Chemostats are a continuous culture system in which cells are grown in a tightly controlled, chemically constant environment where culture density is constrained by limiting specific nutrients. Unlike batch cultures, the selective pressure imposed in a chemostat is constant. This has made them a desirable tool for evolution and competition experiments. Traditionally, chemostat experiments with S. cerevisiae have been constrained due to the limited number of cultures that can be run at once. In order to solve this problem our team is working with a new culturing system that allows 64 chemostats to be run simultaneously. In our experiment we evolved 96 biological replicates of haploid MATa yeast cells under either constant sulfur, phosphate, or glucose limiting environments for 300 generations. We are now using a variety of techniques including array-comparative genomic hybridization and whole genome sequencing of evolved populations to characterize mutations that have been selected for during the course of these evolution experiments. These techniques have revealed that amplification of genes that code for nutrient transporters are a common mutation that occur in the evolved populations over the course of the experiments. Therefore, we will also be experimenting with strains that have the most common amplified genes knocked-out in the hopes of identifying alternative pathways for nutrient-limited fitness increases. Changes in the genome can be correlated to changes in relative fitness, which we assayed through competition with a green fluorescent protein (GFP) expressing ancestral strain every 50 generations. Ultimately it is our hope that higher replicate number will better reveal the spectrum of genes important for adaptive growth in specific nutrient-limited environments.

Most people think of idealism as an old and forgotten notion from antiquity. However, today, this concept seems to have taken on an afterlife. This essay looks at how Photoshop goes beyond stylistic preferences of the past and investigates how photo editing informs our current notion of ideal forms. Instead of a sculptor such as Praxiteles carving his vision of Aphrodite of Knidos, a designer using Photoshop idealizes the figure with key commands.  These altered types permeate dominant media, producing a widespread prescription for the female body. Through creating a case study of edited photos seen in magazines and advertising I will provide evidence that a widespread ideal is in fact being created, an ideal which would not be able to be created without the help of Photoshop. Ralph Lauren Co. took Photoshop too far when they morphed Filippa Hamilton, a beautiful model, into an unnatural creation. In this Photoshopped image of Hamilton in which her head is larger than her hips, many have noted that she looks painfully emaciated and almost cartoonish. It is unrealistic to think that any woman could naturally be that thin. This is an example of how Photoshop is being used to create an unattainable ideal beauty, one which cannot even be obtained with the help of plastic surgery. This widespread ideal has led many women to go so far as to use plastic surgeries in the hopes of obtaining the current, electronically enhanced, ideal form of feminine beauty. I will also be examining how these examples of excessive photo editing and the unnatural ideal they create have become a problem within our society. This research helps to examine how current technologies are exacerbating the societal problem of low self-esteem seen in females who do not fit into this ideal.

Ai WeiWei, a contemporary Chinese artist and self-described "dissident," is the first to admit that political activism forms the basis of his aesthetic. In an artist’s statement, from a recent exhibition at the Hirshhorn Museum in Washington, DC, Ai plainly stated: “I’ve always believed it is essential for contemporary artists to question established assumptions and challenge beliefs.” The majority of Ai’s installations at the Hirshhorn function as a platform for his renegade agenda, and his piece He Xie is no exception. The striking collection of ceramic river crabs, in various shades of red and brown, is invested with manifest symbolism. However, a deeper investigation of the work reveals a latent significance, not readily gleaned from a limited investigation of its formal elements. In order to adequately engage with Ai’s work, one must look beyond the surface and trace the installation back to its historical origins and cultural conditions. To draw out his strategic use of symbolism, I analyze Ai’s installation according to German art historian Erwin Panofsky's iconographical approach. Panofsky begins with the simplest translation of visual forms and works his way toward a more nuanced historical and culturally relevant perspective. In short, Panofsky’s three-pronged methodological approach allows me to demonstrate the complexity of Ai’s He Xie. In this presentation, I discuss the conceptual stimulus behind Ai's sprawling display of porcelain delicacies, exploring its political significance and identifying a larger metaphysical trend in the artist's career.

