measured directly. The degree of social tolerance is positively correlated with the length of time required to reach maturity. / Science, Faculty of / Zoology, Department of / Graduate

Clusterin has previously been identified as a gene potentially involved in development of the cochlear sensory epithelium. In order to be able to predict the cellular roles that clusterin may play in the development of this organ, an understanding of the spatiotemporal expression pattern is required. Therefore, clusterin gene expression during mouse inner ear development was studied using riboprobes from the mouse gene. Clusterin mRNA demonstrates a dynamic expression pattern within the developing cochlear sensory epithelium. Clusterin mRNA expression is initiated at 12.5dpc (days post coitum) along the entire length of the cochlear sensory epithelium. Throughout in utero development, expression is maintained but becomes progressively restricted in this sensory epithelium. Postnataly expression resolves to specific cellular regions, but clusterin expression ceases at some time point between P2-P17. The analysis of clusterin protein expression revealed this was not restricted to the developing sensory epithelium alone, but also was detected transiently in the periotic mesenchye, otic capsule, as well as Reissner's membrane, a non-sensory epithelium. The detailed localisation of clusterin was compared to other inner ear markers. Using α and β tectorin mRNA markers, clusterin mRNA was shown to localise to the developing inner and outer sulcus and spiral prominence. Clusterin expression also overlaps with both Myosin VIIA and Prox1, markers for hair cells and supporting cells respectively. Clusterin mRNA and protein was absent from the developing mouse vestibular system. In order to study the regulatory mechanisms underlying inner ear clusterin expression, a clusterin BAC was modified by insertion of ZsGreen reporter gene into clusterin genomic regions using recombineering technique. The pronuclear injection of this construct has not been successful so far although these studies are ongoing. Finally in order to determine the fate of clusterin expressing cells after the expression is ceased in the inner ear, clusterin BAC was modified by insertion of Cre recombinant gene at the same location as ZsGreen gene for the generation of Cre transgenic mouse. This transgenic mouse will be crossed with a silent reporter mouse for future clusterin fate mapping studies.

Thesis (Doctoral)--Georg-August-Universität zu Göttingen, 1932.

Thesis (Ph. D.)--University of Virginia, 2000. / Spine title: Food for thought: Brain ECF glucose. Includes bibliographical references (p. 161-201). Also available online through Digital Dissertations.

Thesis (Doctoral)--Georg-August-Universität zu Göttingen, 1932.

La microstructure de l'émail est étudiée depuis longtemps, mais ses modalités de formation sont encore floues. J'ai employé une approche multi-disciplinaire alliant paléontologie et biologie cellulaire dans une perspective évolution-développement afin de parvenir à une vision intégrée et en profondeur de la microstructure, de sa morphologie et de ses modes de formation. J'ai ainsi pu décrire en 2D l'évolution de la microstructure chez un grand groupe de mammifères fossiles et actuels, les cétartiodactyles, qui ont révélé que tous les caractères de l'émail ne se valent pas, et font état de différentes contraintes développementales les rendant plus ou moins labiles aux changements évolutifs. J'ai également travaillé au niveau cellulaire et en 3D avec des modèles actuels, en particulier des rongeurs, sur les rapports entre les prismes d'émail et leurs cellules sécrétrices, les améloblastes, révélant que l'agencement de ces derniers contribue en grande part à la morphologie de la microstructure. Enfin, j'ai réalisé une démarche de synthèse, en proposant un modèle de la microstructure de l'émail chez les mammifères sur la base de mes données 2D+3D. Il en est ressorti d'une part un nouveau logiciel de reconstruction virtuelle de la microstructure, Simulémail, et il a été mis en évidence différents moyens de générer la décussation chez les mammifères, ainsi que les probables mécanismes développementaux sous-jacents. / I approached enamel microstructure's morphology and modes of formation with a dual angle, combining paleontological and cellular biology observations, in 2D and 3D. Studying microstructure of extinct and extant Cetartiodactyla in a phylogenetic context, I discovered that some enamel characters are more likely to evolve and change than others, which is linked to different developmental constrains. I also explored microstructure through the relationship between enamel prisms and ameloblasts, the enamel-secreting cells, showing that the arrangement of the cells is directly associated with the prisms'. Then, combining these data, I constructed a model of mammalian enamel microstructure based on 2D and 3D observations and suggested underlying cellular mechanisms, and created a new software dedicated to enamel reconstruction, Simulémail, based on this model. It helped to show that microstructure is not always created the same way for different mammals, and allowed to explore enamel characters efficiently.

