Abstracts Submitted from
Agriculture, Marine Stuidies, and Wildlife Ecology

Undergraduate Summer Research Symposium August 12, 2009

Ordered alphabetically by student's last name

Amiri Edwards Johnson Panunto Taylor Zaccaria
Bedi Fisher
Kane Rodriguez Turley
Cordova Gibson
Lingham Schieler Welch
Crum Irvin McKee Sun Willis

Effects of Sulfur on the Growth and Development of Capsicum Chinese Var. Habanero

Sunita Amiri and Cyril E. Broderick
Delaware State University

Some 109 elements are on the Periodic Table; however, sulfur is one of only 16 elements required by plants. The element sulfur is a constituent of the amino acids cysteine and methionine, and vitamins Biotin and Thiamine, as well as major other organic compounds. Sulfur plays important metabolic roles in plants and animals. The objective of this project is to determine the effects of sulfur on growth and development of Capsicum chinese Var. Habanero, and protein and capsaicin synthesis in pepper fruits. Because capsaicin is not synthesized in Capsicum annuum Var. Bell, a comparable trial was carried out with Bell peppers as a negative control. Soil was washed from plant seedlings, and 50 Habanero plants, with soilless roots, were placed in one-gallon containers of distilled water. Each gallon was then wrapped in black plastic to prevent light from reaching the roots of the plants. Chemical salt solutions were then added to the gallons to form the five (5) treatments in ten (10) replications for Habanero pepper experiment and three (3) replications for Bell peppers. We observed that the plants with Complete (C) treatment were the tallest, averaging 17.1 cm on July 16. Plants without sulfur (Treatments C-S and SC-S) were shorter, averaging 14.1 cm and 12.5 cm, respectively. The Supercomplete (SC) and Supercomplete + Supersulfur (SC + S) treatments were not the tallest plants, but they were first to flower and bear fruits. Initial results show that sulfurless plants have a poor roots growth and plant development.This research was funded by Evans-Allen Research fund and EPSCOR.

Sequencing the Unique Short Region of Infectious Laryngotracheitis Virus

Tanu Bedi, Ida Chung, Cynthia M. Boettger, and Calvin L. Keeler Jr.
Department of Animal and Food Science

Infectious laryngotracheitis virus (ILTV) is a herpesvirus which causes an extremely contagious respiratory disease of chickens.  The disease is characterized by signs of respiratory distress and the mortality rate can be as high as fifty percent. The ILTV genome is 148,665 base pairs in length. The unique short (US) region of the genome (~14,000 base pairs) contains 9 genes including 6 glycoprotein genes.  Glycoproteins play an important role in eliciting an immune response from the host , and in viral attachment and pathogenicity. /  / The goal of this project is to compare the US sequence of  two ILTV field isolates, two vaccine strains and a standard challenge virus. This will be accomplished by amplifying, cloning, sequencing, and then comparing the sequence of this region of the viral genome from these five strains.  The purpose of this comparison is to observe any evolutionary modifications over time. Also, if sequence polymorphisms are found between the five strains, they can be used in the future to develop novel diagnostic tools.

The Effect of Thymol on Intracellular and Extracellular Reactive Oxygen Species Production by Bovine Neutrophils

Sarah L. Cordova, Changqing Wu, Kerrie A. Davison,  and Tanya F. Gressley
Department of Animal and Food Science

Mastitis is a bacterial infection of the udder and is the most common disease of commercial dairy cattle the United States. One reason that mastitis is so prevalent is that the natural immune response to mastitis can be harmful to the cow. Neutrophils, which are white blood cells involved in the innate immune response, release intracellular and extracellular reactive oxygen species (ROS). Intracellular ROS, produced when neutrophils engulf bacteria, are necessary because they enable the neutrophil to kill bacteria. Extracellular ROS can destroy both extracellular bacteria as well as healthy tissue. We are interested in identifying antioxidant compounds that will reduce mammary tissue damage from extracellular ROS while preserving the neutrophil’s function. In this experiment, thymol, a natural compound found in thyme was tested using several different in vitro assays to determine its impact on total ROS production, extracellular ROS production, and intracellular ROS production. Neutrophils were collected from healthy cows and incubated without thymol or one of four different concentrations of thymol: 0.0001 mg/ml, 0.001 mg.ml, 0.01 mg/ml, and 0.1 mg/ml. Thymol dose-dependently inhibited extracellular ROS using an isoluminol chemiluminescence assay. We are currently conducting luminol chemiluminescence assays to determine total ROS production, CM-H2DCFDA assays to determine intracellular ROS production, and an S.aureus kill assay to evaluate neutrophil function. If results indicate that thymol has the desired effect on ROS, then it will be tested in vivo to determine if it is helpful in fighting mastitis.

