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Articles 1 - 11 of 11

Full-Text Articles in Life Sciences

The Response Of Naive Channel Catfish To Chemical Cues Associated With Predation, Marinda Coulter Dec 2013

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 Dec 2013

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 Aug 2013

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 Aug 2013

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 ...


Development Of Pectoral Apparatus In Ictalurid Catfish, Shweta Lahiri Aug 2013

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 Jul 2013

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 Jul 2013

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 Jun 2013

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 ...


Genetic And Molecular Analysis Of The Maize R1 Locus, Jennifer Derkits Jun 2013

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 ...


Inhibition Of Retinoic Acid Receptors Results In Defasciculation Of The Trigeminal Nerve In Xenopus Laevis, Jeremy Thompson May 2013

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 Apr 2013

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 ...