Poster Sessions - Second Floor

Second Floor #1

Multiscale Evaluation of Technetium Remediation Technology in Saltstone
A.C. Hatfield1, D.I. Kaplan2, B.A. Powell3, and Y. Arai1
1Institute of Environmental Toxicology, Department of 3Environmental Engineering and Earth Sciences, and 2Savannah River Site (Aiken, SC)
Faculty Mentor: Dr. Yuji Arai

ABSTRACT: Cementitious materials are an important component of the strategy to stabilize nuclear waste developed by DOE. In particular, technetium (99Tc) is one major risk driver at the Savannah River Site, Aiken, SC. In saltstone, Tc presumably remains as insoluble Tc(IV) species as long as reducing conditions are maintained. However, with gradual oxygen diffusion into saltstone matrices, Tc could potentially reoxidize and mobilize as Tc(VII)O4- species. Previous analytical data is incongruous in determining the Tc oxidation rate, therefore this study investigates the oxidation of saltstone samples spiked with relevant oxidation indicators, Cr and Re (500-1000 mg/kg). In-situ leaching tests, a macro-scale evaluation, were conducted with saltstone slices of millimeter increments to evaluate the oxidation of Cr and Re species. The micron-scale solid-state speciation of Cr and Re will be conducted using a synchrotron based X-ray microprobe technique. The multiscale investigations will be associated with the predicted measurements of the oxidation front.

Second Floor #2

Radiographic Analysis of Ruminants
C. Crowder, M. Kelley, K. Rowland, and H. Dunn

Department of Animal & Veterinary Science
Faculty Mentor: Heather Walker Dunn

ABSTRACT: Ruminants play an indispensable role in the success and diversity of modern day food industry. They also play a well-documented role in the health of the environment as well as the economy. In order to understand their importance, then, it is necessary to understand ruminant physiology. The structural anatomy of the ovine ruminant, acquired through the Godley Snell Research Center at Clemson, was analyzed through x-ray imaging. These radiographs were analyzed for their structural characteristics and the impact they have on the physiological function of the ruminant. The internal organs visible on the images were also noted for their position in the body and what their significance was to the overall function of the ruminant system. This series of images will serve as a component of a photographic atlas regarding the ruminant structural anatomy.

Second Floor #3

Modeling Pigeon Neuroanatomy
Rajiv Bery and James Peterson
Department of Biological Sciences
Faculty Mentor: James Peterson

ABSTRACT: A model of a pigeon's neuroanatomy is developed using Matlab. The focus is on the avian visual system and the primary literature is used to find the neural modules that are connected dynamically to form the functioning pigeon brain. The neural modules and their interconnections are modeled as graphs of computational nodes connected by edges. The nodes are neurons and the edges are the synaptic connections. Our focus is on mapping visual cue inputs to the desired landmark recognition using a variety of graph training algorithms implemented in Matlab. The graph models are built using a hierarchical or vector based system which allows us to easily find where a given module's neuron is located in full computational graph.

Second Floor #4

Novel Chalcone Synthase (CHS) gene structure in the genus Amaranthus
Sarah Barfield and Kristin Beard

Department of Genetics & Biochemistry
Faculty Mentor: Amy Lawton-Rauh

ABSTRACT: The flavonoid synthesis pathway produces various protective compounds in plants, whose function ranges from protection against UV light and infection to drought resistance and herbivore deterrence. Chalcone synthase (CHS) catalyzes the first committed step of this pathway. As such, it is an important regulatory point in the pathway. Among the fourteen type III polyketide synthases that have been discovered to date (CHS included), all have a very similar gene structure consisting of two exons interrupted by a single intron. A homologous chalcone synthase gene from the genus Amaranthus was sequenced and shown to contain a novel intron in the second exon of the gene. Further screening for the presence of the intron has revealed that it is conserved across the genus Amaranthus, yet restricted to the Amaranthaceae family of plants. A second CHS homolog was discovered in Amaranth and partially sequenced, which revealed that this gene did not contain the novel intron. However, based on sequence alignments the two genes contain various polymorphisms, suggesting that the original CHS was duplicated sometime during the evolution of Amaranth and has resulted in the divergence and perhaps functional differentiation of the copied gene.

