Biology Commons^™

Sponges Of The Caribbean: Linking Sponge Morphology And Associated Bacterial Communities, Ericka Ann Poppell

Master's Theses

The ecological and evolutionary relationship between sponges and their symbiotic microflora remains poorly understood, which limits our ability to understand broad scale patterns in benthic-pelagic coupling on coral reefs. Previous research classified sponges into two different categories of sponge microbial associations: High Microbial Abundance (HMA) and Low Microbial Abundance (LMA) sponges. Choanocyte chamber morphology and density was characterized in representatives of HMA and LMA sponges using scanning electron microscopy from freeze-fractured tissue. Denaturing Gradient Gel Elextrophoresis was used to examine taxonomic differences among the bacterial communities present in a variety of tropical sponges. The results supported the hypothesis that choanocyte …

An Investigation Of The Changes Of Species Richness And Distribution Of The Unionidae (Bivalvia: Molusca) Within The Pamunkey Watershed, William Robert Lees

Master's Theses

A survey of the Unionidae within the Pamunkey Watershed was conducted to investigate changes in distribution and species richness compared to a previous survey (Riddick, 1973) conducted over 30 years ago. Species richness decreased from 10 species in the previous survey to four species in the present survey. Notable increases of species richness were found in the upper South Anna and the lower North Anna regions, while sizable decreases were found in the lower South Anna and the upper and middle regions of the Pamunkey River. Regression analyses and t-tests comparing mussel survey data with habitat parameters were conducted to …

Cytokine Expression By T. Helper Cells Responding To Stress, Dina Zanetti

Master's Theses

Stress causes alterations to the immune system. These alterations have lead to increased susceptibility to antigens. The present study explores shifts in T helper (TH) cell balance (TH1 and TH2), through their cytokine expression. This study was performed in three phases, and focused mainly on animals subjected to a 10 day a chronic unpredictable stress paradigm. Phase one used ELISAs to confirm the cytokine profile produced from TH 1 and TH2 murine cell-lines. Phase two used SDS PAGE and Western Immunoblotting to show that splenocytes from Long Evan's Hooded rats subjected to the stress paradigm, had decreased in intercellular in …

The Vascular Flora Of Powhatan County, Virginia, Michael Austin Terry

Master's Theses

The project was undertaken with three main goals in mind: to provide as current and complete an account as possible of the flora of Powhatan County in the form of an annotated checklist; to integrate the information obtained from the inventory into phytogeographical and ecological generalizations currently being developed for the state of Virginia; and, to report any significant or anomalous discoveries. There is no previous county-wide inventory of plant diversity for Powhatan County. However, Corcoran (1981) published a list of plants from the Jones and Mill Creek watershed located in the Fine Creek Mills area of northeastern Powhatan.

The Status Of Leptodactylus Validus As A Single Taxon And Its Relationship To Letptodactylus Pallidirostris, Kenneth Christopher Yanek

Master's Theses

Leptodactylus validus exhibits an unusual distribution inhabiting Trinidad, Tobago, and the Lesser Antilles, but not the mainland of South America. This distribution is inconsistent with other distribution patterns observed for these islands. Although slight variation in adult morphology has been observed among the island populations, call data suggest the presence of a single species. Calls of Leptodactylus pallidirostris from Venezuela suggested that this taxon might be conspecific with L. validus. Herein sequence data from the 12S and 16S mt rRNA genes were collected and analyzed in order to address: 1.) whether more than one species is represented within L. validus, …

Acalypha Deamii : Distribution East Of The Appalachians And Comparative Studies Of Reproductive Anatomy, Patricia A. Truman

Master's Theses

Acalypha deamii (Euphorbiaceae), once thought restricted to flood plains of the Ohio and mid-Mississippi River systems, is now documented from similar habitats in Virginia, Maryland, and West Virginia along the James, Potomac, Rappahannock, Roanoke (Staunton), and Shenandoah rivers. This species is recognized by two-carpellate gynoecia, large seeds, and the routine occurrence of allomorphic flowers and fruits, features sporadically found within this large genus. In addition to documenting the newly recognized range extension of Acalypha deamii, this thesis also investigates the nature of its allomorphic reproductive structures. Staminate, pistillate, fruiting, and allomorphic reproductive structures of Acalypha deamii and a closely related …

A Mitochondrial Dna Phylogeny Of The Leptodactylus Fuscus Species-Complex (Leptodactylidae: Anura, Arley Camargo

