2010 AAAS Student Poster Competition Winners

Congratulations to the 2010 AAAS Student Poster Competition Winners

AAAS recognizes the winners of the 2010 Student Poster Competition that took place at the AAAS Annual Meeting in Chicago. Their work in a variety of fields displayed originality and understanding that set them apart from their colleagues.

Brain and Behavior

Winner: Nicholas Olivas, University of California, Irvine

High Resolution Imaging and Precise Evaluations of Hippocampal Circuit Organization and Dynamics

The hippocampus is an important cortical structure with extensively studied trisynaptic networks. Although the anatomical organization in the hippocampus is well-defined, its functional circuit organization and dynamics require further investigation. In the present study, we extended a high resolution and fast functional mapping technique developed in our laboratory to investigate mouse hippocampal circuitry. Laser scanning photostimulation was used to provide precise and powerful stimulation of neural circuits, allowing functional connectivity and spatiotemporal dynamics of neuronal population activity to be examined by voltage sensitive dye (VSD) imaging. During experiments, selective neuronal activation via glutamate uncaging in different locations in DG and CA3 was achieved by photostimulation; evoked VSD responses were monitored to understand how excitatory activity initiated and propagated throughout the hippocampal circuitry. Different stimulation locations and strengths in DG and CA3 led to differential spatial patterns and temporal dynamics of evoked activity which propagated throughout CA1. Blocking inhibition with bath application of bicuculline, the hippocampal circuits exhibited dramatic re-organization, particularly evidenced by the substantial back-propagation from CA3 to DG, and increased CA1 output. Taken together, these new findings have shed new light on functional circuit organization of the hippocampus.

Honorable Mention: Chelsea Ruller, San Diego State University

Coxsackievirus B3 Infection Affects Neurogenesis and Hinders Normal Brain Development

Coxsackieviruses are significant human pathogens and the neonatal central nervous system (CNS) is a major target for infection. Despite the extreme susceptibility of newborn infants to coxsackievirus infection, tropism for the CNS, and a relatively high infection rate among infants, few studies have been aimed at determining the long-term consequences of infection on the developing CNS. We previously described a neonatal mouse model of coxsackievirus B3 (CVB3) infection, and discovered that proliferating stem cells in the CNS were preferentially targeted for infection. Since CVB3 is a cytolytic virus and therefore may damage target cells, we evaluated the later stages of infection, the ensuing inflammatory response, and subsequent developmental defects that may occur following the loss of neural stem cells. We infected 3 day-old mice (intra-cranially) with a recombinant CVB3 expressing eGFP (107 pfu) and characterized brain pathology (by histology and immunofluorescence for neural markers, viral protein, and apoptosis) and wet weight measurements of surviving mice. Intriguingly, CVB3 may persist in the CNS as a low level, non-cytolytic infection. A significant decrease was seen in wet weight measurements of brain in both young (1, 2, and 5 days post-infection - pi) and older (10, 30, and 90 days pi) mice, as compared to mock-infected mice. We also observed an inverse relationship between the amount of infectious virus present during acute infection and brain wet weight measurements: the more infectious virus present, the lower the brain wet weight values. This relationship became progressively stronger over time. At 10 days pi, infectious virus was no longer present. Despite the lack of infectious virus, a significant decrease in brain wet weight values was observed up to 90 days pi, as compared to mock infected control mice. Furthermore, apoptosis was observed in the subventricular zone of infected mice, which might indicate the early loss of proliferating (Ki67+) neural stem cells. Hence, developmental defects induced by a relatively common infection during the neonatal period may be long-lasting, and the prognosis for newborn infants recovering from acute infection needs to be re-explored. With this in mind, long-term neurological sequelae might be expected following neonatal CVB3 infection.