Second Floor #5

Nutritional Quality of South Carolina Peaches
Asma Abdelghafar and Ksenija Gasic
School of Agricultural, Forest, & Environmental Sciences
Faculty Mentor: Ksenija Gasic

ABSTRACT: Peach fruit is one of the most important commodities consumed worldwide and presents and important source of bioactive compounds that benefit human health. Relative antioxidant capacity (RAC), anthocyanins, flavonoids and total phenolics have been evaluated in yellow fleshed peach varieties grown and marketed in the South Carolina and significant differences have been observed. In 2012 growing season fruit accumulated on average 135 µg Trolox /g FW antioxidants, 12 mg C3GE / kg FW anthocyanins, 6.6 mg CE / g FW flavonoids and 16 mg GAE/ 100g FW total phenolics. The best nutritional value with highest content in all bioactive compounds, except for anthocyanins was observed in ‘Juneprince’ variety. Bioactive compounds need to be evaluated over several growing seasons before definitive conclusion can be made but these preliminary data provide important information for growers and consumers on the nutritional quality of peach varieties grown and marketed in South Carolina.

Second Floor #6

Organization and Structure of the Ruminant Skeletal System
R. Miller, A. Harmon, E. Pisik, and H. Dunn
Department of Animal & Veterinary Science
Faculty Mentor: Heather Walker Dunn

ABSTRACT: The purpose of this study is to create a comprehensive instructional text and to further educate the participating students about large animal ruminants while gaining hands-on experience. The ruminant skeletal system plays key roles throughout an animal’s life such as support, protection of organs, mineral absorption and storage, and locomotion. A life-size bovine skeleton was observed to help identify, compare, and assess the organization and structure of bones in the ruminant body. Images and supporting material obtained from the study will be compiled into “A Photographic Atlas of Ruminants” that will be used to provide visual learning tools of ruminants (bovine, ovine, and caprine) to aid future students in their animal science courses.

Second Floor #7

Pharmaceuticals and Personal Care Products in a Wastewater Receiving Stream During Normal and Low Flow Conditions
Alan J. Jones and Elizabeth R. Carraway
Institute of Environmental Toxicology
Faculty Mentor: Elizabeth R. Carraway

ABSTRACT: The Reedy River, located in the piedmont of South Carolina, is a stream receiving effluent from two wastewater treatment facilities (WWTPs) serving the greater metropolitan area of Greenville, SC. The work presented here details two sample collections during a normal flow condition and a low flow condition. Endocrine Disrupting Compounds (EDCs) and Non-stereroidal anti-inflammatory drugs (NSAIDs) can result in negative effects on aquatic populations at very low concentrations (ng/l, pg/l) in surface waters. Variability in pharmaceuticals and personal care products (PPCPs) under low flow situations has been poorly studied. Sample enrichment was accomplished with solid phase extraction and the samples were analyzed using liquid chromatography – tandem mass spectrometry. Analytes of interest are caffeine, diphenhydramine, ibuprofen, naproxen, triclosan, estrone, 17β-estradiol, and 17α-ethynylestradiol. The results indicate significantly higher concentrations of all analytes, with the exception of estrone, during low flow conditions. In addition, caffeine and diphenhydramine were found in the Reedy at locations upstream of the two WWTP outfalls. Generally decreasing analyte concentrations on a downstream gradient from the WWTP inputs to the stream suggest some removal mechanisms, which may include sorption and degradation.

