Undergraduate Research Symposium Abstracts for Agriculture and Marine Studies 2007

Abstracts from the Colleges of Agriculture and Marine Studies
Undergraduate Summer Research Symposium August 8, 2007

Ordered alphabetically by student's last name

Baldanza	Eierman	Jackson	Lenihan	McCole	Panunto	Rivera	Smarsh	Tibuah	Wehner
Barton	Fischel	Legasse	Lovett	Mills	Paras	Romag	Speier	Ukaegbu	Wolters
Dougherty	Green	Lapera	Marchesiello	Morgan	Peters	Schaeffer	Thomas	Villard	Yoskowitz

Jun binding protein p21 SNFT as a target for Meq oncogene function
Vince Baldanza, Mark Parcells and Carl J. Schmidt
Department of Animal and Food Sciences

The Jun family of transcription factors plays an important role in oncogenesis. One member of this gene family, Meq is required for oncogenesis by Marek’s Disease Virus (MDV), which causes T-cell lymphoma in chickens. Another member of the Jun family is the protein p21 SNFT (also known as Jun-binding protein), which functions as a negative regulator of the transcription activation functions of other Jun proteins. p21 SNFT inhibits the function of other Jun proteins by binding and inhibiting their ability to activate transcription. One possible mechanism by which Meq may cause tumors is by binding p21 SNFT, thereby freeing the cellular Jun proteins to stimulate cellular growth. To test this hypothesis, we have set out to clone the chicken p21 SNFT cDNA by PCR and ultimately test the ability of Meq protein to bind the p21 SNFT protein. Currently, we are testing different primer combinations and different sources of mRNA in an effort to clone p21 SNFT. Supported by USDA grant.

A Comparison of Butterfly Foraging on Joe-pye weed and Butterfly bush
Elizabeth Barton and Douglas Tallamy
Department of Entomology and Wildlife Conservation

Many backyard gardeners are enthralled with the idea of attracting butterflies into their yards and increasing biodiversity in their gardens. The “butterfly gardens” these people have created almost always include the invasive, exotic species Butterfly bush (Buddleia davidii) that ironically does not support the larval development of any North American butterflies. Joe-pye weed is a native alternative that not only attracts adult butterflies because of its nectar but also supports the entire life cycle of 41 species of Lepidoptera. The objective of the project was to compare quantitatively the attractiveness of Joe-pye weed and Butterfly bush. Sites were identified through contact with UDBG friends, Master Gardeners, and public gardens and consist of campus gardens, backyard habitats, and public gardens. Data on butterfly visitation (quantity and species variety) on Joe-pye weed and Butterfly Bush was or will be recorded in two consecutive 15-minute periods on sunny days during the month of August when both species were/are in full bloom. Research was funded by EPSCoR.

Multi-species Use of an Avian Microarray
Lorna Dougherty, Michele Maughan, Ida Chung, Calvin Keeler
Department of Animal and Food Sciences

A 4,959 element avian cDNA microarray has been created for the purpose of examining the avian (chicken) innate immune response (Bliss et al., 2005; Keeler et al., 2007). These elements were obtained from EST libraries of chicken origin. Many avian pathogens, such as avian influenza, infect not only chickens but other avian species such as turkeys and ducks. The goal of this project is to develop methodology enabling the use of this microarray to study the immune response of other avian species. Experimental conditions have been altered to achieve the optimal hybridization of chicken, turkey or duck spleen fluorescently-labeled amplified RNA (aRNA) to the elements present on the avian innate immunity microarray (AIIM). This will allow us to identify which immune related elements are suitable for study across species, and will permit us to compare the transcriptional response of chickens, turkeys, and ducks to pathogens in order to achieve a more holistic perspective of the avian innate immune response. Funding provided by the USDA.

Effectiveness of the Buck Effect in Inducing Out-of-Season Breeding in Goats
Jodi L. Eierman, Richard A. Barczewski, and Dahlia J. Jackson
College of Agriculture and Related Sciences, Delaware State University

Fifty-two Boer and Boer-crossbred meat-type does and 4 bucks located at Delaware State University were used to examine the effectiveness of the synthetic progestagen, altrenogest (commercially available as Regumate™), in combination with the buck effect, when compared to no hormonal priming before buck introduction during the summer. Males were removed from sight, sound and smell of females for 3 weeks prior to the beginning of the study. All goats were group-fed a 12% corn soybean meal diet with ad libitum hay and water. For a period of 7 days, the treatment group (n=26), received the labeled dosage of Regumate™ (1ml/50kg), while the control group (n = 26) received a similar dose of water. Following the treatment period, females were grouped for mating (= day 0) with bucks wearing marking harnesses for 15 days. Females were checked twice daily for mating and number of does marked was recorded to determine days to first mating and percentage mated. The percentage of does mated was similar for control (100%) and Regumate-treated does (100%). However, Regumate treatment reduced (p<0.001) the total number of days to mating when compared to the control group (2.9 ± 1.8 and 6.3 ± 4.1 days, respectively). In summary, altrenogest decreased days to first mating, but all females regardless of treatment were mated in 15 days. Therefore, this study indicates that the buck effect alone might be sufficient for out-of-season breeding in meat goats. Funding for this program was made possible by Delaware State University’s College of Agriculture and Related Sciences and EPSCoR..