Master's Theses

Leptodactylus fuscus is a broadly distributed frog species in the Neotropical region. Previous allozymic evidence supported the hypothesis of L. fuscus as a composite of several species. However, morphological and advertisement call data supported the hypothesis of a single-species taxon. These competing hypotheses were evaluated using cladistic analyses of mitochondrial DNA sequences. Fragments of 12S rRNA, 16S rRNA, and ND1 protein-coding genes from 17 populations were sequenced. Phylogenetic analyses were performed using: maximum parsimony, maximum likelihood, and Bayesian analysis. Data sets were analyzed separately and combined. Analyses of the combined data set show four exclusive clades of L. fuscus: …

A Quantitative Histological Evaluation Of Articular Cartilage And Regenerated Tissue From A Stress-Shielded In Vivo Model, Jeremy Matthew Kupsco

Master's Theses

Cartilage does not normally repair lesions. Cartilage induced to regenerate experimentally degenerates quickly, perhaps because stresses of articulation do not allow normal extracellular matrix to develop. I examined normal cartilage from dogs, pigs, rabbits, and humans, and canine patellar tissue regenerated in a stress-shielded environment. SEM of canine cartilage after trypsin digestion revealed meshworks of fibrils oriented with a bias normal to the surface in the deep zone, random in the middle zone, and parallel to the surface in the superficial zone. SEM after freeze-fracture revealed tubules of fibrils within the deep zone. I found no evidence of collagen arcades. …

Storm-Related Suspended Particulate Matter In Little Westham Creek, John R. Jordan

Master's Theses

Properties of a watershed regulate the amount of suspended particulate matter (SPM) in a stream. The present study examined relationships between storm-related SPM and impervious area and tree cover in the suburban watershed of Little Westham Creek, Richmond, Virginia during Summer and early Fall, 1999. SPM concentration, SPM discharge, and turbidity due to clay, silt and sand, and the areas of impervious surface and tree stand cover in the watershed were measured at three sites. SPM concentration, SPM discharge, and turbidity due to clay were greater upstream than downstream. The percentages of watershed area covered by impervious surfaces and tree …

The Role Of Matrix Metalloproteinase-2 In Glioma Invasion, Nicole Danielle Sauers

Master's Theses

Overexpression of matrix metalloproteinase 2, MMP-2, is correlated with highgrade gliomas in vivo. The purpose of this study was to investigate whether MMP-2 overexpression in glioma cell lines leads to increased invasion of glioma cells in vitro. The entire MMP-2 gene was isolated from U87, a glioma cell line known to have high expression of wild-type MMP-2. This :tvIMP-2 gene was inserted in a sense and antisense orientation into pCR3 .1 vectors with a CMV promoter to ensure high levels of expression. Glioma cell lines were transfected with the sense and antisense constructs, as well as the pCR3.l vector alone …

An Ulstrastructural Study Of Acetabularia Acetabulum, Rachel Vangilder

Master's Theses

Calcification within the cell and the cell wall Acetabularia acetabulum, a large single cell alga, is examined through an ultrastructural investigation, electron diffraction, and an elemental analysis. These methods suggest that amorphous calcium carbonate is located adjacent to and within the cell wall. The location of the crystals within and directly outside the cell wall suggests the calcium is obtained from the surrounding environment. Fibrillar structures are seen through SEM in areas where calcification is occurring. This fibrillar material appears to serve as the organic matrix where calcification initiates. Intracellularly electron dense materials is seen in the chloroplasts. This …

Transplanting Broodstock Oysters, Crassostrea Virginica, Onto Reconstructed Oyster Reefs To Increase Spat Recruitment In The Piankatank River, Dawn Chentil Sherwood

Master's Theses

Four oyster reefs were recreated from oyster shells to historical proportions in the Piankatank River from 1993-1995. In December 1997, two of the reconstructed reefs were supplemented with large broodstock oysters from Tangier and Pocomoke Sounds. Since total quantity as well as density ofbroodstock were believed to be limiting factors for recruitment in this river, adding stock was expected to raise spat recruitment. Methods included dive surveys on the reefs, and dredge and patent tong surveys on the natural oyster bars. The recruitment of spat to both reefs and bars was significantly higher in 1998 (p<0.001) than in the previous four years and a positive interaction (p<0.005) was seen between the reefs and the year 1998. Based on these dat~ stock enhancement in the Piankatank River successfully improved recruitment and suggest oyster restoration may be facilitated in other areas of the Chesapeake Bay by strategic enhancement of spawning stocks.