Cellular and Molecular Biology

Winner (tie): Molly Burke, University of California, Irvine

Genomic Analysis of Adaptive Differentiation in Laboratory-Selected Populations of Drosophila melanogaster

Historically, experimental evolution has provided a powerful means of studying adaptation at the phenotypic level. In sexual organisms, relatively little is known about the molecular population genetics of adaptation. Here we describe genomic data from laboratory-evolved populations of Drosophila melanogaster that have been well characterized at the phenotypic level. These replicated populations have diverged for over 800 generations and belong to two selection treatments: the ancestral treatment “CO”, and the derived treatment “ACO”, which involves strong selection for rapid development time. The ACO treatment results in significantly differentiated life-history phenotypes including faster development, decreased lifespan and stress-resistance, and smaller body size. To map this differentiation throughout the genome, we compared two genomic DNA libraries with extensive coverage from pooled samples of ACO and CO flies. We identified single-nucleotide polymorphisms (SNPs) that were significantly differentially represented in the two libraries, accounting for an expectedly high false discovery rate and using a “sliding window” analysis. We also identified the proportion of these SNPs that encode an amino acid change or disrupt a splice junction site relative to the published Drosophila reference genome. These putatively non-synonymous mutations are distributed non-randomly with respect to gene function, implicating regions involved in morphogenesis, larval development, metamorphosis, and cell communication. This portrait of differentiation provides a genomic perspective on adaptation and the maintenance of standing genetic variation in laboratory-evolved populations.

Environment and Ecology

Winner (tie): Emuejevoke Olokpa, Olivia Dziadek and Mahjabeen Khan, Baylor College of Medicine

A Novel Xenograft Model Identifies Centrosome Pathways as Therapeutic Targets for Uterine Leiomyosarcoma

Despite aggressive therapy, uterine leiomyosarcoma (ULMS) continues to ravage women, and efforts to develop more effective treatments have been hampered. We developed a novel xenograft model for ULMS to identify gene products potentially useful as clinical targets. TLSMC were cultured in DMEM and injected into 8 week athymic NCr-nu/nu mice or 6-8 week female NOD-SCID/NCr. RNA was prepared using MirVana Kit (Ambion). Illumina’s Human Whole-Genome Expression v2.0 Beadchip was used to obtain a transcriptional profile for each specimen. Gene expression was validated by PCR and immunohistochemistry. Two-sided t-tests were used, and injection of TLSMC-B cells produce tumor in both athymic NCr-Nu/Nu and NOD-SCID mice, both when cells were injected subcutaneously and intraperitoneally. At 5/8 SC injection sites, tumor invaded the peritoneal cavity, producing implants and ascites. Peritoneal implants ascites were observed in 8/8 animals injected intraperitoneally. In 2/4 NOD-SCID mice, tumor penetrated the diaphragm, creating hemorrhagic pleural effusions. Algorithms comparing gene expression demonstrate that TLSMC-B closely resemble specimens of human ULMS; over 212 gene products were found to be differentially expressed in TLSMC tumors and ULMS (>2-fold, p < 0.01) when compared to myometrium and leiomyomas. Over expression of Aurora A and B kinases were consistently observed in cancer but not benign tumors or healthy myometrium. Transcriptional profiling demonstrates that TLSMC create tumors that share similar patterns of gene expression with human ULMS. Gene products related to centrosome function are highly over-expressed in both types of tumors and may provide readily accessible therapeutic targets that can now be validated.

Developmental Biology, Physiology, and Immunology

Winner: Lamar Blackwell, University of California, Irvine

An Investigation into the ERK Phosphorylation (de) Cycle Via in vitro Kinase Assays

Egg maturation, apoptosis, and many other processes require cells to respond, irreversibly, to environmental stimuli with all or nothing changes in cellular physiology. Mitogen-Activated Protein Kinases (MAPK) serve as relay-systems that translate extracellular stimuli into specific changes in cellular physiology. The changes in cellular physiology are either changes in gene expression or protein activity. Ultrasensitivity and bistable responses are all-or-nothing responses found in MAPK cascades. The core of a MAPK cascade is made up of three enzymes that activate each other in series; generically speaking, the core of MAPK cascade includes a MAPKKK that activates a MAPKK, which in turn activates a MAPK. MAPKs can be inactivated by phosphatases. Here we use recombinant MEK1 (MAPKK), ERK (MAPK) and MAP kinase phosphatases (MKPs) to study whether we can generate all-or-nothing responses in an in vitro kinase assay. We found that ERK activity can be turned off in an ultrasensitive manner when we titrate increasing amounts of MKP1 into kinase assays with constant MEK1 concentration. Moreover, we found that we could generate bistable responses by titrating MEK1 and comparing the ERK activity when MKP1/3 is added to the kinase reaction at the start vs the middle of the reaction. We conclude that there are kinetic conditions where MAPK cascades can display ultrasensitivity and bistable responses in an in vitro kinase system.

