David Altman, Associate Professor of Physics
The inside of a cell is crowded and organized. It is because of its ordered state that a cell is a dynamic and exciting environment. Molecular motors are the biomolecules that generate force and motion, and thus do the work that is necessary to maintain the cell’s organization. In my lab, we investigate how the activity of the molecular motor myosin is regulated within a cell. To draw a connection between our understanding of biological systems at the molecular and cellular levels, we explore myosin motors at a variety of size-scales and levels of complexity. For more information, see our lab website. Two projects will be the focus of our summer work:
1) Studies of individual myosins: We will study purified myosins at the single-molecule level using an optical trap setup to apply picoNewton-scale forces to the motor. Our goal is to understand how forces imposed on a motor in the cell alter and regulate its function.
2) The role of myosins in phagocytosis: We will study myosins’ roles in phagocytosis by a human retinal cell line. We will allow a cell to internalize microscopic beads and use the optical trap to apply known forces to beads as they are trafficked throughout the cell. Our long-term goal is to relate force-sensitivities observed in vitro to those observed in a cell.
Melinda Butterworth, Assistant Professor of Environmental & Earth Sciences
My research focuses on the emergence of environmentally mediated infectious diseases. One important factor governing spatial and temporal disease activity is climate, specifically temperature and precipitation. The disease of study for this SCRP project is dengue fever and the associated mosquito vector (Aedes aegypti). Dengue fever has reappeared in the southern United States every year since 2009, after an absence of nearly 70 years. While there are many reasons contributing to this, there is growing scientific evidence that climate change may be partially facilitating this re-emergence. This is because warmer temperatures allow for longer mosquito seasons and decrease the extrinsic incubation period of the dengue fever virus inside the mosquito. This summer we will study how climate variability impacts the potential for dengue transmission in key sites in Florida and Texas. To do this, we will use a mosquito simulation model driven by observed meteorological data and future climate change projections. Our goal is to understand: (1) how frequently the climate in these locations can support local transmission, (2) the average season length of dengue transmission potential, and (3) how this may change under future climate scenarios.
Luke Ettinger, Assistant Professor of Exercise Science
Joint proprioception gives information regarding limb position and movement direction. For shoulder proprioception, quantification of proprioceptive acuity can be achieved through measurement of joint angles during reach-remembered tasks, known as joint position sense. Through collaboration with researchers at the University of Oregon, we created an application for the iPod touch that is designed to measure joint position sense. Using this technique, proprioception from various joints can be measured using minimally invasive techniques, with little to no risk of injury to the participant. Recent studies indicate that proprioceptive acuity of the shoulder and elbow improves as joint angles approach 90 degrees of flexion in the sagittal plane. This finding suggests that external torques may have an influence on proprioceptive acuity as external torque on the arm peaks at 90 degrees. It is unknown what contribution gravitational torques on the arm have on shoulder proprioception. We propose a study to investigate the influences of these external moments on shoulder proprioception through manipulation of external arm torque from either increasing external arm load or by decreasing this moment with submersion of the arm in water.
Alison Fisher, Associate Professor of Chemistry
Plants exchange hundreds, if not thousands, of diverse volatile (gaseous) organic compounds (VOCs) with the air around them. Although we generally can't see it, plants emit millions of tons of reactive organic carbon into the air each year, significantly impacting the chemistry of the lower atmosphere. As a result of the environmental impacts of VOC emissions from plants, the atmospheric processes these compounds participate in have been the subject of intense research for the last two decades. The biological questions surrounding these emissions have received less attention and, as a result, are less well understood. Students collaborating with me this summer will use classic biochemistry techniques combined with modern molecular genetic methods to answer some of the outstanding questions about plants and the volatile compounds they make.
David Griffith, Assistant Professor of Chemistry
My research is focused on understanding the chemical processes that control the fate of estrogens in aquatic environments using a variety of analytical techniques, including high performance liquid chromatography, UV-visible spectroscopy, degradation kinetics experiments, and high-resolution mass spectrometry. Estrogens are potent hormones that are excreted by vertebrates (e.g., humans and fish) and can enter natural waters through the discharge of treated and raw sewage. Estrogens disrupt the growth and proper development of aquatic organisms at extremely low (sub-ng L-1) concentrations. Yet, we know very little about the distribution and fate of estrogens in rivers, lakes, and oceans. To address this gap, my research group will be conducting fieldwork and laboratory experiments to better understand environmental removal processes, characterize the primary mechanisms driving estrogen distributions, and develop methods to accurately measure estrogen concentrations and potency. The results of our work will be used to predict environmental concentrations, anticipate problem areas, and mitigate the associated risk to aquatic organisms and human health.
