Biology Commons^™

Genetic Variability, Pathogen Susceptibility, Subspecies Identity And Conservation Of The Endangered Northern Flying Squirrel (Glaucomys Sabrinus) In Virginia, James Lincoln Sparks Jr.

Theses and Dissertations

I examined the population genetic structure of three known subspecies of Glaucomys sabrinus from Appalachia, Washington State, and two previously unexamined populations from Mount Rogers National Recreation Area (MRNRA) in Southwestern Virginia. Mean FST (0.107) and an AMOVA (P G. sabrinus subspecies populations in the southern Appalachians are genetically differentiated. Glaucomys sabrinus at MRNRA were less inbred than expected. Gene flow, a consensus tree based on Nei's genetic distance, elevated heterozygosity and morphometric data suggest that the MRNRA G. sabrinus population is an intergrade of the two recognized Appalachian subspecies, G. s. fuscus and G. s. coloratus. I compared inbreeding …

Material And Acoustic Properties Of Swimbladders Of Tilapia And Channel Catfish, Mohammed Ali Nawaz

Theses and Dissertations

Acoustically, teleost swimbladders have been considered resonant underwater bubbles. Contrary results indicating that bladders are tuned less sharply than such a bubble have been explained by damping of surrounding fish tissue. Recent findings in toadfish and weakfish, however, suggest that the bladder is a highly damped structure and that the frequency of the fish sounds is deternlined as a forced response to sonic muscle movement rather than by resonance of the bladder. In this study I examined acoustics and material properties of swimbladders in Tilapia (an auditory generalist) and the channel catfish (an auditory specialist). The swimbladder was struck with …

Seasonal And Spatial Variation In Leaf Area Index, Litter Production, And Light Levels In Myrica Cerifera,Shrub Thickets Across A Barrier Island Chronsequence, Steven T. Brantley

Theses and Dissertations

Leaf area index (LAI), litter production and understory light levels of Myrica cergera shrub thickets were assessed on Hog Island, Virginia to quantify spatial and seasonal variations in leaf area and light attenuation among four thickets representing a successional chronosequence and compare methods of estimating LA1 in shrub- dominated systems. Seasonal LA1 estimates were made seven times throughout the year with a portable integrating radiometer (Li-Cor LAI-2000) and three times by measurement of photosynthetically active radiation (PAR) and use of the Beer-Larnbert law. Leaf area index was also estimated through leaf litter collection and use of allometric relationships between stem …

The Effect Of Loading On Disturbance Sounds Of The Atlantic Croaker Micropogonius Undulatus: Air Versus Water, Michael L. Fine, Justin Schrinel, Timothy M. Cameron

Biology Publications

Physiological work on fish sound production may require exposure of the swimbladder to air, which will change its loading (radiation mass and resistance) and could affect parameters of emitted sounds. This issue was examined in Atlantic croaker Micropogonius chromis by recording sounds from the same individuals in air and water. Although sonograms appear relatively similar in both cases, pulse duration is longer because of decreased damping, and sharpness of tuning (Q factor) is higher in water. However, pulse repetition rate and dominant frequency are unaffected. With appropriate caution it is suggested that sounds recorded in air can provide a useful …

Regulation Of Fc Receptor Expression And Signaling On Murine Mast Cells, Hey Jin Chong

Theses and Dissertations

Mast cells have long been appreciated as the primary effector cells in allergy and asthma, and recently have been implicated in other inflammatory diseases. Using high density oligonucleotide probe arrays, we assessed genome-wide transcriptional profiles after FcεRI aggregation for 90 minutes, 5 hours and 24 hours. We describe novel gene regulation in response to FcεRI signaling, including altered expression of CD44, Pari, osteopontin, Nur77, E4BP4, and NDRG 1. In addition, the gene encoding FcεRI β was downregulated 5 hours after mast cell activation according to both microarray analysis and RPA, and western blotting confirmed the downregulation of the beta subunit …