Honorable Mention: Lauren Imbornoni and Fatma Hanif, Arizona State University

Impact of Inspired Oxygen Concentration on Cerebral Blood Flow in Univentricular Circulation

Purpose: Infants born with single ventricle heart deformities undergo surgical treatment to allow the functioning ventricle to supply blood to the pulmonary and systemic systems. Unlike normal circulation where pulmonary flow equals systemic flow, univentricular circulation has higher pulmonary flow because of lower pulmonary resistance, which can result in insufficient blood flow to vital organs. This study assessed the effects of the fraction of inspired oxygen on blood flow in univentricular circulation. Methods: Univentricular circulation was established in ten piglets by systemic to pulmonary shunt, atrial septostomy, tricuspid avulsion, and pulmonary artery occlusion. This allowed for measurement of cardiac output, pulmonary flow, and carotid flow, and calculation of systemic flow, pulmonary/systemic flow ratio, oxygen delivery, and oxygen extraction. Data collection took place at 21% and 100% oxygen. Results: Increasing the inspired oxygen from 21% to 100% corresponded with an increase in the pulmonary/systemic flow ratio and pulmonary flow, and corresponded with a decrease in systemic flow by 17% and carotid flow by 23%. At 100% oxygen, oxygen delivery decreased and oxygen extraction increased. Conclusion: Increasing inspired oxygen in a univentricular model decreases systemic blood flow and disproportionately decreases carotid blood flow, which is crucial for cerebral blood flow. This decrease may impact neurological function in children with univentricular circulation.

Environment and Ecology

Winner: Christine Goedhart, University of California, Irvine

Linkages Between Community Composition and Plant Physiological Traits Along a Depth to Watertable Gradient in Owens Valley, California

Owens Valley, California is an important source of water for Los Angeles; however, recent studies have documented loss of grass cover coinciding with decreased watertable depths in many areas of Owens Valley. This change in community composition is assumed to be associated with shallower rooting depths and greater vulnerability to declining watertable depths in grasses than in shrubs. Grass cover has been shown to influence soil nitrogen (N) content, but this has seldom been investigated in Owens Valley. In this study we investigated the linkages between community composition and plant physiology at 9 sites along a 0.3-5.7m depth to watertable gradient in Owens Valley. At each site we measured shrub and grass canopy cover, plant and soil water isotopes, root and branch vulnerability to cavitation, and leaf and soil percent N from two dominant shrub species and one dominant grass species. Contrary to expectations, the grass species was more resistant to cavitation than either shrub species. However, grass cover declined in sites with deeper watertables while shrub cover remained constant. Water isotopes indicated shallower rooting depth in grasses than in shrubs. Sites with less grass cover also had less and more isotopically depleted soil nitrogen, and in all species, leaf N was not correlated with soil N. These results suggest that grass cover is likely constrained by rooting depth, and that soil N, but not leaf N, is linked to percent grass cover in Owens Valley.

