Section I: biological sciences science building, room 103 Shane Webb, presiding.
** Denotes student "in progress" research
1:15 POLYMERIZATION OF DENTAL COMPOSITE: LIGHT ANGLE AND MICROSHRINKAGE INFLUENCE ON RESTORATIVE LONGEVITY **, Katie P. Dyer *, Ronnie L. Dyer and Linda G. Jones, Young Harris College. Young Harris, GA 30582. We propose that the angle of light that induces polymerization of dental composite and inherent composite shrinkage determine the longevity of a dental restoration. Preliminary trials indicated that with ineffective curing angles, fillings had fractures. These results were compared to the control group (autocure composite), which had significantly fewer fractures. We correlated the angle of light focused on the tooth to induce polymerization with the fractures present after the curing process using 40 extracted human teeth (10 control and 10 per experimental group cured at 90, 180, or 225[degrees] angles). After drilling a 3 mm deep by 3 mm wide cavity in each tooth, we placed etchant in each cavity which was subsequently washed. Each tooth cavity was painted with a Dentin Primer for 20s before painting the cavity with SE Bond that was cured using a Plasma Arc light source. For the control group, 3 mm of autocure composite was placed in the cavity and allowed to harden for two minutes. With the remaining 30 teeth, 3 mm of hybrid shade A2 composite was placed in each cavity and cured using the Plasma Arc at the designated angle (90, 180, or 225[degrees]) as measured by a protractor. Afterwards, all teeth were sliced, placed in methylene blue for 48 h, and washed. We examined teeth for gaps and fractures using a dissecting microscope. Results are currently being obtained by counting fractures in each experimental group and comparing these with the control.
1:30 THE EFFECT OF XYLITOL ON PERIODONTAL DISEASE-CAUSING FUSOBACTERIUM NUCLEATUM SP. POLYMORPHUM, Meg Ruth Patterson *, Andrea L. Kwiatkowski and Paul T. Arnold, Young Harris College, Young Harris, GA 30582. Fusobacterium nucleatum is an obligate anaerobic, gram-negative bacterium that is known to contribute to periodontal disease. This bacterium is a main component of periodontal plaque due to its abundance and ability to co-aggregate with other species of bacteria in the oral cavity. Xylitol is a five-carbon sugar alcohol sweetener used as a naturally occurring sugar substitute, and is extracted from the fibers of many fruits and vegetables. Xylitol has been shown to inhibit growth of Streptococcus mutans, the main periodontal disease-causing bacterium in the oral cavity, at concentrations of 0.01% or higher. The objective of this study was to determine the extent of growth inhibition of F. nucleatum caused by varying concentrations of xylitol in culture media. A F. nucleatum sp. polymorphum culture (taken from the inflamed gingiva of an adult male, ATCC# 10953) was grown anaerobically using BBL Schaedler Broth with vitamin K1. Tubes containing 8 mL of broth at four different xylitol concentrations (0, 1, 2, and 3%) were each inoculated with 100 [micro]L of F. nucleatum from the same stock culture. These concentrations correspond to the range of xylitol concentrations reported in the literature from saliva samples of individuals chewing a piece of xylitol gum for 10 min. Tubes were incubated for 30 h at 37[degrees]C in an anaerobic chamber using BBL Gas Paks. A Genesys 20 spectrophotometer was used to measure the absorbance in each tube after incubation. Our results indicate that all concentrations of xylitol greater than 1% inhibit growth of F. nucleatum.
1:45 EFFECTS OF METHAMPHETAMINE ON MICROGLIA ACTIVATION AND DOPAMINERGIC NEURONS IN THE ARCUATE NUCLEUS **, Rick L. Roberts *, Beau Corkill *, Ezra U. Bortner *, Trevor Mott *, Steven A. Lloyd and Ryan A. Shanks, North Georgia College & State University, Dahlonega, GA 30597. Methamphetamine (METH) induces excessive release of dopamine (DA) leading to oxidative damage and reactive gliosis in several areas of the brain. However, METH's effect on microglia and neurons in the tuberoinfundibular DA pathway is not clear. Alterations of the TI pathway and hypothalamic function have implications for the nervous system and neuroendocrine functioning. Microglia are innate monocytic cells, which phagocytose cellular debris and release inflammatory mediators in response to brain insults. Reactive microglia are morphologically distinct. Their increased number is a hallmark of neuronal toxicity and/or vulnerability. Using lectin histochemistry and image analysis, we observed a decreased number of reactive microglia in the TI pathway after chronic METH exposure in C57B1/6J mice. Using immunohistochemistry for tyrosine hydroxylase, we will also investigate the effect of chronic METH exposure on the number of dopaminergic neurons in the TI pathway. Finally, we will investigate proinflammatory cytokine signaling alterations in the ventromedial hypothalamus after chronic METH exposure using qPCR anlaysis of total RNA isolated from fresh brain dissections. Based on preliminary data, we expect to find METH-induced down-regulation of cytokines, which is in keeping with reduced microglia activation, but a lack of effect on DA neuron loss.