Arsenic Mobilization in the Critical Zone: Oxidation by Hydrous Manganese Oxide
Jason S. Fischel, Matthew Ginder-Vogel, and Donald L. Sparks
Department of Plant and Soil Science

Manganese(IV) oxides represent one of the main redox catalysts in the subsurface environment, while also extensively sorbing a number of anions and cations. Their wide-spread distribution in soil combined with their highly reactive surfaces allow manganese oxides, even in low concentrations, to oxidize trace metals such as arsenic from arsenite which is fairly toxic and mobile to arsenate, a much less reactive and mobile species. However several variables can influence the oxidation reaction: a variety of particle sizes can be found in nature ranging from a nanometer to micrometer size particles, thus altering the exposed surface area. Also, as manganese oxide minerals age under natural conditions it presumably goes through the Ostwald ripening process, where the numerous small crystalline particles formed at first begin to precipitate into a larger, more crystalline structure, having the potential to significantly reduce surface area and thus overall reactivity. Through the synthesis and use of one batch of hydrous manganese oxide (HMO), a poorly crystalline Mn oxide, with an initial particle size of 700 m, we were able to observe an overall trend of the oxidation reaction slowing. The conversion of arsenite to arsenate occurred rapidly following one week of aging; however, a decrease in reactivity was observed during the next four weeks. In addition, hydrous manganese oxide was synthesized weekly following a standard method at room temperature, while other techniques were employed to vary particle size: heating, chilling or adding sulfuric acid in addition to the standard procedure appeared to increase particle size up to several microns, while sonicating or reducing the formation time decreased particle size to as small as 175 m. Scanning Electron Microscopy was used to characterize the various manganese oxides. Funding was generously provided through the Delaware EPSCoR Grants, by the National Science Foundation.

Characterization of Escherichia coli Isolates from the Delmarva Peninsula
Stacy S. Green, Cynthia M. Boettger, and John E. Dohms
Department of Animal Science

Colibacillosis, a devastating disease and a cause for economic loss in the poultry industry, is caused by avian pathogenic Escherichia coli (APEC). APEC having no specific characteristic separating it from non-pathogenic strains contains a number of virulence factors including tsh, iss, iucC, intI1, and traT. Colibacillosis along with other pathogenic diseases in the poultry industry are currently being treated with antibiotics for clinical treatment. Concern is growing due to the increased chance of the development of resistant microorganisms. The characterization of the E. coli isolates from the Delmarva Peninsula is being completed by determining virulence genes, determining antimicrobial susceptibility to nalidixic acid and ciprofloxacin, and typing of the O-antigens. Virulence genes are being determined with the use of genomic DNA extraction, polymerase chain reaction (PCR), and gel electrophoresis. Antimicrobial susceptibility is being determined utilizing BBL Sensi-Disc Susceptibility test discs in accordance with NCCLS methods. Zones of inhibition are being measured and analyzed according to the manufacturer’s interpretive standards. Supported in part by USDA grant.

The Effects of High Pressure Treatment on the Conformation
of Capsid Proteins of Enteric Viruses Known to Cause Foodborne Illness
Brittany A. Jackson¹, Carl J. Schmidt², and Kalmia E Kniel²
Departments of ¹Biological Sciences and ²Animal and Food Sciences

The food production industry employs high pressure treatments as means of inactivating enteric viruses on food products. Despite significant reductions in virulence, little research is concerned with how pressure causes this change, and this information can be used to improve the efficiency of the method. The purpose of this project was to test the concept that high pressure causes conformational changes in viral capsid proteins, thus altering active site orientation, inhibiting the binding to host cells, and resulting in decreased virulence. Trypsin is a protease that cleaves proteins after arginine or lysine residues. If pressure induces changes in conformation and exposes different tryptic cleavage sites, then variations in protein fragments should be observed between pre- and post-pressure treated samples. Comparison of protein fragments from non-pressure-treated and pressure-treated samples of Aichi virus, Hepatitis A virus, and Feline calicivirus were performed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) before and after tryptic digestions. All samples exhibited a predominant peptide, which displayed decreased intensity after tryptic digestion, as well as the appearance of new, smaller fragments; an effect amplified by increased trypsin concentrations. Pressure treatment yielded new tryptic fragments not observed in the non-treated samples. These differences in the tryptic peptide map indicate that the viral capsid protein undergoes a conformational change as a result of pressure treatment. Funding was provided by the United States Department of Agriculture (USDA).

Sequencing the Unique Short Region of Infectious Laryngotracheitis Virus
Michelle Lapera and Calvin Keeler
Department of Animal and Food Sciences

Infectious laryngotracheitis virus (ILTV) is a herpesvirus which causes an extremely contagious respiratory disease of chickens. The virus is characterized by signs of respiratory distress, accompanied by gasping and coughing up of bloody material. Vaccines are used only in areas where there is an outbreak due to the relatively high pathogenicity of the vaccine. In addition, vaccine viruses are believed to revert to increased virulence, and they are generally undistinguishable from field strains of the virus. The goal of this project is to compare ILTV isolates from 1985, 1995, and 2005. The purpose in doing this is to see how much the virus has changed, or evolved, over the past twenty years. This will be accomplished by amplifying, cloning, sequencing, and then comparing the unique short region of the viral genome from these three strains. This region of the genome consists of 13,000 base pairs of double-stranded DNA encoding 9 genes (including 6 glycoprotein genes). Glycoproteins play critical roles in immune recognition by the host cell and in the attachment, maturation and spread of the virus. If these glycoproteins change over time, it can reveal a lot about the virus and can answer many questions about it.

