Managers of forest and plantation ecosystems are encountering growing problems involving plant pathogens and the expanding geographic ranges of these pathogens. Historically unexposed stands are exceptionally vulnerable when a non-native pathogen is introduced because these pathogens can cause devastating disease in a host population that lacks co-evolved resistance mechanisms. One...
Limnology is undergoing a transition to high-throughput -omic analysis of freshwater
bacterial communities. An important first step in making the transition is to
characterize several genomes that can be used as references to guide metagenome
assembly and analysis. Here I characterize four new freshwater cyanobacterial
genomes, a pair of lake...
Pseudomonas aeruginosa is an environmental bacterium as well as an opportunistic pathogen that primarily infects immunocompromised individuals, including those suffering from cystic fibrosis. The density-dependent regulation of gene expression via cell-to-cell communication, also termed quorum sensing (QS), is an important virulence determinant in this organism. Generally, P. aeruginosa uses three...
Social behavior leading to the production of common goods is prone to exploitation. One such behavior in Pseudomonas aeruginosa is quorum sensing (QS), by which the bacteria produce signals to regulate extracellular common goods. Exploitation comes in the form of cheaters which have a mutation in the central quorum sensing...
The fungus Cochliobolus victoriae causes Victoria blight of oats and Arabidopsis and is pathogenic due to its production of a compound called victorin, which induces programmed cell death in sensitive plants. Victorin sensitivity in Arabidopsis is conferred by the dominant gene LOCUS ORCHESTRATING VICTORIN EFFECTS1 (LOV1), which encodes a coiled-coil-nucleotide...
The fungus Nothophaeocryptopus gaeumannii is the causative agent of Swiss needle cast (SNC), a foliar disease of Douglas-fir. Disease is characterized by premature loss of foliage and reduced growth resulting from the inhibition of photosynthesis due to the occlusion of stomata by the ascocarps of N. gaeumannii. Although the disease...
Members of the SAR11 clade of heterotrophic α-proteobacteria are ubiquitous and abundant in the world's oceans where they are thought to play a pivotal role in the global carbon cycle. The first SAR11 bacterium cultivated in vitro, 'Candidatus Pelagibacter ubique' HTCC1062 (Ca. P. ubique), was isolated by dilution into sterile...
Reef building corals are the foundation of an entire ecosystem, but they are threatened primarily by rising ocean temperatures due to climate change. Corals depend on a thermally sensitive symbiosis with intracellular dinoflagellates. As oceans warm, this symbiosis is disrupted and results in coral mortality, declining populations and degraded reefs....
Differential expression (DE) analysis is a key task in gene expression study, because it uncovers the association between expression levels of a gene and the covariates of interest. This dissertation pertains to two particular aspects of DE analysis—identifying stably expressed genes for count normalization and accounting for correlation between DE...
The bioavailability of chemical compounds in the marine environment fundamentally influences the growth and physiology of microorganisms. Organic and inorganic chemicals that are produced by some marine plankton can be consumed by other plankton for energy production, growth, or to initiate essential physiological processes. Cultures of the diatom Thalassiosira pseudonana,...