2:00 CELL SIGNALING CHARACTERIZATION OF AN IN VITRO MODEL OF MICROGLIA ACTIVATION **, Jonathan R. Taylor *, Ryan A. Shanks and Steven A. Lloyd, North Georgia College & State University, Dahlonega, GA 30597. Understanding the signaling pathways responsible for microglial activation is crucial for the prevention of microglia-enhanced neurodegeneration. Microglia are monocytic-derived immune cells in the central nervous system (CNS) that respond to cellular disruption by phagocytosing cellular debris and producing inflammatory cytokines. Stimulation of specific signaling cascades leads to the activation of microglia and neurodegeneration caused by microglia-induced inflammation. The outer membrane component of gram negative bacteria, lipopolysaccharide (LPS), is commonly used to induce microglia activation in in vitro systems. We believe that homogenized mouse brain (HMB) provides a better system to model the in vivo neurodegenerative microenvironment that stimulates microglia. We hypothesize that although both HMB and LPS signal microglia activation, these stimulatory treatments work through different signaling mechanisms ultimately leading to alternative gene expression patterns. Phagocytosis assays will provide a functional assay for microglia activation following specific inhibition of three cornerstone signaling molecules, PKA, PI3 kinase, and protein phosphatases. The 50% inhibitory concentration for each signaling inhibitor will be identified using HMB as a stimulant, and compared to inhibition with LPS. We expect to find significant differences between the signaling mechanisms responsible for LPS and HMB microglial stimulation, indicating potential differences in downstream gene regulation of cytokines. These studies will provide insight into the signaling mechanisms responsible for microglia activation, and identify HMB as an alternative stimulatory model.
2:15 ISOLATION OF PROTOPLASTS FROM NEPENTHES **, Jaylen B. Sweat * and Michael S. Bodri, North Georgia College & State University, Dahlonega, GA 30597. Protoplasts are plant cells that have been altered by mechanical and/or enzymatic procedures for the purpose of removing the cell wall. This research was aimed at isolating and culturing protoplasts from Nepenthes grown and maintained under greenhouse conditions in order to develop a protocol suitable for wild species. Preliminary data was generated by attempting to liberate leaf mesophyll protoplasts from N. ampullaria and the hybrid N. 'Rokko' Exotica following surface sterilization of the lamina. Effects of using various concentrations of cellulase, hemicellulase, and pectinase in differing molarities of mannitol or sorbitol were evaluated. The most successful treatment for protoplast isolation from N. 'Rokko' Exotica was a 25[degrees]C digestion under low light in a 0.5 M sorbitol enzymatic media of 5% Cellulase Onozuka RS + 0.5% Macerozyme R-10 + 0.3% Pec-tolyase Y-23, shaken gently at 40 rpm for four hours. Our protocol produced an average protoplast yield of 4.35 x 106 / gm of leaf tissue (n=3) of which a mean of 62.1% were viable as determined by fluorescein diacetate (FDA) staining. In an attempt to regenerate plants, varying densities of protoplasts in modified Murashige and Skoog media were cultured by a variety of methods including hanging drops, thin-film alginate, embedding in low melting point agarose, and liquid culture on agarose with differing concentrations of the synthetic plant auxins 2,4-Dichlorophenoxyacetic acid (2,4-D) or picloram and the cy-tokinin kinetin. The osmotic environment of the media was maintained with sorbitol and sucrose during culture attempts. Subsequent staining with FDA and Calcofluor-white verified cells survived in vitro and regenerated a cell wall. Cell division has not been observed. This plant tissue culture method shows promise for regenerating whole Nepenthes plants from these cells and is the basis for ongoing research.