Impacts of Shoreline Modification on the Nearshore Fish Assemblage in Delaware Bay

Kevin P. Crum, Richard G. Balouskus, and Timothy E. Targett
University of Delaware School of Marine Science and Policy

Shoreline modifications such as bulkheading and riprap impact nearshore habitat for estuarine nekton by altering water quality, wave dynamics, and nutrient inputs.  This study quantified differences in the abundance and diversity of fish species along various types of shorelines on a localized scale.  Sampling sites were located within a 200m stretch of shoreline along the University of Delaware campus in Lewes, Delaware.  Five types of shorelines were examined: bulkhead, riprap, Spartina marsh, sand beach, and Phragmites marsh.  Seine hauls were made parallel to shore when water depth reached approximately .25m at each site.  Preliminary results suggest differences in fish assemblages between shoreline types.  Low species diversity and high fish abundance were found at the bulkhead and beach sites, whereas the riprap exhibited intermediate diversity and abundance.  The highest species diversity was found at Spartina and Phragmites, with Spartina supporting intermediate abundance and Phragmites supporting low abundance.  Menidia menidia (Atlantic silverside) was the predominant species at all sites, and its relative abundance was correlated with species diversity.  High M. menidia abundance corresponded with low species diversity (M. menidia accounted for ≥94% of fish caught at the bulkhead and beach, 90% at the riprap, 80% at the Spartina, and 65% at the phragmites).  The only shoreline types where any species other than M. menidia represented >5% of the total fish population were the Spartina and Phragmites sites, exemplifying the importance of preserving even small stretches of natural marsh to protect ecosystem diversity.  This research was supported by NOAA (CSCOR) and NSF EPSCoR Grant EPS-0447610.

Progesterone Measurement to Determine Estrus Activity in Does at Hickory Hill

T.N. Edwards*, J. L. Eierman and D.J. O’Brien
College of Agriculture and Related Sciences, Delaware State University

Goats are considered seasonal breeders with cycling occurring during the shorter days of fall and subsequent kidding occurring in early spring.  Late spring/early summer is considered a period of anestrous (no cycling) in many breeds in temperate climates.  The seasonality of reproduction is however affected by many factors including type and breed of goat.  It was therefore the objective of this experiment to determine progesterone concentrations as an indicator of cycling in crossbred Boer does during the summer (June) at Delaware State University’s Hickory Hill Farm.  Two blood samples were taken by jugular venipuncture on d -9 and d 0 from 25 does.  Blood samples were allowed to clot at 4o C for 24 hrs and serum was harvested after centrifugation at 3300 rpm for 15 minutes and stored at –20o C until later analysis.   Progesterone concentration was determined by radioimmunoassay at the Texas Veterinary Medical Diagnostic Laboratory, College station, TX.  The majority of does sampled (64%) had progesterone levels below 0.20 ng/ml on both days measured.  Average progesterone concentrations were 0.33 ± 0.07 and 0.30 ± 0.07 ng/ml for d -9 and d 0, respectively.  No individual doe serum progesterone concentration was > 1.0 ng/ml on either day tested.  In summary, the majority of does had low levels of progesterone in their blood concluding that they were not cycling or in anestrous.

Comparison of the Efficiency of Two- and Three-Chambered Slides on Fecal Egg Counts in Goats.