Second Floor #8

Photographic Illustration of Internal Ruminant Anatomy
R.J. Teasdall, C. Albowicz, D. Williams, and H. Dunn

Department of Animal & Veterinary Science
Faculty Mentor: Heather Walker Dunn

ABSTRACT: The purpose of this project is to present high quality images of internal organs from ruminant animals that portray how form follows function. Structures may include; heart, lungs, diaphragm, kidneys, liver, rumen, reticulum, omasum, abomasum, small and large intestine, male and female reproductive systems, spleen, pancreas, and gall bladder. These structures enable the ruminant animal to develop and possess unique digestive characteristics to allow them to process plant matter as their main source of nutrition. The increasing human population derives many of their food products from ruminant animals, therefore having sound knowledge of ruminant anatomy and physiology could prove beneficial for improving the increased food demands.

Second Floor #9

The Influence of Dissolved Organic Carbon and Coating on the Toxicity of Silver Nanoparticles in Daphnia magna

Kim Newton and Stephen J. Klaine  

Institute of Environmental Toxicology, and Department of Biological Sciences

Faculty Mentor: Dr. Stephen Klaine


ABSTRACT: Silver nanoparticles (AgNPs) are by far one of the most extensively used nanoparticles in general consumer products. However, the major concern regarding its prevalent use is the potential toxicity to aquatic organisms. The unrelenting question here is whether the toxicity is due to the AgNPs or the ions (Ag+) they release. The AgNP coating and the dissolved organic carbon of the medium control silver ion release and influence the toxicity of Ag+ to aquatic organisms. This research investigated the role of these variables on AgNP toxicity to D. magna and tested the hypothesis that toxicity could be explained by Ag+ concentration. Forty-eight hour median lethal concentration (LC50) values were obtained using AgNO3 and three AgNPs with different coatings; Gum Arabic-coated (AgGA), polyethylene glycol-coated (AgPEG) and polyvinylpyrrolidone-coated (AgPVP) nanoparticles in moderately hard reconstituted water (MHW) alone or augmented with Suwannee River dissolved organic carbon. Measurements of the total silver and the dissolved silver at the LC50 concentrations were determined. The findings indicated that in MHW, AgNO3 (1.06 μg/L) was the most toxic to D. magna, AgPVP (14.81μg/L) was the least toxic. The dissolved silver concentration of the AgNPs in MHW at their respective total Ag LC50 concentrations was comparable to the ionic concentration of AgNO3 at its LC50 concentration. These results suggested that the toxicity was explained by ionic silver concentration.


Second Floor #10

Role of the Mei5-Swi5 complex in homologous recombination
M. Paige McKeithan1, LeAnna L. Ledford2, and Michael G. Sehorn1
Departments of 1Biological Sciences, and 2Genetics & Biochemistry
Faculty Mentor: Michael Sehorn

ABSTRACT: Homologous recombination (HR) is an essential process that repairs double-stranded breaks (DSBs) in DNA. If DSBs are not repaired correctly, the results can include trisomy of certain chromosomes, cancer, and eventually cell death. Rad51 and Dmc1 are RecA-like recombinases that are required for HR to occur. Both Rad51 and Dmc1 require accessory proteins for HR to proceed efficiently. The purpose of this project is to study the proteins Mei5, Swi5, and Mei5-Swi5 complex, which was recently shown to stimulate Rad51 in HR and may function to target Rad51 to DSBs. Specifically, our goal is to biochemically characterize the human proteins Mei5, Swi5, and Mei5-Swi5 complex. We have expressed and purified the Mei5-Swi5 complex. Purified Mei5-Swi5 complex was tested for the ability to bind both single-stranded and double-stranded DNA. The ability of the Mei5-Swi5 complex to interact with other recombination proteins was also investigated.

Second Floor #11

Royal Jelly-induced Prolongevity in Caenorhabditis elegans is mediated by a Suspected Protein Complex of DAF-16/SIR-2.1/14-3-3/HCF-1
Xiaoxia Wang , Cole G. Murbach, Jessica Dinh, Sujay Guha, Min Cao, and Yuqing Dong
Department of Biological Sciences
Faculty Mentor: Yuqing Dong