Conservation of Nucleotide Sequence in microRNAs from MDV Field Isolates and Reference Strains
Grace Lagasse, Emily Huang, Amy Anderson, Erin Bernberg, Grace Isaacs, Joan Burnside, Robin Morgan
Department of Animal and Food Science

MicroRNAs (miRNA) are single-stranded RNAs usually 20-22 nucleotides in length. Marek’s disease virus (MDV) is an alphaherpesvirus of chickens that causes tumors and encodes its own viral miRNAs. MiRNAs regulate gene expression by base pairing to target sequences within the 3’ untranslated region of protein-coding genes, and because of their size, single-nucleotide polymorphisms (SNPs) within MDV miRNAs might affect their activity. It was hypothesized that SNPs within MDV miRNAs could be related to pathogenicity. Our lab has previously identified eighteen MDV miRNAs within the meq and LAT regions of the genome. Several SNPs have been identified in these regions in various field isolates. All SNPs were initially identified by sequencing PCR-amplified products and then confirmed by TA subcloning and sequencing. Sequencing data indicated that MDV miRNA SNPs do not correlate with pathogenicity of MDV. Additionally, the promoter region that lies upstream of the meq microRNAs was sequenced in order to identify additional SNPs and correlations with pathogenicity or expression profiles. Several SNPs were found in the promoter region. Overall, the sequence of the microRNAs is by and large highly conserved, and this highlights the importance of miRNAs. Funded by INBRE.

Construction of Recombinant Marek’s Disease Viruses In Vivo
Dawn Lenihan and Mark S. Parcells
Department of Animal and Food Sciences

Marek’s Disease Virus (MDV) is a highly contagious herpesvirus that causes lymphomas in chickens. Although there are vaccines that prevent lymphoma formation, MDV has become increasingly virulent as new strains evolve in the field. Mutations have been identified in the meq gene of MDV strains that appear to directly correspond to the virulence level of the virus. Our first aim is to create recombinant viruses using MD5∆meq in which the meq gene has been deleted from the MD5 strain of the virus. MD5∆meq replicates in chickens, but will not cause disease. The meq gene from three different strains; JM102, RB1B and MK will be co-transfected with MD5∆meq DNA into chicken embryo fibroblasts, allowing the creation of viruses that differ only in the meq gene. Our second aim is to generate a similar recombinant using the RB1B meq locus that has Lox-P sites inserted adjacent to the meq locus. This insert will then be combined into the MD5∆meq virus using the in vivo selection method described above, creating a recombinant virus with meq regions that can be rapidly interchanged. Treating the virus with Cre recombinase will recombine sequences between the Lox-P sites, removing the meq gene from the virus and allowing the meq gene from other strains to then be added to the virus. The overall affect of different strains of the meq gene on the virulence of the virus can then be tested. This project is currently funded by a USDA grant.

The Effects of Acidified Soil on Bacteria and Viruses
Jacqueline Lovett¹, Timothy I. Mills², Sharath Srinivasiah¹, K. Eric Wommack¹¹University of Delaware, Department of Plant and Soil Sciences, ²Delaware Technical & Community College

The chemistry of soils is important for the proper functioning and balance of biological processes. An understanding of the interactions between soil pH , bacterial and viral population dynamics, and processes like carbon cycling are crucial to discern the relationships occurring in soil ecosystems. The effects of acidifying soil on bacteria and viruses was investigated using soil samples collected from the University of Delaware Agricultural College fields. These soils were used in twelve microcosms and an acidifying agent, aluminum sulfate, was added to six of the microcosms. Soil from each microcosm, at pre-determined time points, was sampled for bacterial abundance (BA), viral abundance (VA), bacterial respiration (BR), and pH. Overall, BA was higher in the native pH soil; VA and BR were higher in the acidified soil. Bacteria prefer neutral pH, accounting for the higher BA in native pH soil. In the acidified soil, the higher BR but lower BA may be due to CO₂ being released more rapidly into the atmosphere in acidified soils, or a more rapid respiration rate because of increased stress or viral production. The latter could explain the higher VA in acidified soils. Interestingly, after 3 days of incubation, VA and viral to bacterial ratio (VBR) of both the treatments decreased. Supported by EPSCoR.

Formation patterns of radiation fog in relation to evapotranspiration in the Central Valley of California
Greg Marchesiello, Delphis Levia*, and S. Jeffrey Underwood#
*Department of Geography, University of Delaware, Newark
#Department of Geography, University of Nevada, Reno

Examination of radiation fog formation patterns is critical: (1) to agriculture in the Central Valley of California because fog is a key hydrological input; and (2) to the development of a fog product by the California Department of Transportation that will help ensure the safety of California drivers during fog episodes. Radiation fog is quite frequent in the Central Valley of California during winter. This research seeks to characterize meteorological conditions during the antecedent period prior to a fog event to evaluate the effects of fog thickness and spatial extent on evapotranspirational losses. Based on data from the National Climatic Data Center (NCDC), the California Irrigation Management Information System (CIMIS), and GOES-10 and GOES-11 satellite imagery along a north-south transect, the relationship between evapotranspiration (ET) and air temperature, relative humidity, and surface wind speed in the antecedent period were examined in relation to fog thickness and spatial extent. A key finding of this research was that increases in air temperature had a direct, positive effect on evapotranspiration rates with low wind speeds and high relative humidity. In turn, the accumulated moisture in the air from increased evapotranspiration during the day led to radiation fog formation near dawn, when temperatures were at their minimum. As this is a work in progress, more detailed analysis is currently underway to better understand the relationships between the antecedent period and the physical characteristics of fog episodes. It is our intention to submit the results of this research to the international peer-reviewed journal Boundary Layer Meteorology. This research (publication, presentation, etc.) was made possible by the National Science Foundation EPSCoR Grant No. EPS-0447610.

