Thesis (M.Sc.)--York University, 2009. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 53-57). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR51603

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 38-51).

Orientador: Rosicleire Veríssimo Silveira / Resumo: A atividade de piscicultura em tanques-rede encontra-se em expansão nas represas brasileiras, entretanto, esta prática pode alterar a biologia reprodutiva das espécies que vivem ao seu entorno. Deste modo, pretendeu-se avaliar a influência de pisciculturas em tanques-rede na reprodução de espécies de peixes, (mandi) Pimelodus cf. platicirris, (corvina) Plagioscion squamosissimus e (porquinho) Geophagus proximus, comparando dois pontos. As coletas foram realizadas em dois pontos no reservatório de Ilha Solteira, rio Grande. Um ponto denominado Área Tanque (AT), uma piscicultura em tanques-rede no munícipio de Santa Clara D’Oeste – SP, no braço Can-Can do reservatório de Ilha Solteira, rio Parana e um segundo ponto, Área Controle (AC) a aproximadamente 10 km, a montante. Os espécimes foram coletados bimestralmente com auxílio de dois lotes de redes com malhas 3, 4, 5, 6 e 7 cm e um lote de redes com malhas 7, 8, 10, 12 e 14 cm, no período de Dez/2014 a Dez/2016). Realizou-se a caracterização morfológica da gametogênese e do ciclo reprodutivo das espécies, além do uso do Ìndice gonadossomático e medida do diâmetro dos oócitos maduros nas diferentes áreas. A frequencia sexual foi similar em P. squamosissimus espécie sedentária e G. proximus territorialista e um pouco discrepante para P. cf. platicirris, espécie migratória, mas se mostrou um dado constante não havendo interferência da piscicultura. A proporção de femeas na fase de apto a desova foi similar para as três espécies, r... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The fish farming activity in net cages is in expansion in Brazilian dams, however, this practice may modify the biology of the species which live around it. This way, this work aimed to evaluate the influence of fish farming in net cages in the reproductive biology of fish species such as (mandi) Pimelodus cf. platicirris, (corvina) Plagioscion squamosissimus and (porquinho) Geophagus proximus, comparing the Net Cage Areas (NCA) to Control Areas (CA). The samples were collected at two points at Ilha Solteira reservoir, Rio Grande. One of them named Net Cage Area (NCA), a fish farm with Net Cages in the County of Santa Clara D’Oeste – SP, at the Can-Can arm of Ilha Solteira reservoir, Parana River and the other one, Control Area, (CA) at about 10 km upstream. The specimens were collected bimonthly with the use of two lots of nets with mesh of 3, 4, 5, 6 e 7 cm and one lot of net with mesh of 7, 8, 10, 12 e 14 cm, between December/2014 and December/2016. Besides the morphological characterization of gametogenesis and the reproductive cycle of the species, the Gonadosomatic index and the measurement of mature oocytes diameter at different areas were made. The sexual frequency was similar in P. squamosissimus secondary species and G. proximus territorialist and with a little discrepancy to P. cf. platicirris, migratory species, but it showed constant data not having interference from the fish farm. The proportion of females, which were suitable for spawning, was similar for the t... (Complete abstract click electronic access below) / Doutor