ABSTRACT: Royal jelly is a honey bee secretion, which possesses the beneficial functions of anti-inflammation, anti-oxidative stress and anti-bacteria. Our lab found that royal jelly and its products can significantly prolong the lifespan of C. elegans. However, little is known about the role of royal jelly on lifespan regulation mechanistically. Our latest data showed that the royal jelly-mediated lifespan extension in C. elegans depends on the activities of daf-16 and sir-2.1. Considering that the transcriptional activity of daf-16 is co-regulated by sir-2.1, hcf-1 and 14-3-3, we examined whether hcf-1 and 14-3-3 may also involve into the royal jelly-mediated lifespan extension. Our findings indicate that royal jelly extends the lifespan through a suspected protein complex, DAF-16/HCF-1/14-3-3/SIR-2.1. Furthermore, our data also reveal that royal jelly has anti-bacterial effects to protect C. elegans against the infections of vibrio and enterococcus. Currently, more intensive studies on royal jelly’s anti-aging and anti-bacteria properties are being conducted.

Second Floor #12

Short term changes in substrate and the macroinvertebrate community following dam removal
Patricia A. Whitener, William R. English, and Jeremy Pike
School of Agricultural, Forest, & Environmental Sciences
Faculty Mentor: William 'Rockie' English, Ph.D.

ABSTRACT: Dam removal is gaining global attention as a potential restoration tool of impacted rivers. Under the Lake Hartwell Restoration and Compensation Determination Plan, two dams (>9 m) were removed from the 12-Mile Creek watershed (170 km2) in Pickens county, South Carolina. To assess the short term impacts of dam removal on the 12-Mile Creek ecosystem we conducted a before and after control impact (BACI) study design. Biomonitoring of macroinvertebrate species and surveys of river substrate and channel geomorphology was conducted in 2006 prior to dam removal and again in 2011-12 following dam removal. Preliminary results suggest a decrease in macroinvertebrate species sensitive to sedimentation and an increase in the embededness of the substrate coupled with a change in channel shape. As the practice of dam removal increases, physical and biological monitoring contributes to our understanding the short-term ecological consequences of dam removal.


Second Floor #13

Survival of Escherichia coli O157:H7 in finished compost in the presence of competitive exclusion bacteria
Claudia Ionita, Jinkyung Kim, and Xiuping Jiang
Department of Food, Nutrition & Packaging Sciences
Faculty Mentor: Xiuping Jiang

ABSTRACT: Composting represents an efficient method to transform animal-based waste into soil amendment. Foodborne pathogens present in the raw material can survive composting process or recontaminate the finished compost and persist in the environment.

This study evaluated the effectiveness of selected competitive exclusion microrganisms (CE) isolated from compost for E. coli O157:H7 reduction in compost with 20-, 30- and 40 % moisture levels. A cocktail of three avirulent E. coli O 157:H7 strains were inoculated onto dairy-based compost (105 CFU/g) along with CE strains (108 CFU/g). Two inoculation approaches were used: (i) heat-adapted E. coli O157:H7 to simulate cells that survived composting and (ii) inoculation in compost to simulate environmental recontamination.

Results indicate that heat-adaption and higher moisture content afforded E. coli O157:H7 survival in compost. In CE treatments E. coli O157:H7 population significantly decreased compared with the controls (P0.05) by day 2 and 4 in heat-adapted cultures for 40- and 30% moisture contents, respectively. Our findings will identify scenarios to effectively eliminate E. coli O157:H7 in compost.

Second Floor #14

Targeting, Solubilizing, and Degrading Biphenyls Using Synthetic Biology
Matthew Bickford, Whitney Crain, Ryan Kane, Rachel Louie, Kelly Merchant, Andreea Nicolaica, Aaron Scanlan, Tyler Smith, Jessica Tzeng, Jenny Wilson, Min Cao, and Jeremy Tzeng
Department of Biological Sciences
Faculty Mentors: Min Cao and Jeremy Tzeng

ABSTRACT: Polychlorinated biphenyls (PCBs) are a major pollutant linked to the causation of cancer, skin problems, and immunological interference. PCBs are now banned in the US, but were previously used mainly as liquid insulators in the manufacture of electrical equipment. The pollutant is a major problem in Twelve-Mile Creek and Lake Hartwell, as well as globally. We are using synthetic biology to engineer a small consortium of bacteria with the ability to degrade biphenyls. Our three-pronged approach includes (1) a guider magnetotactic bacterium which gravitates towards the PCB contaminated sediments and sends out a chemoattractant when in contact with biphenyls, (2) a biosurfactant-producing E. coli that will reduce surface tension and increase the bioavailability of the PCBs, and (3) E. coli overexpressing the catabolic enzymes required for biphenyl degradation. We are attempting to demonstrate a significant increase in the rate of PCB degradation using this combined approach.


