http://repositorio.uem.br:8080/jspui/handle/1/314 2026-07-28T02:15:40Z 2026-07-28T02:15:40Z Baumgartner, Dirceu http://repositorio.uem.br:8080/jspui/handle/1/5121 2018-09-17T19:25:32Z 2010-01-01T00:00:00Z

Título: Zonação, variabilidade e inter-relação da fauna de peixes de dois reservatórios do rio Iguaçu, Paraná, Brasil. Autor(es): Baumgartner, Dirceu Abstract: This study aimed to evaluate the formation of longitudinal and vertical gradients (zonation) of fish fauna and limnological variables, as well as assess the variability of abundance and interrelation of fish species from the Salto Osório (run-of-river) and Salto Santiago (water storage) reservoirs, both positioned in the central region of the Iguaçu River reservoirs cascade. For this, samples were taken monthly during the period from July 2003 to June 2005, and bimonthly from July 2005 to May 2006 for fish, and bimonthly from July 2003 to May 2006 for limnological variables. Data were obtained from three sampling stations in the longitudinal axis (herein named riverine, transitional and lacustrine zones) and two sampling stations in the vertical axis (surface and bottom). This study was divided into two chapters, the first entitled "Effect of dam operation on formation of longitudinal and vertical gradients in reservoirs of the Iguaçu River, Paraná, Brazil" aimed to evaluate if reservoirs with different operation systems presented differences in limnological and ichthyological variables according to vertical and longitudinal directions of the reservoirs. Another objective was to verify if there were increasing differences in the longitudinal direction of the reservoir, which would indicate formation of gradients. In the second chapter, entitled "Variability and inter-relation of the ichthyofauna from the Salto Osorio (run-of-river) and Salto Santiago (water storage) reservoirs, Iguaçu River, Paraná, Brazil", the variability (by the coefficient of variation) of the species abundance was estimated, which was correlated with hydrological variables to observe possible influences of these variables on the regulatory mechanisms of the assemblage. Inter-relation was assessed from the dominant eigenvalue of the error covariance matrix of first-order autoregressive models of species abundances in the reservoirs. We tried from these metrics to identify whether reservoirs with different operations types had different behaviors.

2010-01-01T00:00:00Z Batista, Vinicius Guerra http://repositorio.uem.br:8080/jspui/handle/1/5120 2018-09-17T19:25:32Z 2018-01-01T00:00:00Z

Título: Vocalizações e atividade acústica de anuros brasileiros : conhecimento atual, novas descrições e variação temporal em múltiplas escalas. Autor(es): Batista, Vinicius Guerra Abstract: Acoustic signals of anurans are important mechanisms of reproductive isolation and provide informative characters for identification and delimitation of the species, being used in studies of behavioral, ecology, conservation, taxonomy, biodiversity inventories and influence of environmental impacts on species. In this thesis, we reviewed and measured the knowledge about the advertisement calls of Brazilian anurans, contributing with this knowledge when describing new calls, and also analyzing the temporal variation of the acoustic activity of different species and communities, evaluating the influence of different environmental and social factors. We identified a large knowledge gap regarding call descriptions. Calls of Rhinella abei, Limnomedusa macroglossa e Boana jaguariaivensis were described. Additionally, we evaluated the variation of acoustic parameters in Physalaemus centralis. In relation to the three sympatric Dendropsophus species studied (D. cruzi, D. minutus and D. rubicundulus), there was partition of the acoustic space, as well as of the calling sites. Besides, the Dendropsophus modified their acoustic parameters throughout the night, which may be associated with female preferences or to decrease energetic costs to maintain vocalization activity throughout the reproductive season. At the community level, the anurans presented a circadian pattern, with temporal niche overlap in the acoustic activity during the night, although when evaluated separately the species presented different periods of maximum vocal activity. Climatic variables act as driving factors to determine acoustic activity and the species may use different strategies to avoid overlap in the acoustic niche and facilitate coexistence.

