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Antimicrobial Activity Screening Of Recombinant And Synthetic Varasin A Defensin From The Hard Tick Dermacentor Variabilis Against Various Bacteria, Julia A. Sharp

Biological Sciences Theses & Dissertations

Hematophagous arthropods, such as ticks and mosquitoes, rely on their innate immune system for defense against pathogens ingested in a blood meal as well as those acquired through injury. In response to pathogen recognition, the production of antimicrobial peptides, such as defensin, is typically upregulated. Varisin, a defensin, is thought to be a key component in the immunocompetence of the hard tick D. variabilis against Borrelia burgdorferi, the causative agent of Lyme disease. To study the antimicrobial effects of varisin, recombinant varisin was expressed by both insect cells and E coli. Purification of the protein followed by enterokinase treatment yielded …

Hydrodynamic Fin Function Of Brief Squid Lolliguncula Brevis, William Jeffreys Stewart

Biological Sciences Theses & Dissertations

Although the pulsed jet is often the foundation of a squid's locomotive system, the lateral fins also play an important role in swimming, potentially providing thrust, lift, and dynamic stability. Fin morphology and movement vary greatly among squid species, but the locomotive role of the fins is not well understood. To begin to elucidate the locomotive role of the fins in squids, fin hydrodynamics were studied in the brief squid Lolliguncula brevis, a species that exhibits a wide range of fin movements depending on swimming speed. Individual squid were trained to swim in both the arms-first and tail-first orientations against …

Seasonal Variation In Diet Of The Cotton Rat (Sigmodon Hispidus) Based On Fecal Analysis, Lynn A. Walker

Biological Sciences Theses & Dissertations

Cotton rats, Sigmodon hispidus, live in oldfields, habitats with a variety of mostly herbaceous plants. Based on other studies, the hispid cotton rat eats predominantly grasses, but grasses rarely are the only food. Fecal samples were collected each month during an ongoing capture-mark-release demographic study of the rodent community at a location in southern Chesapeake, Virginia. In the lab, five fecal pellets per animal were stained, placed on a microscope slide, and covered with starch-gel medium and coverslip. Then a clear nail polish was applied to produce a semi-permanent slide. Using a microscope and a set of reference slides, plant …

The Plasmodium Falciparum Chloroquine Resistance Transporter, Pfcrt, Mediates The Activity Of Chloroquine-Resistance Reversal Agents In The Malaria Parasite, Kristin Lane

Biological Sciences Theses & Dissertations

Chloroquine (CQ) resistant Plasmodium falciparum is a serious problem affecting 3.2 billion people in over 100 countries today. Most endemic malarious countries are among the poorest in the world and lack the resources to replace the inexpensive and highly effective CQ. CQ resistance (CQR) reversal agents are a potentially inexpensive solution to restoring CQ efficacy. CQR reversal agents are drugs that have little to no antimalarial activity alone, but in combination with CQ, they increase dmg accumulation in the parasite and enhance the sensitivity to CQ in CQR parasites. PfCRT is a putative transporter located on the parasite digestive vacuole …

Modeling Habitat And Environmental Factors Affecting Mosquito Abundance In Chesapeake, Virginia, Alan Scott Bellows

Biological Sciences Theses & Dissertations

The models I present in this dissertation were designed to enable mosquito control agencies in the mid-Atlantic region that oversee large jurisdictions to rapidly track the spatial and temporal distributions of mosquito species, especially those species known to be vectors of eastern equine encephalitis and West Nile virus. I was able to keep these models streamlined, user-friendly, and not cost-prohibitive using empirically based digital data to analyze mosquito-abundance patterns in real landscapes.

This research is presented in three major chapters: (II) a series of semi-static habitat suitability indices (HSI) grounded on well-documented associations between mosquito abundance and environmental variables, (III) …

Evidence For Disease Mediated Extinction: Correlation Between An Introduced Pathogen And Extinction Of Rattus Macleari On Christmas Island, Kelly B. Wyatt

Biological Sciences Theses & Dissertations

The Durham Collection and the Cambridge and Oxford University Museums provided the materials to investigate the possibility that the extinction of indigenous rats of Christmas Island was a result of disease introduced by infected ship rats (R. rattus) in 1899. The collections of H.E. Durham in 1901-1902 reveal that R. macleari was present on Christmas Island up to then and includes specimens of R. rattus together with specimens that exhibit characteristics of both R. rattus and R. macleari. Durham's notes indicate both R. rattus and R. macleari specimens were heavily infected with trypanosomes at the time of collection. In …

Effects Of Elevated Atmospheric Co2 On Root Dynamics, Biomass And Architecture In A Scrub-Oak Ecosystem At Kennedy Space Center, Florida, Daniel Benjamin Stover

Biological Sciences Theses & Dissertations

A major gap in whole-plant ecology lies with our understanding of root system growth, function and distribution. Large belowground structures, in addition to fine roots, are of particular interest because of their role in carbon sequestration. Non-destructive methods, including ground-penetrating radar (GPR) and minirhizotron observation tubes, were used to investigate effects of elevated CO₂ on root biomass, dynamics (productivity, mortality, and turnover), root persistence and architecture in a fire dominated scrub-oak ecosystem. Open-top chambers have been exposed to elevated atmospheric CO₂ for the past eleven years at Kennedy Space Center, Florida. No significant sustained CO₂ treatment effects …

Molecular Phylogenetics Of Perciform Fishes Using The Nuclear Recombination Activating Gene 1, Andrew R. Mahon

Biological Sciences Theses & Dissertations

The order Perciformes contains one-third of all extant fishes in twenty different suborders and over 10,000 species. Few systematic investigations have been performed on this large group of fishes at the suborder level and their evolutionary history is widely recognized as problematic. This dissertation presents three studies: a molecular phylogenetic analysis of the putative suborders of the order Perciformes, an analysis of interrelationships of the families of the perciform suborder Percoidei, and a multi-gene investigation of the percoid superfamily Sparoidea.

The taxa sampled in this dissertation represent one of the most inclusive molecular datasets, to date, testing the monophyly of …

Behavioral Enhancement Of Onshore Transport By Postlarval Caribbean Spiny Lobster (Panulirus Argus), Jason Seth Goldstein

Biological Sciences Theses & Dissertations

The onshore transport of meroplanktonic marine larvae or postlarvae is often complex, involving both active (i.e., behavior, swimming) and passive (i.e., oceanographic elements) transport mechanisms. Behaviors that modify passive transport have presumably evolved to situate larvae in settlement habitats where survival is enhanced. Active transport mechanisms have not been described for the puerulus postlarvae of any species of spiny lobster, despite their extraordinary mobility and known preference for specific settlement habitats. In the Florida Keys, for example, Caribbean spiny lobster (Panulirus argus) pueruli travel from oceanic waters into coastal areas where they settle within bushy, red macroalgae. I …

Plant Assemblage Structure On Barrier Island ‘Pimple’ Dunes At The Virginia Coast Reserve Long-Term Ecological Research Site, Brett A. Mcmillan

Biological Sciences Theses & Dissertations

The habitats at the VCR LTER that were the focus of the current study are the Hog Island and Parramore Island 'pimples', small, rounded dunes forming along main dune ridges of the barrier islands. There are distinct plant assemblage zones found on pimples, although most of these dunes are 10–20 m in diameter. Hypotheses of the study were that fresh water availability was a main determinant of differences between assemblages and that pimple size and location would influence diversity and assemblage structure. Research goals were (1) to describe the plant assemblages on pimples, (2) to relate edaphic and geomorphological factors …