Biology Commons^™

A Nuclear Dna Perspective On Delineating Evolutionarily Significant Lineages In Polyploids: The Case Of The Endangered Shortnose Sturgeon (Acipenser Brevirostrum), Tim L. King, Anne P. Henderson, Boyd E. Kynard, Micah C. Kieffer, Douglas L. Peterson, Aaron W. Aunins, Bonnie L. Brown

Biology Publications

The shortnose sturgeon, Acipenser brevirostrum, oft considered a phylogenetic relic, is listed as an “endangered species threatened with extinction” in the US and “Vulnerable” on the IUCN Red List. Effective conservation of A. brevirostrum depends on understanding its diversity and evolutionary processes, yet challenges associated with the polyploid nature of its nuclear genome have heretofore limited population genetic analysis to maternally inherited haploid characters. We developed a suite of polysomic microsatellite DNA markers and characterized a sample of 561 shortnose sturgeon collected from major extant populations along the North American Atlantic coast. The 181 alleles observed at 11 loci …

Spatiotemporal Variability And Sound Characterization In Silver Croaker Plagioscion Squamosissimus (Sciaenidae) In The Central Amazon, Alfredo Borie, Hin-Kiu Mok, Ning L. Chao, Michael L. Fine

Biology Publications

Background

The fish family Sciaenidae has numerous species that produce sounds with superfast muscles that vibrate the swimbladder. These muscles form post embryonically and undergo seasonal hypertrophy-atrophy cycles. The family has been the focus of numerous passive acoustic studies to localize spatial and temporal occurrence of spawning aggregations. Fishes produce disturbance calls when hand-held, and males form aggregations in late afternoon and produce advertisement calls to attract females for mating. Previous studies on five continents have been confined to temperate species. Here we examine the calls of the silver croakerPlagioscion squamosissimus, a freshwater equatorial species, which experiences constant …

The Effect Of Fluvastatin On Mast Cell Function: Genotype Dependence, Elizabeth M. Kolawole

Theses and Dissertations

Fluvastatin, the HMG-CoA reductase inhibitor known for its role in the treatment of hypercholesterolemia and cardiovascular disease, has more recently been shown to play a role in the immune response. Given the critical role that mast cells play in allergy and inflammatory diseases such as asthma, which effects one third of America’s population, we assessed the effect of fluvastatin on mast cell and basophils function. We demonstrate that fluvastatin downregulated IgE-mediated cytokine production. Additionally, in vivo studies showed that fluvastatin suppressed IgE-mediated anaphylaxis. Interestingly, the effects of fluvastatin showed dependence on genetic background, as C57BL/6 mast cells were sensitive, while …

The Role Of Nitric Oxide Scavenging In Hemoglobin-Based Oxygen Carrier Induced Hypertension: Systemic And Microvascular Effects, Alan Ottarson

Theses and Dissertations

The purpose of this study was to identify the effects of a hemoglobin-based oxygen carrier, HBOC-201, on the cardiovascular system. Systemic cardiovascular parameters of mean arterial pressure (MAP), pulse pressure, heart rate, and oxygen saturation, as well as vascular resistance, were examined. A murine model of the cardiovascular system and microvasculature was employed. Sprague-Dawley rats (male; 230-530g; N = 13) were anaesthetised and surgically prepared for intravital microscopy of the spinotrapezius muscle. Increasing doses of HBOC-201 (2 mg/kg, 22 mg/kg, 230 mg/kg, and 780 mg/kg) and an iso-oncotic volume control were administered to assess for a dose-response relationship. MAP displayed …

Historical Tidal Forest Composition And Contemporary Woody Recruitment Following Dam Removal From A Mid-Atlantic Coastal Plain Tidal Freshwater Wetland, Richard E. Ward Jr.

Theses and Dissertations

Tidal freshwater forest restoration after dam removal has been unexplored to date. This study elucidated pre-dam forest composition, as well as post-dam edaphic and microtopographical attributes and woody species recruiting along a narrow ecotone of a 29.3-ha tidal freshwater wetland. The ≈65-year-old historical forest (15 species, 200 stems ha-1) and ≈7-year-old contemporary forest (40 species and 11,009 stems ha-) community dominants were dissimilar (Fraxinus spp. vs. Liquidambar styraciflua, respectively). Pre-dam environmental conditions were unknown. Post-dam edaphic water content, organic matter, redox potential and microtopography differed significantly across tidal sites but were less variable in non-tidal sites. Shifts in the contemporary …

"Mining" For A Reference Condition In Southern West Virginia Streams, Matthew Rouch