Second Floor #15

Testing the Multimeric Strand Hypothesis of Silk Protein Self-assembly
Lindsey Weed and Dylan Sobin

Department of Genetics & Biochemistry
Faculty Mentor: Dr. William Marcotte

ABSTRACT: The research objective is to test the multimeric strand hypothesis of spider silk assembly. Using an existing plasmid, simplified mini silk proteins containing the N- and C-terminal domains connected by an unstructured linker have been expressed in E. Coli. These proteins will serve as spidroin models in the characterization of the assembly process. Using surface plasmon resonance (SPR), the mini spidroins can be tethered to the surface of a metal through the C-terminal domain. The dimerization and disassociation of additional spidroins allowed to flow across the surface can be detected electronically to determine the binding affinity between N-terminal domains. Repeating this procedure for several pHs will be indicative of the bond strength at different points during the assembly process. Additionally, fluorescent labeling of the terminal domains of the spidroins will be used to view the self-assembly process.

Second Floor #16

The effect of coyote (Canis latrans) scent on feeding behavior of mammalian species native to the southeastern U.S.
Jenna Kohles, Wesley Boone, Cady Etheredge, and Greg Yarrow

School of Agricultural, Forest, & Environmental Sciences

Faculty Mentor: Cady Etheredge

ABSTRACT: While coyote populations have increased in southeastern states, their impacts on native fauna are unknown. As a large-bodied predator, coyotes have the potential to alter foraging behavior of a variety of mammalian prey species. If these species feel threatened by the presence of a coyote, they may adjust their behavior to reduce risk of predation. This study was conducted to determine the effects of coyotes on the feeding behavior of herbivorous and mesopredacious mammalian species native to South Carolinas piedmont. Nocturnal attendance of mammals at established supplemental food sites is being recorded using game cameras at locations treated with scent extracted from coyote feces and control scents. The amount of food eaten each visit is visually estimated. Mammalian species diversity and abundance should decrease when coyote scent is present. Likewise, length of time spent at food sites and amount of food consumed should decrease in presence of coyote scent.

Second Floor #17

The Effects of Anthropogenic Compounds on Fish Brain Chemistry and Behavior

Anna Lee McLeod, Lauren Sweet, and Dr. Stephen J. Klaine
Department of Biological Sciences, and Institute of Environmental Toxicology
Faculty Mentor: Dr. Steve Klaine

ABSTRACT: Most anthropogenic compounds are not efficiently removed from sewage before they reach streams and rivers, increasing their prevalence in the environment. Previous work has shown that upon exposure to the antidepressants, fluoxetine and venlafaxine, brain serotonin levels in hybrid striped bass decreased significantly upon exposure to sub-lethal concentrations. Additionally, these studies correlated depressed serotonin levels with behavioral alterations that decrease organisms’ ecological fitness. While these antidepressants are designed to alter neurotransmitter levels, other studies have suggested that common contaminants such as metals can also affect brain chemistry. This study characterized the effects of copper exposure on behavior in fathead minnows. Based on the results of the light-dark anxiety behavioral bioassay, there was no statistical difference between exposed and unexposed fish. However, there was a dose-dependent trend in fish exposed to copper that suggested they spent less time in the light. These preliminary results suggest that several modifications to the bioassay are necessary to improve the statistical sensitivity. 

