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Full-Text Articles in Life Sciences

Nucleocytoplasmic Shuttling Of The Thyroid Hormone Receptor, Vincent R. Roggero Jan 2008

Nucleocytoplasmic Shuttling Of The Thyroid Hormone Receptor, Vincent R. Roggero

Dissertations, Theses, and Masters Projects

No abstract provided.


Nuclear Export Of The Thyroid Hormone Receptor [Alpha], Matthew Edward Grespin Jan 2008

Nuclear Export Of The Thyroid Hormone Receptor [Alpha], Matthew Edward Grespin

Dissertations, Theses, and Masters Projects

No abstract provided.


Status, Distribution And Reproductive Rates Of American Oystercatchers In Virginia, Alexandra Lee Wilke Jan 2008

Status, Distribution And Reproductive Rates Of American Oystercatchers In Virginia, Alexandra Lee Wilke

Dissertations, Theses, and Masters Projects

No abstract provided.


Effects Of Adaptive Foragers On The Diversity And Functioning Of Assembled Model Communities, William J. Tarantino Jan 2008

Effects Of Adaptive Foragers On The Diversity And Functioning Of Assembled Model Communities, William J. Tarantino

Dissertations, Theses, and Masters Projects

Previous research suggests that prey-switching behavior by consumers (adaptive foraging) contributes to the stability of food web networks and may help explain the apparent contradiction between the complexity of natural ecosystems and theory that suggests such complex systems should be unstable. However, no previous study has explored the consequences of adaptive foraging behavior on ecosystem processes (or `functioning'). I assembled communities from regional pools while varying searching efficiency, connectance, and the fraction of adaptive foragers in order to observe the effects these properties have on the diversity and functioning of the resultant communities. In general, pools with increased connectance, a ...


Interspecific Interactions In Oyster Reef Communities: The Effect Of Established Fauna On Oyster Larval Recruitment, Brian B. Barnes Jan 2008

Interspecific Interactions In Oyster Reef Communities: The Effect Of Established Fauna On Oyster Larval Recruitment, Brian B. Barnes

Dissertations, Theses, and Masters Projects

The behaviors of oyster larvae are difficult to monitor or experimentally manipulate, especially in field conditions. As a result, little is known of the fate of oysters in the larval portion of their life cycle, prior to recruitment. At the transition from pelagic larvae to benthic adults, larvae are likely to come into contact with many invertebrates resident on oyster reefs. Of these, fouling epifauna are generally believed to reduce the settlement of interspecific larvae through competitive exclusion and predation. Studies of these interactions, however, often utilize artificial settlement panels, which can exhibit different recruitment patterns to those observed on ...


Stable Isotope Dynamics In Summer Flounder Tissues, With Application To Dietary Assessments In Chesapeake Bay, Andre Buchheister Jan 2008

Stable Isotope Dynamics In Summer Flounder Tissues, With Application To Dietary Assessments In Chesapeake Bay, Andre Buchheister

Dissertations, Theses, and Masters Projects

Stable isotope techniques were applied to summer flounder, Paralichthys dentatus, in Chesapeake Bay to elucidate the relative importance of different prey groups on the growth and productivity of this species. Prior to field application, a laboratory diet-shift study was conducted to evaluate methodological assumptions and obtain necessary isotopic parameters. Specifically, the goals of the laboratory study were to 1) determine isotopic turnover rates and fractionations of δ13C and δ15N in liver, whole blood, and white muscle and 2) estimate the relative importance of growth and metabolic processes on isotopic turnover. Groups of captive juvenile summer flounder (130-255mm total length) were ...


Effects Of Shoreline Development And Oyster Reefs On Benthic Communities In Lynnhaven, Virginia, Amanda Sue Lawless Jan 2008

Effects Of Shoreline Development And Oyster Reefs On Benthic Communities In Lynnhaven, Virginia, Amanda Sue Lawless

Dissertations, Theses, and Masters Projects

Shoreline hardening and construction of restoration oyster reefs are occurring at rapid rates throughout Chesapeake Bay and little research has been conducted to determine whether installment of a hardened shoreline and oyster reef placement has an effect on the surrounding benthic infaunal communities. I investigated the effects of shoreline development and oyster reefs on benthic communities in Lynnhaven, Virginia. Throughout Lynnhaven, I determined the effects of shoreline type (natural marsh, oyster reef, rip-rap and bulkhead), sediment grain size, Total Organic Carbon/Total Nitrogen (TOC/TN) of the sediment, and predation (caging study) on density, biomass, and diversity of benthic infauna ...