The Use of the Inland Bays’ Beaches as Horseshoe Crab Nesting Sites (Limulus polyphemus).
Kathleen M. McCole and Douglas C. Miller
College of Marine and Earth Studies

This project seeks to answer the question of whether or not the Inland Bays are important nesting sites for the American Horseshoe Crab. Due to the crab’s importance to the food chain as well as to human economy and health, we found it important to identify all areas that Horseshoe Crabs nest in order to better monitor and conserve the population. To help answer this question, three adult censuses were performed on James Farm Beach in the Indian River Bay. In addition to these adult censuses, four beaches were cored for the presence of eggs; Delaware Seashore State Park and Savages Ditch in Rehoboth Bay, and Holts Landing as well as James Farm in Indian River Bay. Eggs were found only at Holts Landing and James Farm, and we performed two egg censuses on both of these beaches. Numbers from the James Farm adult census were compared to censuses that took place on the Delaware Bay in 2006. It was found that James Farm is within range, and even surpasses some of the Delaware Bay’s beaches in the number of crabs/m. The egg censuses at Holts Landing and James Farm were compared to previous data from egg censuses that occurred in 1999 on beaches in the Delaware Bay. Once again, although the number of crabs has increased since 1999, James Farm and Holts Landing are right within the range of the Delaware Bay’s beaches in terms of the number of eggs per square meter. Although this project does not cover all beaches in the Inland Bays, it shows that Indian River Bay contains beaches that are important spawning sites to many Horseshoe Crabs. The results and discussion presented in this project provide a stepping stone for continued research to occur within the Inland Bays to get a better idea of just how many Horseshoe Crabs are using its beaches. This project was funded by the National Science Foundation as a part of the REU Intern program.

Carbon Source and Acidification effects on Soil Microbial Ecologies
Timothy I. Mills¹, Jacqueline Lovett², Sharath Srinivasiah², and K. Eric Wommack²¹Delaware Technical & Community College, Stanton, DE ².University of Delaware, Department of Plant and Soil Sciences, Newark, DE.

Soils are complex medium that are influenced by various intricately linked biotic and abiotic processes. One such critically important, but as yet unknown relationship is between soil pH, carbon sources, and bacterial and viral population dynamics. What are the effects of acidification on soil bacterial and viral assemblages? Do carbon sources play a role even under these adverse conditions? To investigate the magnitude of the impact of acidification on soil microbial ecologies, soils from the University of Delaware agricultural fields were acidified and incubated for 30 days in microcosms that received various carbon treatments viz., chitin, yeast extract, and methanol. Bacterial abundance (BA), viral abundance (VA), pH, and bacterial respiration (BR) were quantified throughout the incubation. The yeast-extract treatment was the most effective carbon source as expected, even under these adverse conditions. These treatments recorded highest BR, highest BA at 30 days, as well as the highest VA, and highest viral to bacterial ratio (VBR) after 7 days of incubation. However, BA did not increase until 10 to 14 days. Also, pH of the yeast-extract treated soils increased over time by one unit. Chitin treatments showed an increased rate of carbon mineralization starting at 14 days. This polymeric carbon source was broken down to less complex forms and then used by a wide array of acidophilic chitin degraders. Methanol treatments had lower BA and BR in comparison with other treatments. At 10 days of incubation all the treatments showed a decrease in BA, VA, and VBR. Supported by EPSCoR and INBRE.

The effect of riparian corridor width on the presence of invasive plants
Jessica Morgan, Chris Williams, and Gavin Ferris
Department of Wildlife and Entomology

Riparian corridors are strips of forested area between a natural watercourse and human impacted land. This area is thought to provide protection for the stream against the harmful effects of surrounding human activities. This buffering effect includes the exclusion of invasive plants within the corridor. These invasive species are a concern because they are considered a threat to native ecological biodiversity. It was our goal to determine the width of a buffer that would provide significant protection against invasion of the non-indigenous plants. We sampled 31 forested riparian corridors of varying widths (ranging from 0– 150M) and conducted 3 replicated transects across the corridor. Across each transect we sampled invasive plant presence as well as forest density and canopy coverage. Using multiple regression we will determine the impact of forest structure, distance to edge, and corridor width on invasive plant presence. Supported by Undergraduate Research Program-Science and Engineering Scholars Program.

Mapping the Loss of Wetlands in the Milford Neck Coastal Region of Delaware
Matthew Panunto¹, Bruce E. Allison¹, Carl Yetter²,and Dan Trese²¹Wesley College, Environmental Sciences and ²DNREC, Delaware Coastal Management Programs

Coastal wetland loss is an environmental concern in Delaware. Loss of wetlands affects the overall environmental integrity of a coastal landscape. Wetland integrity is vital in order to protect natural habitats and communities, to keep intact the filtering mechanism of the wetland ecosystem, and to protect inland land areas from flooding. The objective of this research was to determine the amount of wetland loss for the coastal region north of the Mispillion River to just south of the Murderkill River. Increased amounts of open water were determined using ortho-imagery from 1968 and 2002. Ortho images were imported to ArcGIS 9.2 and heads up digitizing was done to map the vertices of the surface water bodies for both years. No ground truth analysis of the surface waters was completed in this initial phase. In general, wetland loss occurred throughout the entire coastal zone, with some regions having more wetland loss than others. Specifically, the loss within the southern half of the coastal zone was more dramatic than in the northern region. The reason for the loss of wetlands is unexplained at this time. These findings can assist in future analysis of coastal wetland areas, as well as aid in proper planning in order to conserve and maintain as much wetland area as possible. This research was made possible by the National Science Foundation EPSCoR Grant No. EPS-0447610.