Honorable Mention: Gouri Shankar Mishra, University of California, Davis

Life Cycle Analysis of Alternative Transportation Fuels: A Case Study Approach

The project will assess and characterize the water footprint of two alternative transportation fuels likely to be adopted in near term - electricity and biofuels. I will focus on water impacts of electricity from two renewable sources—solar and geothermal, and biofuels from agricultural waste like corn stover; all the three pathways are expected to achieve significant reduction in greenhouse gas emissions relative to traditional petroleum fuels. A lifecycle perspective that includes resource extraction / farming and transportation; fuel production and transportation / transmission; and operation of the vehicle will be adopted. In the recent past, a host of policies targeting GHG emissions have been enacted like the Low Carbon Fuel Standard in California and Renewables Standard at the federal level. While the carbon reduction potential of these policies been analyzed in some detail, the impact of these standards on water availability and quality relative to BAU is barely understood. In fact, other sustainability standards like land footprint, food prices, effect on wild life, and water availability and quality have not been considered by these policies. I expect my research to fill this gap, and also highlight limitations imposed by water shortages to achieve higher penetration of alternative fuels. I also expect my research to provide a planning tool for policy makers to analyze the tradeoffs between carbon reduction and water impacts. Our choice of alternative transportation fuels for water impact analysis: Plug-in Hybrids and Battery Electricity Vehicles powered by electricity, and Flex Fuel Vehicles powered by biofuels are the only well established technologies likely to be adopted in the next few years to comply with carbon reduction goals of various regulations in US and EU. Within the power sector, electricity from renewable sources like solar, geothermal, wind and biomass offer the greatest potential for early adoption given lack of viability of carbon capture and sequestration technology as it exists today; political, security and economic difficulties associated with nuclear power technology; and limited untapped potential of hydroelectricity in developed countries especially US. We excluded wind energy because its water footprint is negligible. The carbon reduction potential of biofuels from food crops like corn and sugarcane relative to traditional petroleum fuels is limited due to indirect land use effects. Further, the food versus fuel debate and rising prices of food especially in third world countries indicates that role of such fuels will diminish in future. Agricultural waste especially corn, rice and wheat stover have attracted lot of attention given their availability, limited alternative uses, and finally development of cellulosic fuel conversion technologies. Further, unlike some other potential biomass feedstocks like energy crops and forest residues, agricultural wastes need only limited additional resources for farming, collection and transportation. For solar power, the four major concentrating solar power (CSP) technologies—Power Tower, Parabolic Trough, Linear Fresnel, and Dish Engine—are considered. Water is required for cooling purposes to condense steam produced during the Rankine power cycle, dust suppression, and mirror washing. Estimation of water usage needs to account for differences in efficiencies of the CSP technologies; differences in cooling systems—wet, dry and hybrid; and potential savings due to water treatment technologies including Zero Liquid Discharge. Unlike other power generation technologies, solar power have large land footprint and water is required during construction phase for grading of land and dust suppression. While estimating water required for geothermal electricity, we will account for (i) different geothermal resource types - Hydrothermal and Hot Dry Rock (HDR); (ii) different power plant technologies—Binary or Organic Rankine cycle, Kalina cycle, and Flash technology; (iii) different cooling technologies—dry, wet recirculating and hybrid; and (iv)water treatment technologies. We will also consider water required for recharging steam based hydrothermal resources as well as potential water losses during heat mining of HDR resources. For bioethanol from agricultural waste, we will consider crop evapotransipration, account for irrigation water efficiencies using different technologies—flood, sprinkler and drip irrigation, and also consider conveyance losses through evaporation and percolation. Water will be allocated between corn and stover based on mass, energy, economic value, system expansion or displacement/substitution methods. A similar allocation approach will be adopted for distributing water usage between ethanol and other by-products created during conversion of stover to ethanol. To estimate water footprint, we will depend upon literature review of peer-reviewed articles, government research reports, new power plant applications; statistical analysis of government databases; primary systems analysis if required; and interview of experts including industry and academic personnel. For crop evapotranspiration estimates, we will use models like CROPWAT model developed by FAO and Consumptive Use Model (CUP) developed by California Department of Water Resources.

Math, Technology and Engineering

Winner: Jose Rios, Arizona State University

Self-Assembled Nanostructures Based on Combinations of Poly(ethylene glycol) and Polyphenols

Nanoparticles have the potential to be used as therapeutic macromolecules. The self-assembled nanoparticles of polyethylene glycol (PEG) with a polyphenol compound called Quebracho Tannin (QT) due to hydrogen bonding was studied. PEG based brush like polymers were synthesized using atom transfer radical polymerization (ATRP) to achieve low polydispersity and controlled molecular weight. The PEG based brush like polymers were combined in an aqueous solution with QT, in the presence of anti-oxidants. Four arm star shape PEG polymers were combined with QT as well. When PEG and polyphenol compounds are combined in water they self-assemble into nanoparticles due to hydrogen bonding. Low polydispersity index (PDI) was achieved using ATRP (PDI = 1.32). Nanoparticle sizes between 167 and 297 nm were obtained with very low polydispersity (=<0.2). PEG and polyphenol compounds can self-assemble into small nanoparticles and should be further studied for their potential to be used as therapeutic macromolecules.