O objetivo, deste estudo foi investigar o comportamento dos hormônios esteróides 17β-Estradiol (E2), 17α-hidroxiprogesterona (17α-OHP), Testosterona (T) e 11-Ketotestosterona (11-KT), em piracanjuba Brycon orbignyanus de diferentes sexos e idades, na estação reprodutiva, e nas fêmeas submetidas à reprodução induzida. Os animais utilizados no trabalho, eram criados em piscicultura comercial, mantidos em 3 viveiros, separados por lotes de diferentes idades. A coleta dos animais, consistiu de quatro machos e cinco fêmeas (48 meses), identificados através do dimorfismo sexual da espécie, e as demais idades, (12 e 24 meses), coletaram-se, 20 peixes de cada idade, para identificação do sexo através de histologia. Já o experimento de caracterização dos esteróides sexuais na reprodução induzida, foram coletadas cinco fêmeas, selecionadas através das características com: abdome abaulado, papila urogenital, saliente e avermelhada. Após captura, os peixes foram transportados ao laboratório, onde houve coleta de sangue, para quantificação do perfil plasmático de E2, 17α-OHP, T e 11-KT. Posteriormente, os animais foram abatidos e suas gônadas coletadas e fixadas, a fim de que fosse realizada análise histológica para identificação do sexo. Na reprodução induzida, foi coletado sangue em dois momentos: pré-indução (PI) e pós-extrusão (PE). O nível plasmático de E2 nos machos de 12 meses destaca sua ação no processo de proliferação e renovação das espermatogônia observado em machos imaturos. Nas fêmeas o E2 apresentou os maiores níveis (P<0,05) nos animais de 48 meses, confirmando assim, sua principal função na estimulação do processo de vitelogênese, e maturação final do oócito. Quanto aos andrógenos T e 11-KT, os maiores níveis (p<0,05) foram observados nos peixes adultos (48 meses), permitindo afirmar que estes atuam como feedback negativo, do FSH e feedback positivo do LH, fundamental no processo de maturação final e liberação dos gametas, além de regular o comportamento reprodutivo. O resultado da 17α-OHP, sugere que, nas idades estudadas, é indispensável por participar como precursor dos principais esteróides (T, E2 e 11-KT), além da 17α,20β dihydroxy-4-pregnen-3-one (17α,20β-DHP), essencial no estágio final de maturação, e desova na reprodução induzida. / The objective of this study was to investigate the physiological behavior of steroid hormones 17β-Estradiol (E2), 17α-hydroxyprogesterone (17α-OHP), testosterone (T) and 11-Ketotestosterone (11-KT) in Brycon orbignyanus with different sex and ages on the reproductive season and in females submitted to induced reproduction. The animals used in the study were kept in three ponds on a commercial fish farming, separated by lots with different ages. The sampling of animals consisted of the collection of four males and five females (48 months) identified by the sexual dimorphism of the specie. In the other groups (12 and 24 months), 20 fish of each age were collected for identification of sex through histology. In the experiment with characterization of the sexual steroids in the induced reproduction, were collected five females selected through the following characteristics: bulging abdomen and prominent reddish genital papilla. After capture, the fish were transported to the laboratory, where blood was collected for quantification of the plasma profile of E2, 17α-OHP, T and 11-KT Subsequently, the animals were slaughtered and their gonads were collected and fixed for histological analysis. In the induced females, blood was collected at two moments: pre-induction (PI) and post-extrusion (PE). The plasma profile of E2 is fundamental in immature males, highlighting its action in the process of proliferation and renewal of spermatogonia, observed in males of 12 months. In females E2 presented the highest levels (P <0.05) in animals at 48 months, thus confirming its main function in the stimulation of the vitellogenesis process and final oocyte maturation. The highest levels (p <0.05) of T and 11-KT androgens were observed in adult fish (48 months), allowing to affirm that they are acting as FSH negative feedback and LH positive feedback, fundamental in the final maturation and release of the gametes, besides regulating the reproductive behavior of the fish. The results of 17α-OHP suggest this hormon is fundamental in the studied ages because it is a precursor of the main steroids (T, E2 and 11-KT) and 17α, 20β-dihydroxy-4-pregnen-3-one (17α, 20β-DHP), essential in the final stage of maturation and spawning in induced reproduction.

