Tag: Natural Science

Synthesis and Characterization of Ru(II) Cycloparaphenylene Complexes

Presenter(s): Shayan Louie − Biochemistry

Faculty Mentor(s): Ramesh Jasti, Jeff Van Raden

Poster 87

Research Area: Natural Science

Funding: Presidential Undergraduate Research Scholars

Ruthenium polypyridyl complexes undergo metal-to-ligand charge transfer (MLCT) in the presence of light, allowing energy from light to be captured in the form of an electron transfer. These molecules possess great potential as catalysts for efficient and clean chemical processes. To develop light-harvesting complexes that perform advanced functions, new ligands, or groups around metal ions, must be made. Cycloparaphenylenes (CPPs) are hoop-shaped photoactive molecules with virtually unexplored roles as ligands. They possess exceptional size-dependent optic and electric properties, and show potential as a new class of macrocycles for supramolecular chemistry, ultimately making them suitable for charge-transfer complexes. Through the incorporation of nitrogen atoms into the backbone of [8]CPP, we found that CPPs act as versatile ligands for a variety of metals including Ru(II). However, the effects of CPP diameter on the electric properties of Ru(II)-based light- harvesting complexes are unknown. We have recently synthesized CPP ligands of various sizes and coordinated them to ruthenium centers, which has allowed for the investigation of size/diameter on these properties.

The optic and electric properties of the complexes have been studied using UV-Vis spectroscopy and cyclic voltammetry. Here, we present our findings.

Bacterial and Fungal Community Composition Within Corn Seed

Presenter(s): Roxanne Fieldhouse − Biology

Faculty Mentor(s): Lucas Nebert, Brendan Bohannan

Poster 58

Research Area: Natural Science

Funding: UnderGrEBES Research Award

All plants contain within them an associated microbial community, functioning similar to the human gut community. These plant associated bacteria and fungi have recently come into focus as an important factor in fitness, helping to aid plants by increasing drought resistance, increasing limiting macronutrients available, and providing pathogen resistance. Importantly, many of these beneficial microbes can be inherited in the seed. Because some species can become pathogenic when the plant comes under stress, agricultural communities look to sterilize their seed of these complex communities. Little is known about the ecology of seedborne bacteria and fungi. The objective was to evaluate the microbial community of corn seeds, determine significant environmental factors, such as seed type, climate, and farm, affecting the microbial community composition. Additionally, we attempt to separate these environment-microbe interactions from the microbe-microbe interactions happening within the seed. We hoped to find microorganisms that negatively affect the presence of pathogenic microbes, specifically Fusarium, a genus of fungi that contains multiple species of corn pathogens. These fungi are relevant to human health because they produce a mycotoxin, fumonosin, which negatively impacts neurological development and liver function. Preliminary results have shown type of corn is a significant environmental factor in determining the composition of the microbial community and that significant microbe-microbe associations occur within a subset of the data. This research could allow future investigators to more clearly understand how host microbe interactions operate and reinforces the importance of

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a diverse microbiota.

Abundance, Density, and Diet of Duikers at Lomako, DRC

Presenter(s): Troi Feinberg − General Science

Faculty Mentor(s): Frances White, Colin Brand

Poster 65

Research Area: Natural Science

Duikers are a widespread family of tiny forest-living antelope that occur across sub-Saharan Africa. While approximately 22 species have been identified, little is known about the biology and behavior of many of these species due to their solitary and reclusive nature. Additionally, these species are sensitive to human disturbance and are often among the first species to be hunted and relocate. The objective of this study was to characterize the abundance and density of duikers inhabiting the forest near the N’dele field site in the Lomako Forest Reserve, Democratic Republic of Congo. Auditory or visual observation of duikers was recorded using all-occurrence sampling over nine months from 1983-1984. We also analyzed stomach contents of animals taken by hunters from outside the study area to gain insight on their diets. We encountered three species of duiker at the field site: Cephalophus weynsi, Cephalophus silvicultor, and Philantomba monticola. We detected C. weynsi 63 times, C. silvicultor once, and P. monticola 35 times. A preliminary estimate of overall density was 4.075 per sq. km. across all species. This result is comparable to duiker densities in other protected areas. Analyses of stomach contents (N=6) revealed that C. weynsi consumed at least 23 different plant species, including the following most prevalent food items: Celtis tessmanii, Dialium sp., and Landolphia congolensis. These data contribute to our broader understanding of duiker biology and are useful for monitoring trends in population size and density at this location over time.