Zooplankton Community Structure In A Cyclonic And Mode-Water Eddy In The Sargasso Sea, Bethany Rose Eden Jan 2008

Zooplankton Community Structure In A Cyclonic And Mode-Water Eddy In The Sargasso Sea, Bethany Rose Eden

Dissertations, Theses, and Masters Projects

Recent evidence suggests that mesoscale eddies are an important mechanism for supplying nutrients to the surface waters of oligotrophic gyres. However, little is known about the biological response to these physical perturbations. Because mesozooplankton play a key role in food-web interactions and the flux of carbon and other elements from surface waters, changes in mesozooplankton community structure can affect biogeochemical cycling. During the summers of 2004 and 2005, respectively, we followed the development of a cyclonic eddy and an anti-cyclonic mode-water eddy in the Sargasso Sea. Zooplankton tows were conducted across both eddies using a Multiple Opening and Closing Net ...


A Molecular Phylogeny Of The Genus Bonamia Based On Sequence Data Of The Ribosomal Rna (Rrna) Gene Complex, Delonna M. White Jan 2008

A Molecular Phylogeny Of The Genus Bonamia Based On Sequence Data Of The Ribosomal Rna (Rrna) Gene Complex, Delonna M. White

Dissertations, Theses, and Masters Projects

No abstract provided.


Mesopelagic Zooplankton Feeding Ecology And Effects On Particle Repackaging And Carbon Transport In The Subtropical And Subarctic North Pacific Ocean, Stephanie E. Wilson Jan 2008

Mesopelagic Zooplankton Feeding Ecology And Effects On Particle Repackaging And Carbon Transport In The Subtropical And Subarctic North Pacific Ocean, Stephanie E. Wilson

Dissertations, Theses, and Masters Projects

Differences in zooplankton community structure and diet within the mesopelagic zone (base of euphotic zone to 1000 m) play a key role in affecting the efficiency by which organic matter is exported to depth, but how the structure of mesopelagic food webs change with depth or location is poorly known. I examined how mesopelagic zooplankton affect particle export in an oligotrophic (Hawaii Ocean Time-series site ALOHA) compared to a mesotrophic (Japanese time series site K2) open-ocean system. In the first part of the study, I investigated how fecal pellet characteristics change with depth in order to quantify the extent of ...


Impacts Of Gelatinous Zooplankton On Dissolved Organic Matter Cycling And Bacterioplankton Communities In The York River Estuary, Robert Howard Condon Jan 2008

Impacts Of Gelatinous Zooplankton On Dissolved Organic Matter Cycling And Bacterioplankton Communities In The York River Estuary, Robert Howard Condon

Dissertations, Theses, and Masters Projects

Large gelatinous zooplankton (GZ) blooms of lobate ctenophores, Mnemiopsis leidyi, and scyphomedusae, Chrysaora quinquecirrha , occur throughout Chesapeake Bay and its tributaries. The mechanisms of GZ bloom formation, and the roles GZ blooms play in dissolved organic matter (DOM) and carbon (C) cycling are not fully understood. During 2003--2006, I conducted laboratory experiments and field surveys in the lower York River to determine factors controlling timing and magnitude of GZ blooms, and to evaluate their effects on C cycling. Highest biomass of M. leidyi occurred in early summer (May-June) and in late winter. Peaks in ctenophore biomass in the mesohaline region ...


Age, Growth, And Demography Of The Sandbar Shark, Carcharhinus Plumbeus, Over Temporal And Spatial Scales, Jason G. Romine Jan 2008

Age, Growth, And Demography Of The Sandbar Shark, Carcharhinus Plumbeus, Over Temporal And Spatial Scales, Jason G. Romine

Dissertations, Theses, and Masters Projects

Numbers of sandbar sharks, Carcharhinus plumbeus, in the Northwest Atlantic have experienced drastic declines since the early 1980's reaching their minima during the early 1990's. Catch rates in the early 1990's were a mere 25% of those during the 1980's. Such drastic reductions in other fish stocks have often caused compensatory responses, most notably the cod stocks in the Northwest Atlantic. Compensatory responses in depressed populations may include decreased natural mortality, increased fecundity, or increased growth rates. Compensation for population fluctuations below carrying capacities have been recognized for many terrestrial and oceanic r-selected organisms, but few ...