Surface Characteristics Of Bacillus Spores, Darlene Danette Sabio

Theses and Dissertations

Rapid isolation and identification of spores from various environmental samples is necessitated because anthrax spores can be used as biological weapons. The hydrophobic nature of spores may allow for their rapid concentration and partial purification from contaminating materials. In this study, spores from four taxonomic groups of Bacillaceae were isolated, purified and characterized for hydrophobicity by hexadecane partitioning, surface morphology by scanning electron microscopy, and steady-state fluorescence by spectroscopy. The morphology of spores was similar within taxonomic groups and dissimilar between groups. Spore hydrophobicity ranged from 0.3% to 65% and all spores had fluorescence emission peaks at 335 nm and …

Acoustic Communication In Two Freshwater Gobies: Ambient Noise And Short-Range Propagation In Shallow Streams, Marco Lugli, Michael L. Fine

Biology Publications

Noise is an important theoretical constraint on the evolution of signal form and sensory performance. In order to determine environmental constraints on the communication of two freshwater gobies Padogobius martensii and Gobius nigricans, numerous noise spectra weremeasured from quiet areas and ones adjacent to waterfalls and rapids in two shallow stony streams. Propagation of goby sounds and waterfall noise was also measured. A quiet window around 100 Hz is present in many noise spectra from noisy locations. The window lies between two noise sources, a low-frequency one attributed to turbulence, and a high-frequency one (200–500 Hz) attributed to bubble …

Acoustic Competition In The Gulf Toadfish Opsanus Beta: Acoustic Tagging, Robert F. Thorson, Michael L. Fine

Biology Publications

Nesting male gulf toadfish Opsanus beta produce a boatwhistle advertisement call used in male–male competition and to attract females and an agonistic grunt call. The grunt is a short-duration pulsatile call, and the boatwhistle is a complex call typically consisting of zero to three introductory grunts, a long tonal boop note, and zero to three shorter boops. The beginning of the boop note is also gruntlike. Anomalous boatwhistles contain a short-duration grunt embedded in the tonal portion of the boop or between an introductory grunt and the boop. Embedded grunts have sound-pressure levels and frequency spectra that correspond with those …

Studies On The Role Creb As A Mediator Of Neurotrophin-3 Actions In Oligodendrocytes, Jamie Richard Johnson

Theses and Dissertations

In the central nervous system (CNS), oligodendrocytes (OLGs) are the cells responsible for producing the myelin membrane which allows for the saltatory conduction of neuronal impulses. We have previously shown that CREB (cAMP response element binding protein), a transcription factor that belongs to a large family bZip (basic leucine zipper) proteins, could be a mediator of neuronal signals that, coupled to different signal transduction pathways, may play different regulatory roles at specific stages of oligodendrocyte development. We have found before that, in committed OLGs, CREB activation by phosphorylation can be triggered by β-adrenergic stimulation and appears to play a role …

Determination Of Rates And Patterns Of Recombination At The Maize Red Color (R1) Locus, William R. Dietrich

Theses and Dissertations

Homologous recombination has been studied in many plant and animal systems. In maize, most recombination occurs intragenically. The current study assessed the frequency and location of meiotic recombination at the maize red color (r1) gene. Three independent mutant (colorless seed) alleles derived from the colored seed allele, R-sc:124, were made heterozygous with the colored plant allele, r-r:n142. Each mutant resulted from the insertion of a Dissociation (Ds) transposable element into the 3' end of R-sc:124. In the presence of Activator (Ac), each Ds insertion allele (r-sc:mutables) produced spotted seeds and germinal reversion to fully colored seeds due to the vi …

Trophic Ecology Of Native And Introduced Catfishes In The Tidal James River, Virginia, Louis Fairfax Chandler

Theses and Dissertations

Species introductions have been linked to the decline of native taxa, and in many cases have resulted in the elimination of native species in both terrestrial and aquatic systems throughout the United States. In aquatic systems, a particular threat is the introduction of large piscivorous fish that may alter the native fish community structure. For example, introductions of large ictalurids such as blue catfish, (lctalurus furcatus), and flathead catfish, (Pylodictus olivaris), into coastal Virginia rivers, including the James River twenty years ago have resulted in the establishment of these large, predatory fishes.