Sarah Kirk, Professor of Chemistry
The Kirk research group focuses on designing medications that target receptors in the eye for the purpose of treating eye disease by, a process known as “rational drug design”. They work to understand the relationships among the drug’s molecular structure, the interaction with the receptors in the body, and a therapeutic result.
Cyclic nucleotide-gated (CNG) channels are Ca2+-permeable, non-selective cation channels gated by the binding of the cyclic nucleotides cAMP and cGMP. While CNG ion channels are found in many tissues throughout the body, only those present in the retinal rod and olfactory epithelium have been extensively studied. Alteration of CNG channel activity has been observed in some forms of retinitis pigmentosa, a degenerative eye disease. Mutations that cause elevated cGMP levels in the eye cause CNG channels to remain open. The resulting overabundance of Ca2+ ions in the cell leads to progressive degeneration of rod and cone photoreceptors and ultimately blindness. One potential strategy to treat retinitis pigmentosa is through the derivatization of the local anesthetic tetracaine, which binds to CNG channels with moderate affinity and blocks the flow of cations. The development of stronger CNG channel blockers based on the tetracaine scaffold is an area of continuing interest in our research group. In order to better understand the functional architecture of the pore and gating machinery, a series of tetracaine derivatives have been synthesized and assayed for their ability to block the CNG channel. Modifications of the lipophilic tail, the head group attachment, and the aromatic core of tetracaine have revealed distinct structure-activity relationships in the CNG channel.
This summer, our focus will be on designing and synthesizing novel derivatives that further explore the role of the aromatic ring and aniline hydrogen on tetracaine on channel bolck.
Melissa Marks, Assistant Professor of Biology
My research concerns the genetics, physiology, ecology, and evolution in populations of aquatic bacteria (Caulobacter crescentus). Since its initial isolation, C. crescentus has been propagated and studied in many laboratories throughout the world. During this time, a number of notable phenotypic changes evolved in lab strains of this species, including changes in outer membrane structure that confer increased resistance to predators (bacteriophage) and changes in transport proteins that result in improved survival rates. In my lab, student researchers and I will collaborate to (1) analyze the biochemical composition of outer membranes from strains with different phenotypes, (2) map the gene(s) responsible for differences in outer membrane phenotype, (3) assess the relationship between outer membrane phenotype and susceptibility to phage infection, (4) assess the genetic interaction between related nutrient transport genes and survival rates, and (5) measure fitness advantages and tradeoffs conferred by these nutrient transport alleles.
Katja Meyer, Assistant Professor of Environmental & Earth Science
The reduction of oxygen in the oceans, or ocean deoxygenation, is one of many expected impacts of modern anthropogenic climate warming. Because oxygen is essential to all animal life, we are interested in understanding the distribution of marine oxygen changes and the impacts on marine ecosystems. In our lab, we look at ancient climate warming events to study the relationship between changes in the chemistry of the ocean and the response of marine animal ecosystems. Much of our work is focused on the end-Permian mass extinction, which resulted in the loss of over 95% of marine species and occurred ~252 million years ago. This summer we will work to improve the tools geoscientists have for identifying the presence of euxinic (anoxic and sulfidic) conditions in ancient samples. Using both modern lake sediments and end-Permian rocks, we will examine the size distribution and isotopic composition of pyrite mineral grains found within these rocks as a proxy euxinic conditions. Students will use a variety of lab techniques to prepare samples and examine rock/sediment samples using scanning electron microscopy (SEM).
Chuck Williamson, Professor of Chemistry
In the Williamson research group, we use lasers and other techniques to probe the chemical and physical properties of molecules. One major area of interest for us is the behavior of partially-miscible binary liquid mixtures. These are mixtures of two liquids, such as methanol and carbon disulfide, that are completely miscible above a certain critical temperature, but separate into two layers for certain composition ranges below that temperature. The separated layers, or phases, are also mixtures of the two liquids, but with differing compositions. We use elastic laser light scattering, Raman spectroscopy (inelastic laser light scattering), and nuclear magnetic resonance spectroscopy to study the properties of liquid-liquid mixtures.
This summer our focus will be on elastic laser light scattering. We use elastic laser light scattering to make maps of the macroscopic behavior of binary liquid mixtures. These maps are called phase diagrams, and they show the temperature boundary between one-phase and two-phase behavior as a function of composition. In recent years we have identified a region of the phase diagram that does not behave as expected: a small number of droplets separate out of solution at temperatures slightly higher than the main phase transition. This newly-identified behavior is very puzzling, but it appears to be fundamental in nature because it occurs in the exact same way in at least six different liquid-liquid systems. Our goal for the summer is to learn more about these droplets by clarifying the conditions under which they form, and by hopefully isolating them for chemical characterization. To meet this latter objective, we will need to design and construct a new instrument from scratch.