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

Investigation Of Different Patterns Of Induction Of Amylases In Different Cultivars Of Rice, Oryza Sativa L., Angela M. Mosley

Master's Theses

This study investigated whether rice exhibits exceptions to the accepted model, in cereals, for the induction of a and P-amylase in the embryo and endosperm during germination. We also tried to establish whether different patterns of induction were cultivar specific, or due to the influence of ripening temperature, or a component of the incubation medium. An isoelectric focusing technique was used to monitor a- and P-amylase activities, a spectrophotometric assay was used to quantify the activity of a-amylase, and two cDNA clones, RAmy3D and RAmylA, were used to measure a-amylase RNA accumulation by Northern analysis. Distinct patterns of induction of …

An Evaluation Of Hands-On Instruction As A Method To Improve Observation Skills In Second Grade Students, Lydia Rogers

Master's Theses

A hands-on assessment tool for testing second-grade students' ability to discriminate physical attributes (size, shape, color, texture, pattern, edge, part-to-whole, and type) of mollusk shells was developed, pretested, and administered to 48 second-grade students at Maybeury Elementary School, Henrico County, Virginia. Treatment group students (n = 24) attended five afterschool, activitybased classes in which close observation of object a~tributes was taught. The classes included the same discriminations as did the assessment test but used different materials. Control and test group students were retested. Neither paired t test nor question-by-question analysis showed a significant improvement in the test group's score. Presence …

Relationships Of Epidermal Morphology And Breeding Behaviors In Pebble Nest-Building Minnows (Pisces: Cyprinidae), William R. Mcguire

Master's Theses

Abstrad The objective of this study was to determine if epidermal morphology corresponds with reproductive behavior in cyprinid fishes. Representative species of nest-building fishes (Nocomds leptocephalus, Semotilus atromeculatus, exoglossum maxillingua) and non nest-building fishes (Campostoma anomaulm and Clinostomus funduloides) were studied. Light and scanning electron microscopy were used to examine epidermal morphology and keratin distribution of skins from the snout, cheek, mandible, anterior dorso-lateral trunk, and caudal peduncle of breeding males of nest-building species and were compared to those in non nest-building cyprinid species. Previous frame-by-frame analysis of video tapes of reproductive activities of each species and literature accounts were …

Localization Of A Collagenous Protein In The Organic Matrix Of Spicules From The Octocoral Leptogorgia Virgulata (Cnidaria: Gorgonacea), Jeffrey L. Dupree

Master's Theses

Calcareous body inclusions are commonly found throughout the invertebrate taxa. Elaborately structured calcium carbonate spicules are the major mineralized body inclusions of the gorgonian, Leptogorgia virgulata. Spicule formation in this octocoral, as well as other calcium carbonate invertebrate structures, is apparently regulated by the intra-spicule organic matrix. Recent findings show that the insoluble fraction of the spicule organic matrix is collagenous. Collagen, although integral to calcium phosphate structures found in vertebrates is not usually associated with the formation of invertebrate calcium carbonate structures. Interestingly, collagen is present in the organic matrix during the summer but absent in winter. This suggests …

Investigating The Viability Of Yeast Expressing Histone From Extrachromosomal Dna : Progress In Construction Of A Plasmid Bearing One Copy Of Each Yeast Histone Gene, Ralph Donaldson Hellams Jr.

Master's Theses

Much of the current information on histones has been based on in vitro studies. The original goal of this research was to construct a mutant strain of Saccharomyces cerevisiae containing all chromosomal copies of the yeast histone genes made nonfunctional. This project would demonstrate whether such a strain could be rescued by a plasmid carrying the wild-type copies of the four core histone genes. Furthermore, this yeast strain construct would allow future investigations to take advantage of histone mutant analysis in vivo. The critical step in beginning this work was the construction of a plasmid which contained the genes …

Atrial Natriuretic Factor In Meriones Unguiculatus, The Mongolian Gerbil, Kyriakos Tarasidis

Master's Theses

The basis for the great osmoregulatory ability in Meriones unguiculatus, the Mongolian gerbil, has been studied previously, but as yet no clear mechanism has been determined. The present study investigated the level of cardiac atrial natriuretic factor (ANF) under high and low sodium stress. In addition, cardiac ANF values for the Mongolian gerbil were compared with another desert mammal (Mesocricetus auratus, the Syrian golden hamster) and a non-desert mammal, (Rattus norvegicus, the white rat). ANF was found to exist in the hear atria of the Mongolian gerbil at a level of 388±66 µg ANF/g tissue. High and low sodium stress …