B. W Fisher, E. K. Crook and D. J. O'Brien
College of Agriculture and Natural Resources, Delaware State University

The main health problem in small ruminants is internal parasites and their developed resistance to available anthelmintics/chemical dewormers. A fecal egg count (FEC) is the best way to assess the level of parasitism and is conducted according to the Modified McMaster technique. This technique utilizes a two-chambered slide, however; a three-chambered slide had recently been introduced for FEC. Therefore, the objective of this study was to determine if the three-chambered McMaster slide is more efficient in determining FEC when compared to the two-chambered slide. In this experiment, fecal samples were obtained rectally from seventy-seven goats and placed in individually labeled Ziploc (tm) bags. Samples were then stored at 4 degrees C until analysis which was completed in less than one week. FEC were then determined using the Modified McMaster technique utilizing a three-chambered slide in addition to the two-chambered slide. Each slide was read under the microscope and numbers of eggs in all chambers were recorded to determine FEC. Data was then analyzed using the GLM precedure of SAS with means separated using LSMEANS. FEC was not influenced by type of slide utilized and average 469.6 eggs per gram (epg). In conclusion, under the conditions of this study, the three-chambered slide was not more efficient or sensitive in determining FEC when compared to the two-chambered slide. 

Examination of Ancient Egyptian Plant Consumption Using GC/MS Techniques

Aaron Gibson, A. O. Tucker, and Sandy Jacobsen
Department of Agriculture and Natural Resources, Delaware State University

In 1992, Balabanova et al. tested Egyptian mummy hair, bone and soft tissue for various drugs and their concentrations.  She found high levels of morphine alkaloids (from opium poppy) and THC (Δ1,9-tetrahydrocannabidiol from marijuana), but, surprisingly, she also found high levels of nicotine and cocaine, alkaloids thought to be only produced in plants native to the Americas (Nicotiana and Erythroxylum spp.).  This unusual finding sparked a firestorm of controversy and was even the subject of television documentaries; however, Balabanova’s findings were tested and supported by herself and others.   /  / Consumption of the flowers of the blue lotus (actually a water lily), Nymphaea caerulea, as a narcotic by the ancient Egyptians is documented in archaeological evidence, in both pictorial representations and physical remains.  The rhizomes of several members of the genus Nymphaea and the related genus Nelumbo (lotus) are capable of producing a mixture of alkaloids, which may be potentially psychotropic. /  / In order to uncover a possible link between Balabanova’s findings and the consumption of flowers of N. caerulea in ancient Egypt, we investigated different methods for the extraction of alkaloids from raw plant material using tobacco and tea.  The resulting solutions were then analyzed by gas chromatography/mass spectroscopy in order to identify the presence of specific chemicals.  The methods, once perfected, will be applied to the flowers of N. caerulea in order to determine if these plants could be responsible for the peculiar appearance of nicotine and cocaine alkaloids in the bodies of ancient Egyptians, as well as evidence supporting the consumption of this plant. /


Eric Irvin, Ken Duren, Christopher K. Williams, Jeffrey L. Buler, and Bill Jones
Department of Entomology and Wildlife Ecology

Many grassland songbirds across North America, including the grasshopper sparrow (Ammodramus savannarum), are reported to be experiencing drastic declines in population levels. Since 1967, there has been a 65% decrease in the population of grasshopper sparrows across their range.  Most of the decline has been directly attributed to the loss of grassland habitat.  As a result, it is imperative to determine the locations of remaining suitable habitat for successful management of the species. From May 15 to August 15 2009, we conducted 3 replicates of 180 point-count surveys to sample the presence of grasshopper sparrows in Delaware. We recorded presence/absence and associated habitat to 1) build a predictive habitat distribution model that identifies scale-dependent relationships in habitat use, 2) produce a habitat suitability map that reflects predicted presence of breeding grasshopper sparrows within Delaware, and 3) use model outcome and distribution map to target future land conservation of existing habitat and optimize the impact of management efforts. Data from 3 additional replicates of 180 point-count surveys which were conducted from May 15 to August 15 2008 will be compiled with this year’s data. Two hundred and seventy points will be randomly selected to construct the model. We will use the remaining 90 points to validate the model. Grasshopper sparrows were detected at 121 points out of the total 360 points. Funding provided by the Undergraduate Research Program, a community based research grant from the Office of Service Learning, and the Department of Natural Resources and Environmental Control.