This study described the trophic ecology of four …

Coxsackievirus B4 Induced Diabetes In Cd-1 Mice, Mary C. F. Anderson

Theses and Dissertations

Most evidence to date clearly indicates that CB4 virus can affect the pancreas of both man and mice during acute infection. Yet, conflicting evidence exists relative to the consequence of the infection in both man and mice. The study described here attempted to provide definitive evidence on the relative role of the virus isolate (i.e. heterogenous virion populations vs. purified clones) in induction of prolonged diabetes-like disease in mice.

A Nutritional And Morphological Study Of Two Cyanobacteria Free Azolla Ferns, Michael Paul Bonner

Theses and Dissertations

The symbiotic association between the aquatic water fern Azolla and its symbiont, Anabaena azollae Straus. has been extensively studied in the past ten years. The cyanobacteria has received much of the attention due to its ability to fix atmospheric nitrogen while the fern free of the cyanobiont has been somewhat neglected. The purpose of this research was to determine the nutritional requirements of the cyanobacteria free (CBF) ferns and study the morphology of the leaves and branches of these CBF ferns.

Azolla filiculoides and Azolla pinnata were freed of the cyanobiont using the surface sterilization technique adopted from Duckett, et …

Multivariate Analyses Of Mid-Winter Fattening In Two Species Of Passerine Birds, Michael Harold Shelor

Theses and Dissertations

Although the adaptive significance of daily and seasonal fattening of birds has been studied by many investigators (see Odum, 1965; King, 1972; Blem, 1976a), surprisingly little is known about the interactions of proximate and ultimate environmental factors regulating avian lipid levels. An exception is the study by Evans (1969). He found that lipid levels in Yellow Buntings (Emberiza citrinella) were more closely correlated with long-term temperature averages than with temperatures of the day of capture, or the days preceding or following capture. This is an indication that temperature may be more important as an ultimate control of fattening, through natural …

The Chronic Effects Of Estradiol Benzoate On Ventricular Myocardial Blood Flow In The Adult Female Rat, Stephen Maurice Ashe

Theses and Dissertations

Clinical and experimental data suggest that humans and some animals are protected from acute myocardial infarction by estrogen. There has been much speculation of the exact role which estrogen plays in the circulation. The mechanism of this hormonally related protection is unclear.

In the present study the chronic effects of estradiol benzoate on coronary blood flow in adult female rats were studied. Female control rats, castrates and castrates receiving estrogen for a period of 16 weeks were used. In vivo tracer microsphere studies of myocardial blood flow allowed the quantification of the effects of estrogen on coronary circulation. Results of …

An Interphysiographic Analysis Of Herb And Shrub Vegetation In Virginia Forests, Stephen James Binns

Theses and Dissertations

Thirty upland deciduous stands were sampled from the mid-coastal Plain to the mid-Piedmont in New Kent, Hanover, and Louisa Counties. Density data for herb and shrub species were collected and soil samples were collected in each stand. A cluster analysis of the vegetation data was performed using Euclidean Distance and "furthest-neighbor" clustering. Four clusters of stands were identified. A cluster of six stands with Euonymus americanus as the dominant species was strongly related to the Coastal Plain, but the other clusters were not physiographically associated. Other important species in the analysis were Vaccinium vacillans, Gaylussacia baccata, and Mitchella repens.

The …

Characterization Of The Bursicon-Mediated Pathway For Membrane Permeability Enhancement In The American Cockroach, Periplaneta Americana, David Alan Compton

Theses and Dissertations

The presence of an adenyl cyclase system within the haemocyte of Periplaneta americana has been confirmed by previous investigations, with corresponding experiments using dibutyryl cyclic AMP to show enhancement of 14c-tyrosine uptake into the cuticle linked to stimulation of the sclerotization process.

In the present studies, American cockroaches held at depressed temperatures were treated with bursicon, revealing an increase in haemocyte cyclic AMP concentrations. The levels declined with progression of time, probably resulting from enzymatic hydrolysis.

