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.
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. In this SCRP summer project, students will study end-Permian rocks collected from China and determine whether or not the oceans were anoxic. There are multiple ways to determine if ancient marine sedimentary rocks were deposited in oxic, anoxic, or even sulfidic conditions. Our work will focus on examining the size distribution of pyrite mineral grains found within these rocks as a proxy for anoxic and sulfidic conditions. Students will learn geochemical techniques in the lab, examine rock samples using scanning electron microscopy (SEM), and forge connections between anoxia and mass extinction.
Todd Silverstein, Professor of Chemistry
Ongoing biochemistry research projects in the Silverstein group include:
- Photochemistry of suncreens: Do they enhance free radical production?
Sunscreen active ingredients protect against the oxidation of DNA nucleotide bases by oxidants in the presence of UV-light. Such DNA oxidative damage can easily cause mutations that lead to skin cancer. TiO2 is a common ingredient in a number of sunscreens. However, TiO2 is known to catalyze the photogeneration of oxygen free radicals, which can in turn oxidize DNA and cause the very damage the sunscreen is supposed to protect against. We are using the FOX assay to probe the kinetics of the TiO2-catalyzed photogeneration of ROS in aqueous solution.
- How toxic heavy metal ions inhibit enzymes: Cysteine is not the only problem.
Toxic heavy metals such as Hg2+, Cd2+, Pb2+ are known to bind to and inhibit many critical enzymes, causing cell death. By far the most widely studied enzyme-metal binding is that involving the cys-SH thiol. However, a number of enzymes that either lack cys-SH thiols are known to be inhibited by heavy metal cations. We have studied the little-known interaction between histidine imidazole N: and Hg2+. However, we have evidence that suggests that in the absence of cys-SH, his=NH is not the only side chain that can bind Hg2+. The next logical suspect in metal binding would be the glu-/asp- carboxylates; these remain to be studied.
- Enzyme-Linked Electrochemical Biosensors: Do the negative activation energies predicted by Marcus Theory really exist?
Glucose oxidase (GOx) oxidizes glucose to gluconolactone, and this enzyme-catalyzed reaction forms the basis of the common glucose biosensor. Quinones can replace oxygen as the GOx oxidant substrate. Different quinones have different standard reduction potentials (E°'), which yield different cell potentials (∆Ecell°'), which yield different reaction spontaneities (∆Gredox°). Although reaction thermodynamics rarely influence reaction kinetics, Marcus Theory (1992 Nobel Prize) demonstrates that for many redox reactions, just such a connection can be made. In fact, Marcus Theory predicts that for certain cell potentials, the activation energy should be negative! We are building a GOx-based biosensor to assay the kinetics of the glucose oxidation reaction; ultimately we are searching for quinones that afford the cell potential necessary to yield a negative activation energy.
- Electrolyzed Water: Health Benefits and Chemical Processes
In this electrolysis reaction, water is split (as in photosynthesis) and the O-2 atom transfers its 2e- to the 2H+ in water. The H2 product is an excellent reducing agent/anti-oxidant and can be ingested. The ClO- is an effective topical anti-microbial and can be used to heal skin lesions. We are studying ways to assay ClO- and H2 production, and influences on the kinetics of the electrolysis reaction: voltage, concentration, pH, etc.
Rick Watkins, Professor of Physics
Variable stars change their brightness over time. Some variable stars, called pulsating variables, change brightness due to an imbalance between gravity and pressure, which can cause the gas in the star to move inward and outward, so that the star changes its size and temperature, and hence brightness, periodically in time. Stellar pulsations provide a window through which we can investigate the internal structure of stars and improve our understanding of how they work. This project will focus on a particularly rare class of pulsating variables that pulsate in three independent frequencies at once. By measuring the interactions of these pulsations we hope to understand why and how these stars pulsate in their unusual way. Data, in the form of a time series of CCD images, will be collected on clear nights during the summer at a small observatory located at Willamette's Zena Forest. Images will be analyzed using a Unix-based system called IRAF (Image Reduction and Analysis Facility), producing brightness vs. time curves. These curves will then be Fourier analyzed to extract the frequencies and amplitudes of pulsation using the program Period04.
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.