Theses and Dissertations

Quarterly samples were used to estimate assemblage-level (all species combined) fish production within three minimally-impacted, southern West Virginia streams. The total annual fish production estimate was highest in Slaunch Fork (37.52 kg∙ha^-1∙y^-1), a tributary of the Tug Fork River, and lowest in Cabin Creek (10.59 kg∙ha^-1∙y^-1), a Guyandotte River tributary. Creek Chub Semotilus atromaculatus, Mottled Sculpin Cottus bairdii and Blacknose Dace Rhinicthys atratulus were the most abundant species among sites, accounting for >90% of all sampled individuals. Reference condition criteria were also selected and metrics calculated for each of the three …

The Response Of Naive Channel Catfish To Chemical Cues Associated With Predation, Marinda Coulter

Theses and Dissertations

The chemosensory abilities of fishes, are important in order to understand how prey can perceive and avoid predators. Predator-naïve Channel catfish were exposed to four extracts over eight sessions (naïve bass water (NBW), bass that were fed catfish water (BFCW), catfish skin extract (CS), and naïve bass water paired with catfish skin extract (CO)) to determine whether they have an innate predator response to potential chemical cues indicating possible predation risk. Movement was quantified as grid squares crossed, directional changes, and tail beats. Response increased during the first minute following stimulus injection and decreased during the second minute. Channel catfish …

Who's Your Daddy? A Study Of Extra-Pair Copulation And Mating Behaviors Of Protonotaria Citrea, Morton Catherine Heidrich

Theses and Dissertations

Mating behavior has a profound impact on reproductive success and the resulting genetic structure of offspring. Extra-pair copulation is a widely observed behavior within avian species. This study explored the genetic effects of mating behaviors of Prothonotary warblers, Protonotaria citrea (Parulidae), using co-dominant microsatellite markers. Prothonotary warblers are migratory songbirds that build nests in cavities, commonly found in wetland habitats. A set of artificial nest boxes were initiated by Dr Robert Reilly in 2002 in Dutch Gap, Chesterfield County Virginia, USA, a tidal tributary off the James River. From this population, 28 nest boxes were surveyed yielding 47 adults and …

Confocal Microscopy Study Of The Embryonic Development Of The Viviparous Nemertean Prosorhochmus Americanus Reveals Larval Features Supporting Indirect Development In Hoplonemerteans, S Tyler Spindle

Theses and Dissertations

Recent studies of hoplonenemertean planuliform larvae have clarified their development and provided insight into larval evolution within the phylum. However, an assessment of viviparous development using modern techniques is lacking. To help facilitate a comprehensive comparative evaluation of developmental diversity within hoplonemerteans, we have conducted a confocal laser scanning microscopy investigation of the development in Prosorhochmus americanus, one of the few viviparous hoplonemertean species. Phalloidin staining provides evidence of a modified transitory larval epidermis, and reveals that the foregut, midgut, proboscis, central nervous system, and body wall musculature form early in development, consistent with observations for planktonic and encapsulated hoplonemertean …

Environmental Influences On Sex Ratio And Spatial Distribution Of Dioecious Morella Cerifera L. On A Virginia Barrier Island., Molly Hokkanen

Theses and Dissertations

For dioecious plant species, sex ratios within a population depend on multiple environmental and life history characteristics. Sex ratio is an indicator of population health and can be a predictor for genetic bottlenecking. My study established the previously unknown sex ratio for the shrub, Morella cerifera, on a Virginia barrier island. The ratio was compared with multiple environmental and reproductive traits to determine their potential influence on sex determination and/or distribution of male and female plants. Multivariate analyses were used to identify relationships between sex, sex ratio and environmental drivers. The sex ratio for M. cerifera changed depending on scale. …

Development Of Pectoral Apparatus In Ictalurid Catfish, Shweta Lahiri

Theses and Dissertations

The thesis contains two manuscripts- 1) Developmental changes in pectoral muscle fiber diameter and number in the Blue Catfish, Ictalurus furcatus and 2) Reduction in pectoral spine and girdle in domesticated Channel Catfish, Ictalurus punctatus is likely caused by the absence of fish predators. The first study showed that fiber diameter increased linearly with fish size, whereas fiber number increases non linearly with fish size in the Blue Catfish correlated with dietary shift. The second study showed shorter spines in domesticated Channel Catfish as compared to wild Channel Catfish was a result of reduction in selection pressure during domestication in …

The Effects Of Saltwater Intrusion On Methanogen Community Abundance, Structure, And Activity, Jaimie Gillespie