Forebrain Control Of Social Behavior In Zebrafish Model

Presenter(s): Adeline Fecker − Biology

Faculty Mentor(s): Sarah Stednitz

Poster 43

Research Area: Natural Sciences

The zebrafish animal model provides valuable insight into social behavior and social impairments. Zebrafish exhibit a stereotyped orienting pattern called shulling when they interact with another fish. Our goal is to identify the neurons involved in this social behavior. We control the shulling behavior by placing one fish on each side of a clear divider. This assay allows
us to track their shulling pattern and control the duration of the interaction. After running a social behavior test in zebrafish, the brain is immediately dissected, cleared and stained for activity. This procedure labels the neurons that were recently active during the social behavior condition. Activity was labeled on three channels: GFP, ERK, and phospho ERK. We used zebrafish bred with the GFP transgene and stained the dissected brains with ERK and phospho ERK antibodies. The brains of fish who received no social stimulation were also dissected and stained as a control. The lateral septum of the forebrain is highly active in the stimulated condition. In a follow-up experiment, ablations of the lateral septum revealed social deficits in the behavior tests. This suggests the lateral septum is important for social behavior. Similar research on mammalian models supports the importance of the forebrain in social behavior. Our finding not only strengthens the validity of the fish model but also has implications for the localization of social deficits in autism and schizophrenia.

Do Chiton Larvae Have Kidney Stones? Unidentified Crystal Structures in the Larval Development Of Mopalia Hindsii

Presenter(s): Christina Ellison − Marine Biology

Faculty Mentor(s): Richard Emlet

Poster 59

Research Area: Natural Science

Funding: National Science Fund (REU program)

Chitons are marine molluscs in the class Polyplacophora. Like many marine organisms, chitons have a pelagic, dispersive larval stage which settles and metamorphoses into an adult form that lives on the benthos. During development, chitons must acquire structures that enable them to function in each of these environmental contexts. While many features of development have been well documented, one structure has yet to be reported. Chiton larvae consistently form a pair of birefringent, crystalline structures, best viewed with cross-polarized light. What they are made of and their function in the animal are unknown. The location and timing of these structures appear consistent with the “larval kidneys” as described by Baeumler et. al 2011, so we hypothesized they could be involved in kidney function. The purpose of this study was to establish a developmental timeline for these structures, to determine their chemical composition, and to record morphological data concerning their appearance (size, shape, number, location). This was achieved by raising chiton larvae and monitoring their development through microscopy. Calcein-tagging, fluorescence microscopy, and a murexide test were used to infer chemical composition. Our results suggest the structures form 4 days post-fertilization and persist at least 5 days after metamorphosis. The structures are composed of many small, calcium-containing crystals. They have been observed in 7 species across 2 suborders and may be a universal feature of chiton development. Our findings are consistent with possible kidney involvement, but functional studies must be done to further support this idea.

Inflammation as a Mediator of Depression and Diabetes in the Study on global AGEing and adult health (SAGE)

Presenter(s): Allison Dona − General Science, Spanish

Faculty Mentor(s): Josh Snodgrass, Alicia DeLouize

Poster 62

Research Area: Natural Science

Funding: NIH NIA Interagency Agreement; Ministry of Health in Mexico; University of Oregon Bray Fellowship