Second Floor #18

The influence of aggression and habitat loss on juvenile caribbean spiny lobster (Panulirus argus) denning behavior
K.A. Heldt and M.J. Childress
Department of Biological Sciences
Faculty Mentor: Dr. Michael Childress

ABSTRACT: Spiny lobsters are highly gregarious and use shelters for protection from predators. In recent years, sponge loss events in Florida Bay have decreased the amount of natural shelters available for juvenile spiny lobsters. However, den use, den sharing and lobster numbers have remained relatively constant suggesting that aggression and den competition may have increased. To estimate the role of aggression on denning behavior, individuals were size-matched and housed as pairs in an aquarium with a single crevice shelter and total number of aggressive acts were measured by direct observation. Then, ten pairs of marked individuals were observed daily in a mesocosm with 10 crevice shelters. On day four, five crevice shelters were removed to study the impact of sudden shelter loss. We measured the frequency of den use, den sharing and den fidelity of each individual before and after shelter loss. We found that aggression was highly correlated with size and that large, aggressive lobsters exhibited less den sharing. Surprisingly, when shelter number was reduced, den sharing remained constant but den use and den fidelity decreased for large, aggressive lobsters. These data suggest that vulnerability rather than aggression predicts which individuals remain in a den after sudden shelter loss.

Second Floor #19

The Influence of Wastewater on Gold Nanoparticle Physicochemical Characteristics and Subsequent Accumulation in Daphnia magna
Austin T. Wray and Stephen J. Klaine
Department of Biological Sciences
Faculty Mentor: Stephen J. Klaine

ABSTRACT: The journey from consumer use to aqueous release is particularly relevant to nano-toxicology because this journey will define the physicochemical characteristics of the nanomaterial that could have implications on the behavior and fate within the receiving ecosystem. Nanomaterials released from consumer and industrial products are likely to face the gauntlet of a wastewater treatment facility wherein an individual particle will be open to a number of interactions with both the wastewater components and activated sludge modifying the particle prior release into an aquatic ecosystem. The aim of our research is to define how these interactions will affect the downstream particle-biota relationship. Specifically we are interested in simulating the effects of wastewater incubation on waterborne gold nanoparticle uptake and elimination kinetics in Daphnia magna. We utilized particles with two different surface charges, positive and zwitterionic, and separated the exposures into two treatments: unadulterated nanoparticles and adulterated nanoparticles that were incubated for 1 hour with synthetic wastewater. Uptake and elimination rate constants were derived for each particle configuration to predict bioaccumulation potential. Overall, we observed differential uptake and elimination based on initial particle surface charge and a noticeable shift in uptake and elimination patterns for daphnids exposed to positively charged particles that were incubated in wastewater. Uptake and elimination of zwitterionic particles, however, was unaffected by the presence of wastewater. The size and to a lesser extent the surface charge of the positively charged particles were the only characteristics altered by wastewater incubation, which may explain the accelerated elimination rate constant and depressed uptake rate constant observed for that particle type. Presence of bacteria in the synthetic wastewater exposures is another probable cause of the differential accumulation patterns for both particle types and will be addressed in future experiments to confirm our results.

Second Floor #20

The Relationship Between Fruit Maturity and Fruit Quality in Peach (Prunus persica)
Jonathan Windham and Dr. Ksenija Gasic
School of Agricultural, Forest, & Environmental Sciences – Horticulture
Faculty Mentor: Dr. Ksenija Gasic

ABSTRACT: Peach maturity at harvest affects fruit quality and consequently consumer preference in the market. Fruit size and red coloration of skin are the most common indicators of fruit maturity used to decide when to harvest in everyday orchard operations. These attributes do not allow for fully reliable assessment of maturity, especially in newly released varieties with extensive red skin color. Fruit firmness (FF), soluble solids concentration (SSC) and/or total acidity (TA) are better indicators of fruit maturity. Their simple and rapid assessment, however, does not provide all necessary information and requires fruit destruction. The DA meter, a newly developed portable spectrometer, has been evaluated for determining fruit maturity index (IAD) and its relationship to ripening (related changes in fruit quality parameters). Data revealed that few varieties were harvested at the correct maturity. FF positively correlated with maturity index, while SSC and TA showed no difference between fruit of different maturities.