Theses and Dissertations

Tidal freshwater wetlands (TFW) are at significant risk of loss or alteration due to global climate change, and saltwater intrusion from sea level rise is of particular concern for these habitats due to their proximity to coastal areas. A space-for-time model was used to investigate the effects of saltwater intrusion on soil methanogen communities along naturally occurring salinity gradients on the Waccamaw, James, and Hudson Rivers. Amplification of the methyl coenzyme-M reductase (mcrA) functional gene was used in qPCR, reverse transcription qPCR, and T-RFLP to measure the abundance, activity, and community composition of soil methanogens. Both the abundance and activity …

Phylogeography And Species Status Of Ramphogordius Sanguineus, Cora Runnels

Theses and Dissertations

Ramphogordius sanguineus (Rathke 1799) is a gregarious nemertean with a worldwide distribution and found mainly on hard substrates associated with mussels, oysters and other organisms of the fouling community. Asexual reproduction occurs by spontaneous fragmentation and only anecdotal accounts of sexual reproduction exist. This is the first phylogeographic study of R. sanguineus as well as the first species delimitation analyses employing DNA markers. Analysis of the mitochondrial gene nad6 and nuclear ISSR markers showed little diversity among geographically widespread populations, but AMOVA analyses of both markers revealed moderate to high genetic differentiation. Populations from Maine and Massachusetts exhibited the highest …

Impact Of Self-Fertilization On Fecundity, The Timing Of First Reproduction, And Population Genetic Structure: Is A Mate Worth The Wait?, Serena Caplins

Theses and Dissertations

Organisms capable of self-fertilization typically exhibit two evolutionary syndromes uniting high inbreeding depression with low levels of selfing, or low inbreeding depression and high levels of selfing. This study tests for inbreeding depression in an apparent self-compatible, hermaphroditic marine nemertean worm, Prosorhochmus americanus. Fecundity and timing to first reproduction were assessed in isolated and paired worms. Isolated worms produced significantly more offspring than paired worms and did not show inbreeding avoidance. The selfing rate of natural populations was evaluated using species-specific microsatellites and is consistent with preferential selfing (mean: 0.801), though some outcrossing appears to take place. Population genetic structure …

Genetic And Molecular Analysis Of The Maize R1 Locus, Jennifer Derkits

Theses and Dissertations

Canalization, the stability of phenotypes in the presence of a specific genotype and environment is important for trait selection and understanding gene expression pathways. The goal of this study was to investigate mechanisms involved in the loss of canalization at the maize r1 locus. A specific lightly colored R-sc derivative, R-sc:86-17(L), was mutagenized with ethyl methyl sulfonate (EMS), and the progeny screened for restoration of dark seed color and canalization. Putative revertants/mutants were mapped relative to the r1 locus, tested for complementation to each other to identify a minimum number of genes involved in canalization, tested for cis silencing of …

Inhibition Of Retinoic Acid Receptors Results In Defasciculation Of The Trigeminal Nerve In Xenopus Laevis, Jeremy Thompson

Theses and Dissertations

The anatomy of the cranial peripheral nervous system has been studied for over a century, yet surprisingly little is known about how the nerves are guided to their targets. The study of the development of these nerves has important implications for our understanding of craniofacial anomalies and possible treatments for both injury and genetic disorders of nerve development such as Goldenhar-Gorlin syndrome. We have discovered that retinoic acid (RA) may play a role in the development of the trigeminal nerve. Inhibition of retinoic acid receptors (RAR) results in trigeminal nerves that become unbundled or defasciculated in the eye region. To …

The Role Of Camk-Ii In Skeletal Muscle Function And Swimming Behavior In Zebrafish, Minh Nguyen

Theses and Dissertations

Previous research showed mutations in muscle sarcoplasmic reticulum-bound calcium handler proteins cause swimming defects in embryonic zebrafish. CaMK-II is a highly conserved Ca2+/calmodulin-dependent protein kinase expressed in all vertebrates has been defined to activate and inactivate multiple Ca2+ handler proteins involved in excitation- contraction coupling and relaxation of cardiac and skeletal muscle. In this study, evidence is provided through pharmacological and genetic intervention that CaMK-II inhibition and overexpression causes swimming defects, particularly response to stimuli and swimming ability, reinforced by immunolocalization of skeletal muscle. Transient CaMK-II inactivation does not have any long-term defects to swimming behavior. Overexpression of wild-type, constitutively …

A Macrophysiological Analysis Of Energetic Constraints On Geographic Range Size In Mammals, Salvatore J. Agosta, Joseph Bernado, Gerardo Ceballos, Michael A. Steele

