Organizational Unit:
School of Biological Sciences
School of Biological Sciences
Permanent Link
Research Organization Registry ID
Description
Previous Names
Parent Organization
Parent Organization
Organizational Unit
Includes Organization(s)
Organizational Unit
ArchiveSpace Name Record
Publication Search Results
Now showing
1 - 10 of 53
-
ItemNative parasite combating an invasive species: an oomycete vs. Echinogammarus ischnus(Georgia Institute of Technology, 2010-12-20) van Rensburg, KarlaIn the context of invasions in ecology, parasites can play an important role in mediating the outcomes of competition between the native and invasive species. For example, a native parasite in the upper St. Lawrence River area has been found infecting both native and non-native gammarid amphipods, Gammarus fasciatus and Echinogammarus ischnus, respectively. Usually when the non-native species invades an area, the native amphipod is rapidly replaced by the non-native species. However, in this specific region the native amphipod was not replaced by the non-native species, and the non-native species was observed to be infected by a parasite. To determine infection rates in the native and non-native hosts, DNA was extracted from both species of amphipods and specific primers for the 18S rRNA gene were created to generate quantitative analysis of the incidence of the parasite in the amphipods. These data indicate that the effect of the parasite on the native and non-native amphipods could be the mechanism preventing the dominance of the non-native species in this specific area for the past ten years, since the parasite was found to infect the non-native amphipod more frequently and at a higher level than the native amphipod.
-
ItemThe effect of a pathogen on the population dynamics and reproductive method of Asplanchna girodi(Georgia Institute of Technology, 2010-12-20) Reynolds, Abigial NicoleStudies show that the abundance of Asplanchna girodi can be affected by many factors including food density, temperature and pH. One such aspect not yet explored is the effect that parasitism has on Asplanchna girodi populations. During weekly samplings of a local lake, a parasitic oomycete was discovered to frequently infect the Asplanchna girodi population. Based on multi-year sampling data, this study supports recent work showing that parasitism of a zooplankton has the potential to have reproductive and evolutionary consequences. I show that epidemics of this parasite, Pythium, occur frequently and that an increased number of males in the population can be correlated to the presence of the parasite. Sexual reproduction involving males provides for Asplanchna girodi's only means of genetic recombination and production of diapausing eggs that overwinter. This study shows that there is a correlation between the rate of infection by Pythium and the density of males in the Asplanchna girodi population. By increasing the number of males in a population, the rate of diapause egg production is also increased. Infection by this parasite could therefore be associated with increased sexual reproduction and genetic recombination of A. girodi populations.
-
ItemZooplankton population dynamics in Clayton County Water Authority reservoirs(Georgia Institute of Technology, 2010-12-20) Ahmed, TamannaReservoirs supply most of Georgia s drinking water, and plankton dynamics can greatly influence the water quality of these reservoirs. Therefore, understanding the dynamics of zooplankton as well as phytoplankton is necessary. Unlike reservoirs in the northern United States, zooplankton dynamics in reservoirs in the South remain largely uncharacterized. Samples were collected from the Clayton County Water Authority reservoirs to study correlations between zooplankton taxa distribution and environmental variables. Population count data has demonstrated that the zooplankton dynamics in southern lakes vary from the dynamics typically seen in northern lakes. While temperature noticeably shaped seasonal densities in some species, other species had variable dynamics and seemed to not be affected by this environmental factor or other taxa of zooplankton, suggesting additional factors may regulate population composition and abundance.
-
ItemEvaluation of GSK2487213A on [³h]-ryanodine binding to RyR1(Georgia Institute of Technology, 2010-12-17) Balog, Edward M.