Efficacy of Neem Oil against External Parasites on Laying Hens

Jade M. Johnson1 and B. A. McCrea2

The use of Neem oil may provide an alternative pesticide for those in the poultry industry as well as backyard poultry owners looking for natural pesticide remedies.  The neem tree (Azadirachta indica) produces an oil that has biocidal effects against nearly 200 arthropod pests without any adverse effects on most non-target organisms.  There are three main external parasites in poultry and they are as follows:  Northern Fowl Mite, Chicken Louse, and Shaft Louse.  It was the objective of this study to determine the effectiveness of neem oil over a four week period when sprayed on 15 laying hens infested with external parasites.  The information generated in this trial will benefit producers of organic poultry, natural poultry, and small flock owners.  Birds were housed individually and monitored daily.  A 1% neem oil solution was applied once weekly (Mondays) and the external parasite population was counted daily in three areas of the bird (vent, wing, back) for the remainder of the week.  External parasites were counted on both feathers and skin when they fell within a 1 x 1in2  template.  Preliminary results in this small scale trial indicate that there is a significant difference in birds spayed with neem when compared to control birds (not sprayed). Birds sprayed with neem had a lower level of external parasites.  Additionally, there were significant differences between the three areas of the bird where parasites were counted (vent, wing, back).  These results show that neem oil does have an effect the number of external parasites. 

Tidal Marsh Arthropod Diversity and Abundance in Response to Prescribed Fire

Cassandra L. Kane, Rebecca A. Kern, and W. Gregory Shriver
Department of Entomology and Wildlife Ecology

Natural fire regimes are an important component of many disturbance driven ecosystems, therefore the absence of fire in fire dependant ecosystems can change the overall state of the system. The interruption of these fire cycles has created the need to use prescribed fire to attempt to restore more natural fire regimes. The Blackwater National Wildlife Refuge (Cambridge, Maryland), is a tidal marsh dominated refuge located along the Chesapeake Bay. The Refuge has been using prescribed fire to burn the marsh for over 30 yrs. The natural fire regime in tidal marsh systems is not clearly understood; therefore the refuge is conducting a study to determine the effect of prescribed fire on different tidal marsh attributes (i.e. vegetation, physical properties, and birds). No studies have previously been conducted to determine the effects of the fire regime on arthropods; important bird food. The objectives of this study were to determine the arthropod diversity and abundance in relation to time since prescribed fire. Arthropods were sampled from tidal marshes located in four treatment types; annual burn, 3-5 yrs post fire, 5-7 yrs post fire, and > 7 yrs post fire. There are 25 samples from each burn class. At each point, five one-meter square arthropod collection points were randomly selected. At each location we sampled the vegetation and used a vacuum sampler to collect arthropods from each 1 m square. Arthropods were placed into test tubes to be taken to the lab for identification. Supported by Delaware EPSCoR, through National Science Foundation Grant.

Mating behavior of bucks during the non-breeding season after estrus synchronization protocols in meat does

T.S. Lingham, J.L. Eierman, and D.J. O’Brien
College of Agriculture and Related Sciences, Delaware State University

A high percentage of pregnancies in goat operations in the U.S. are achieved from natural mating. Buck breeding ability is often not considered and there are a number of factors that influence a buck’s ability to mate including breed, buck: doe ratio, and breeding season. It was the objective of this experiment to determine the mating frequency of bucks (2 different breeds) during the non-breeding season after estrus synchronization protocols in does. Forty-six Boer-crossbred does and 2 bucks (1 Kiko and 1 Boer) located at DSU were used in the experiment. To facilitate the use of the buck effect, males were removed from sight, sound and smell of females for 3 wks prior to the beginning of the study. Does were separated into two groups including a control (CON; n=22) and a controlled internal drug releasing device (CIDR; n=24) group. On d-9, CIDRs were inserted vaginally into females in the CIDR group and at removal (d0), 300 IU of pregnant mare serum gonadotropin (PMSG) was given i.m. Females were then grouped for mating with 2 bucks wearing marking harnesses for 14 days. Data was analyzed using the FREQ procedure of SAS. Percentage of females mated was similar and averaged 91.6±0.1% for CIDR and 77.3±0.1% for CON females. The Kiko buck (74.4±0.1%) mated a higher proportion (P<0.001) of females compared to the Boer buck (25.6±0.1%). In conclusion, progesterone priming was not necessary for inducing estrus and buck breed needs to be considered when using natural mating during the non-breeding season. This research presentation was made possible by the National Science Foundation EPSCoR Grant

