Social animals often rely on hierarchical dominance relationships to avoid costly agonistic encounters resulting from competition for resources with conspecifics. We demonstrate that zebra finches do form dominance hierarchies in the laboratory under a food competition setting. Birds were placed into single-sex groups and competed against each other for food in repeated dyadic encounters. The dominant and subordinate behaviors each bird displayed towards another were recorded and analyzed in order to determine the dominance hierarchy of each group of birds. Each hierarchy was further validated by analyzing differences in feeding behaviors of dominant and subordinate birds. As zebra finches are a model organism used in genetics and neurobiology, further studies can examine the link between proximate mechanisms and ultimate explanations behind dominant/subordinate interactions. Studying dominance hierarchies in the laboratory can also help us understand the evolution of social structure and associated cognitive abilities.

Hyperspectral Imaging (HSI) is a technique that can be used with darkfield microscopy for investigating biological interactions of optically active nanoparticles (NP) based on their spectral signatures. The objective of this study is to investigate the capabilities of HSI technology to characterize (1) spectral characteristics of gold, silver, and manganese NPs, (2) stability of gold NPs in exposure media and growth media based on spectral shifts, and (3) cellular interaction of NPs by correlating spectral data between NPs in water or media and NPs exposed to cells. Results demonstrate the unique spectral characteristics of the NPs investigated. Gold and silver NPs both display plasmonic properties; however, gold NPs exhibited a more narrow spectral profile. Silver NPs demonstrated several distinct scattering spectra due to the strong dependence on morphology. Manganese NPs do not display plasmonic properties, but still exhibited a unique spectral response, allowing them to be detected in cells. Due to the narrow spectral profile for gold NPs, stability was investigated in biological media, demonstrating the ability for HSI to detect the stabilizing effect of serum on NPs. Cellular interaction studies showed that the peak scattering wavelength for NPs in cells deviated from NPs in water or media, but NPs were still able to be identified based on intensity and shape of the scattering curves. Overall, HSI was demonstrated as a useful technique for evaluating optically active NPs in biological media and cellular environments.

Migratory avian frugivores act as long distance carriers of seeds for fruit-producing plants in return for fleshy fruit, but not all fruits are equal in value. Bird preference for and selection of fruits are affected by factors including caloric value, seed load, fruit color, and foliar flags. Caloric values of whole fruits, pulp, and seeds of three pairs of closely related fall-ripening plants found in western North Carolina are reported. Seed load, water content, fruit color, and the presence of foliar flags of each species are also compared. Euonymus americanus, Cornus florida, Cornus amomum, and Viburnum nudum are native species; Viburnum setigerum is an exotic species, and Euonymus alatus is an exotic invasive species. The exotic invasive species E. alatus has high caloric value and other favorable characteristics for bird dispersal, as does the native species C. florida.

Cattle fecal material has been shown to be a major reservoir for the foodborne pathogen Escherichia coli O157. Contaminated fecal material that comes into contact with the hide can lead to contamination of the carcass at slaughter. Thus, it is essential to minimize the prevalence of E. coli O157 in cattle feces in order to minimize the number of contaminated meat products. The Midwestern United States has variable weather patterns and is home to a large percentage of cattle used in the beef industry. The objective of this study was to determine if a prevalence difference of E. coli O157 exists among different Midwestern cattle herds and to assess fecal shedding in the winter and spring. Five Midwestern herds entering a single feedlot in Nebraska were sampled in February and May. Fecal samples (n=50) from each herd were collected and processed by multiple culture-dependent methods. Results of this study indicated that there was no difference in prevalence rates by location but a prevalence rate difference between seasons. The May sampling had an overall feedlot E. coli O157 prevalence rate of 0.32, while the February sampling had a 0.04 prevalence rate. Further studies need to focus on determining differences in prevalence rates by location as well as assess the effect seasonality has on prevalence and risk of infections.

Ants are a type of foraging insect species which harvests food resources based on availability. When ants locate food resources that are scarce within their habitat, they tend to be more strongly attracted to that food resource. This study used protein, carbohydrate and control based baits to examine if there was a deficiency in resources demonstrated by the ants at two different wetland habitats. We sampled Argentine ants (Linepithema humile Mayr) within the saltwater and freshwater marshes of Ballona Wetlands in Los Angeles, CA. We found significant differences in the rapid deployment of Argentine ants towards protein baits over carbohydrate and control baits. We saw more Argentine ants at the protein baits in the saltwater marshes than in the freshwater marshes. We propose that a protein limitation exists in both wetland habitats with increased protein limitation in the saltwater marshes.

Invasive plants such as Castor bean (Ricinus communis) are known to threaten ecosystems due to their competition for resources. The Ballona Wetlands and Temescal Canyon managers employ different techniques to manage the spread of R. communis, potentially resulting in differences in plant survivorship. To investigate this possibility, height of the stems of individual R. communis plants at each site were recorded in order to assign them to cohort groups. Based on the hypothesis predicted that R. communis would have a similar cohort structure at both sites but would exhibit higher survivorship at Temescal Canyon, where R. communis are removed less frequently than at the Ballona Wetlands. However, results indicate that management does not affect cohort structure or stability at either site, but rather, it may have contributed to the significantly higher overall survivorship of R. communis at Temescal Canyon.

For annuals, the timing of flowering is directly related to fitness and many factors influence it including temperature, photoperiod, resource level, physical stress, and pathogenic infection. The expression of “flowering genes” is regulated by these factors in order to mediate this timing. The FT gene is thought to be expressed in response to all of these factors while the NPR1 gene is induced by salicylic acid (SA), a signaling molecule in the stress-induced flowering pathway. It is unknown whether stress-induced expression of NPR1 may alter expression of specific “flowering genes” such as FT or whether SA may directly influence the expression of FT. Thus, we examined the expression of FT and NPR1 in Arabidopsis thaliana in response to exogenous application of SA. Gene expression was measured using RT-qPCR. Student t-tests were used to assess differences in expression of both FT and NPR1 in response to SA application. FT expression did not significantly differ in response to SA; however, this is likely a result of mispriming due to homology of FT-related genes. Surprisingly, NPR1 expression was not induced by SA in our study. Although our results provide some insights, creative primer design to measure FT expression and modifications to the experimental design are needed to fully elucidate the relationship between FT and NPR1 expression and SA.

The following chapters have sent in officer slates for 2013-2014. Officers are listed in the order of President, Vice President, Secretary, Treasurer, Historian, and Faculty Advisor unless otherwise noted. The chapters are listed alphabetically by Greek name. Please submit new slates, changes and corrections to Lori.Kelman@montgomerycollege.edu.