O objetivo, deste estudo foi investigar o comportamento dos hormônios esteróides 17β-Estradiol (E2), 17α-hidroxiprogesterona (17α-OHP), Testosterona (T) e 11-Ketotestosterona (11-KT), em piracanjuba Brycon orbignyanus de diferentes sexos e idades, na estação reprodutiva, e nas fêmeas submetidas à reprodução induzida. Os animais utilizados no trabalho, eram criados em piscicultura comercial, mantidos em 3 viveiros, separados por lotes de diferentes idades. A coleta dos animais, consistiu de quatro machos e cinco fêmeas (48 meses), identificados através do dimorfismo sexual da espécie, e as demais idades, (12 e 24 meses), coletaram-se, 20 peixes de cada idade, para identificação do sexo através de histologia. Já o experimento de caracterização dos esteróides sexuais na reprodução induzida, foram coletadas cinco fêmeas, selecionadas através das características com: abdome abaulado, papila urogenital, saliente e avermelhada. Após captura, os peixes foram transportados ao laboratório, onde houve coleta de sangue, para quantificação do perfil plasmático de E2, 17α-OHP, T e 11-KT. Posteriormente, os animais foram abatidos e suas gônadas coletadas e fixadas, a fim de que fosse realizada análise histológica para identificação do sexo. Na reprodução induzida, foi coletado sangue em dois momentos: pré-indução (PI) e pós-extrusão (PE). O nível plasmático de E2 nos machos de 12 meses destaca sua ação no processo de proliferação e renovação das espermatogônia observado em machos imaturos. Nas fêmeas o E2 apresentou os maiores níveis (P<0,05) nos animais de 48 meses, confirmando assim, sua principal função na estimulação do processo de vitelogênese, e maturação final do oócito. Quanto aos andrógenos T e 11-KT, os maiores níveis (p<0,05) foram observados nos peixes adultos (48 meses), permitindo afirmar que estes atuam como feedback negativo, do FSH e feedback positivo do LH, fundamental no processo de maturação final e liberação dos gametas, além de regular o comportamento reprodutivo. O resultado da 17α-OHP, sugere que, nas idades estudadas, é indispensável por participar como precursor dos principais esteróides (T, E2 e 11-KT), além da 17α,20β dihydroxy-4-pregnen-3-one (17α,20β-DHP), essencial no estágio final de maturação, e desova na reprodução induzida. / The objective of this study was to investigate the physiological behavior of steroid hormones 17β-Estradiol (E2), 17α-hydroxyprogesterone (17α-OHP), testosterone (T) and 11-Ketotestosterone (11-KT) in Brycon orbignyanus with different sex and ages on the reproductive season and in females submitted to induced reproduction. The animals used in the study were kept in three ponds on a commercial fish farming, separated by lots with different ages. The sampling of animals consisted of the collection of four males and five females (48 months) identified by the sexual dimorphism of the specie. In the other groups (12 and 24 months), 20 fish of each age were collected for identification of sex through histology. In the experiment with characterization of the sexual steroids in the induced reproduction, were collected five females selected through the following characteristics: bulging abdomen and prominent reddish genital papilla. After capture, the fish were transported to the laboratory, where blood was collected for quantification of the plasma profile of E2, 17α-OHP, T and 11-KT Subsequently, the animals were slaughtered and their gonads were collected and fixed for histological analysis. In the induced females, blood was collected at two moments: pre-induction (PI) and post-extrusion (PE). The plasma profile of E2 is fundamental in immature males, highlighting its action in the process of proliferation and renewal of spermatogonia, observed in males of 12 months. In females E2 presented the highest levels (P <0.05) in animals at 48 months, thus confirming its main function in the stimulation of the vitellogenesis process and final oocyte maturation. The highest levels (p <0.05) of T and 11-KT androgens were observed in adult fish (48 months), allowing to affirm that they are acting as FSH negative feedback and LH positive feedback, fundamental in the final maturation and release of the gametes, besides regulating the reproductive behavior of the fish. The results of 17α-OHP suggest this hormon is fundamental in the studied ages because it is a precursor of the main steroids (T, E2 and 11-KT) and 17α, 20β-dihydroxy-4-pregnen-3-one (17α, 20β-DHP), essential in the final stage of maturation and spawning in induced reproduction.

No description available.

No description available.

No description available.

MtDNA mutations in mammalian cells are implicated in cellular ageing and encephalomyopathies, although mechanisms involved are not completely understood. The mitochondrial genetic bottleneck has puzzled biologists for a long time. Approximate models of genetic bottleneck proposed in the literature do not accurately model underlying biology. Recent studies indicate mitochondrial morphology changes during cellular aging in culture. In particular, the rates of mitochondrial fission and fusion are shown to be in tight balance, though this rate decreases with age. Some proteins involved in mitochondrial morphology maintenance are implicated in apoptosis. Hence, mitochondrial genetic and morphologic dynamics are critical to the life and death of cells. By working closely with experimental collaborators and by utilizing data derived from literature, we have developed stochastic simulation models of mitochondrial genetic and morphologic dynamics. Hypotheses from the mitochondrial genetic dynamics model include: (1) the decay of mtDNA heteroplasmy in blood is exponential and not linear as reported in literature. (2) Blood heteroplasmy measurements are a good proxy for the blood stem cell heteroplasmy. (3) By analyzing our simulation results in tandem with published longitudinal clinical data, we propose for the first time, a way to correct for the patient's age in the analysis of heteroplasmy data. (4) We develop a direct model of the genetic bottleneck process during mouse embryogenesis. (5) Partitioning of mtDNA into daughter cells during blastocyst formation and relaxed replication of mtDNA during the exponential growth phase of primordial germ cells leads to the variation in heteroplasmy inherited by offspring from the same mother. (6) We develop a “simulation control” for experimental studies on mtDNA heteroplasmy variation in cell cultures. Hypothesis from the mitochondrial morphologic dynamics model: (7) A cell adjusts the mitochondrial fusion rate to compensate for the fluctuations in the fission rate, but not vice versa. A deterministic model for this control is proposed. Contributions: extensible simulation models of mitochondrial genetic and morphologic dynamics to aide in the powerful analysis of published and new experimental data. Our results have direct relevance to cell biology and clinical diagnosis. The work also illustrates scientific success by tight integration of theory with practice. / Ph. D.