Analysis Of Sequence Variation At Two Helicobacter Pylori Genetic Loci Potentially Involved In Virulence, George Warren Liechti Jan 2008

Analysis Of Sequence Variation At Two Helicobacter Pylori Genetic Loci Potentially Involved In Virulence, George Warren Liechti

Dissertations, Theses, and Masters Projects

No abstract provided.


Mercury Levels In Newly Independent Songbirds, Anne Moire Condon Jan 2008

Mercury Levels In Newly Independent Songbirds, Anne Moire Condon

Dissertations, Theses, and Masters Projects

No abstract provided.


Effects Of Urban Development On Breeding Bird Diversity: The Role Of Diet And Migration, Elise Anne Larsen Jan 2008

Effects Of Urban Development On Breeding Bird Diversity: The Role Of Diet And Migration, Elise Anne Larsen

Dissertations, Theses, and Masters Projects

No abstract provided.


Interactions Between Feather-Degrading Bacteria And Feather Coloration, Alexander Rahn Gunderson Jan 2008

Interactions Between Feather-Degrading Bacteria And Feather Coloration, Alexander Rahn Gunderson

Dissertations, Theses, and Masters Projects

No abstract provided.


Vascular Flora Of The Totuskey Creek Watershed, Richmond County, Virginia, Christopher W. Johnstone Jan 2008

Vascular Flora Of The Totuskey Creek Watershed, Richmond County, Virginia, Christopher W. Johnstone

Dissertations, Theses, and Masters Projects

No abstract provided.


A Versatile Imaging System For In Vivo Small Animal Research, Jianguo Qian Jan 2008

A Versatile Imaging System For In Vivo Small Animal Research, Jianguo Qian

Dissertations, Theses, and Masters Projects

In vivo small animal imaging has become an essential technique for molecular biology studies. However, requirements of spatial resolution, sensitivity and image quality are quite challenging for the development of small-animal imaging systems. The capabilities of the system are also significant for carrying out small animal imaging in a wide range of biological studies. The goal of this dissertation is to develop a high-performance imaging system that can readily meet a wide range of requirements for a variety of small animal imaging applications. Several achievements have been made in order to fulfill this goal.;To supplement our system for parallel-hole ...


Pathogenicity Of The Purportedly Toxic Dinoflagellates Pfiesteria Piscicida And Pseudopfiesteria Shumwayae And Related Species, Vincent J. Lovko Jan 2008

Pathogenicity Of The Purportedly Toxic Dinoflagellates Pfiesteria Piscicida And Pseudopfiesteria Shumwayae And Related Species, Vincent J. Lovko

Dissertations, Theses, and Masters Projects

The heterotrophic dinoflagellates Pfiesteria piscicida and Pseudopfiesteria shumwayae (here referred to as Pfiesteria) have been reported to secrete potent toxins responsible for inducing lesions in Atlantic menhaden, causing deaths of fishes in natural systems and laboratory assays and impacting human health. Many aspects of Pfiesteria biology and ecology have been questioned, including its complicated life-cycle, its role in fish kills, fish lesion events and human health effects as well as its ability to produce toxins. Although the involvement of Pfiesteria in major estuarine fish kills and lesion events has been disputed, there is a demonstrated ability of these organisms to ...