When animals which had been held at room temperature were treated with bursicon, the levels of haemocyte cyclic AMP were lowered, with a declination …

Temporal Aspects Of Calling Behavior In Oyster Toadfish, Opsanus-Tau, Michael L. Fine

Biology Publications

The oyster toadfish, Opsanus tau (Linnaeus), produces two calls: an agonistic grunt and a boatwhistle associated with courtship (Fish 1954; Tavolga 1958,1960; Gray and Winn 1961). The boatwhistle is produced only by males on nests (Gray and Winn 1961) and is endogenously driven as well as influenced by calling of surrounding males (Winn 1964, 1967, 1972; Fish 1972). A toadfish, not hearing other males, may still boatwhistle for long periods and attract a female. Although toadfish may be influenced to call by the calling of adjacent males, one would assume the circadian patterning of the boatwhistle to be influenced by …

Incorporation Of Phosphoproteins And Phenol-Bound Proteins Into The Cuticle Of Periplaneta Americana, Joseph Atchison Florence Iv

Theses and Dissertations

The incorporation of phosphoproteins and phenol-bound proteins into the cuticle of Periplaneta americana was analyzed. Radioactive monosodium phosphate was injected into newly ecdysed cockroaches. Incorporation into haemolymph proteins as well as tanned cuticle was observed. Phosphoproteins were observed to be combined with the cuticle to a greater extent than monosodium phosphate. This suggests that phosphate is being incorporated into the cuticle more readily than monosodium phosphate. The relevance of these observations is discussed in light of phosphate being a possible crosslinking agent between chitin and cuticle protein.

Binding of dopamine metabolites to cuticle proteins was investigated. Specific metabolites studied were …

Distribution And Effects Of Bacterial Endotoxin, Anne Carter Adams

Theses and Dissertations

In this study the distribution and effects of bacterial endotoxin were examined. Adult male BALB/c and adult male DUB/ICR mice were used in all experiments. Endotoxic activity of a number of strains from three genera of bacteria, Pseudomonas, Bacteroides, and Listeria, was detected using vincristine-treated mice as sensitized indicators for endotoxin and resistance to purified endotoxin induced by pretreatment with selected bacteria. Also, the effect of bacterial endotoxin and endotoxin-like substances on the course of primary amebic meningoencephalitis in mice, caused by Naegleria fowleri, was assessed.

Food Habits Of The Game Fishes Of Lake Anna, Virginia, Thomas Kenneth Rohrer

Theses and Dissertations

Beginning in May, 1973 and continuing through August, 1974 the food habits of several species of game fishes from Lake Anna, Virginia were investigated via gut content analysis. A variety of collecting methods were employed to secure specimens for examination and stomach contents were reported as percent frequency of occurrence. A total of one hundred and two collections were made yielding 287 largemouth bass, Micropterus salmoides (Lacépède); 166 chain pickerel, Esox; niger LeSueur; 53 bluegill, Lepomis macrochirus Rafinesque; 32 pumpkinseed, Lepomis gibbosus (Linnaeus); and 63 black crappie, Pomoxis nigromaculatus (LeSueur). It was found that M. salmoides and E. niger were …

The Effect Of Aflatoxin B1 On Growth Rate And Iron Metabolism In Juvenile Mongolian Gerbils (Meriones Unguiculatus), William Stanley Hastings Jr.

Theses and Dissertations

The metabolic secretions from Aspergillus flavus, aflatoxins. are often found as contaminants of agricultural products used for human and animal consumption. Aflatoxin B1 is the most toxic and carcinogenic of the aflatoxins. A reduction in weight gain has been observed when juvenile animals are fed aflatoxin B1 over an extended period of time. This reduction in weight gain may possibly result from an anemic condition induced by an alteration of iron absorption and/or distribution. The effect of chronic sublethal levels of this hepatocarcinogen on weight gain and the uptake and distribution of 59Fe++ were studied in this investigation.

An experimental …

A Variation Of The Standard Steepest Ascent Search Procedure For Response Surface Experiments, George Whitfield Cobb

Theses and Dissertations

The results of this chapter lead to a modification of the standard stopping rule which breathes new life into the method of steepest ascent, but which is unfortunately not sufficient to effect a total resuscitation. As expected, there is no uniformly optimum stopping rule, nor even a uniformly best test statistic; both the optimum statistic and the optimum test level depend on the model parameters y1 and y2. One can, however, adopt a compromise rule which works reasonably well for all parameter combinations by testing at the 25% level with the statistic zn = 1/2(yn -yn-2). In many cases the …