Diabetes and depression are major global health concerns, affecting over 400 million and 300 million worldwide, respectively. Numerous studies have found that these diseases are commonly comorbid, suggesting the possibility of an underlying shared physiological process such as an inflammatory pathway. As a biomarker of inflammation, C-reactive protein (CRP) has not been consistently linked to these conditions, despite the fact that diabetes and depression have both been linked to inflammatory mechanisms. This study uses Mexico Wave 1 data from the Study on global AGEing and adult health (SAGE) to examine if CRP mediates the relationship between depression and diabetes risk. It is hypothesized that, in participants 50-plus, inflammation will mediate the effect between the two conditions. Depression was estimated using a behavior-based diagnostic algorithm, inflammation was assessed using dried blood spot (DBS) CRP, and diabetes risk was assessed using DBS glycated hemoglobin (HbA1c). The association between depression and diabetes risk was partially mediated by inflammation. The presence of depression is associated with increased CRP, which is associated with increased HbA1c. This suggests that inflammation may be associated with the comorbidity of depression and diabetes. This may be the first study to use a large sample of older adults in a middle-income nation with high-resolution biomarker information to investigate physiological processes that might be involved in both conditions, an understanding of which could lead to better treatments.

Mapping Interactions Of Single-Stranded (Ss) DNA With the Ss-DNA Binding Protein (Gp32) of the T4 DNA Replication Complex at Specific Nucleotide Residue Positions

Presenter(s): Anson Dang − Biochemistry

Faculty Mentor(s): Pete von Hippel

Poster 19

Research Area: Natural Science, Biochemistry

Funding: Dreyfus Undergraduate Mentorships

The single-stranded (ss)DNA binding protein (gp32) of bacteriophage T4 plays a central role in regulating the functions and integration of the helicase, polymerase and primase components of the T4 DNA replication system. To understand how gp32 interacts with itself and with the other regulatory proteins and sub-assemblies of the T4 replication complex, we must first understand the structural details of how this protein binds to ssDNA lattices, both as isolated monomer subunits and as cooperatively bound gp32 clusters. We have explored these issues by monitoring differences in the fluorescence and circular dichroism (CD) spectra of site-specifically positioned monomers and dimer-pairs of 2-aminopurine (2-AP) probes located at various ssDNA positions within the binding site. In its cooperatively bound form gp32 spans 7 nucleotide residues per protein subunit, and by mapping spectral changes on binding to ssDNA lattices that are exact multiples of 7 residues in length we have been able to characterize interactions at defined positions within the gp32 binding cleft. We have extended these studies using acrylamide quenching and permanganate foot-printing assays to monitor degrees of base exposure at various lattice positions. Our results show that gp32 binds randomly at low concentrations, and then shifts toward preferential binding at the 5’-ends of the lattice as cooperatively bound gp32 clusters form at higher gp32 concentrations. Bases located near the middle of a gp32 binding site display lower solvent accessibility than those near the ends of the site. These differences in base ‘shielding’ may reflect deeper burial of the middle bases within the electropositive binding cleft, while bases at the ends may be made more accessible by fluctuations of the C- and N-terminal regulatory sub-domains of the protein. Insights into gp32- ssDNA interactions involved in controlling the functions of the T4 DNA replication complex that result from these studies will be discussed.

Inflammatory Phenotypes Of Zebrafish Enteric Nervous System Mutants

Presenter(s): Lillian Carroll − Biology

Faculty Mentor(s): Judith Eisen, Kristi Hamilton

Oral Session 4S

Research Area: Natural Science

Funding: OURS Program

Intestinal health depends on the microbial community within the dynamic intestinal environment. The enteric nervous system (ENS) innervates the intestine and modulates the microbial community composition. ENS reduction causes Hirschsprung disease (HSCR), resulting in intestinal dysmotility. Many HSCR patients develop potentially life-threatening intestinal inflammation. HSCR is genetically complex, with multiple HSCR genetic loci. The zebrafish is an excellent model in which to study the relationship between inflammation and genes linked to HSCR. Zebrafish with a mutation in the HSCR gene, sox10, have fewer enteric neurons, increased intestinal epithelial cell proliferation, and develop microbiota-dependent intestinal inflammation. Zebrafish with a mutation in another HSCR gene, ret, also have fewer ENS neurons but do not exhibit increased intestinal inflammation. sox10 acts in neural crest cells that form the ENS and ret acts within ENS cells, thus, I hypothesized that the intestinal phenotype of sox10;ret double mutants would be similar to the phenotype of sox10 mutants. To test this hypothesis, I analyzed the phenotypes of double mutants. I used PCR to identify mutants and quantified inflammation by counting intestinal neutrophils and recently-proliferated intestinal epithelial cells, and by determining the intestinal bacterial abundance. Surprisingly, and contrary to my hypothesis, sox10;ret double mutants did not exhibit increased intestinal inflammation or cell proliferation compared to wild-types. These results prompt me to reconsider the potential interactions