Honorable Mention: Rotem Ben-Shachar, University of California, Los Angeles

A Mathematical Model of Food Intake Effects on Human Serum Leptin

Leptin is an important regulator of food intake and energy balance, providing a satiety signal to the brain. Leptin is secreted by adipose tissue, with high fat mass/BMI correlated with high serum leptin levels. However, obese individuals may have high food intake in spite of high leptin levels, contradicting the idea of leptin as a satiety signal. An emerging theory is that this counterintuitive leptin regulation is evolutionarily more advantageous— even in times of abundance, it is disadvantageous to store energy inefficiently. We developed a mathematical model of leptin regulation and food intake to explore the underlying factors behind desensitization to high leptin levels in obesity. We began by examining the pathways linking leptin and food intake. Changes in food intake cause relatively rapid changes in serum leptin, over a few hours to a few days. These changes are more rapid and of larger magnitude than the comparatively slow adjustments in fat mass/BMI, suggesting that food intake may affect leptin via both short and long-term pathways. Our model depicts leptin secretion, distribution between plasma and tissues, and elimination, including regulatory effects of changes in fat mass (long-term pathway) as well as more rapid, possibly insulin-mediated effects of changes in food intake (short-term pathway). We quantified our model using human clinical data, finding that both long and short-term pathways are essential for mediating leptin effects on weight loss and obesity.

Medicine and Public Health

Winner: Ashley Masters, Midland College

Inducing Triclosan Resistance

Triclosan is an antimicrobial agent used in a variety of personal hygiene products, plastic wares, and as a medical treatment for Staphylococcus aureus infections. It is suspected that the wide spread use of this compound contributes to low level resistance in some bacteria. The purpose of this study is to determine if resistance to Triclosan can be induced in Methicillin susceptible Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus cereus that have had no previous exposure to Triclosan. Bacteria were cultured over sixty days, alternating between media containing Triclosan and non-Triclosan media. Staphylococcus epidermidis developed Triclosan resistance, while Staphylococcus aureus and Bacillus cereus did not develop resistance.

Honorable Mention: Joanne Osburn, California State University, East Bay

Re-Evaluating the Florida Dentist Case with a New Statistical Framework

The use of genetic data for microbial source attribution in biocrime cases is controversial due to the lack of quantifiable statements about confidence levels. This is apparent in the 1991 investigation by the Centers for Disease Control and Prevention (CDC) into suspicions that a dentist with HIV had infected six of his patients. This project applies a new statistical method of analysis to this well‐known case. We compared viral DNA sequence data from the HIV‐1 env V3 region obtained from the dentist and the patients in question, and reference data from viral isolates of patient pairs known to be related by direct transmission. The reference sequence pairs determined a statistical distribution of mutational differences resulting from direct transmission. The comparison of dentist/patient sequences showed whether they fell within the distribution, and gave a statistical likelihood of a direct transmission relationship. We found a probability range of 26-69% that the dentist and the patients claimed by CDC to have been infected by him were separated by a single transmission step, while those theoretically infected by a different source had a probability of 8-45%. In future work, we may achieve better resolution by using a larger part of the genome and altering our methods of DNA comparison. As we continue to explore this model we hope to realize its usefulness as a tool in the future of microbial forensics, and in shedding light on this controversial case.