Biology Publications

Physiological processes are essential for understanding the distribution and abundance of organisms, and recently, with widespread attention to climate change, physiology has been ushered back to the forefront of ecological thinking. We present a macrophysiological analysis of the energetics of geographic range size using combined data on body size, basal metabolic rate (BMR), phylogeny and range properties for 574 species of mammals. We propose three mechanisms by which interspecific variation in BMR should relate positively to geographic range size: (i) Thermal Plasticity Hypothesis, (ii) Activity Levels/Dispersal Hypothesis, and (iii) Energy Constraint Hypothesis. Although each mechanism predicts a positive correlation between …

Characterization And Generation Of Male Courtship Song In Cotesia Congregata (Hymenoptera: Braconidae), Justin P. Bredlau, Yasha J. Mohajer, Timothy M. Cameron, Karen M. Hester, Michael L. Fine

Biology Publications

Background

Male parasitic wasps attract females with a courtship song produced by rapid wing fanning. Songs have been described for several parasitic wasp species; however, beyond association with wing fanning, the mechanism of sound generation has not been examined. We characterized the male courtship song of Cotesia congregata (Hymenoptera: Braconidae) and investigated the biomechanics of sound production.

Methods and Principal Findings

Courtship songs were recorded using high-speed videography (2,000 fps) and audio recordings. The song consists of a long duration amplitude-modulated “buzz” followed by a series of pulsatile higher amplitude “boings,” each decaying into a terminal buzz followed by a …

Characterization Of Microsatellite Loci And Pilot Population Genetic Analysis In Hickory Shad, Alosa Mediocris, Fnu Vishakha

Theses and Dissertations

The hickory shad (Alosa mediocris) is a relatively understudied species of the anadromous fish sub-family Alosinae. This study, the first population genetic analysis of this species, employed 12 neutral microsatellite loci to estimate genetic diversity and population structure in tributaries of lower Chesapeake Bay, Virginia including James River and its tributaries (Appomattox and Chickahominy Rivers), Rappahannock River, and Pamunkey River. Genetic variation was extremely low. Estimates of observed heterozygosity were lower than expected heterozygosity. Significant population structure was detected among the six samples (FST = 0.093, p = 0.01). Effective population sizes were low (Ne ranged from 2 to 134). …

Ocean Acidification: Understanding The Coastal Carbon Pump In A High Co2 World, Rachel Cooper

Theses and Dissertations

Since the 1800s, carbon dioxide emissions due to human activities have contributed significantly to the amount of carbon in the atmosphere. Approximately a third of this carbon is absorbed by the ocean, through air-sea fluxes at the ocean surface (Sabine, 2004). Increased CO2 has changed the carbon chemistry of the ocean and hence the pH. pH is expected to drop by 0.4 by the year 2100. It is unclear how this lower pH will affect carbon cycling and sequestration with respect to the biological carbon pump. Most studies have focused on open ocean phytoplankton or bacterial communities in large, stationary …

Effects Of Leaf Litter Diversity On Nutrients And Mosquito Communities In Neotropical Artificial Tree Holes, Rachel Komosinski

Theses and Dissertations

Inputs from terrestrial habitats to aquatic habitats are important for structuring aquatic communities. Terrestrial producer diversity in the tropics may decline due to anthropogenic causes. I investigated how tree diversity affects aquatic communities. We used leaves from three timber-producing species (Dalbergia retusa, Pachira quinata, and Tectona grandis) to test the effects of leaf litter species composition and richness on invertebrate aquatic communities in Gamboa, Panama. We quantified macroinvertbrate species richness and abundances, leaf litter mass loss, and dissolved carbon to nitrogen ratios (C:N) after 4 weeks. We found that litter types differed in breakdown and C:N. Tectona grandis had lower …

Sex-Specific Habitat Use And Responses To Fragmentation In An Endemic Chameleon Fauna, Philip Shirk

Theses and Dissertations

Chameleons are an understudied taxon facing many threats, including collection for the international pet trade and habitat loss and fragmentation. A recent field study reports a highly female-biased sex ratio in the Eastern Arc Endemic Usambara three horned chameleon, Trioceros deremensis, a large, sexually dimorphic species. This species is collected for the pet trade, and local collectors report males bring a higher price because only this sex has horns. Thus, sex ratios may vary due to differential rates of survival or harvesting. Alternatively, they may simply appear to be skewed if differences in habitat use biases detection of the sexes. …

The Role Of A And B Vitamins During Orofacial Development Of Xenopus Laevis, Allyson Kennedy

Theses and Dissertations

Orofacial anomalies make up about a third of the 120,000 birth defects each year in the United States. Children born with these abnormalities must undergo immense physical and emotional strain in order to correct the defects. In fact, about $697 million is spent every year surgically treating children with cleft lip and/or cleft palate (2011). In countries where surgery is not an option, this abnormality causes immense difficulties in eating, hearing, speech, and psychosocial development. The causes of cleft lip/palate are extremely complex. Genetics play a role in the anomaly; however, 95% of cleft palate cases are non-syndromic and likely …