Environmental Assessment of Worton and Mill Creeks:  Preliminary Bathymetric Mapping

Greg M. McKee, Matthew H. Panunto, Kashi N. Subedi, and Bruce E. Allison
Wesley College, Environmental Sciences

An environmental analysis of any landscape that involves a body of water will include bathymetric data. For navigational bodies of water, National Oceanic and Atmospheric Association (NOAA) nautical depth charts are available.  However, there is a possibility that the NOAA depth charts do not accurately reflect the effects of channelization and siltation, which can produce inaccurate simulation data when utilized in computer models. A project was initiated to compare measured depth soundings with published NOAA depth charts to determine if current nautical charts depict sufficiently detailed depth information for environmental assessments and modeling use.  The objective of this research was to compare water depth and perimeter locations on current NOAA nautical charts with field measurements at Worton and Mill Creeks.  Water depths and their respective GPS coordinates were determined in a grid layout for the full length of Worton and Mill Creeks.  The grid point depths and GPS coordinates were imported into ArcGIS 9.3 and Surfer 8 to create interpolated images of the creek’s physical dimensions.  These images were compared to the current NOAA navigational charts.  Preliminary results indicated that there are discrepancies in the creek perimeters and depth values of current nautical charts when compared to the field measurements.  For environmental assessments or modeling applications, measured bathymetric data may be required.  These depth measurements will eventually be utilized in the AQUATOX model and an analysis of the model output will be completed.  This project was supported by Delaware EPSCoR, through National Science Foundation Grant EPS-0447610 and Wesley College.

Preliminary Description of the Chemical Makeup of Worton and Mill Creek

Matthew H. Panunto, Greg M. McKee, Kashi N. Subedi and Bruce E. Allison
Wesley College, Environmental Sciences

Water quality not only encompasses the physical and chemical properties of a body of water, but it is also an indicator of the ability of a water body to sustain aquatic life.  Surrounding land use, non point source pollutants and natural modifications to the aquatic landscape affect water quality.  Through monitoring water quality properties and land use practices, a better understanding of the impact these conditions have on marine life is achieved.  The objective of this research was to determine the chemical makeup of Worton and Mill Creek and to use the Long-term Hydrologic Impact Assessment (L-THIA) Model to predict nitrogen, phosphorus and sediment loadings to these water bodies. Chlorophyll, turbidity and dissolved oxygen were measured in a horizontal grid at a depth of 60 cm throughout the length of Worton and Mill Creeks.  At each measurement point, GPS coordinates were taken.  Diurnal runs were completed for three specific locations and chlorophyll, turbidity and dissolved oxygen were measured at 30 cm depth intervals.  Water quality measurements were taken with a YSI Sonde 6600 Environmental Monitoring System and analyzed using Microsoft Excel.  Water quality data and GPS coordinates were imported into ArcGIS 9.3 and Surfer 8 to create interpolated images of the creek’s chemical environment.   These parameter values will be eventually used in the AQUOTOX model to assess changes over time.  This assessment will assist scientists and managers in making sound environmental decisions.  This project described was supported by Delaware EPSCoR, through National Science Foundation Grant EPS-0447610 and the Wesley College.  