2018-01-01T00:00:00Z Cordeiro, Maiara Mikuska http://repositorio.uem.br:8080/jspui/handle/1/9542 2025-12-18T13:25:25Z 2025-01-01T00:00:00Z

Título: A vitamina D diminui a doença hepática esteatótica associada à disfunção metabólica (MASLD) e modifica o metabolismo hepático na obesidade Autor(es): Cordeiro, Maiara Mikuska Abstract: Resumo: INTRODUÇÃO E OBJETIVOS: A doença hepática esteatótica associada à disfunção metabólica (MASLD) é uma das principais complicações da obesidade, afetando cerca de 30% da população mundial. Essa condição caracteriza-se pelo acúmulo de lipídios no fígado, inflamação crônica e estresse oxidativo hepático. A MASLD pode progredir para esteatohepatite metabólica e, eventualmente, cirrose. A resistência à insulina (RI) é um dos principais fatores envolvidos na fisiopatologia da MASLD e, além de promover maior síntese hepática de lipídios, também está associada à ativação anormal da gliconeogênese, contribuindo para a hiperglicemia observada nesses pacientes. Tanto a obesidade quanto a MASLD estão relacionadas à deficiência de vitamina D; no entanto, os benefícios da suplementação dessa vitamina nessas condições ainda são controversos, com estudos relatando desde melhora clínica até ausência de efeitos significativos. O tratamento da MASLD com vitamina D também tem sido associado à redução da gliconeogênese hepática; entretanto, essa conclusão foi inferida unicamente a partir de dados de expressão gênica, sem medidas diretas dos fluxos metabólicos no fígado. No entanto, não há como quantificar a gliconeogênese com base apenas em dados de expressão gênica. Diante do exposto, este estudo investigou os efeitos da suplementação com vitamina D sobre a MASLD em ratos obesos induzidos por dieta de cafeteria, com ênfase na RI, metabolismo lipídico, inflamação e estresse oxidativo hepático. Também foram avaliados os efeitos da vitamina D sobre a gliconeogênese e o catabolismo do glicogênio em fígados perfundidos, bem como sobre a fosforilação oxidativa em mitocôndrias hepáticas isoladas. A dieta de cafeteria é considerada o modelo experimental que melhor simula a condição obesogênica humana, pois oferece os nutrientes típicos da dieta ocidental na forma de alimentos hipercalóricos, ultraprocessados e altamente palatáveis. MÉTODOS: Ratos Wistar com 30 dias de idade foram alimentados por 60 dias com dieta de cafeteria ou dieta padrão. Parte dos animais de ambos os 10 grupos (obesos e controles) recebeu vitamina D (5.600 UI/kg/semana) por gavage oral durante 5 semanas adicionais juntamente com as respectivas dietas. A RI foi avaliada por meio do teste de tolerância à glicose oral (OGTT) e do teste de tolerância à insulina (ITT). Ao final do protocolo, os animais foram anestesiados para coleta de sangue (obtenção de plasma) e remoção do fígado, que foi processado para análises histológicas (HE), quantificação de lipídios, 25-hidroxivitamina D [25(OH)D], estresse oxidativo e extração de RNAm hepático. Os depósitos de gordura branca visceral foram coletados e pesados. Os níveis de triglicerídeos (TGL), colesterol total e HDL, 25(OH)D, e as atividades de AST, ALT e mieloperoxidase (MPO), assim como a capacidade antioxidante foram determinados no plasma. O estresse oxidativo foi avaliado no fígado por meio da determinação dos níveis de substâncias reativas ao ácido tiobarbitúrico (TBARS), de espécies reativas de oxigênio (ROS), glutationa reduzida (GSH) e oxidada (GSSG), assim como atividade das enzimas catalase e superóxido dismutase (SOD) e níveis do RNAm do fator 2 relacionado ao fator nuclear eritróide 2 (Nfr2) e das enzimas glutationa S-transferase, catalase e heme oxigenase 1. A inflamação hepática foi avaliada por meio de escore histológico e quantificação do RNAm do fator de necrose tumoral alfa (TNF?), interleucina 1 beta (IL-1?), interleucina 6 (IL-6), interleucina 10 (IL-10), fator nuclear kapa B (NF-kB) e sirtuína 1 (Sirt-1). Foram também quantificados no fígado os níveis do RNAm do receptor da vitamina D (VDR), do receptor ativado por proliferador de peroxissoma alfa (PPAR?), do substrato 2 do receptor de insulina (IRS-2), assim como a atividade das enzimas ácido graxo sintase (FAS) e metabolizadoras da vitamina D (CYP2R1 e CYP24A1). O fígado de rato em perfusão isolada com tampão Krebs/Henseleit foi utilizado para avaliar o catabolismo do glicogênio (condição pós-prandial) e a gliconeogênese (jejum de 15 h). O Lactato foi utilizado como precursor de glicose. Amostras do fluido de perfusão efluente foram coletadas em intervalos regulares e analisadas quanto ao conteúdo de glicose, lactato e piruvato. A respiração de mitocôndrias isoladas foi deteminada por polarografia. 