-
ItemActive Co-Factors of the Class I RNRs(Georgia Institute of Technology, 2010-11-30) Stubbe, JoAnne
-
ItemComputational tools for molecular epidemiology and computational genomics of Neisseria meningitidis(Georgia Institute of Technology, 2010-11-17) Katz, Lee ScottNeisseria meningitidis is a gram negative, and sometimes encapsulated, diplococcus that causes devastating disease worldwide. For the worldwide genetic surveillance of N. meningitidis, the gold standard for profiling the bacterium uses genetic loci found around the genome. Unfortunately, the software for analyzing the data for these profiles is difficult to use for a variety of reasons. This thesis shows my suite of tools called the Meningococcus Genome Informatics Platform for the analysis of these profiling data. To better understand N. meningitidis, the CDC Meningitis Laboratory and other world class laboratories have adopted a whole genome approach. To facilitate this approach, I have developed a computational genomics assembly and annotation pipeline called the CG-Pipeline. It assembles a genome, predicts locations of various features, and then annotates those features. Next, I developed a comparative genomics browser and database called NBase. Using CG-Pipeline and NBase, I addressed two open questions in N. meningitidis research. First, there are N. meningitidis isolates that cause disease but many that do not cause disease. What is the genomic basis of disease associated versus asymptomatically carried isolates of N. meningitidis? Second, some isolates' capsule type cannot be easily determined. Since isolates are grouped into one of many serogroups based on this capsule, which aids in epidemiological studies and public health response to N. meningitidis, often an isolate cannot be grouped. Thus the question is what is the genomic basis of nongroupability? This thesis addresses both of these questions on a whole genome level.
-
ItemControls on nitrogen fixation and nitrogen release in a diazotrophic endosymbiont of shipworms(Georgia Institute of Technology, 2010-11-15) Horak, Rachel Elizabeth AnnNitrogen fixation is an ecologically important microbial process that can contribute bioavailable combined N to habitats low in N. Shipworms, or wood-boring bivalves, host N2-fixing and cellulolytic symbiotic bacteria in gill bacteriocytes, which have been implicated as a necessary adaptation to an N-poor C-rich (wooden) diet. Shipworm symbionts are known to fix N within the gill habitat and newly fixed N is subsequently incorporated into non-symbiont containing host tissue. The presence of N2-fixation in gill bacteriocytes presents a conundrum because N2-fixation is tightly regulated by oxygen in most other diazotrophic microbes. Also, the direct evidence of new N being incorporated into the host tissue indicates that there are potentially complex nutrient cycles in this symbiosis, which have not been investigated. We used the cultivated symbiont Teredinibacter turnerae, which has been isolated from many shipworm species, as a model organism to elucidate controls on N2-fixation and N release in the shipworm symbiosis. Our results indicate that headspace oxygen concentration does not control biomass specific N2-fixation and respiration activity in T. turnerae, but it does influence the magnitude of the growth rate and timing of culture growth. Also, we examined the controls of oxygen on inorganic nutrient uptake rates, and documented a small amount of dissolved inorganic nitrogen release. While the N budget is only partially balanced, we provide indirect evidence for the allocation of fixed N to the excretion of exopolymeric substances and dissolved organic nitrogen; future studies that measure these additional N sinks are necessary to close the N budget. Although there are limitations of using pure cultures to investigate a complex symbiotic system, this study provides direct experimental evidence that T. turnerae has adaptations that are conducive to N2-fixation in gill bacteriocytes.