Comparative study of sulfur metabolism in model green sulfur bacteria to new isolates from the Mid-Atlantic

Jesse L. Rodriguez,  Jennifer Hiras, and Thomas E. Hanson
Delaware Biotechnology Institute

Chlorobium tepidum (syn. Chlorobaculum tepidum) has become the model organism for the study of anaerobic sulfur oxidation in green sulfur bacteria (GSB).  Anaerobic sulfur oxidation in the biogeochemical sulfur cycle prevents the efflux of reduced sulfur compounds from anaerobic environments into the atmosphere. C. tepidum utilizes sulfide, elemental sulfur, and thiosulfate as electron donors for photosynthesis.  The genome of C. tepidum has been sequenced and annotated, identifying many genes encoding proteins hypothetically involved in sulfur oxidation.  These genes are tightly clustered in specific regions of the genome, which has allowed the use of in vitro transposon mutagenesis (IVTM) to create knock-out mutants that focus on these specific regions. One particular cluster of interest is that containing the gene which encodes a RubisCO-like protein (RLP).  A mutant strain lacking the RLP was found to be defective in elemental sulfur and thiosulfate oxidation. In this study, additional mutant strains containing transposon insertions in genes near the RLP-encoding gene were screened for growth on sulfide, thiosulfate, or the combination as electron donors in Pf-7 medium. The results will indicate whether or not genes in the RLP region, aside from that encoding the RLP itself, are required for anaerobic sulfur oxidation in C. tepidum.  This knowledge will help to refine models of sulfur oxidation pathways in this model organism and in general.  In addition, screening of sulfur compound utilization by new, local isolates of green sulfur bacteria will also be reported. This project was supported by Delaware EPSCoR, through National Science Foundation Grant EPS-0447610 .

Characterization of the Summer Larval Fish Assemblage in Delaware Bay and the
Effect of Vertical Distribution on Measured Larval Density and Diversity

Brittany M. Schieler, Edward A. Hale, and Timothy E. Targett
University of Delaware, School of Marine Science and Policy

Estuarine nursery habitats play an indispensable role in the early life history of many important marine fishes. Successful ingress and retention of the larval stages of these species into estuaries is linked closely with the continuation of the adult stock. Consequently, it is important to understand the processes of larval ingress and retention. It is also known that some larval fish species utilize vertical migrations in order to facilitate up-estuary transport and retention, causing vertical stratifications in density and diversity.  To examine larval fish ingress and retention in Delaware Bay, a two-fold study of icthyoplankton assemblage was conducted throughout the summer of 2009 at Roosevelt Inlet, near the mouth of the Delaware Bay. Mid-water samples were taken once a week from June 2- July 21 as part of a long-term effort to characterize weekly variability in the icthyoplankton assemblage. Changes in larval density, mean length, and diversity are reported. An intensive study sampling both the surface and bottom of the water column was conducted every other night from July 26 –August 5 to determine if vertical position of sampling significantly influenced measured larval density and diversity.  Initial observations indicate that many species, especially the most common species Anchoa mitchilli (Bay Anchovy), are more abundant in the surface waters during the night-time flood tides. This research is part of an ongoing study aimed to better understand variability in larval ingress and retention across spatial, temporal, and species boundaries in Delaware Bay.  Research supported by NOAA (Sea Grant) and NSF EPSCoR Grant EPS-0447610.

Quantifying the Impacts of Alien Plants on Native Spider Diversity

Catherine C. Sun and Douglas Tallamy
Department of Entomology and Wildlife Ecology

Invasive, nonnative plants often displace native ones, altering ecological services provided by the area and reducing available resources for higher trophic levels, including herbivores and predators.  Such losses are often disproportionately magnified – a phenomenon called ‘trophic skew’ – and if left unchecked can possibly degrade an entire ecosystem. This study quantified the impact of nonnative plants on spider densities and diversities. Spiders prey upon small native-plant-dependent herbivorous insects and therefore may be negatively impacted by nonnative plants. Spiders collected from 13 pairs of congeneric native and nonnative plants were counted, identified, and weighed. Spider abundance and richness were greater on 8 of 13 native plants than on their nonnative counterparts. However, Simpson’s diversity indices and preliminary analysis showed no significant differences in spider diversity between native and nonnative plants. Furthermore, analyses suggest that not all nonnative plants are equally unsupportive of spiders, nor that all native plants are equally supportive.  Further investigation is required in order to understand fully the effect of alien plants on spider diversity. Funding generously provided by NSF EPSCoR, Grant EPS-0447610. /

