Biology Commons^™

Chondrocranial And Oral Morphology Of Leptodactylid Larvae, William Hagood Turner

Master's Theses

I focused my research on Leptodactylidae in order to determine the usefulness of chondrocranial and internal oral characters in systematic and phylogenetic studies of this anuran family. To achieve this goal, I examined the chondrocrania of eight species of the Leptodactylinae: Adenomera marmorata, Edalorhina perezi, Limnomedusa macroglossa, Physalaemus gracilis, P. henselii, P. pustulosus, Pleurodema brachyops, and P. tucumana. Furthermore, I analyzed and described the internal oral anatomy of Physalaeum us gracilis, P. henselii, and Limnomedusa macroglossa and the skeletogenesis of P. gracilis and P. pustulosus. Subsequently, I integrated these data with all available data on the larval chondrocrania and internal …

Area-Species Curve Applies To Gaps In A Canada Hemlock (Tsuga Canadensis (L.) Carr.) Forest In The Shenandoah National Park, Joseph John Lacroix

Master's Theses

A typical area-species curve shows that species richness (number of species) and island size are positively correlated. I tested whether the area-species concept, which was developed using islands, could be applied to herbaceous plants in canopy gaps in a hemlock community.

I conducted studies in Limberlost, Shenandoah National Park. I measured the species richness of herbaceous plants in six gaps during the summer and fall of 1995 and eight gaps and one non-gap site in the spring of 1996. The two additional gaps in 1996 extended the upper range of gap sizes. I calculated the correlation between species richness and …

Chondrocranial And Oral Morphology Of Pipoid Frogs, Charles Christopher Swart

Master's Theses

The Pipoidea are a diverse group of frogs. Their diversity is demonstrated in their morphology, ecology, and behavior. One pipoid species, Xenopus laevis, has been used as a model system of developmental, physiological, and molecular studies of vertebrates. My work has focused on the developmental morphology of the chondrocranium and oral morphology of four pipoid taxa: Hymenochirus boettgeri, Rhinophrynus dorsalis, Pipa carvalhoi, and Xenopus laevis. Previous studies have suggested that the Anura may be diphyletic based on the unique characteristics of the chondrocanial morphology of pipoids. The chondrocranial and internal oral morphology of the pipoids indicates that as a group …

Sequence Characterization And Phylogenetic Analyses Of The Pol Region From Sire-1, An Endogenous Retrovirus From Glycine Max, Eric A. Gaucher

Master's Theses

No abstract provided.

Isolation And Characterization Of A Genomic Clone For A Nitrate Reductasae Isoform From Soybean, Glycine Max, Brent Chyna

Master's Theses

No abstract provided.

A Profile Of Antibiotic Resistant Bacteria In The James River, Keith Allen Boisvert

Master's Theses

Spatial and temporal variability in the antibiotic resistance of bacterial assemblages in the lower portion of the James River was examined. The antibiotic resistance of culturable coliforms was compared to the resistance in the microbial community. Antibiotic resistance was determined via colony formation on media containing antibiotics. The antibiotics ampicillin, chloramphenicol, streptomycin and tetracycline were used at concentrations ranging from 10 to 500 ug/ml. Statistically significant differences in the mean number of antibiotic resistant isolates were observed among both sample sites and dates. The sampling site at river mile 99 just below Richmond showed both increased antibiotic resistance and bacterial …

Semipermeable Membrane Devices Are Effective Surrogates Of Fish In Concentrating Polychlorinated Biphenyls, Christopher Gardner Collins

Master's Theses

This study examined the effectiveness of Semipermeable Membrane Devices (SPMDs) as surrogates for fish in concentrating polychlorinated biphenyls. Golden shiners (Notemigonus crysolucas) and SPMDs were exposed to three different concentrations (0.5, 1.5, and 3.0ppm) of Aroclor 1254 for 1, 3, and 5 days under laboratory conditions. Concentrations of Aroclor 1254 were measured in the SPMDs and fish tissue using extraction techniques and gas chromatography. The concentrations of PCB in SPMDs and N. crysolucas were positively correlated. This relationship compared favorably with data from other studies. The relationship between the concentration of PCB in SPMDs and tissue offish and …

The Soybean Retroelement, Sire-1, Encodes An Envelope-Like Protein-Sire-1 Is An Endogenous, Proretrovirus-Like Genomic Element, Arpita Majumdar

Master's Theses

No abstract provided.