Physical Sciences

Winner: Samuel Penwell, University of Wisconsin, and Clara Duzgalski, University of California, Irvine

Thin Film Graphene for Transparent Electrodes

Transparent conductive films on insulating substrates are important for many optical electronic devices, including solar cells. Graphene films have been greatly anticipated as a potentially cost effective replacement for the current standard transparent electrode, Indium Tin Oxide (ITO). Here in, chemical vapor deposition (CVD) was used to grow thin films of graphene on copper foil substrates under a low-pressure methane/hydrogen atmosphere. A solution based transfer process was then used to deposit these films on glass substrates. The resulting transparent electrodes were characterized with Raman spectroscopy, optical microscopy, UV-Vis spectroscopy, and four point probe Van Der Pauw measurements. The graphene films were shown to have transparencies >94% at 550 nm, maintaining >90% transmittance in the measured range (350-3000 nm), and sheet resistances of 753±334 Ω/sq. ITO was shown to have a similar transparency in the visible region, but is much less transparent in the near infrared (NIR), making graphene a superior transparent electrode for IR active solar cells. However, ITO has a much lower sheet resistance, measured here to be 24 Ω/sq. Thus, more work will be required to improve the conductivity of these sheets in order to make them competitive with ITO. Finally, preliminary studies of multiple layer graphene electrodes produced in this manner, show the potential to greatly reduce the sheet resistance of graphene at the cost of slightly reduced transparency.

Honorable Mention: Andrew Ault, University of California, San Diego

Investigations into the Chemically-Resolved Optical Properties of Transported Asian Outflow Particles at Gosan, Korea

Atmospheric particles alter the amount of sunlight reaching the earth by scattering and absorbing solar radiation. This study examines the optical properties of particles as a function of chemistry on Jeju Island, Korea, downwind of China (~300 miles). An aerosol time-of-flight mass spectrometer (ATOFMS) measured the chemical mixing state and optical properties of single particles in real-time. The transported dust and pollution showed considerable variability in their optical properties depending on the origin of the air mass. Determining radiative properties using this novel approach to bridge chemistry and optical properties will provide an improved understanding of the impact of particles on climate.

Social Sciences

Winner: Sébastien Casault, University of Ottawa

Putting a Price on It: Using Real Options To Encourage R&D Investments

Innovation, the translation of knowledge into a useful product or service, is key to increasing the quality of life for all. Consequently, innovation is a private sector priority however; macroeconomic data indicate that markets do not currently provide enough incentives for firms to optimally invest in innovative activities. This study presents a real option methodology to limit financial risk by offering a tool to value R&D. Options are used extensively in financial markets although their use was rare originally; largely due to the complexity of pricing them. Following the publication of the Black-Scholes (B-S) formula for determining the price of an option however, this issue was addressed and their popularity grew tremendously. Myers later coined the term "real option", postulating that growth opportunities such as R&D expenditures can be viewed as options. This study suggests that the B-S formula does not perform well for R&D valuation - because the underlying typically undergoes large, uncorrelated monetary fluctuations. The B-S formula assumes the price of the underlying to follow an unbiased random walk process, leading to normally distributed price increments that ignore large fluctuations - inherent in R&D. Consequently, a statistical approach based on historically observed fluctuations is more accurate. Using this modified real option approach; access to more reliable quantitative information is made available providing impetus for growth in R&D investments.

Honorable Mention: Allyn Knox and Bethany Cutts, Arizona State University

Peer Influence on Student Water Use Practices

This study examines the role that social context plays in college students’ water use practices. Surveys were completed by sixty-seven students living in four different on-campus residences. These surveys assess the respondent’s water conservation knowledge, interest and practices; perception of others’ interest and practices; and the social ties within a residential unit. In addition to personal factors, two social factors are studied for their influence on the respondent’s water-use practices: 1) the relative importance, to the respondent, of their social network within the residence hall, and the perceived relative importance of water conservation within that network; and 2) the relative importance, to the respondent, of college peers’ opinions more generally, and the perception of water conservation norms within that community. The relative influence of each factor is expected to vary by age, gender, water knowledge, overall environmental views and familiarity with Arizona. First-year students from outside of Arizona are expected to be most influenced by the residential network. Outcomes of this study can be used to inform efforts to promote water conservation on college campuses. This is important because social influences can reinforce or undermine the development of water conservation values and practices that will solidify as our future leaders enter adulthood.