Architectural strategy and plant species composition of Veery nests in Delaware

Syrena M. Taylor  and  Christopher M. Heckscher
Delaware State University

The Veery (Catharus fuscescens) is a poorly known forest thrush that nests on the Piedmont physiographic province of northern Delaware.  We investigated Veery nest architecture and the species composition of nest materials used by Veeries.  Specifically, our objectives were (1) to clarify the architectural strategy used by Veeries to construct nests, (2) to determine the species composition of materials used in Delaware Veery nests, and (3) to determine whether Veeries used alien plant parts in the nest construction process.  Each nest layer was dissected and the components were identified to species level.  We then categorized all leaf litter based on its state of decomposition.  We found that nests have three distinct layers:  (1) outer, (2) structural, and (3) lining.  The outer layer is a platform of leaves that assists with nest camouflage and support.  The structural layer is made from bark strips, twigs, and leaves, and provides additional structural support. The lining is the inner-most layer of the nest.  Flexible materials are used for the lining such as rootlets, fungus, and seed catkins.  In our study, we found that 25% (n = 20) of species used for nest construction were alien invasive plants.  Veeries were consistent in their reliance on leaf litter of varying decomposition stages for the outer and structural layers.  Our study is the first to confirm the architectural strategy and species composition of Veery nests in this region and is the first to report the use of alien plant species in the nest construction process.

Changes in the Antioxidant Content of Tomato and Watermelon During Storage
Alexandra Turley and Changqing Wu
Department of Food Science, University of Delaware

Antioxidants are a class of compounds that protect cells from the damaging effects of reactive oxygen species. Many foods, especially fruits and vegetables, are good sources of antioxidants. Because the antioxidant content of fruits and vegetables changes after harvest, there is interest in the optimum storage time and temperature for produce. Studies have been done on pre-market storage conditions, but not on home storage conditions. Tomatoes and watermelons are two commonly consumed fruits with abundant antioxidants and are used in our study as representative produce to study the effect of home storage conditions on the antioxidant content. In this study, tomato and watermelon samples were kept at room temperature at 22°c and in the refrigerator at 4°c for two weeks to mimic consumer behaviors. Samples were tested every three days for their antioxidant activities using the 1,1-Diphenyl-2-picrylhydrazyl (DPPH) assay and the Folin-Ciocalteau assay. The samples were also extracted and tested for lycopene content and total antioxidant activity using both hydrophilic and lipophilic oxygen radical absorbance capacity (ORAC) assays. The tomato samples initially had a phenolic content of 305.1 mg Gallic acid equivalents (GAE)/kg juice, with a final content of 233.7 mgGAE/kg juice and 231.1 mgGAE/kg juice for the tomatoes stored at 22°c and at 4°c, respectively. The watermelon stored at 4°c had an initial content of 83.0 mgGAE/kg juice and a final content of 62.4 mgGAE/kg juice. The room temperature and the 4°c tomatoes had similar DPPH scavenging effects, with a peak in antioxidant activity at nine days. In general, tomatoes were found to have greater antioxidant content than watermelons under all storage conditions.

Expression of Involucrin in the Normal and Ulcerated Bovine Sole Region

Amanda L. Welch, Trista L. Reeder and Robert M. Dyer
Department of Animal and Food Sciences

