Photic-zone euxinia (PZE) is associated with several times in Earth's history including Phanerozoic extinction events and long parts of the Proterozoic. One of the best modern analogues for extreme PZE is Mahoney Lake in British Columbia, Canada where a dense layer of purple sulfur bacteria separate the oxic mixolimnion from one of the most sulfidic monimolimnions in the world. These purple sulfur bacteria are known to produce the carotenoid okenone. Okenone's diagenetic product, okenane, has potential as a biomarker for photic-zone euxinia, so understanding its production and transport is important for interpreting the geologic record. In the following dissertation, I examine Mahoney Lake with a multi-proxy approach. I use lipid biomarkers to understand organic matter production burial in the lake and find strong evidence of lateral transport of organic matter from shoreline microbial mats to the lake-bottom sediments. I also find evidence of okenone production in these shoreline mats and a carotenoid previously unreported in the environment, Thiothece-484, associated with the okenone synthetic pathway. Finally, I develop a new bioinformatics method to examine high-throughput metagenomic data and use this method to start understanding how the metabolic and lipid synthetic pathways of microbial communities in the lake are associated with each other. / Earth and Planetary Sciences

Submitted by (edna.saturno@ufrpe.br) on 2017-02-15T13:46:56Z No. of bitstreams: 1 Karine Kelly Cavalcanti Oliveira.pdf: 775211 bytes, checksum: a252b067bc8c7be94d94fe9b48509a38 (MD5) / Made available in DSpace on 2017-02-15T13:46:56Z (GMT). No. of bitstreams: 1 Karine Kelly Cavalcanti Oliveira.pdf: 775211 bytes, checksum: a252b067bc8c7be94d94fe9b48509a38 (MD5) Previous issue date: 2012-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The piau-verdadeiro (Leporinus elongatus) is a freshwater fish that inhabits rivers of Paraná-Paraguai and São Francisco basins. Along these regions were built huge dams for power generation, which is hindering the reproductive migration of many species. Populations of L. elongatus have decreased, with greater decline in the region of sub-middlle São Francisco. Many electric companies and government are restocking perform without worrying about ecological principles, so little genetic. These management actions, in the long run, may lead to a decrease in the genetic diversity of these stocks, which can aggravate the adaptation of these populations. In this study, microsatellite markers of L. elongatus were constructed through a genomic library enriched for tetranucleotide motifs (GACA)4 and (GATA)7. Of a total of 14 markers that consistently amplified, seven were monomorphic and seven polymorphic. All markers successfully amplified for L. elongatus, however, for species of the same genus, L. reinhardt and L. taeniatus, only the marker Lelo 12 amplified to L. reinhardt. The seven polymorphic markers were assessed in a wild population of 44 individuals caught in the Upper São Francisco (MG). The number of alleles varied between five (Lelo 20) to 29 (Lelo 13), the observed and expected heterozygoties ranged from 0.568 to 0.977 and from 0.533 to 0.964, respectively. All the markers studied are in Hardy-Weinberg equilibrium and null alleles were not detected, however, two markers, Lelo 4 and Lelo 14 are connected on the same chromosome. These are the first microsatellite markers developed for this species and its characteristics allow it to be used in studies of population genetics, conservation and monitoring of restocking programs of the São Francisco River. / O piau-verdadeiro (Leporinus elongatus) é um peixe de água doce que habita rios das bacias do Paraná-Paraguai e do São Francisco. Ao longo destas regiões foram construídos imensos barramentos para geração de energia, o que vem prejudicando a migraçao reprodutiva de muitas espécies. As populações de L. elongatus têm diminuído, com maior declínio na região do submédio São Francisco. Muitas empresas hidrelétricas e governamentais realizam repovoamento sem a preocupação com princípios ecológicos, tão pouco genéticos. Estas ações de manejo, em longo prazo, podem provocar uma diminuição na diversidade genética destes estoques, o que pode agravar a adaptação destas populações. Neste trabalho, marcadores de microssatélites de L. elongatus, foram construídos através de uma biblioteca genômica enriquecida para motivos tetranucleotídeos (GACA)4 e (GATA)7. De um total de 14 marcadores que amplificaram consistentemente, sete foram monomórficos e sete, polimóficos. Todos os marcadores amplificaram com sucesso para o L. elongatus, no entanto, para espécies do mesmo gênero, L. reinhardt e L. taeniatus, apenas o marcador Lelo 12 amplificou para o L. reinhardt. Os sete marcadores polimórficos foram avaliados em uma população selvagem de 44 indivíduos capturados no Alto São Francisco (MG). O número de alelos variou de cinco a 29, as heterosigozidades observadas e esperadas variaram de 0,568 a 0,977 e de 0,533 a 0,964, respectivamente. Todos os marcadores estudados estão em equilíbrio de Hardy-Weinberg e não apresentaram alelos nulos, entretanto, dois marcadores, Lelo 4 e Lelo 14 estão ligados em um mesmo cromossomo. Esses são os primeiros marcadores de microssatélite desenvolvidos para esta espécie e suas características permitem que sejam usados em estudos de genética populacional, conservação e monitoramento de programas de repovoamento do rio São Francisco.