2:30 A REVERSIBLE SMOKE-INDUCED SECONDARY DORMANCY IN VENUS FLYTRAP (DIONAEA MUSCIPULA) SEED, Timothy Kennel, Jr.*, Chuck Robertson and Michael S. Bodri, North Georgia College & State University, Dahlonega, GA 30597. The Venus flytrap (VFT), Dionaea muscipula, is fire adapted because it can regenerate vegetatively from its rhizome after seasonal fires. Additionally, fire triggers regrowth of VFT after plants have gone dormant when outcompeted for light by other vegetation. Many plants that are fire adapted also have fire adapted seed that only germinate after exposure to smoke, yet VFT seed are quiescent at maturity and germinate almost immediately when exposed to the correct combination of physical environmental factors. Here we show that exposure to smoke induces a secondary dormancy in VFT seed. Smoke-exposed seed exhibited either complete inhibition or a significant delay of germination; however, our results indicate that the smoke-induced, secondary dormancy can be reversed by soaking the seed in a hydrogen peroxide solution or stratifying the seed. Whereas the treatment with hydrogen peroxide resulted in immediate germination comparable to controls, stratification resulted in germination of VFT seed over a prolonged time period. Therefore, we propose that smoke-induced dormancy of VFT seed demonstrates a unique fire adaptation as dormancy would prevent summer germination under potentially adverse conditions and will stagger germination in the spring following winter stratification, allowing seeds to germinate over a wider and more favorable range of environmental conditions.
2:45 ANALYSIS OF ENAMEL HYPOPLASIA IN VIRGINIA OPOSSUMS IN BALDWIN COUNTY, GEORGIA, Ray J. Cornay * and Alfred J. Mead, Georgia College & State University, Milledgeville, GA 31061. Characterized by pits, furrows, or grooves on the surface of teeth, enamel hypoplasia is a permanent record of disturbances that hindered the development of ameloblasts (cells responsible for enamel deposition). These defects are suggested to be the result of physiological stressors that disrupt normal enamel formation. In this study, the mandibles of fifty-seven road-killed opossums (Didelphis uirginiana) collected from Baldwin County, Georgia, were inspected macroscopically for the presence of enamel hypoplasia. Pits and furrows were noted in 54% of the opossums, most commonly on the buccal surface. Amongst the subset displaying the defect, enamel hypoplasia was observed on 45% of m1's, 68% of m2's, 35% of m3's and 3% of m4's. No difference was observed in the frequency of occurrence between males and females. Analysis of the order of tooth formation in the Virginia opossum indicates that ml and m2 are developing at the time of weaning and m3 is developing during post-weaning dispersal. The high frequency of hypoplasia on ml and m2 suggests that weaning is a time of severe physiological stress in young opossums.
3:15 THE EFFECT OF TEMPERATURE ON THE LIFESPAN OF ADULT BEAN BEETLES (CALLOSOBRUCHUS MACULATUS) **, Caroline Hanrahan *, Allison D'Costa and Mark Schlueter, Georgia Gwinnett College, Lawrenceville, GA 30043. Callosobruchus maculatus, commonly referred to as bean beetles or cowpea weevils, are common agricultural pests found in the tropics and subtropics of both Africa and Asia. Bean beetle larvae feed and develop exclusively inside the seeds of legumes (Fabaceae). They have a rapid life cycle that includes a 10-14 day adult stage. During this brief two-week period, adult bean beetles focus solely on reproduction, and it is believed that they may not feed. The main purpose of this study was to determine whether temperature influences the lifespan of the adults. Adult lifespan was monitored at three different temperatures: 25[degrees]C, 30[degrees]C and 35[degrees]C. At each temperature, petri dishes containing whole mung beans and 1-2 virgin males or 1-2 virgin females, or combinations of 1-2 virgin males and 1-2 virgin females were established with five replications per group. To determine the average lifespan at each temperature, beetles will be monitored every 4-8 h, and the time of death of each beetle will be recorded. We hypothesize that colder temperatures will prolong beetle lifespan. In addition, we also hypothesize that temperature will have a greater effect on female lifespan than male lifespan because reproductive activities may have a larger impact on males. Male bean beetles lose up to 10% of their body weight after their first successful reproductive interaction with a female.