Antipredator Defense of the Weevil Rhinoncomimus latipes a Biological Control Agent of Polygonum perfoliatum
Kelsey Paras and Judith Hough-Goldstein
Department of Entomology and Wildlife Ecology

The weevil, Rhinocomimus latipes, is a Chinese species imported to Delaware for biological control of the invasive weed species mile-a-minute weed, Polygonum perfoliatum. R. latipes adults produce an orange coating that covers the integument and may protect against generalist predators. To test this hypothesis, assassin bug nymphs, American robins, and ants were fed black adult weevils and orange adult weevils. In addition, the assassin bugs and robins were fed Drosophila melanogaster as a control. Both species ate all three insect choices without significant difference. Ants that were offered plain sucrose water and sucrose water containing orange coating drank more plain sugar water than sugar water with orange coating mixed in. A different species of ant was offered dead black and orange weevils. They attacked and carried both black and orange weevils back to their nest, but the black weevils were removed an average of 18.4 minutes sooner than the orange weevils. Weevils feed exposed on the host plant and drop to the soil when disturbed. The results of this study suggest that the orange coating may protect this insect against at least some generalist predators. Funding for this research was made possible by the United States Forest Service, EPSCOR, and the National Science Foundation.

A Comparative Evaluation of Tipping-Bucket and Weighing Raingages
Omar J Peters and David R Legates
Department of Geography, University of Delaware

The Delaware Environmental Observing System (DEOS) is a tool for decision makers involved with emergency management, natural resource monitoring, transportation, and other activities throughout the State of Delaware. As the primary mechanism for measuring rainfall, DEOS uses primarily Texas Electronics Tipping-Bucket gages (TE525). Although tipping-bucket raingages are inexpensive, operate mechanically, and are widely used, they have the potential of underestimating rainfall amounts – particularly during high wind and intense rainfall conditions. A substantially more expensive raingage, the Geonor T-200 Weighing Gage, utilizes a spring weighing mechanism, which is more accurate than tipping buckets. This study highlights the quantitative differences between the TE525 and the T-200 at the site near Fair Hill, MD. Hourly rainfall data, collected between September 2004 and June 2007, have been analyzed and compared against neighboring weather stations and observers. Preliminary results indicate that the tipping bucket undercatches by 5.5% with the majority of these incidences occurring during light rainfall events of 10 mm and below. 13.3% of all the examined events contain recordings where the measured difference between the weighing gage and the tipping-bucket gage exceeds 0.5mm. No correlation between the gages’ rainfall measurement and wind speed has been shown. Further study will determine whether the gages’ precipitation measurements are correlated, allowing DEOS to assess the validity of the Texas Electronics Tipping-Bucket gages. This research was made possible by the National Science Foundation EPSCoR Grant No. EPS-0447610.

Assessment of the Potential Damage and Economic Impact of Stink Bugs (Heteroptera: Pentatomidae)
on Soybean in Delaware
Monique J. Rivera, Joanne Whalen, and Judith Hough-Goldstein
Department of Entomology and Wildlife Ecology

Soybean, Glycine max (L.), is consistently grown on more land than any other crop in Delaware, which makes it a very important economic commodity. In previous studies, various species of stink bugs have been shown to reduce soybean yields. Unfortunately, most of these studies are from different regions. This study is part of the collective efforts of Delaware, Maryland, and Virginia to seek the impact of stink bug species on local soybeans. In Delaware, the predominant stink bug species found in soybean fields is the green stink bug, Acrosternum hilare (Say). Through a combination of rearing and field collection, Acrosternum hilare (Say) will be applied at multiple growth stages to test plots of soybean at the current threshold. The insects will be placed in the field using mesh cages. The information gathered from these procedures will be used to make inferences about the relationship between stink bug feeding and yield and quality losses in soybean. In particular, we hope to determine which reproductive growth stage of soybean is most impacted by stink bug feeding. This study was funded by the Delaware Soybean Board, National Science Foundation and Delaware EPSCoR.

Analyzing Magnaporthe oryzae Spore Behavior in the Presence of Host vs. Non-host Volatile Compounds
Amanda Romag, Kyle Stern, Nicole Donofrio, John Pelesko, and Harsh P. Bais
University of Delaware, Department of Plant and Soil Sciences and Math Department

Magnaporthe oryzae is a fungus capable of infecting multiple plant hosts such as rice, wheat, barley and rye. Typically known as the cause of rice blast disease, it is estimated to kill enough rice plants to feed 60 million people a year. Of late, M. oryzae has been disturbingly considered as a potential weapon for bio-terrorism. The main infective agents in M. oryzae are the asexual spores; therefore, understanding the mechanisms by which they disperse is crucial to developing disease control and protection management against this pathogen. The biggest dogma in the plant-pathogen interaction concerning M. oryzae is how does this pathogen sense the host plants? Previous studies related to spore dispersal debates the involvement of climatic conditions and air flow as two chief factors governing the dispersal routes. We argued that this multi host infecting fungi would evolve to utilize host volatile cues as the chemo-sensors to detect and target hosts. To this end, the objectives of this project were two-fold. First, we ask: How does M.oryzae spore behavior depend on the presence of volatile compounds released by host plants, such as rice and barley, vs. non-host plants, such as lima bean? Second, we ask: Are the spores released from their stalks by an active or passive method? To answer these questions, we examined spore growth under different conditions in an in-vitro set up. Germination tubes were measured and compared after exposure to liquid forms of the limonene, a known rice volatile, and farnesyl acetate, a lima bean volatile. Germ tubes showed slight differences, however no directional growth favoring a specific volatile was established. Evidence for an active dispersal mechanism was determined after measuring distances of spores released from M. oryzae growing on the vertical side of an agar block. Using a mathematical approach, a distribution of these distances compared to a model distribution of particles after diffusion suggested the presence of an active dispersal mechanism, which to the best of our knowledge has previously been suggested, but not experimentally characterized for this fungus. This research is funded by the Experimental Program to Stimulate Competitive Research and the Howard Hughes Medical Institute.