11 RESULTADOS E DISCUSSÃO: A dieta de cafeteria induziu obesidade, MASLD, dislipidemia e RI, acompanhados de estresse oxidativo e inflamação hepática. A suplementação com vitamina D reduziu a ingestão alimentar, ganho de peso corporal e adiposidade visceral. Também foi observado um aumento na sensibilidade à insulina e tolerância à glicose, o que foi associado à reduzida adiposidade visceral e esteatose hepática. A vitamina D também reduziu a expressão em termos de RNAm de NF-?B e dos mediadores inflamatórios TNF? e IL-6, assim como diminuiu o estresse oxidativo hepático com aumento da expressão de Nrf2. O tratamento com vitamina D aumentou a expressão do VDR e PPAR? hepáticos, o que deveria aumentar oxidação de lipídios, e reduziu a expressão da ácido graxo sintase (FAS), o que deveria diminuir a lipogênese no fígado. A vitamina D aumentou a expressão de Sirt-1, que foi associado aos efeitos benéficos da vitamina D no fígado por aumentar a expressão de IRS-2, PPAR? e Nrf2, e diminuir a expressão de NF-?B. No entanto, a suplementação com vitamina D causou um aumento discreto da expressão de mediadores inflamatórios no fígado dos ratos controles. Em relação aos experimentos utilizando o fígado em perfusão isolada, os resultados mostraram que ratos obesos em jejum apresentaram maior produção hepática de glicose a partir de lactato e menor consumo de oxigênio do que ratos controles. A suplementação de ratos obesos com a vitamina D diminuiu a produção hepática de glicose e aumentou o consumo hepático de oxigênio para os valores controles. Ratos obesos apresentaram uma aumentada glicogenólise e glicólise hepática quando comparado aos ratos controles. Este resultado parece ser a consequência de um maior conteúdo de glicogênio hepático que resulta da RI. O tratamento de ratos obesos com a vitamina D diminuiu significativamente a glicólise e a glicogenólise hepática. O tratamento de ratos controles com vitamina D não modificou a gliconeogênese, o consumo de oxigênio, a glicólise e a glicogenólise hepática. CONCLUSÃO: Este estudo demonstrou que a suplementação com vitamina D atenua a obesidade induzida por dieta de cafeteria, promovendo redução 12 da adiposidade visceral, RI e MASLD em ratos. Esses efeitos benéficos envolvem a modulação do metabolismo lipídico, da inflamação e do estresse oxidativo hepático, mediados principalmente pela ativação de VDR e pelo aumento da expressão hepática de Sirt-1. Além disso, a suplementação restaurou os níveis séricos de 25(OH)D em animais obesos, sem alterar suas concentrações hepáticas. A vitamina D também reduziu a gliconeogênese e o catabolismo do glicogênio hepático, efeito que parece decorrer da melhora da MASLD e da RI, associada ao aumento da expressão de Sirt-1. Apesar dos resultados positivos, foi observado um discreto efeito pró-inflamatório em ratos controles tratados, o que ressalta a necessidade de cautela quanto à suplementação indiscriminada. Esses achados reforçam o potencial terapêutico da vitamina D na MASLD, mas também destacam a necessidade novos estudos para esclarecer sua segurança.; Abstract: BACKGROUND AND AIMS: Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is one of the main complications of obesity, affecting approximately 30% of the global population. This condition is characterized by lipid accumulation in the liver, chronic inflammation, and hepatic oxidative stress. MASLD may progress to metabolic steatohepatitis and, eventually, cirrhosis. Insulin resistance (IR) is one of the key factors involved in the pathophysiology of MASLD and, in addition to enhancing hepatic lipid synthesis, is also associated with abnormal activation of gluconeogenesis, contributing to the hyperglycemia observed in these patients. Both obesity and MASLD are linked to vitamin D deficiency; however, the benefits of vitamin D treatment in these conditions remain controversial, with studies reporting outcomes ranging from clinical improvement to no significant effects. MASLD treatment with vitamin D has also been associated with reduced hepatic gluconeogenesis; however, this conclusion has been