Second Floor #21

The role of diet in the expression of alternative male mating strategies in the sailfin molly, Poecilia latipinna
Eric W. Rice, Rachel M. Hite, Grant G. Davidson, and Elizabeth C. Lange
Department of Biological Sciences
Faculty Mentor: Margaret B. Ptacek

ABSTRACT: The insulin-like growth factor (IGF) influences growth rate and development of male secondary sexual characteristics. Diet is known to alter IGF pathway activity in several fish species. The goal of this study is to understand how the IGF pathway affects growth in poeciliid fishes by examining changes in life history traits and allometry of morphological traits in the sailfin molly (Poecilia latipinna) in response to different diets. Offspring of known genotypes for male size at maturity were produced, and fed either a control (high protein, low carbohydrate) or experimental (low protein, high carbohydrate) diet. At maturity, morphological traits of offspring were measured. Diet influenced size at maturity and mass growth with experimental-fed males having decreased length and mass growth rate. Experimental-fed males also had weaker allometries for dorsal fin area. Sire genotype was important in length growth rate with males from small sires growing most quickly.

Second Floor #22

The role of phosphorylation in regulation of the Salmonella enterica acetate kinase
J. Tumolo, A. Stevens, K. Smith, and C. Ingram-Smith
Department of Genetics & Biochemistry
Faculty Mentor: Cheryl Ingram-Smith

ABSTRACT: Acetate Kinase (ACK) catalyzes the reversible phosphorylation of acetate to acetyl phosphate and can form a pathway with the enzyme phosphotransacetylase (PTA) to catalyze the formation of acetyl coenzyme A, a key metabolic intermediate. ACK is present in the human pathogen Salmonella enterica and the ACK-PTA pathway has been shown to be required during Salmonella infection. Thus ACK may serve as a novel drug target as it is absent in the human host. Analysis of Salmonella ACK has shown that incubation of the enzyme with acetyl phosphate conferred thermal stability. However, incubation with ATP resulted in inactivation. This inhibition was not observed with non-hydrolyzable ATP analogs, suggesting that phosphorylation of the enzyme may be responsible for inhibition. This result raises the possibility that phosphorylation may play a role in regulation of ACK activity and that ACK may have an alternative physiological role beyond production of ATP or acetyl phosphate.

Second Floor #23

Thermal Inactivation of Desiccation-Adapted Salmonella spp. in Aged Chicken Litter
Zhao Chen and Xiuping Jiang
Department of Biological Sciences
Faculty Mentor: Xiuping Jiang

ABSTRACT: Thermal inactivation of desiccation-adapted Salmonella in aged chicken litter was investigated. Salmonella were inoculated into the finished compost for a 24-h desiccation adaptation. Afterwards, the compost with desiccation-adapted cells was added into the aged chicken litter with 20, 30, 40, and 50% moisture contents for heat treatments. A 5-log reduction of the desiccation-adapted Salmonella at 20% moisture content required >6, >6, and 6 h exposure at 70o, 75o, and 80oC, respectively, whereas the same reduction in non-adapted control was achieved within 2, 1.5, and 1 h at 70o, 75o, and 80oC, respectively. Time required to obtain a 5-log reduction became shorter as temperature and moisture content were increased. At 150oC, desiccation-adapted Salmonella survived for 50 min at 20% moisture content, whereas control cells were detectable by enrichment until only 10 min. Our results demonstrated that the thermal resistance of Salmonella in aged chicken litter was increased significantly after desiccation adaptation.

Second Floor #24

Total-Evidence Species Phylogeny for Amaranthus: A Framework for Molecular Evolution of Herbicide Resistance
Kristin Beard
Department of Genetics & Biochemistry
Faculty Mentor: Amy Lawton-Rauh

ABSTRACT: The Amaranthus genus is diverse, containing leaf vegetable and grain crops, horticultural varieties, and weedy plants distributed throughout the world. Although weedy species make up only a few of the 70 recognized species in this genus, their impact on agriculture through resistance to herbicides, specifically RoundUp (glyphosate), is serious. Several species have characteristics that accelerate their negative impact on agroecosystems through rapid population expansion and evolutionary adaptation such as long seed viability, high seed count, potential hybridization with other Amaranthus species, and the capacity to widely disperse seeds.