Accounting for 12% of diagnosed conditions and 17% of all deaths in US dairy cattle, lameness from claw horn lesions in cattle is the second most important health problem in the modern dairy industry. Sole ulceration is the most serious claw horn problem and  arises from defective, poor quality claw horn production. Bovine claw horn forms by growth of basal keratinocytes located in the deepest basal cell layer of the claw epidermis while maturation, keratinization and cornification occurs in the suprabasal layers. Changes in keratinocyte growth, keratinization and cornification could adversely impact hoof horn quality in ulceration. Involucrin is a structural protein expressed during formation of the cornified envelope in  suprabasal keratinocytes. We proposed expression and distribution of involucrin would be altered in ulcerated sole region. Immuofluorescent stains of normal and ulcerated epidermal-dermal tissues of the sole region were prepared with anti-involucrin primary antibody and FITC conjugated secondary antibodies. Expression of involucrin in normal tissues was evenly distributed throughout the cytoplasm of suprabasal keratinocytes across several suprabasal layers of epidermis. Keratinocyte nuclei were clearly visible as symmetric, circular unstained areas within the cytoplasm. Ulceration was associated with increased, highly irregular intensity of cytoplasmic immunofluorescence that obscured keratinocyte nuclei and exended across several suprabasal strata. Areas of irregularly increased immunofluorescence of the epidermis were interspersed with areas of less intense, more even fluorescence. Disturbed keratinocyte homeostasis in ulcerated sole regions may be manifest as altered patterns of involucrin expression. (Funding provided by the University of Delaware’s Undergraduate Research Program and by the USDA.)

The Function of Lippolysaccharide in Symbiotic Root Nodule Formation

Corinna L. Willis1, D. Janine Sherrier, and Heather Danysh
1Lincoln University of Missouri

Leguminous plants interact with rhizobia, soil microbes, to form symbiotic root nodules.  The relationship is specific and is dependent on many factors including flavonoids secreted by the host plant and the lippolysaccharides (LPS) membrane of the bacteria.  In previous studies we found the long-chain fatty acid to be crucial to the development of nodules.  The focus of this research was on the function of the LPS epitope in the establishment of this mutualistic relationship.  Soybean (Glycine max Williams 82) plants were inoculated with either a wild type bacteria, Bradyrhizobium japonicum USDA 110, which has 27-hydroxyoctacosanoic acid in its tetraacylated lipid A or mutant bacteria, Bradyrhizobium japonicum WC3807, which lacks 27-hydroxyoctacosanoic acid in its structure.  The progression of symbiosis was then documented using confocal microscopy.  Specifically, we evaluated four stages of the relationships:  1. bacterial binding to the root hairs, 2. root hair deformation, 3. infection thread formation 4. nodule formation.  We found that the mutant and wild type bacteria bind to the root hair surface, and induce root hair deformation.  Work is on-going to determine if infection threads and nodules are induced by infection with each of the bacterial stains.  Support for this work was obtained through the National Science Foundation (NSF) Experimental Program to Stimulate Competitive Research (EPSCoR), Grant EPS-0447610 and NSF Grant 05-0520586. 

Dumetella carolinensis) ABUNDANCE IN SUBURBAN FOREST

Jamie R. Zaccaria1, Amanda M. Conover1, Christopher K. Williams1, and Vincent D’Amico2
1 Dept. of Entomology and Wildlife Ecology, University of Delaware. 2U.S. Forest Service.

Due to increasing urban development into forested areas in the United States, the quality of habitat for songbird communities has been impacted as the forested area becomes fragmented and invaded by non-native plant species. It has been hypothesized that the density of non-native vegetation can negatively affect populations of songbirds in these fragmented areas. The objective of this project is to estimate abundance and occupancy of the gray catbird (Dumetella carolinensis) as a function of native plant density. We collected data at 100 random plots within forested areas, each 25m from a field edge within and around New Castle County, Delaware. To examine the gray catbird abundance and occupancy at each plot, five minute passive listening surveys were conducted three times between 15 May and 6 August 2009. Vegetation composition was also measured within each survey plot at three intervals (at the edge, 25m from the edge and 50m from the edge). Measurements of understory structure and species composition were taken along a five meter transect at each distance interval from the field edge. The results of this research can be used by land managers to better understand and maintain fragmented and invaded areas to benefit songbird communities. This project was supported by a grant by the United States Forest Service.

Links: Summer 2009 Undergraduate Research Symposium, Symposium Abstracts from other Colleges and Departments,
2009 Undergraduate Research Summer Enrichment ProgramUnversity of Delaware Undergraduate Research Program, Howard Hughes Undergraduate Program.
Created  7 August 2009. Last up dated 19 August 2009 by Hal White
Copyright 2009, University of Delaware