3:30 THE EFFECT OF FOOD ON ADULT BEAN BEETLE (CALLOSOBRUCHUS MACULATUS) SURVIVAL: DOES FEEDING INCREASE ADULT LIFESPAN? **, Christy Morgia *, Allison D'Costa and Mark Schlueter, Georgia Gwinnett College, Lawrenceville, GA 30043. Bean beetles (Callosobruchus maculotus) are common agricultural pests found in the tropics and subtropics of both Africa and Asia. Bean beetle larvae feed and develop exclusively inside the seeds of legumes (Fabaceae). They have a rapid life cycle that includes a 10-14 day adult stage. It is currently believed that adult bean beetles do not feed. The purpose of this study was to determine whether food would influence the lifespan of adult bean beetles. Seven different food treatment groups were tested: 1) no food (control group), 2) whole mung beans, 3) natal beans (mung beans from which adults emerged), 4) naked beans (mung beans without seed coats), 5) prepared fruit fly media (cooked with water), 6) yeast paste, and 7) sugar water. For each food treatment group, Petri dishes were provisioned with 1-2 virgin males, or 1-2 virgin females, or one virgin male and one virgin female. Each combination had five replications. All groups were tested at room temperature in the same light/dark cycle. To determine average beetle lifespan in each food treatment, dishes were observed every 4-8 h until all beetles died. We hypothesize that beetles will live longer in Petri dishes that contain food items.
3:45 GOLDEN MOUSE (OCHROTOMYS NUTTALLI) AND WHITE-FOOTED MOUSE (PEROMYSCUS LEUCOPUS) DIETARY RESOURCE PARTITIONING UNDER EXPERIMENTAL HELD CONDITIONS, Alexander D. Wright * and Gary W. Barrett, Eugene P. Odum School of Ecology, University of Georgia, Athens, GA 30602. Ochrotomys nuttalli and Peromyscus leucopus are two small mammal species that share similar life histories and body mass. This relationship allows for a high degree of sociality between the two species and extreme niche overlap. We investigated differences in diet preference and daily caloric intake under experimental field conditions based on reported diets for each species in nature to better understand this relationship. Five food resources were provided to 20 adult individuals (10 male, 10 female) of each species for three consecutive days. Individuals were contained in separate covered mesocosm tanks located in a riparian forest ecosystem. The dietary choices were Chinese privet (Ligistrum sinense) and Staghorn sumac (Rhus typhina) seeds, Water oak (Quercus nigra) and White oak (Quercus alba) acorns, and Flowering dogwood (Cornus florida) fruits. Golden and white-footed mice preferred acorns of Q. nigra, and to a lesser extent, acorns of Q. alba and fruits of C. florida. Although dietary preference did not vary between species, white-footed mice consumed more energy per day than golden mice (0.89 and 0.72 kcal
* [g.sup.1] live wt, respectively). These caloric values are considerably less (2.38 and 1.48 kcal
* g live wt, respectively) than those reported by Gibbes and Barrett (Am. Midl. Natur., in press) when fed identical diets under laboratory conditions. This study was supported in part by funds from the Eugene P. Odum Endowed Chair held by Gary W. Barrett.
4:00 SEASONAL ASSESSMENT OF NATIVE BUTTERFLY, BEE, AND POLLINATING FLY SPECIES RICHNESS IN NORTH GEORGIA APPLE ORCHARDS, Nicholas Stewart * and Mark Schlueter, Georgia Gwinnett College, Lawrenceville, GA 30043. Recent concerns over Colony Collapse Disorder (CCD) in European Honeybee (Apis mellifera L.) populations have prompted interest in identifying native insect pollinators which could replace or supplement the dwindling commercial honeybee. In this study, four apple orchards in North Georgia were sampled from early-March through October to determine species presence and density of native flies (Order Diptera) and bees (Superfamily Apoidea). Domesticated apple trees (Malus domestica Borkh.) have an earlier flowering period than most other commercial agricultural crops in Georgia, which means fewer pollinator species may be potentially available. In March, prior to the bloom, native pollinator species are present at low initial numbers, marginally increasing until the first blossoms open in early April. Upon flowering, both the diversity and abundance of native pollinator species (especially bees) explode. While calyptrate dipteran flies were consistently diverse and abundant throughout the study, hymenopteran (bee) taxa varied in abundance from pre- through post-bloom. Overall, andrenids and apids proved to be the most prevalent of all native bee taxa before and during the bloom, while many halictid bees showed a steady increase over the same period, reaching maximum abundance well after the last apple blossoms had dropped. Syrphid flies were present during the bloom, but like halictid bees, became abundant only later in the season. Butterflies were present, but never in significant numbers. Overall, the most abundant native pollinators available during the apple bloom were bees in the family Andrenidae.