The purpose of this research is to compare the patterns of molecular evolution of candidate genes hypothesized to be responsible for herbicide resistance to non-candidate genes. The first step is to examine the genetic relationships among Amaranthus species and estimate a best fit phylogeny as a framework for molecular evolution studies. It is this phylogenetic tree of the relationship between Amaranthus species that is presented here.

Second Floor #25

Two Partners of Acetate Kinase in Eukaryotic Microbial Pathogens
Tonya Taylor, Cheryl Ingram-Smith, and Kerry Smith

Department of Genetics & Biochemistry

Faculty Mentor: Kerry Smith

ABSTRACT: Acetate kinase (ACK) is a key bacterial enzyme that partners with phosphotransacetylase (PTA) to interconvert acetate and acetyl-CoA. We identified genes encoding ACK in eukaryotic microbial pathogens, including the oomycete Phytophthora ramorum and the basidiomycete fungus, Cryptococcus neoformans. P. ramorum has two type II PTAs (PTA1II and PTA2II). Biochemical characterization of PTA1II indicates the enzyme is allosterically regulated by ATP, ADP, AMP, NAD, NADH, NADP, and NADPH.

In fungi, PTA is absent and xylulose 5-phosphate/fructose 6-phosphate phosphoketolase (XFP) has been proposed as ACK’s partner. C. neoformans has two XFPs (XFP1 and XFP2), indicating biochemical and physiological differences between these two enzymes. To study the metabolic and physiological roles of XFP1, gene knockouts will be utilized to determine essentiality of this gene. Production of recombinant C. neoformans XFP1 is being optimized in order to investigate the role XFP plays in eukaryotes; this will provide unique insight into the enzymology of XFP.

Second Floor #26

Update on CU Hemlock Woolly Adelgid / Predator Beetle Rearing Project: Overview of past efforts and current status

LayLa Burgess and Joseph Culin

School of Agricultural, Forest, & Environmental Sciences

Faculty Mentor: Joseph Culin

ABSTRACT: Hemlock woolly adelgid (HWA), a potential invasive pest of hemlock trees, was accidentally introduced into eastern North America in the 1950’s in Virginia. HWA was considered a controllable pest of ornamental hemlock for nearly 30 years. In the 1980s, HWA began spreading through natural forest stands of both eastern (Tsuga canadensis (L.) Carrière) and Carolina (Tsuga caroliniana Engelmann) hemlocks. On these two species, HWA feeding causes needle loss, limb dieback, and eventual tree death. Since its accidental introduction into the eastern US, HWA has spread throughout more than half of the natural range of eastern hemlock and most of the range of the geographically restricted Carolina hemlock. The Nature Conservancy has listed HWA as the greatest threat to the southern Appalachian forest ecosystem (Knauer et al. 2002). Low HWA infestations on hemlock in Asia and the Pacific Northwest have been attributed to host plant resistance, the occurrence of effective natural enemy complexes, or a combination of these factors (McClure 1991, Cheah & McClure 1996). The relationship between HWA and hemlock species is not new to eastern North America. South Carolina first detected the presence of HWA in its forests in 2001. The main front of the HWA infestation can move up to 15 miles per year (McClure 2001) and has colonized much of the native southeastern range of hemlock in the tri-state regions of North Carolina, South Carolina and Georgia. Efforts to combat the spread of HWA into new areas and to promote the regeneration of hemlock in infested areas currently rely on the effectiveness of the USDA Forest Service’s biological control initiative against HWA. Clemson University has assisted in these efforts since 2003 targeting Sumter, Nantahala and Chattahoochee National Forests with the mass rearing and release of predator beetles of HWA.