drawn solely from gene expression data, without direct measurements of hepatic metabolic fluxes. Yet, gluconeogenesis cannot be quantified based solely on gene expression data. In light of this, the present study investigated the effects of vitamin D treatment on MASLD in cafeteria diet-induced obese rats, with an emphasis on IR, lipid metabolism, hepatic inflammation, and oxidative stress. The effects of vitamin D on gluconeogenesis and glycogen catabolism were also evaluated in perfused livers, as well as on oxidative phosphorylation in isolated liver mitochondria. The cafeteria diet is considered the experimental model that best simulates human obesogenic conditions, as it provides the typical nutrients of the Western diet in the form of hypercaloric, ultra-processed, and highly palatable foods. METHODS: Thirty-day-old Wistar rats were fed either a cafeteria diet or a standard diet for 60 days. Some animals from both groups (obese and controls) received vitamin D supplementation (5,600 IU/kg/week) via oral gavage for an additional 5 weeks. IR was assessed through fasting blood 14 glucose levels, the oral glucose tolerance test (OGTT), and the insulin tolerance test (ITT). At the end of the protocol, animals were anesthetized for blood collection (to obtain plasma) and liver removal, which was processed for histological analysis (H&E), lipid quantification, 25-hydroxyvitamin D [25(OH)D] levels, oxidative stress markers, and hepatic mRNA extraction. Visceral white adipose tissue depots were collected and weighed. The levels of triglycerides, total and HDL cholesterol, 25(OH)D, as well as the activity of AST, ALT and myeloperoxidase (MPO), and antioxidant capacity were determined in the plasma. Hepatic oxidative stress was assessed by measuring the levels of thiobarbituric acid reactive substances (TBARS), reactive oxygen species (ROS), and reduced (GSH) and oxidized glutathione (GSSG), as well as the activities of catalase and superoxide dismutase (SOD), and mRNA levels of nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione S-transferase (GST), catalase, and heme oxygenase 1 (HO-1). Hepatic inflammation was evaluated by histological scoring and quantification of mRNA expression of tumor necrosis factor-alpha (TNF?), interleukin 1 beta (IL-1?), interleukin 6 (IL-6), interleukin 10 (IL-10), nuclear factor kappa B (NF-?B), and sirtuin 1 (Sirt-1). mRNA levels of the vitamin D receptor (VDR), peroxisome proliferator-activated receptor alpha (PPAR?), insulin receptor substrate 2 (IRS-2), as well as the activities of fatty acid synthase (FAS) and vitamin D-metabolizing enzymes (CYP2R1 and CYP24A1), were also quantified in the liver. The isolated perfused rat liver, using Krebs-Henseleit buffer, was employed to assess glycogen catabolism (in fed rats) and gluconeogenesis (in rats fasted for 15 hours). Lactate was used as the glucose precursor. Effluent perfusate samples were collected at regular intervals and analyzed for glucose, lactate, and pyruvate content. Mitochondrial respiration in isolated liver mitochondria was determined by polarography. RESULTS AND DISCUSSION: The cafeteria diet induced obesity, MASLD, dyslipidemia, and IR, accompanied by hepatic inflammation and oxidative stress. Vitamin D supplementation reduced food intake, body weight gain, 15 and visceral adiposity. Improved insulin sensitivity and glucose tolerance were also observed, which were associated with reduced visceral fat, hepatic steatosis and increased hepatic expression of IRS-2. Vitamin D reduced mRNA expression of NF-?B and inflammatory mediators such as TNF? and IL-6, as well as hepatic oxidative stress, along with increased Nrf2 expression. The treatment also enhanced hepatic expression of the vitamin D receptor (VDR) and PPAR?, which are expected to promote lipid oxidation, and decreased fatty acid synthase (FAS) expression, suggesting a reduction in hepatic lipogenesis. Vitamin D increased Sirt-1 expression, which was associated with its beneficial hepatic effects by promoting the expression of IRS-2, PPAR?, and Nrf2, and downregulating NF-?B. However, vitamin D supplementation slightly increased the expression of inflammatory mediators in the livers of control rats. In isolated perfused liver experiments, fasting obese rats showed higher hepatic glucose production and lower oxygen consumption compared to controls. Vitamin