Life Sciences Commons^™

Does Light Control Algal Abundance In Large River Systems?, Amy Macdonald

Theses and Dissertations

A limited amount of research has been done to investigate the factors influencing algal abundance in large river systems. This study examines light as the primary factor that controls algal abundance in the Upper Mississippi, Missouri and Ohio Rivers. Data were collected for 2004 in conjunction with the Environmental Monitoring Assessment Program- Great River Ecosystems EMAP-GRE project using EPA approved methods. Chlorophyll a concentrations were 34.6 µg•L-1 in the Upper Mississippi, 19.8 µg•L-1 in Missouri River and 9 µg•L-1 in the Ohio River for 2004. Chlorophyll a concentrations were significantly different among the three rivers (p<0.0001) but not between years. Inter-river variation could be loosely correlated with light availability: mean Average Irradiance Dosages, which consider factors that affect light climate (depth, transparency, velocity, surface irradiance), by river corresponded with mean chlorophyll a levels by river. Intra-river variation seemed to be due to both the influence of light and nutrients.

Avian Dispersal Of The Actinomycete Frankia Across A Barrier Island Landscape, Spencer Bissett

Theses and Dissertations

In the nutrient-poor soils characteristic of coastal environments, symbiotic association with the nitrogen-fixing root endosymbiont Frankia is essential to establishment and survival of the woody shrub Morella cerifera. Nutrient deficiency quickly becomes severe unless seedlings are infected by Frankia soon after germination. However, the means of arrival of Frankia prior to shrub establishment has not been determined. Using sterilized lab-grown M. cerifera seedlings and fecal samples collected from passerine birds on the Eastern Shore of Virginia, viability of avian dispersal of the bacteria was tested. Although passerine fecal samples did produce nodules on some sterilized M. cerifera seedlings, these experimental …

Application Of Shortest-Path Network Analysis To Identify Genes That Modulate Longevity In Saccharomyces Cerevisiae, Jr Managbanag

Theses and Dissertations

Shortest-path network analysis was employed to identify novel genes that modulate longevity in the baker’s yeast Saccharomyces cerevisiae. Based upon a set of previously reported genes associated with increased life span, a shortest path network algorithm was applied to a pre-existing protein-protein interaction dataset in order to construct a shortest-path longevity network. To validate this network, the replicative aging potential of 88 single gene deletion strains corresponding to predicted components of the shortest path longevity network was determined. The 88 single-gene deletion strains identified by a network approach are significantly enriched for mutation conferring both increased and decreased replicative life …

Plumage Ornamentation As An Indicator Of Female Age And An Influence In Male Mate Choice In Protonotaria Citrea, The Prothonotary Warbler In Virginia., Terry Smith

Theses and Dissertations

Flamboyant plumage and ornamentation is common and well-known in male birds; it serves as a sexual display to attract potential mates. While flamboyant plumage is less common and usually more subtle in female birds, it does occur in some species such as Dark-Eyed Juncos (Junco hyemalis) and Prothonotary Warblers (Protonotaria citrea). Prothonotary Warblers display relatively subtle sexual dimorphism. This study examines variations in tail spot patterns in Prothonotary Warblers and relates those variations to age in females. Females with fewer than six spots tend to be two years old or younger; females with six spots or more tend to be …

The Effect Of Nacl On Akinete Differentiation In The Cyanobacterium Nostoc Punctiforme, Jonathan Heekin

Theses and Dissertations

Nostoc punctiforme is a nitrogen-fixing, symbiotic/free-living cyanobacterium. There has been a great deal of research conducted on the genomic nature of N. punctiforme as it pertains to its ecologically important role in the nitrogen cycle in varied environments around the world. My study concentrated on the dormant cell type known as the akinete. Increasing concentrations of NaCl were used to follow the growth phases from germination to akinete formation (lag phase-logarithmic growth phase-stationary phase). I found that increased salt concentrations caused N. punctiforme to form akinetes faster when compared to the control. Germination rates were not greatly increased or shortened …

The Ecology Of Fear: Oviposition And Colonization In Aquatic Systems, Leeanna Pletcher