Estrogen has been shown to directly influence auditory function, with high levels of estrogen receptor expression in the central auditory system of mice correlated with elevated high-frequency auditory thresholds. These findings and others raise the possibility that hormonal modulation might be used to treat some hearing deficiencies. The big brown bat, Eptesicus fuscus, provides a unique opportunity to study an easily accessible, complex auditory pathway in a highly social mammalian species. Bats experience large seasonal differences in both estrogen levels and behavior. During fall mating season, males produce “song” calls to attract females. During winter torpor, a state of decreased physiological activity, the need for hearing is greatly reduced. During spring gestation, estrogen levels are high to support a healthy pregnancy and, after giving birth, females are sensitive to the call frequency of their pups. We hypothesized that seasonally fluctuating estrogen levels in the bat brain have a direct effect on auditory processing which varies throughout the year. We measured blood estrogen levels of male and female bats over the course of the year, and recorded sound-evoked responses of single neurons in the central nucleus of the inferior colliculus (IC), the midbrain auditory center. We specifically measured changes in basic response properties such as call selectivity, frequency tuning, and threshold changes. Afterwards, we perfused the bat, sliced the brain into 40µ sections, and stained for estrogen receptors. These measurements enabled us to correlate blood estrogen levels with both estrogen receptor expression throughout the central auditory system of the brain and functional measurements of neural sensitivity and selectivity across the audible frequency range.

Exposure to vocalizations from members of their own species can influence how infants learn to hear and communicate. Eptesicus fuscus is a social mammal that lives in large colonies and uses many types of vocalizations for both communication and echolocation. We hypothesize that due to the fact that they live in large, well organized social groups, big brown bats should be social learners. In order to test this, we presented altered calls that have been raised or lowered in frequency and bandwidth to bats as they developed from infancy to adulthood. In order to limit exposure to natural maternal vocalizations, pups were reversibly deafened with silicon earplugs whenever they were in the presence of other bats. Every other day, we isolated the pups, removed the earplugs, presented altered calls and recorded the pups’ response. At the end of the study, we tested changes in the organization of the auditory nuclei by measuring frequencies of neurons in several layers the inferior colliculus (IC), a central nucleus in the auditory system in response to auditory stimulation. We compared these results to each infant's twin, as Eptesicus fuscus is usually born in pairs. This gives us a genetically similar control raised in identical conditions. Our results suggest a divergence in call frequency beginning in week two, related to the exposure to lowered artificial stimuli. There is also a shift in the organization of the bands of the IC, with larger low frequency bands and smaller high frequency bands. This suggests that the pups not only altered their vocalizations in response to altered stimuli, but that the frequency organization in auditory structures of the brain remains plastic beyond birth. Humans, like bats, are social mammals, and research into mechanisms of IC plasticity may provide some insight into the development of human hearing.

GCS1 is a protein that plays a crucial role in angiosperm plant fertilization. Surprisingly, comparative studies show that GCS1-like proteins exist within a wide variety of eukaryotic species. In Drosophila, the protein Pskl is predicted to have a GCS1-like domain that affects male gametes, but its exact role in sperm formation and sperm function is not well characterized. Studying Pskl is imperative towards broadening our understanding of sexual reproduction in eukaryotes. Comparisons of Pskl to its homologs in angiosperms, algae, and protists may provide insight into mechanisms of fertilization that are evolutionarily conserved across diverse species. Furthermore, defining how the protein works could contribute to the development of reproductive therapeutics or drugs that inhibit the procreation of illness-causing organisms. The goal of this research is to understand how Pskl regulates fertility by defining its functional domains. Through gene deletions generated by imprecise excisions of a transposable element called MiMIC, analysis of both the molecular and phenotypic consequences can improve our understanding of sequences necessary for normal pskl expression. If male flies with the chromosomal derivative are sterile or have reduced fertility, then removed sequences flanking the MiMIC insertion site are likely crucial for successful fertilization. Alternatively, generated deletions may extend in either or both direction of the insertion site and impact viability, shedding light on whether pskl or its adjacent genes are essential for development. In this report, we describe the nature and consequences of the transposon excisions in pskl, both molecularly and phenotypically.

Paternal effect mutations provide experimental tools to identify the unique contributions that fathers provide to their offspring. We are studying the ddbt (deadbeat) gene of Drosophila melanogaster, which encodes a chromosomal protein that is incorporated into spermatid nuclei during spermatogenesis and is required for normal embryogenesis. Embryos fathered by ddbt mutant males have extensive chromosome damage and embryogenesis terminates prematurely. This study asks whether ddbt-induced damage is a consequence of improper mitotic chromosome segregation in the embryo, or if the damage is independent of chromosome segregation. To address these alternatives, ddbt males will be mated to females carrying the giant nuclei (gnu) mutation. This maternal effect mutation permits repeated rounds of DNA replication but prevents chromosome segregation in the embryo. If DNA replicates to the same extent in embryos produced by gnu mothers and ddbt fathers compared to those of control fathers, this would suggest that ddbt-induced breaks occur during chromosome segregation. The alternative is that the chromosomes of ddbt fathers have preexisting damage, in which case replication would arrest due to preexisting DNA breaks. We are examining nuclear size and morphology in experimental and control embryos using confocal microscopy and assay for chromosome damage using techniques that detect breaks in DNA. Investigation of ddbt promises to improve our understanding of the paternal contributions to embryonic development.