Analysis Of The Inheritance Repression Of A Transposable Element In Drosophila Melanogaster, Melissa Leone

Master's Theses

No abstract provided.

Regulation Of The Activities Of The Three Nitrate Reductase Isoforms In Wild-Type Soybean Glycine Max (L.) Merr. (Variety Williams) By Protein Phosphorylation, Maribel T. Joson

Master's Theses

No abstract provided.

Benthic Invertebrate Community Responses To Round Goby (Neogobius Melanostomus) And Zebra Mussel (Dreissena Polymorpha) Invasion In Southern Lake Michigan, Linda A. Benning

Master's Theses

No abstract provided.

Characterization Of Deletion Sites In A Human Collagen-Like Locus, Marissa A. Michaels

Master's Theses

No abstract provided.

Saccharomyces Cerevisiae-Produced Recombinant Pfs230: A Malaria Transmission-Blocking Vaccine Candidate, Kathryn M. Glynn

Master's Theses

No abstract provided.

The Effects Of 2,4-Dichlorophenoxyacetic Acid On The Diazotrophic Soil Microbial Community, Denise M. Brown

Master's Theses

This study measures the effects of 2,4- dichlorophenoxyacetic acid (2,4-D) on growth and nitrogen fixation capabilities of the native microbial soil community during eight field trials conducted over an eight month period. After application of 2,4-D, soil samples were analyzed for enumeration of diazotrophic and general microbial communities, and for nitrogenase activity as measured by the acetylene reduction assay (ARA). Statistical analyses were conducted using Minitab. Results show that 2,4-D significantly stimulated growth of diazotrophic microbes in 87.5% of the trials and was found to have a stimulatory growth effect on the general microbes in 62.5% of the trials. A …

The Effect Of Thyroid Hormone On The Expression Of A7 Myosin Heavy Chain Mrna In Xenopus Laevis, Bradley Thomas Butkovich

Master's Theses

It has long been known that thyroid hormone (TH) is responsible for metamorphosis in tadpoles. It is also known that A7 MHC, an adult muscle isoform, is expressed in adult Xenopus laevis frogs, but not in larvae. Furthermore, the appearance of A7 corresponds with the onset of metamorphosis. The present study investigated the relationship between TH and the expression of A7 MHC mRNA in Xenopus laevis. Isolated tails in culture and 6-n-propyl 2-thiouracil (PTU) treated tails were treated with TH and the presence of A7 mRNA analyzed with in-situ hybridization, and RT-PCR. It was found that TH caused substantial …

Osteology, Morphology, And Female Choice In Species Of The Genus Cynolebias (Cyprinodontiformes: Rivulidae), Marcelo Loureiro Barrella

Master's Theses

Relationships among the species of the annual fish Cynolebias are unclear. An analysis of the utility of different osteological and morphological characters for phylogenetic analyses was done using clear and double stained specimens and measurements of morphometric parameters respectively. Scanning electron microscopy was used to study the morphology of the egg chorion. Female choice tests were also conducted to test male traits that may be preferred by females. The osteological analysis showed that some characters previously unreported may be phylogenetically useful. Head scalation patterns were found to be intraspecifically variable, making them inappropriate to use in systematics. Each morphometric parameter …

Feasibility Of Stocking Grass Carp (Ctenopharyngodon Idella; Cyprinidae) To Control Hydrilla (Hydrilla Verticillata; Hydrocharitaceae) In Lake Anna, Virginia, Paul Matthew Overton

Master's Theses

The goal of this study was to demonstrate the feasibility of using triploid ·Ctenopharvngodon idella (grass carp) to control Hydrilla verticillata in the Waste Heat Treatment Facility (WHTF) in Lake Anna, Virginia. The four objectives were to determine: the frequency of occurrences of grass carp over hydrilla; the proportions of hydrilla to other aquatic macrophytes in the guts of grass carp; effects of physical and chemical factors on movement of grass carp; and a theoretical stocking rate of grass carp for the WHTF. Frequency of occurrence of grass carp over hydrilla was calculated to be 84% and correlated with impoundment …