Theses and Dissertations

Amphibians and aquatic invertebrates have complex life histories that link aquatic and terrestrial food webs. It has been suggested that amphibian reproduction is an important source of carbon to some aquatic systems. This process of energy flow may be shaped by shifts in habitat selection in response to predators. We hypothesized that predators decrease colonization and oviposition of prey, reducing active inputs. Thus predation risk is expected to shift the relative amounts of active and passive subsidies. We manipulated the presence of fish predators in aquatic mesocosms. Results suggest hylid treefrog eggs and hydrophilid beetles were less abundant in predator …

Effects Of Predation Risk, Density And Disease On Energy Efficiency In A Larval Anuran, Sarah Crane

Theses and Dissertations

Predation, density and disease affect behavior, morphology and growth. There is a lack of information on how these changes relate to efficiency of energy transfer in anuran larvae, although previous studies suggest that predation should decrease and competition should increase efficiency. Using a 2 x 2 factorial design, we manipulated predation presence and larval density to test how predation risk and density affect energy efficiency. During the experiment, approximately half of the tadpoles were infected by an unknown disease. Neither predation risk nor density affected assimilation or growth efficiency, despite changes in growth and development. Disease, however, decreased gut length …

The Ecology Of Fear: Colonization And Oviposition In Aquatic Systems [Poster], Leeanna Pletcher, Johanna Kraus, James R. Vonesh

Biology Presentations

Introduction

Amphibians and aquatic invertebrates have complex life histories that link aquatic and terrestrial food webs. It has been suggested that amphibian reproduction is an important source of carbon to some aquatic systems. Movement of organisms across the aquatic-terrestrial habitat boundary can represent important subsidies to the receiving habitat. Subsidies are organisms, nutrients, or detritus that cross habitat boundaries and are consumed, and these allochthonous inputs can affect food web structure. Predators can alter subsidies by consuming organisms that would otherwise move across habitat boundaries. Predator induced shifts in habitat selection are a well known non-lethal effect in aquatic systems. …

Mechanical Abrasion And Electroporation In The Transformation Of Intact Pleurotus Ostreatus Hyphæ And Nutrient-Dependant Resistance To Hygromycin B, Alexander Cordesman

Theses and Dissertations

ABSTRACT 1: Abrasive treatment and subsequent electroporation of the basidiomycete Pleurotus ostreatus in a hypertonic buffer was investigated as a potential method of transforming of intact hyphæ. Mycelia, which are not capable of being transformed via electroporation due to interference by the cell wall, were abraded in an attempt to mechanically degrade the cell wall prior to electroporation. An electroporation field strength of 12,500 V/cm for 500 μs to 1.25 ms was found to be optimal based upon mortality effects. A 32 μm carborundum abrasive was initially evaluated but was quickly found to be inappropriately large so a corundum abrasive …

Camk-Ii Promotes Beta-Catenin-Dependent Transcription By Binding Flightless-I, Jamie Mcleod

Theses and Dissertations

Transient intracellular elevations of Ca2+ are common signaling mechanisms used to allosterically regulate proteins. One potential target of Ca2+ is Ca2+/calmodulin dependent protein kinase type II (CaMK-II). CaMK-II is a multi-functional protein kinase known to influence cellular pathways such as cell motility and cell cycle progression. Within the cell cycle, CaMK-II promotes the expression of the regulator protein cyclin D1, which is necessary for cell cycle progression. To further understand CaMK-II’s role in cyclin D1 expression, the binding partners of cytosolic CaMK-II were studied using mass spectrometry. Several proteins were identified including β actin, β tubulins, tropomodulin- 3 and Flightless-I. …

Role Of The Small Terminase Subunit Encoded By Staphylococcus Aureus Pathogenicity Island Sapi1 In Formation Of Sapi1 Transducing Particles, Nicholas Paul Olivarez

Theses and Dissertations

Staphylococcus aureus pathogenicity island SaPI1 is a genomic element that is mobilized and transduced at high frequency by helper phage 80α. SaPI1 encodes a small terminase protein that belongs to the phage small terminase subunit family. The presence of SaPI1-encoded small terminase suggests that it plays a role in SaPI1-specific packaging into transducing particles by complexing with the 80α large terminase subunit and redirecting recognition to a pac site on SaPI1 DNA from 80α DNA. The effects of deleting the small terminase genes in SaPI1 and in a prophage copy of 80α are consistent with this hypothesis. Induction of the …