O preá (Galea spixii),é um roedor da família Caviidae que vive na Caatinga do Nordeste brasileiro e vêm sendo criados em cativeiro, para sua utilização como fonte alternativa de alimento, preservação da espécie e utilização como modelo biológico em pesquisas. Poucos trabalhos são focados no estudo detalhado da morfologia dos diferentes tipos celulares e expressão enzimática em cada uma das zonas do córtex adrenal, sobretudo em espécies de mamíferos silvestres. As glândulas adrenais fetais de 20 dias de gestação apresentaram córtex indiferenciado. O início de formação da zona fasciculada foi observado nos fetos de 25 dias de gestação e a zona reticulada surgiu nos fetos aos 40 dias de gestação. As zonas descritas anteriormente persistiram nos fetos aos 50 dias de gestação, nos animais de 15 e 30 dias pós-natais e nos animais púberes. A expressão das enzimas citocromo P450c17 e da citocromo b5 nas zonas glomerular, fasciculada e reticulada de embriões e fetos de preás não estão somente relacionadas à produção, respectivamente, de mineralocorticoides, glicocorticoides e esteroides sexuais, pois a citocromo b5 é responsável pela diferenciação cortical em diferentes fases de desenvolvimento da adrenal e a imunoexpressão da citocromo P450c17 na fase final da gestação estão relacionadas com o processo de maturação da glândula adrenal e podem estar relacionadas coma síntese de esteroides sexuais devido a proximidade da puberdade. A imunomarcação da enzima citocromo b5 nas células cromafins das medulas das adrenais de 50 dias de gestação e adulta, podem estar relacionadas à síntese de adrenalina e noradrenalina devido a fatores de estresse. O aumento da duração da gestação para 50 dias ou mais, pode estar relacionado com deficiências na síntese de cortisol/corticosterona pelas enzimas esteroidogênicas / The Spixs yellow-toothed cavy (Galea spixii), is a Caviidae family rodent living in the Brazilian Northeast Caatinga and have been bred in captivity for use as an alternative food source, species preservation and use as animal model research. Few studies are focused on a detailed study of the morphology and ultrastructure of different cell types and expression of enzyme in each of the zones of the adrenal cortex, particularly in wild mammalian species. The fetal adrenal glands 20 days of gestation showed undifferentiated cortex. The early formation of the zona fasciculata was observed in fetuses of 25 days of pregnancy and the reticulated area emerged in fetuses at 40 days of gestation. The areas described above persisted in fetuses at 50 days of gestation, animals at 15 and 30 postnatal days and pubertal animals. The expression of P450c17 enzyme cytochrome b5 and cytochrome in glomerular areas fasciculata and guinea pigs crosslinked embryos and fetuses are not only related to production, respectively, mineralocorticoids and glucocorticoids, sex steroids, as the cytochrome b5 is responsible for cortical differentiation different stages of development and adrenal cytochrome P450c17 immunoreactivity of the final stage of pregnancy are associated with the adrenal gland maturation process and may be associated with the synthesis of sex steroids due to the proximity of puberty. The immunostaining of the enzyme cytochrome b5 in the chromaffin cells of the adrenal marrow 50 days of gestation and adult, may be related to the synthesis of adrenaline and noradrenaline due to stress factors. The increased length of gestation for 50 days or more, may be related to impaired cortisol synthesis / corticosterone by steroidogenic enzymes

O preá (Galea spixii),é um roedor da família Caviidae que vive na Caatinga do Nordeste brasileiro e vêm sendo criados em cativeiro, para sua utilização como fonte alternativa de alimento, preservação da espécie e utilização como modelo biológico em pesquisas. Poucos trabalhos são focados no estudo detalhado da morfologia dos diferentes tipos celulares e expressão enzimática em cada uma das zonas do córtex adrenal, sobretudo em espécies de mamíferos silvestres. As glândulas adrenais fetais de 20 dias de gestação apresentaram córtex indiferenciado. O início de formação da zona fasciculada foi observado nos fetos de 25 dias de gestação e a zona reticulada surgiu nos fetos aos 40 dias de gestação. As zonas descritas anteriormente persistiram nos fetos aos 50 dias de gestação, nos animais de 15 e 30 dias pós-natais e nos animais púberes. A expressão das enzimas citocromo P450c17 e da citocromo b5 nas zonas glomerular, fasciculada e reticulada de embriões e fetos de preás não estão somente relacionadas à produção, respectivamente, de mineralocorticoides, glicocorticoides e esteroides sexuais, pois a citocromo b5 é responsável pela diferenciação cortical em diferentes fases de desenvolvimento da adrenal e a imunoexpressão da citocromo P450c17 na fase final da gestação estão relacionadas com o processo de maturação da glândula adrenal e podem estar relacionadas coma síntese de esteroides sexuais devido a proximidade da puberdade. A imunomarcação da enzima citocromo b5 nas células cromafins das medulas das adrenais de 50 dias de gestação e adulta, podem estar relacionadas à síntese de adrenalina e noradrenalina devido a fatores de estresse. O aumento da duração da gestação para 50 dias ou mais, pode estar relacionado com deficiências na síntese de cortisol/corticosterona pelas enzimas esteroidogênicas / The Spixs yellow-toothed cavy (Galea spixii), is a Caviidae family rodent living in the Brazilian Northeast Caatinga and have been bred in captivity for use as an alternative food source, species preservation and use as animal model research. Few studies are focused on a detailed study of the morphology and ultrastructure of different cell types and expression of enzyme in each of the zones of the adrenal cortex, particularly in wild mammalian species. The fetal adrenal glands 20 days of gestation showed undifferentiated cortex. The early formation of the zona fasciculata was observed in fetuses of 25 days of pregnancy and the reticulated area emerged in fetuses at 40 days of gestation. The areas described above persisted in fetuses at 50 days of gestation, animals at 15 and 30 postnatal days and pubertal animals. The expression of P450c17 enzyme cytochrome b5 and cytochrome in glomerular areas fasciculata and guinea pigs crosslinked embryos and fetuses are not only related to production, respectively, mineralocorticoids and glucocorticoids, sex steroids, as the cytochrome b5 is responsible for cortical differentiation different stages of development and adrenal cytochrome P450c17 immunoreactivity of the final stage of pregnancy are associated with the adrenal gland maturation process and may be associated with the synthesis of sex steroids due to the proximity of puberty. The immunostaining of the enzyme cytochrome b5 in the chromaffin cells of the adrenal marrow 50 days of gestation and adult, may be related to the synthesis of adrenaline and noradrenaline due to stress factors. The increased length of gestation for 50 days or more, may be related to impaired cortisol synthesis / corticosterone by steroidogenic enzymes