Parasitism is a widespread ecological strategy that influences marine ecosystem dynamics. Syndiniales are an Order of unicellular protists within the phylum Dinoflagellata, and most members are parasitic. Species within Syndiniales are ubiquitous in marine environments and significantly impact plankton population dynamics and biogeochemical cycling. Most Syndiniales have complex life cycles that often include a free-living stage, however, despite their importance, there is little knowledge of the fate of free-living dinospores or their host-specificity dynamics. Recent genomic evidence and preliminary laboratory work suggest dinospores may possess metabolic capacities outside a host, and past work has revealed that some dinospore strains can be host generalists. Therefore, this study has two aims to (1) explore the survival mechanisms of Syndiniales spores in the absence of their dinoflagellate host, Scrippsiella sp., and (2) to explore host specificity of dinospores. Understanding Syndiniales' interactions with their environment and hosts is necessary to address issues related to marine food webs and carbon cycles. This study will provide insights into predicting and managing harmful algal blooms that contribute to marine environment conservation and sustainable management.

The study of bacterial pathogenesis is important for the well-being of living populations. Moraxella spp., can be normal flora in mammals, but has been reported to cause disease that is sometimes fatal in multiple hosts. There is limited data has studied the Moraxella genus that only 14 species have been recorded to date. This project examines a potentially novel Moraxella spp. infecting a colony of cynomolgus macaques (Macaca fascicularis). Biochemical testing of the isolates revealed characteristics of Moraxella spp. but further speciation was not possible and indicated the potential for a novel pathogen. My project will encompass 3 portions (1) whole genome sequencing of a pure culture of the putative pathogen, via DNA extraction, library preparation, and sequencing; (2) screening of the other animals in the colony for colonization, via DNA extraction, library preparation, and 16s metabarcoding; and (3) screening of formalin-fixed, paraffin-embedded tissues from postmortem samples of former colony members to attempt to identify historical infections by the pathogen. Included in my project is bioinformatics work, including BLAST and phylogenetic analysis. Ultimately, this research could lead to the study of this new species’ diagnosis tests, antimicrobial susceptibility, prevention, and treatments.

The mismatch repair (MMR) system is a highly conserved pathway responsible for repairing base pair mistakes post-DNA replication. MutS alpha, or Msh2-Msh6, is a repair protein that recognizes and corrects single base mismatches. Mutations in this repair system can lead to Lynch syndrome and an increase in sporadic tumors. Msh2-Msh6 also binds to the DNA Holliday Junction (HJ) with high affinity in the process of double-strand break repair; however, much remains unknown about the structural interactions between the Msh2-Msh6 protein complex and the DNA HJ. To visualize the binding orientations of Msh2-Msh6 with the Holliday Junction, 5-bromouridine (BrU) is substituted for thymine in DNA. This substitution allows the identification of the points of interaction between the protein and DNA on the junction. The unnatural amino acid, p-benzoyl-L-phenylalanine (pBpA), will be employed to identify the protein residues involved in the Msh2-Msh6-HJ interaction. To incorporate the pBpA for successful crosslinking, key residues of the Msh2-Msh6 protein were mutated to a TAG amber stop codon via site-directed mutagenesis. UV photocrosslinking will be used to determine if the mismatch binding region or other regions of the protein are involved in the junction interaction. This structural information will provide insight into the Msh2-Msh6 function in double-strand break repair.