Understanding The Reproductive Behavior And Population Condition Of The Sandbar Shark (Carcharhinus Plumbeus) In The Western North Atlantic: A Molecular Approach To Conservation And Management, David S. Portnoy Jan 2008

Understanding The Reproductive Behavior And Population Condition Of The Sandbar Shark (Carcharhinus Plumbeus) In The Western North Atlantic: A Molecular Approach To Conservation And Management, David S. Portnoy

Dissertations, Theses, and Masters Projects

The sandbar shark, Carcharhinus plumbeus, has a discontinuous cosmopolitan distribution and is exploited throughout much of its range. In the western North Atlantic, it constitutes the majority of the directed commercial fishery. The stock has declined greatly since the fisheries' inception and has not shown signs of recovery despite the implementation of management practices. Like many highly vagile marine species, it is difficult to obtain information about the sandbar shark through direct observation. Therefore, the goal of this dissertation is to use a molecular approach to examine aspects of behavior and reproduction, providing information useful in conservation and management. to ...


Bottom-Up And Top-Down Controls On Sedimentary Ecosystem Functioning In A Seagrass Habitat, Amanda C. Spivak Jan 2008

Bottom-Up And Top-Down Controls On Sedimentary Ecosystem Functioning In A Seagrass Habitat, Amanda C. Spivak

Dissertations, Theses, and Masters Projects

Coastal seagrass ecosystems are complex habitats that are increasingly influenced by human perturbations. Disturbances that affect the strength of bottom-up (i.e. resource availability) and top-down (i.e. consumer) controls may also influence biomass distribution between trophic levels, sediment biogeochemistry, and seagrass ecosystem metabolism. Here, I experimentally tested how top-down and bottom-up perturbations interact with community structure (diversity, food chain length of epibenthic consumers) to alter sediment biogeochemistry and ecosystem metabolism in an experimental eelgrass (Zostera marina ) system. My data indicated that resource availability influenced SOM composition and ecosystem metabolism. Light availability tended to be a stronger determinant of SOM ...


The Relationship Between Antibody Redox Structure And Affinity In Rainbow Trout, Jianmin Ye Jan 2008

The Relationship Between Antibody Redox Structure And Affinity In Rainbow Trout, Jianmin Ye

Dissertations, Theses, and Masters Projects

Teleost immunoglobulin M (IgM), an 800 kDa tetramer, possesses considerable structural diversity due to the non-uniform disulfide polymerization of its halfmeric or monomeric subunits. However, to date, no plausible functional role for this diversity has been demonstrated or proposed. This research was, therefore, designed to investigate the possible functional role(s) for this diversity using the trout model. The possible relationship between this structural diversity and affinity was specifically addressed. The relationship between high levels of disulfide polymerization and high affinity was demonstrated by selective immunoadsorption and analysis of antibodies isolated during the process of affinity maturation. A pivotal determinative ...


A Molecular Analysis Of Atlantic Menhaden (Brevoortia Tyrannus) Stock Structure, Abigail J. Lynch Jan 2008

A Molecular Analysis Of Atlantic Menhaden (Brevoortia Tyrannus) Stock Structure, Abigail J. Lynch

Dissertations, Theses, and Masters Projects

Atlantic menhaden is an ecologically and economically important species along the U.S. east coast. As a filter-feeder and key prey fish, it provides a critical link between primary production, phytoplankton, and larger piscivorous predators, such as striped bass, bluefish, and weakfish. The species is also the target of one of the largest commercial fisheries in the country. Menhaden are assessed as a single, coastwide stock, and recent assessments indicate that it is not overfished. However, there is very limited population genetics data to support the assumption of a single stock. Additionally, the recent consolidation of the fishery and localization ...


Novel Use Of A Natural Isotope Signature To Track Recruitment And Evaluate Age Determination Methods For The 2002 Year Class Of American Shad In The York River, Sally A. Upton Jan 2008

Novel Use Of A Natural Isotope Signature To Track Recruitment And Evaluate Age Determination Methods For The 2002 Year Class Of American Shad In The York River, Sally A. Upton

Dissertations, Theses, and Masters Projects

No abstract provided.


An Evaluation Of Norovirus Persistence In Estuarine Water And Of Methods For Its Detection In Treated Sewage Effluent, Margaret H. Fagan Jan 2008

An Evaluation Of Norovirus Persistence In Estuarine Water And Of Methods For Its Detection In Treated Sewage Effluent, Margaret H. Fagan

Dissertations, Theses, and Masters Projects

No abstract provided.