The Effects of Methylmercury and Calcium Availability on Wood Thrush Reproductive Success.
Kelly Schaeffer and Gregory Shriver
Department of Entomology and Wildlife Ecology

<>Calcium (Ca) availability and mercury (Hg) body burden are two factors which may explain the recent forest bird population declines. Soil acidification caused by acid rain can greatly decrease the amount of Ca available to breeding birds and lower reproductive success. The negative effects of methylmercury (MeHg), the bioactive form of mercury, on terrestrial avian species are only recently being investigated. To determine if either or both of these stressors are playing a role in the recent decline of Wood Thrush I sampled the soil, invertebrate community, and Wood Thrush in the University of Delaware Ecology Woods (UDW). I sampled calcium rich prey at 62 locations systematically selected throughout UDW. At each location, I also sampled the soil to estimate calcium availability. For the Hg component I collected blood from five avian species: American Robin (Turdus migratorius), Gray Catbird (Dumetella carolinensis), Carolina Wren (Thryothorus ludovicianus), Northern Cardinal (Cardinalis cardinalis) and Wood Thrush (Hylocichla mustelina), to create an Hg exposure profile for UDW. To determine the potential effects of Hg body burden on reproductive success, I monitored the reproductive output of Wood Thrush by estimating the number of nesting attempts, eggs laid and hatched, and young successfully fledged for each Wood Thrush. With the data collected in the 2006 field season, I found that UDW was not a high mercury accumulation site and Hg body burden did not have an effect on Wood Thrush reproductive success.This research was made possible by funding from the National Science Foundation EPSCoR Grant No. EPS-0447610 and the McIntire-Stennis Forestry Act.

Validation of the 14K Chicken Integrated Systems Microarray and Its Utility for Other Avian Species
Danielle Smarsh and Larry A. Cogburn
Department of Animal and Food Sciences

The chicken has recently attained model organism status with completion of the genome sequence and development of abundant genomic resources such as cDNA microarrays. For other avian species lacking such genomic resources, a well-annotated chicken cDNA microarray platform allows cross-species hybridization and the discovery of functional genes. The first objective of this project was to determine the number of unique and shared genes across four tissues in the chicken (liver, hypothalamus, breast muscle, and adipose). The second purpose was to demonstrate the utility of the chicken microarray for cross-species hybridization of several bird species (i.e., turkey, duck, Japanese quail, kestrel, and tree sparrow). Gene expression profiles were examined in two tissues (liver and hypothalamus) of three individuals from each species using a pooled RNA reference hybridization design. GeneSpring software was used to normalize the microarray data, to generate gene expression patterns (i.e. heat maps) and gene lists for chicken tissues and avian species. Gene lists were annotated by BlastX and BlastN analysis, and Gene Ontology (GO) terms (cellular compartment, molecular function, and biological process). In the chicken, we found 310 fat-specific genes, 114 liver-specific genes, 44 breast muscle-specific genes, and 201 hypothalamus-specific genes. There are 128 genes that are common to hypothalamus and fat, and 60 genes that are common to fat and liver. Across species, the Japanese quail showed the highest expression of hypothalamic genes, and the duck showed the highest expression of hepatic genes. Therefore, the Del-Mar 14K Integrated Systems Microarray (GEO Accession # GPL1731) is a powerful tool for transcriptional profiling in multiple chicken tissues and in tissues of other avian species. Funded by USDA-NRI Grant 2005-35206-15288 (to LAC) and USDA NRI Grant 2004-02755.

Development of Genotyping Assays for Polymorphic Genes Controlling Growth and Body Composition
Jacqueline S. Speier and Larry A. Cogburn
Department of Animal and Food Sciences

Obesity and the development of type 2 diabetes are two of the major health concerns facing highly developed nations. Identification of the genes involved in deposition of excessive adipose tissue can provide considerable insight into these metabolic disorders. We have identified a large number of differentially expressed genes from transcriptional profiling in tissue of chickens divergently selected for fatness (FL) or leanness (LL). The purpose of this research project was to develop genotyping assays for polymorphisms in several candidate genes, which include -defensin 9 (DEFB9), angiopoietin-like 3 (ANGPTL3), thyroid hormone responsive Spot 14 (THRSP), sterol regulatory element binding protein-2 (SREBP2), and C1q and tumor necrosis factor related protein 5 (C1QTNF5). The expression of these genes is greatly elevated in liver of FL chickens. We developed a genotyping assay to establish the association of two single nucleotide polymorphisms (SNPs) in the coding region of DEFB9 with phenotypic traits measured in an intercross of the FL and LL chickens. Statistical analysis of the DEFB9 genotypic and phenotypic data indicates that polymorphisms in DEFB9 are associated with variation in abdominal fatness. The TT-CC genotype represents the fattest phenotype with 76.9 grams of abdominal fat. A homozygous TT at the DEFB9 SNP1 site leads to a 17% increase in abdominal fat compared to the homozygous CC genotype in this F2 resource population. Therefore, the combination of the transcriptional profiling and genotyping of this novel resource population (FL x LL) represents a powerful tool for identification of major genes controlling important phenotypic traits such as obesity. Funded by USDA-NRI Grant 2005-35206-15288 (to LAC) and USDA NRI Grant 2004-02755.

