Part 1: Prophage induction has been demonstrated to be a sensitive indicator for a wide variety of toxic and mutagenic compounds and, as a consequence, has been utilized for biologically based carcinogen screenings. Fourteen marine bacterial isolates were screened for development into the Marine Prophage Induction Assay (MPIA), for marine samples. The selected isolate (P99-4S3) was identified by 16S rDNA sequencing as Pseudomonas aeruginosa. This isolate demonstrated a log-linear response to increasing dose of mutagens, and sensitivity to known environmental contaminants. Field-testing of the assay over two years demonstrated the MPIA would be a useful screening tool for environmental contamination. Part 2: The observed resistance of natural populations of Synechococcus to viral infection may be due to lysogeny with associated homoimmunity. A thirteen-month study of lysogeny in natural populations of Synechococcus demonstrated that lysogeny does occur and exhibits a seasonal pattern. Experiments were performed along a transect of the Mississippi River plume, which provided a variety of ambient nutrient regimes for comparison of lysogeny in Synechococcus. Nutrient amendments did not enable induction and often led to a decrease in viral production. Lysogeny in Synechococcus was primarily correlated with ambient host and cyanophage abundance. Cross-infectivity studies demonstrated cyanophage isolates possess variable virulence. The 35 isolates were examined by transmission electron microscopy (TEM), with 33 identified as myoviruses and two as podoviruses. This dominance of myovirus lytic cyanophage is consistent with prior observations. Twenty-five Synechococcus isolates were screened for prophage induction utilizing the inducing agent Mitomycin C. Eleven isolates demonstrated a statistically significant increase in virus-like particles (VLP’s) in treatment samples. No correlation was observed between their resistance to lytic viral infection and prophage induction. Isolate P99-14, with consistently high levels of prophage induction, was investigated further. In contrast to lytic cyanophage, the induced cyanophage is non-tailed. Differential staining and nuclease digestion experiments indicate that the induced particle contains single-stranded DNA. Environmental conditions potentially leading to prophage induction were investigated with Synechococcus cultures and natural populations. The isolate P99-14 demonstrated that high, continuous light caused prophage induction. Natural populations determined that shifts in salinity, temperature and phosphate are not triggers of prophage induction.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-04-24T12:13:14Z No. of bitstreams: 2 Tese - Viníciu Fagundes Bárbara - 2017.pdf: 2916938 bytes, checksum: e3841362774c4c7ee6cde936621d4747 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-04-24T12:13:45Z (GMT) No. of bitstreams: 2 Tese - Viníciu Fagundes Bárbara - 2017.pdf: 2916938 bytes, checksum: e3841362774c4c7ee6cde936621d4747 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-04-24T12:13:45Z (GMT). No. of bitstreams: 2 Tese - Viníciu Fagundes Bárbara - 2017.pdf: 2916938 bytes, checksum: e3841362774c4c7ee6cde936621d4747 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-03-27 / The mining industry is known to trigger intense environmental impacts. When the exploitation is done in the open, pit lakes are formed, units still little known in environmental terms, and increasingly common in several countries. Demonstrating complex behavior, open pit lakes differ greatly from natural lakes, what makes their management a challenge. Although there is a need to develop research issues that contribute significantly to a deeper understanding of the degree of environmental commitment of open pit mining lakes, the studies developed so far are few and have a predominantly Analytical Chemistry approach, an important approach, but that only offers momentary and limited answers. The main objective of this research was to analyze the environmental liabilities formed by waters and sediments of open pit mining lakes by application a combined method of environmental assessment based on Chemical, Ecotoxicological and Genotoxicological aspects. With this purpose, water samples were collected in profile and sediments from three lakes of deactivated open - pit gold mines existing in Mara Rosa, Goiás, Brazil, in different climatic seasons and subjected to metal and anion analysis, to ecotoxicological acute tests and genotoxicological tests- Comet assay - with the Danio rerio fish. The results showed different degrees of environmental commitment of the lakes, which present chemically altered waters and sediments, and offer toxicological risks, mainly the Lago Azul. This, being the most used by the local population for recreational purposes and water sports, proved to be subject to intense geological control from acid drainage processes. It is concluded that the environmental assessment methodology used in this thesis, in order to obtain broader and deeper responses to pit lakes, emerging environmental problems, was efficient, being able to constitute an analytical tool that will significantly contribute to the expansion of knowledge to the Environmental Sciences. / A indústria da mineração é conhecida por desencadear impactos ambientais intensos. Quando a exploração se dá a céu aberto, são formadas cavas, unidades ainda pouco conhecidas em termos ambientais e cada vez mais comuns em diversos países. De comportamento complexo, lagos de mineração se diferem muito dos naturais, o que torna sua gestão desafiadora. Embora exista a necessidade do desenvolvimento de questões de pesquisa que contribuam significativamente para um entendimento mais profundo a respeito do grau de comprometimento ambiental de cavas, os estudos desenvolvidos até então foram poucos e tiveram enfoque predominante na Química Analítica, abordagem importante, mas que obtém respostas momentâneas e limitadas. O objetivo principal desta pesquisa foi analisar os passivos ambientais formados por águas e sedimentos de cavas de mineração mediante a aplicação de uma metodologia combinada de avaliação ambiental embasada em aspectos da Química, Ecotoxicologia e Genotoxicologia. Para tanto, amostras de águas coletadas em perfil e de sedimentos de três cavas de ouro desativadas localizadas em Mara Rosa, Goiás, Brasil, foram obtidas em diferentes estações climáticas e submetidas à análise de metais e ânions e a testes ecotoxicológicos agudos e genotoxicológicos – Ensaio Cometa – com peixes da espécie Danio rerio. Os resultados indicam diferentes graus de comprometimento ambiental dos lagos, que apresentam águas e sedimentos alterados quimicamente e oferecem riscos toxicológicos, principalmente o Lago Azul. Este, apesar de ser o mais utilizado pela população local para fins de lazer e prática de esportes aquáticos, demonstrou estar submetido a intenso controle geológico advindo de processos de drenagem ácida. Concluiu-se que a metodologia de avaliação ambiental empregada nesta tese com a finalidade de obter respostas mais amplas e profundas a respeito de cavas, problemas ambientais emergentes, se mostrou eficiente, podendo se constituir em uma ferramenta analítica que contribuirá de forma significartiva para a ampliação do conhecimento na área das Ciências Ambientais.