D supplementation in obese rats reduced hepatic glucose output and increased oxygen consumption to control levels. Obese rats also exhibited enhanced hepatic glycogenolysis and glycolysis compared to controls, likely due to elevated hepatic glycogen content resulting from IR. Vitamin D treatment significantly decreased both glycolysis and glycogenolysis in obese rats. In control rats, vitamin D supplementation had no effect on gluconeogenesis, oxygen consumption, glycogenolysis or glycolysis, CONCLUSION: This study demonstrated that vitamin D supplementation mitigates cafeteria diet-induced obesity by reducing visceral adiposity, insulin resistance, and MASLD in rats. These beneficial effects were linked to the modulation of lipid metabolism, inflammation, and hepatic oxidative stress, primarily mediated by VDR activation and increased hepatic Sirt-1 expression. Additionally, supplementation restored serum 25(OH)D levels in obese animals without altering hepatic concentrations. Vitamin D also reduced hepatic gluconeogenesis and glycogen catabolism, likely as a consequence of improved MASLD and IR, associated with increased Sirt-1 16 expression. Despite these positive outcomes, a mild pro-inflammatory effect was observed in treated control rats, highlighting the need for caution regarding indiscriminate supplementation. These findings support the therapeutic potential of vitamin D in MASLD while underscoring the need for further studies to clarify its safety. Descrição: Orientador: Prof. Dr. Jurandir Fernando Comar; Co-orientador: Profa. Dra. Dionizia Xavier Scomparin; Tese (doutorado em Ciências Biológicas) - Universidade Estadual de Maringá, 2025

2025-01-01T00:00:00Z Oliveira, Fagner Junior Machado de http://repositorio.uem.br:8080/jspui/handle/1/6805 2022-09-07T19:13:16Z 2020-01-01T00:00:00Z

Título: Variáveis relacionadas com a distribuição regional, dominância e estruturação de comunidades de peixes em riachos. Autor(es): Oliveira, Fagner Junior Machado de Abstract: Different ecological processes (e.g., rescue effect, environmental filtering, limiting similarity and dispersal) shape the structure of ecological communities. These processes, which are related to the theories of metapopulation and metacommunities, guided this study. For this purpose, data from fish communities in streams in the Upper Araguaia river basin (Mato Grosso and the Goiás States, Brazil) were used. It was observed that the regional distribution of fish species was modelled according to niche attributes (position and breadth), body size, trophic position, and swimming capacity. The results indicated that average abundance, niche position and niche amplitude predict the regional distribution of the species. Taken together, these results suggest the importance of metapopulation dynamics and niche-based processes explaining the regional distribution of species in the studied system. At another time, it was tested whether the abundance of subordinate species (i.e., any species that are not dominant in a local community) was correlated with the functional distance between dominant and subordinate species. In the results, a negative relationship between these quantities and that the subordinate species had larger body sizes compared to the dominant species in the local communities. These results also suggest that species filtering is more important than the interspecific competition to explain the patterns of species abundance distribution. In this study, was analyzed the relative importance of local environmental, landscape and spatial variables in structuring fish communities in streams of “veredas” (small wetlands in the Cerrado). The local environmental variables, after controlling the effect of space, were clearly more important than those obtained at the landscape scale. In view of the observations, it is concluded that the use of landscape data, in studies seeking environmental correlates of local community structure, should not occur at the expense of obtaining local variables (mainly those related to the habitat structure). The results of the three investigations in this study shown the predominant role of local environmental filters in the structuring of the fish communities analyzed. Species with high niche amplitude tend to have wide regional distributions and small-bodied ones tend to be locally dominant.

2020-01-01T00:00:00Z