Histological Analysis of Blueberry Regeneration
Kate L.Thomas¹, Thompson D.Pizzolato¹, Joanne M. Kramer², Conrad R. Pope², James J. Polashock³, Sherry L. Kitto¹¹Department of Plant and Soil Sciences, ²Department of Animal and Food Sciences, College of Agricultural Sciences,³USDA-ARS, 125 A Lake Oswego Rd, Chatsworth, NJ 08019

Blueberry,Vaccinium corymbosum ‘Aurora’, was cultured in vitro on regeneration medium and histologically analyzed in an effort to identify the regenerative cells. Leaves with petioles were cultured on Woody Plant Medium supplemented with TDZ and IAA with the adaxial surface in contact with the medium and samples were removed daily and fixed to capture all stages of regeneration. Leaves were then processed and embedded in paraffin, sectioned and stained with haematoxylin and eosin for viewing under a light microscope. Identification of the cells responsible for regeneration would not only help us to better understand the regeneration process, but could also prove useful in functional genomic studies of genetically transformed blueberries. This research was made possible by the National Science Foundation EPSCoR Grant No. EPS-0447610.

Developing a Chemoattractant Assay Using the Root-knot Nematode
Anthony Tibuah, Janine Sherrier, Sherry Kitto, Thimmaraju Radruppa, and Harsh P. Bais
Department of Plant and Soil Sciences, Delaware Biotechnology Institute

The root-knot nematode (RKN, Meloidogyne spp.) is an obligate parasitic plant nematode. These host specific parasites invade crops by penetrating the roots of their host plants and forming giant cells or cysts that become their feeding sites. While root-knot nematode infiltration mechanisms of roots have been extensively studied, past research showing root-nematode communication in the rhizosphere is scarce and these interactions have largely been overlooked. This study is aimed at examining the role of root secretions in the initial signaling events that attracts RKNs to the roots of host plants. The interaction between root secretions and nematodes was investigated by studying the chemoattractant effects of Medicago root exudates on Caenorhabditis elegans and root-knot nematodes. C. elegans were used as model organisms for the initial phase of the study. C. elegans adult worms were exposed to pre-infected Medicago root secretions, 6 week old root-knot nematode infected Medicago secretions, a culture of Escherichia coli strain OP50, the flavonoid genistein, and diethyl ether. After an incubation period, all inoculated plates had migrations of C. elegans from the initial inoculation site to the site of OP50. Very little or no migration to the other sites was observed for both types of Medicago secretions, genistein, and diethyl ether. The results revealed that C. elegans preferred and would always move and aggregate towards OP50 when this cue is available. The results for root-knot nematode assays are still being processed. This research was made possible by the National Science Foundation EPSCoR Grant No. EPS-0447610.

Water Quality in Relation to Freshwater Mussel Density (Elliptio complanata) and Aquaculture Pond Water Management
Oluchi A. Ukaegbu*, Jonathan F. McKenzie, and Gulnihal Ozbay, Ph.D.

Department of Agriculture and Natural Resources, Delaware State University

In fish, only 30% of nitrogen and phosphorus are retained from feeding that remaining nutrients in waters may lead eutrophication. Eutrophication can cause algal blooms which lead to the sudden die off of vegetation causing oxygen depletion in the system. Bivalves have been proven to be an inexpensive method for removing suspended solids, dissolved nutrients, and controlling algal growth through suspension feeding. Elliptio complanata is the most abundant species in Delaware and it is additionally favorable because of its hardiness against environmental stress and 66% filtration efficiency. This study examines the possibility that biological filters such as E. complanata can replace expensive chemical and mechanical filtration regiments in aquaculture pond management. The twelve earthen aquaculture ponds located at the Delaware State University were stocked with 1000 and 500 catfish (Ictalurus punctatus) respectively. Four different concentrations (0, 75, 150, 300) of E. complanata were placed in three trays suspended six inches below the surface of an aquaculture pond stocked with catfish. These mussels were suspended in the water column for a period of nine weeks. Water samples were taken weekly during the course of the study and tested for nitrate, nitrite, ammonia, total nitrogen, total phosphorous, soluble reactive phosphorous, alkalinity, total suspended solids, and chlorophyll-a. Fish and mussel growths were measured biweekly starting in May. The lowest density of mussels showed the least effect on water quality from May to July showing increased total nitrogen (1.7-4.550mg/L), ammonia (0.0567-0.240mg/L), total phosphorous (1.4-1.1mg/L), chlorophyll-a (0.121-1.575mg/L), and total suspended solids (0.0123-0.00233mg/L). The highest mussel density had a greater positive effect on water quality from May to July then did the lower density treatments: total nitrogen (0.4-3.767mg/L), ammonia (0.0567-0.040mg/L), total phosphorous (1.527-1.373mg/L), chlorophyll-a (0.437-0.962mg/L), and total suspended solids (0.0217-0.0167mg/L). Our results suggest that mussels have a positive effect on water quality within aquaculture ponds. This study may provide a natural biological control for pond water improvement and effluent management.