4:15 A PRELIMINARY INVESTIGATION ON THE INFLUENCE OF GALLS ON REPRODUCTIVE EFFORT IN GOLDENRODS **, Brian D. West * and Mark S. Davis, North Georgia College & State University, Dahlonega, GA 30597. Goldenrod galls are conspicuous outgrowths that form in response to insects ovipuncturing plant shoots. Larvae hatch from eggs and release chemicals that induce the shoot to produce a gall--gall tissue serves as food and protection for the developing larvae. We examined the effect of galls on the reproductive output of the native goldenrod Solidago altissima. Local populations (Lumpkin County, GA) are attacked primarily by goldenrod rosette gall flies, Rhopalomyia solidaginis (DIPTERA: Cecidomyiidae), and goldenrod ball gall flies, Eurosta solidaginis (DIPTERA: Tephritidae). These species produce galls that are distinct in appearance. Total inflorescence lengths of galled and ungalled stems were measured in random samples of three goldenrod populations. Total inflorescence length is a simple indicator of reproductive output because a positive correlation between inflorescence length and seed production has been demonstrated in goldenrods and other plant species. Data were analyzed using a one-way ANOVA followed by a Tukey-Kramer post-hoc test. Galls significantly reduced reproductive output (F2, 74 = 51.06, P < 0.0001) and rosette gall flies had more impact on reproduction than ball gall flies. All ungalled stems produced flowers, whereas only 74% of ball-galled stems and 22% of rosette-galled stems produced flowers. Our results are consistent with the negative impact hypothesis which states that herbivory can lead to lowered reproductive success in plants.
4:30 A PRELIMINARY REPORT ON INTERSPECIFIC VARIATION IN CRANIAL ARCHITECTURE AND MANDIBULAR GEOMETRY IN AGABINE (COLEOP-TERA: DYTISCIDAE) LARVAL CO-INHABITANTS OF A TEMPORARY HABITAT, Ally Treat *, Jessica Binkowski *, E.H. Barman, W. P. Wall and R. J. Wilkes *, Georgia College & State University. Milledgeville, GA 31061. Mature larvae of Agabus disintegratus and A. punctatus collected concurrently from the same habitat have the potential of engaging in competition for prey. An analysis of larval crania and mandibles using images and dimensions from a Meiji ML2000 microscope and a National DC3-420T digital microscope with Motic Imaging 2000-1.3 revealed significant differences in cranial architecture. Although both species exhibit equivalent maximum head widths, a narrowing of the distal region of the cranium of A. disintegratus results in a significantly (P < 0.0001) smaller gape ([bar.x] = 0.84 [+ or -] 0.03 mm) than that of A. punctatus ([bar.x] = 0.98 [+ or -] 0.02 mm). Mandibles of A. disintegratus ([bar.x] = 0.62 [+ or -] 0.03 mm) are significantly (P < 0.0001) shorter than those of A. punctatus ([bar.x] = 0.71 [+ or -] 0.03 mm) although arcs and angles of attack appear similar. These data indicate that potential competition may be reduced at this site because A. disintegratus may exploit a prey regime characterized by a smaller size than of A. punctatus. Apparent similarities in mandibular geometric parameters indicate that characteristics of the prey regimes other than size may be similar. This project was supported in part by a Faculty Research Grant, Office of Research Services, GC&SU. Aquatic Coleoptera Laboratory Contribution No.80.
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|Title Annotation:||FRIDAY PAPER PRESENTATIONS|
|Publication:||Georgia Journal of Science|
|Article Type:||Conference news|
|Date:||Mar 22, 2011|
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