of the mutated genes, which will provide insights into the role of the ENS as a crucial regulator of the intestinal microbial community and its function in the maintenance of intestinal health.

Engrailed (En) Determines the Morphology of Neurons from Neuroblasts (NB) Lineages of the Ventral Nerve Cord (VNC) in Drosophila

Presenter(s): Claire Bui − Human Physiology

Faculty Mentor(s): Sonia Sen

Poster 84

Research Area: Natural Science

Funding: National Institutes of Health (NIH)

In Drosophila, neuroblasts (NBs) give rise to neurons and glia that make up the central nervous system (CNS). Each NB is characterized by a unique set of molecular markers that are dependent on spatial patterning cues. Spatial pattern is the position of the NB, which determine its cell fate. These patterning cues are crucial for the structure and function of the NBs within cell lineage, the generation of neural diversity, and the proper functioning of the CNS. Previous studies have shown that the transcription factors (TFs) Gooseberry (Gsb) and Engrailed (En) regulate cell fate of neuroblast progeny within the cell lineage. The activation of the Gsb gene has been shown to specify NB 5-6 cell lineage. In contrast, the En gene is expressed in different NBs: 7-1 and 7-4. My research focuses on two different NB cell lineages (5-6, 7-4) and two spatial TF (Gsb & En). En is normally not expressed in 5-6, so I have expressed it in NB 5-6 to see if it is transformed into 7-1 or 7-4. In this experiment, we used molecular markers to quantify NB and neuronal identity at early and late stages of Drosophila embryos. Our data suggested En caused a down-regulation of molecular markers specific to NBs 5-6 and changed the overall morphology of the cell lineage. These findings suggest En regulates the identity of neuronal progeny and provide critical insights into the spatial pattern as a mechanism of generating neuronal morphology.

2018 Native Revegetation and Restoration at Goose Creek

Presenter(s): Emily Bork – Environmental Science, Marine Biology

Co presenter(s): Bren Catt, Lachlan Addicott, Elizabeth Baach, Brianna Ashley, Madeline Cowen, Drew Donahue, Hailey Gilliland, Alice Gregg, Philip Hou, Harrison Satterthwaite

Faculty Mentor(s): Peg Boulay, Alejandro Brambila

Oral Session 4CS

Research Area: Natural Science

Funding: University of Oregon’s Environmental Studies Program

Goose Creek runs through Whitewater Ranch, an organic blueberry farm and timber harvester that is adjacent to the McKenzie River. Since 2014, the Environmental Leadership Program’s (ELP) Riparian Restoration team has been working to reverse the deleterious effects of past livestock grazing along Goose Creek. The overall goal of the restoration project is to replant disturbed native vegetation along Goose Creek, which will revitalize pollinator habitats, control the spread of invasive plant species, and increase stream health via a reduction in temperature. We will monitor these variables by using a variety of methods, including photopoint monitoring, vegetation survival and percent cover, pollinator surveys, stream temperature measurements, and aquatic macroinvertebrate surveys. After restoration, we expect to observe greater populations of native plant communities and native pollinators, less non-native plant species, and an overall improvement of stream health represented by a decrease in temperature and the presence of sensitive macroinvertebrate species. This year’s restoration efforts will augment the overall health of the McKenzie River Watershed and will provide valuable monitoring data for future ELP teams. These protocols will serve as useful guidelines for other agricultural areas that would like to restore native habitat and increase the health of riparian systems.