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Tipo: Tese
Título: Bacteria from freshwater ecosystems: structural aspects and programmed cell death
Autor(es): Silva, Thiago Pereira da
Primeiro Orientador: Melo, Rossana Correa Netto de
Membro da banca: Amado, André Megali
Membro da banca: Cardoso, Simone Jaqueline
Membro da banca: Farjalla, Vinicius Fortes
Membro da banca: Chiarini-Garcia, Helio
Resumo: -
Abstract: Bacteria are important components of the food web structure in aquatic ecosystems in which they influence the flow of carbon and energy. Populations of bacteria in these ecosystems comprise a diverse spectrum of individual cells able to respond to many factors such as nutrient supply, temperature and virus infection, which regulate bacterial life and death. Bacterial death is a key cellular event involved in the control and production of bacteria in aquatic ecosystems with functional meaning in the carbon and nutrient cycles. Therefore, the study of bacterial structural features and cellular mechanisms underlying bacterial death is crucial to understand processes affecting the entire population. However, both bacterial structure and cellular events of death in aquatic ecosystems are still poorly understood. In the present work, we used single cell approaches to study the structural organization of bacteria as well as to characterize cellular processes of death in these organisms. First, by using fluorescence and transmission electron microscopy (TEM), we provided a general panorama of how microscopy techniques, especially TEM, are powerful tools to understand bacterial structure and their responses to environmental stresses. We showed that bacteria from aquatic ecosystems have remarkable ultrastrutural diversity with components such as bacterial envelope of individual cells differing in structure within the same population. Second, we sought to identify and characterize mechanisms of bacterial cell death. Because our TEM analyses revealed morphological signs of apoptosis, a type of program cell death (PCD), in aquatic bacteria directly collected from natural ecosystems, we applied different techniques to detect apoptosis in bacteria cultured from natural samples. We used TEM as well as different probes to detect this type of PCD in cultured bacteria exposed to increased temperature and viral infection, which are recognized inducers of bacterial death. TEM showed, in both situations, ultrastructural changes indicative of apoptosis, such as cell retraction and condensation, similar to those reported for eukaryotic cells. Assays for membrane permeability, DNA fragmentation, phosphatidilserine exposition and caspase activation were significantly increased in treated bacteria compared to the control group. Altogether, our data demonstrate, for the first time, that PCD occur in aquatic bacteria, and that this event may be a basic mechanism for regulation of bacterial communities in these ecosystems.
Palavras-chave: Bacteria from freshwater ecosystems
Ultrastructure
Programmed cell death
Apoptosis
Electron microscopy
Flow cytometry
CNPq: CNPQ::CIENCIAS BIOLOGICAS
Idioma: eng
País: Brasil
Editor: Universidade Federal de Juiz de Fora (UFJF)
Sigla da Instituição: UFJF
Departamento: ICB – Instituto de Ciências Biológicas
Programa: Programa de Pós-graduação em Ecologia
Tipo de Acesso: Acesso Aberto
URI: https://repositorio.ufjf.br/jspui/handle/ufjf/6145
Data do documento: 9-Jun-2017
Aparece nas coleções:Doutorado em Ecologia (Teses)



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