Characterization Of A Newly Cloned Dna Damage- Inducible Gene From Saccharomyces Cerevisiae Strain D43, June-Home Chen

Master's Theses

The identification and characterization of DNA damage-inducible genes is an important topic in the study of the integrity of the cellular genome. Previously, a TnlO-lacZ derivative was inserted randomly into yeast cells and the resulting mutants were screened for insertions in DNA damage-inducible genes. S. cerevisiae strain D43 was identified as one such TnlO-lacZ insertion mutant. DNA sequencing results show the insertion in D43 is located within the TDH2 gene, which encodes glyceraldehyde-3-phosphate dehydrogenase. Treatment of strain D43 with DNA damaging agents and heat shock suggest TDH2 is responsive to DNA damage, but not to heat shock. Haploid mutants carrying …

Density Dependent Limitations And Vertical Position Of Diatoms In A Periphyton Mat, Ronald E. Johnson

Master's Theses

No abstract provided.

The Role Of Protein Kinases In The Regulation Of The Na+/H+ Antiporter In Xenopus Oocytes, Andre P. J. Kulisz

Master's Theses

No abstract provided.

Sculpins As Predators Of Lake Trout Eggs And Larvae: An Assessment Of Their Predatory Capabilities And Constraints, Heather C. Biga

Master's Theses

No abstract provided.

Afferent And Efferent Connections Of The Octavolateral Cerebellum In The Channel Catfish, Ictalurus Punctatus, Richard C. Rayborn

Master's Theses

No abstract provided.

The Distribution Of Gamma-Aminobutyric Acid (Gaba) And Glutamate In The Electrosensory System Of The Channel Catfish, Ictalurus Punctatus, Christian M. Fay

Master's Theses

No abstract provided.

The Effects Of High Colony Density On Filtration, Mortality And Behavior In The Zebra Mussel, Dreissena Polymorpha, Christopher A. Call

Master's Theses

No abstract provided.

Microglial Reactivity To N-Methyl-D-Aspartate (Nmda) Induced Excitotoxicity In The Immature Rat Brain, Laia Acarin

Master's Theses

No abstract provided.

A Taxonomic Revision Of Neotropical Discocarpus (Euphorbiaceae), Sheila Mae Hayden

Master's Theses

This thesis is a taxonomic revision of Discocarpus, a genus of three species of trees from seasonally inundated forests of northern South America. Discocarpus is classified in the family Euphorbiaceae. The Euphorbiaceae or spurge family is a large and diverse taxon of angiosperms consisting of approximately 7000 species placed in 300 genera, comprising 49 tribes and 5 subfamilies (Webster 1994b). The origin of the family is likely Western Gondwanaland, and the earliest fossils identified as Euphorbiaceae date to the Paleocene (Raven & Axelrod 1974). The family is predominately tropical, however, species of Euphorbiaceae are important throughout most of the world …

Relationship Between Bcl-2 Oncogene Expression And Apoptosis In A Human Leukemia T Cell Line, Sascha Hedjbeli

Master's Theses

No abstract provided.

Secondary Production And Dietary Preference In Orconectes Propinquus (Girard), Patricia B. Krema

Master's Theses

No abstract provided.

Topography Of Anterior Lateral Line Nerve Branches In The Electrosensory And Mechanosensory Lateral Line Nuclei Of The Channel Catfish, Ictalurus Punctatus, Sanjay Singh

Master's Theses

No abstract provided.

The Toxicity Of Cadmium To The Aquatic Amphibian, Xenopus Laevis, Sharon S. Millirons

Master's Theses

Cadmium toxicity is poorly understood but is a potentially serious environmental pollutant. This study was initiated to determine the effect of significant concentrations of cadmium on a readily available aquatic laboratory organism.

The lethal concentration (LC50) for 50 percent of I week old Xenopus laevis tadpoles was determined to be 0.1 ppm CdCI 2. For 5 week old animals, the average LC50 was determined to be 0.98 ppm. Thus, cadmium poses greater toxic threats to the early developmental stages. Moreover, these concentrations of cadmium exceed those commonly found in the nation's water supply. Histological examination suggested that the main site …