-
ItemA novel mode of bacterial respiration: iron solubilization prior to electron transfer(Georgia Institute of Technology, 2010-11-11) Fennessey, Christine MichelleMicrobial iron respiration contributes significantly to the biogeochemical cycling of metals and may be one of the earliest respiratory processes to have evolved on early earth. Metal-respiring microbes also hold great potential for use in microbial fuel cells for the generation of "green" energy and for remediation of radionuclides in contaminated environments. Despite its significance in global metal cycling processes, the molecular mechanism of Fe(III) respiration has yet to be determined. Unlike many other terminal electron acceptors, Fe(III) is a solid at circumneutral pH and, therefore, cannot come into direct contact with the microbial inner membrane: the site of terminal electron transfer in gram-negative bacteria. It is postulated that metal-respiring organisms have developed alternate strategies for the reduction of solid iron. One such strategy involves the production of an Fe(III)-solublizing ligand by the metal-respiring bacteria which solubilizes the Fe(III) prior to respiration, rendering the metal more easily accessible to the Fe(III) reductase complex. In this study, the genes involved in the solubilization of Fe(III) by the gram-negative dissimilatory metal reducing bacteria Shewanella oneidensis MR-1 were determined using random mutagenesis to generate mutations in the wild-type genome and high-throughput square-wave voltammetry to screen for the attenuation of Fe(III) production in the mutants. Two mutants unable to solubilize Fe(III) were identified and designated d29 and d64. After mutation complementation analysis, it was determined that the point mutations were both located in type II secretion genes: gspG and gspE respectively, indicating that the type II secretion system is required for Fe(III) solubilization prior to respiration. It was also hypothesized that the ligand produced for Fe(III) solubilization during dissimilatory Fe(III) respiration was a siderophore: a small Fe(III)-chelating molecule produced by the cells for the assimilation of Fe(III) for growth. A siderophore biosynthesis gene (SO3031) and a siderophore ferric reductase gene (SO3034) were deleted in frame and the resultant mutants screened to determine whether they were capable of Fe(III) solubilization and reduction during anaerobic Fe(III) respiration. Both mutants retained Fe(III) solubilization and reduction activity, indicating that the siderophore Fe(III) assimilatory system is distinct from the Fe(III) solubilization system utilized during Fe(III) respiration. The work presented here is significant in that it describes a rapid screening method for identifying Fe(III) solubilization mutants, reports on the involvement of the type II secretion system in Fe(III) solubilization during iron respiration, and finally demonstrates that a dissimilatory metal reducing bacteria synthesizes and secretes Fe(III)-chelating molecules which are distinct from Fe(III)-siderophores.
-
ItemLeveraging Protein Structure to Expedite Drug Discovery(Georgia Institute of Technology, 2010-11-10) Brown, KristinDetailed knowledge of a protein family – whether mechanism of action, known active compounds, or three-dimensional structures – can expedite drug discovery. This knowledge is not constrained to the exact protein that is being targeted for a therapeutic effect. In fact, understanding how multiple members of a protein family interact with small molecules can advance lead optimization in multiple ways. It can identify tool compounds early in drug discovery process, aid in selectivity issues and provide information about the flexibility of a protein. Using examples from the protein kinase & prolyl hydroxylase families, this talk will provide a basic understanding of structure based drug design and demonstrate how using the structure information across a protein family can provide insights that can expedite drug discovery.
-
ItemDetecting specific nucleic acid sequences under challenging but potentially useful circumstances(Georgia Institute of Technology, 2010-11-09) Cantor, CharlesIn this talk I will describe three circumstances where sensitive detection of nucleic acids leads to practical or useful results. All display synergy between academic research and biotechnology companies. The first, involving SEQUENOM in San Diego, uses both mass spectrometry of DNA and high throughput sequencing of DNA to detect traces of fetal DNA that are present n the peripheral blood of a pregnant woman. This allows prenatal diagnosis of fetal traits to be performed without any risk at all to mother or fetus. The second involving DiThera, in Costa Mesa, demonstrates schemes for the detection of specific RNA sequences in living cells. This provides a field of the dynamics of RNA synthesis and decay and offers the potential for the development of diagnostics and therapeutics based on RNA sequence alone. The third project uses technology developed by SelectX Pharmaceuticals, an antibiotic development company in Worcester Mass. Select X has safe technology to subject growing cultures to continuously increasing antibiotic stress. Using this technology and both protein and nucleic acid mass spectrometry the unusual discovery was recently made that some cells in culture at a cost to their own fitness, are able to help other cells to have enhanced antibiotic resistance. This shows that even in the simplest bacteria altruistic behavior is possible.