The impact of alien plants on predacious and parasitoid insect populations
Alexandra Villiard, Douglas Tallamy, Chris Phillips
Deparment. of Entomology

Natives are being replaced by invasive alien species at a rapid rate in natural areas, and many suburban landscapes now consist largely of non-native ornamentals. This project aims to address the hypothesis that, because alien plants share no recent evolutionary history with native insects, landscapes dominated by them are not as capable of supporting natural enemies as landscapes dominated by native plants. The project is being done as an extension of a broader project, which focuses on the effect of non-native plants on herbivorous insect populations. This portion compares populations of natural enemies on native plants with populations on non-natives of the same genus. Ten pairs of commonly seen woody plants were planted earlier in the spring at five sites and the first set of collections was made from them in late June and early July. The numbers of individuals and species of natural enemies from each sample were then established. The preliminary results show no significant difference in productivity or diversity of natural enemy populations. This may be because the aliens were of the same genus and therefore, closely related to the natives. This research was made possible by the National Science Foundation EPSCoR Grant No. EPS-0447610.

Deforestation and Avifaunal Extinctions on Pacific Islands
Nicholas Wehner and Douglas Tallamy
Department of Entomology and Wildlife Ecology, Department of Biological Sciences

Recent models predict that plant and animal extinction rates are equal to the percentage of habitat lost to human activities, but these models have not yet been empirically tested. I will use data from oceanic islands to test this intriguing hypothesis. Human arrival on Pacific islands brought about significant changes to the natural biota of these lands. The natural avifauna of Pacific islands became permanently altered by animals that the early Polynesians imported, like rats and dogs, as well as hunting and agriculture. Early Polynesians practiced slash-and-burn farming, clearing millions of acres of previously undisturbed forest which was only exacerbated later by European colonists. The goal of this project is to see how deforestation can be attributed to avifaunal extinctions, and infer from it what can be expected to happen to habitat islands in the ever-expanding suburbs. To do this, forest cover for numerous Pacific islands will be determined before human arrival and at present day, and a percentage of deforestation calculated. Living and extinct breeding birds of these islands will be found, and a percent extinction calculated. Extinction rates will then be regressed on percentage of forest lost. These variables will be compared resulting in a correlation between the two, showing the effect that humans directly had on extinct birds. Funding for this research was provided by the University of Delaware Science and Engineering Scholars Program and the National Science Foundation.

Evolution in Action: Selection of the Modern Broiler Chicken
Megan E. Wolters, Erika R. Feierstein, Mike Persia, William Saylor, Carl J. Schmidt
Department of Animal and Food Science

Over the past sixy years, the modern broiler chicken has been under intense selection for rapid growth and meat production. Consequently, these birds provide an experimental model for rapid evolution. This study compares the morphometric traits of two broiler lines, Ross 708, a modern production strain, and Illinois, a line which has been unselected since 1950. As anticipated, the overall growth of the Ross 708 line was much quicker than the Illinois line. In addition, the Ross 708 line produced 3.8 fold more breast muscle mass than the Illinois line. In contrast, the hearts of the Illinois line were significantly larger per unit of body mass than the Ross line, which is an apparent side effect of selection for rapid growth and meat production. This is consistent with the increased incidence of cardiac arrest over the past fifty years in broilers. Finally, since both lines were reared in identical environments, a significant component of the variation seen between the Ross 708 and Illinois lines arises from differences in genotype.This work was supported by a USDA Scholarship to MEW and a University of Delaware CANR Seed Grant to WS and CJS.

Removal and inactivation of Escherichia coli O157H7 and Eimeria acervulina from water using zero-valent iron
Adam Yoskowitz¹, Alexandra Derevianko¹, Jennifer Handlin², Pei C. Chiu³, Yan Jin², and Kalmia Kniel¹
Department of Animal and Food Sciences¹, Department of Plant and Soil Sciences², and Department of Civil and Environmental Engineering³

A cost effective means of removing water borne pathogens from the agricultural and factory settings is necessary to reduce the potential for food borne illness outbreaks related to produce adulterated by contaminated water. Recent research has demonstrated that zero-valent iron can effectively remove viruses from water, but it has not been tested on bacteria or protozoa. This study examined zero-valent iron’s ability to remove outbreak strains of Escherichia coli O157H7 and Eimeria acervulina, a surrogate for Cyclospora sp., from water. In a saturated flow-through a column containing zero-valent iron and sand, at a neutral pH, the removal efficiency of E. coli O157H7 was a 3-log reduction. A control column containing just sand demonstrated a 1-log reduction. A spin column containing sand and zero-valent iron (10-500µm) demonstrated a 4-log reduction of E. acervulina. A spin column containing sand and zero-valent iron (10-15µm) demonstrated a 2-log reduction. A control column containing just sand demonstrated less than a 1-log reduction. Both the spin and flow-through columns demonstrate that zero-valent iron can remove significant amounts of both bacteria and protozoa from water. The study suggests that zero-valent iron can potentially be used to treat agricultural water and produce wash water to remove various waterborne pathogens. This research was funded by the University Of Delaware Department Of Undergraduate Research and the United States Department of Agriculture.

Links: Summer 2007 Undergraduate Research Symposium, Symposium Abstracts from other Colleges and Departments,
Undergraduate Research Summer Enrichment Program, Unversity of Delaware Undergraduate Research Program, Howard Hughes Undergraduate Program.
Created 23 July 2007. Last up dated 28 August 2007 by [halwhite at udel.edu]
Copyright 2007, University of Delaware