Community Dynamics In Submersed Aquatic Vegetation: Intermediate Consumers As Mediators Of Environmental Change, James G. Douglass Jan 2008

Community Dynamics In Submersed Aquatic Vegetation: Intermediate Consumers As Mediators Of Environmental Change, James G. Douglass

Dissertations, Theses, and Masters Projects

Natural ecosystems are strongly affected by changes in resource supply (bottom-up forces) and by changes in upper trophic levels (top-down forces). The extent to which these processes impact a system depends largely on the responses of organisms at middle trophic levels. In seagrass beds, a group of mid-level consumers known as mesograzers form a critical link in the chain of impact, connecting seagrass and epiphytic algae with predatory fishes and crustaceans. I observed dramatic seasonal and interannual changes in mesograzer abundance and species composition in eelgrass (Zostera marina) beds of lower Chesapeake Bay, Virginia, and endeavored to explain the top-down ...


Natural Mortality Of Blue Crab: Estimation And Influence On Population Dynamics, David A. Hewitt Jan 2008

Natural Mortality Of Blue Crab: Estimation And Influence On Population Dynamics, David A. Hewitt

Dissertations, Theses, and Masters Projects

The blue crab Callinectes sapidus supports one of the most important fisheries in the Chesapeake Bay and is the leading contributor to blue crab landings in the United States. Assessment and management of blue crab stocks has been hampered by a lack of estimates of natural mortality rates, a key parameter in assessment models. In Chapter 2, we demonstrate that the approach used for estimating natural mortality that had been used in past assessments was flawed, and provide justification for a superior alternative. In Chapter 3, we synthesize our current understanding of natural mortality rates in adult blue crab and ...


Markov Chain Models Of Calcium Puffs And Sparks, Jeffrey R. Groff Jan 2008

Markov Chain Models Of Calcium Puffs And Sparks, Jeffrey R. Groff

Dissertations, Theses, and Masters Projects

Localized cytosolic Ca2+ elevations known as puffs and sparks are important regulators of cellular function that arise due to the cooperative activity of Ca2+-regulated inositol 1,4,5-trisphosphate receptors (IP3Rs) or ryanodine receptors (RyRs) co-localized at Ca2+ release sites on the surface of the endoplasmic reticulum or sarcoplasmic reticulum. Theoretical studies have demonstrated that the cooperative gating of a cluster of Ca2+-regulated Ca 2+ channels modeled as a continuous-time discrete-state Markov chain may result in dynamics reminiscent of Ca2+ puffs and sparks. In such simulations, individual Ca2+-release channels are coupled via a mathematical representation of the local ...


Markov Chain Models Of Instantaneously Coupled Intracellular Calcium Channels, Hilary Deremigio Jan 2008

Markov Chain Models Of Instantaneously Coupled Intracellular Calcium Channels, Hilary Deremigio

Dissertations, Theses, and Masters Projects

Localized calcium elevations known as calcium puffs or sparks are cellular signals arising from cooperative activity of clusters of inositol 1,4,5-trisphosphate receptors (IP3Rs) or ryanodine receptors (RyRs) located at calcium release sites on the endoplasmic or sarcoplasmic reticulum membrane. When Markov chain models of these intracellular calcium-regulated calcium channels are coupled via a mathematical representation of the calcium microdomain, simulated calcium release sites may exhibit the phenomenon of "stochastic calcium excitability" where the IP3Rs or RyRs open and close in a concerted fashion. Although the biophysical theory relating the kinetics of single channels to the collective phenomena of ...


Probability Density Methods For Modeling Local And Global Aspects Of Intracellular Calcium Signaling, G. S. Blair Williams Jan 2008

Probability Density Methods For Modeling Local And Global Aspects Of Intracellular Calcium Signaling, G. S. Blair Williams

Dissertations, Theses, and Masters Projects

Considerable insight into intracellular calcium (Ca) responses has been obtained through the development of whole cell models that are based on molecular mechanisms, e.g., the kinetics of intracellular Ca channels and the feedback of Ca upon these channels. However, a limitation of most deterministic whole cell models to date is the assumption that channels are globally coupled by a single [Ca], when in fact channels experience localized "domain" Ca concentrations. More realistic stochastic Monte Carlo simulations are capable of representing individual domain Ca concentrations but suffer from increased computational demand. This dissertation introduces a novel probability approach which captures ...