Impacts Of Rdx Soil Contamination Across An Age Gradient For The Native Shrub Morella Cerifera., Stephen Via

Theses and Dissertations

Understanding the impacts of explosive contamination on vegetation is key to understanding explosives behavior in the environment. I quantified shrub growth responses to 1,3,5-trinitroperhydro-1,35-triazine (RDX) soil contamination across three life stages and I hypothesized that RDX would have the greatest impact on seed germination. Morella cerifera seeds were germinated on soils amended with RDX up to 1500 mg RDX kg-1 dry soil. Juvenile and adult individuals were exposed for 6 weeks to soil amended with RDX up to 750 and 1500 mg RDX kg-1 dry soil, respectively. Morphological responses were quantified for juveniles while physiological measurements were quantified for adults. …

Functional And Biochemical Consequences Of Single Nucleotide Polymorphisms In The Human Vesicular Monoamine Transporter 1 Gene (Slc18a1) By Sally Gamal Shukry, B.S., Sally Gamal Shukry

Theses and Dissertations

Abstract FUNCTIONAL AND BIOCHEMICAL CONSEQUENCES OF SINGLE NUCLEOTIDE POLYMORPHISMS IN THE HUMAN VESICULAR MONOAMINE TRANSPORTER 1 GENE (SLC18A1) By Sally Gamal Shukry, B.S. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology at Virginia Commonwealth University. Virginia Commonwealth University, 2012 Major Advisor: Jennifer K. Stewart Associate Professor and Graduate Director, Department of Biology Single nucleotide polymorphisms (SNP) in the human VMAT1 gene (SLC18A1) have been associated with schizophrenia in three different populations: Han Chinese, Western European and Japanese. Effects of these mutations on transport function of the hVMAT1 protein have not …

Assessing The Genotoxicity Of Triclosan In Tadpoles Of The American Bullfrog, Lithobates Catesbeianus., David Emery

Theses and Dissertations

Amphibians are particularly sensitive to environmental degradation and, therefore, serve as effective environmental quality indicators. Research has suggested that amphibian declines are exacerbated by manmade environmental toxicants, especially those found in high concentrations in urban areas. The NIH has pinpointed genotoxicity as a major route of cancer causation, and has since developed stringent testing procedures for potentially hazardous chemicals. One such method, recognized for its simplicity and economy, is the micronucleus assay. A study was conducted assessing the genotoxicity of the widely used antimicrobial agent Triclosan to American Bullfrog tadpoles. Lithobates catesbeianus tadpoles were reared in glass aquaria containing ultra-high …

Prey Responses To Predator Chemical Cues: Disentangling The Importance Of The Number And Biomass Of Prey Consumed, Michael W. Mccoy, Justin C. Touchon, Tobias Landberg, Karen M. Warkentin, James R. Vonesh

Biology Publications

To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However, biomass consumed can change by altering either the number or size of prey …

Adam10: A Novel Regulator Of Mast Cell Function And Activation, Travis Faber

Theses and Dissertations

In this study we show, to our knowledge, the first description of the role ADAM10 plays on mast cells. ADAM10 is abundantly expressed on mast cells both in vitro and in vivo. Its expression is inhibited by IL-10, a suppressive cytokine. siRNA depletion of ADAM10 on bone marrow-derived mast cells (BMMC) caused decreased IL-6 production following IgE cross-linking and also impaired BMMC stem cell factor (SCF)-induced migration through collagen IV. Mast cells and T helper cells (Th cells) in the peritoneum were reduced in ADAM10 KO mice. In addition, ADAM10 KO BMMC produced significantly less of all cytokines measured following …

Species Level Differences In The Ecology Of Two Neotropical Tadpole Species: Responses To Nonlethal Predators And The Roles Of Competition And Resource Use, Zacharia Costa

Theses and Dissertations

Closely related species at the same trophic level are often considered to be ecologically equivalent. However, it is clear that individuals species can have unique functional roles that drive community and ecosystem processes. In this study we examine the growth responses of two Neotropical hylid tadpole species, Agalychnis callidryas and Dendropsophus ebraccatus, to intraspecific and interspecific competition. We also look at density-dependent effects of each on phytoplankton, periphyton and zooplankton, as well as their responses to a caged dragonfly predator through ontogeny. Intraspecific competition affected both species similarly, and their effects on resources were qualitatively similar but quantitatively different. Predators …