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During this learning phase, we introduced a multiple-choice generate (MCG)-format of testing, which is a combination of multiple choice and short answer. After one week, during the final recall phase, participants took short answer tests on the four essays. During this final phase, as expected, the percentage of correct recall was higher for all the testing conditions compared to the restudy condition (testing effect). A comparison between initial and final tests indicated that a higher level of effort during the initial test provides more protection against forgetting than a lower level of effort. The initial short answer tests produced the least forgetting over a week, while the typical multiple-choice format produced the greatest forgetting, with the MCG format somewhere in between. These findings offer a simple way to increase the retrieval effort and benefits of a multiple-choice test while maintaining the practical benefits of multiplechoice formats for use in the classroom.
OTHER SOCIAL SCIENCES
Ballroom C - 3
CHANGING PERCEPTIONS AND PRACTICES IN ALASKAN SUBSISTENCE AND SPORT FISHERIESMaggie Nga Chan, Anne Beaudreau.
University of Alaska Fairbanks, Juneau, AK.
In southeast and south-central Alaska, Pacific halibut (Hippoglossus stenolepis) is a commercially valuable species, a primary target for sport fishing, and an irreplaceable subsistence resource for rural communities. In recent years, Pacific halibut populations have faced increasing pressures from fishing, climate change, and shifts in stock structure.
In addition to biological changes to halibut populations, resource users have to adapt to economic fluctuations and
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changing regulations. It is essential to understand how users adapt to a combination of pressures in order to evaluate the socioeconomic impact of management measures. This project will examine how regulations affect users’ fishing behavior, access to halibut, and the effect on other fishery resources. Additionally, we will examine whether existing regulatory categories capture the diversity of fishing practices in the sport and subsistence sectors. Methods include in-depth interviews combined with available historical catch data to evaluate changes to fishing behavior over time.
Interview questions will focus on changes to fishing locations, fishing effort, and target species as well as changes attributed to specific management regulations. While this study is in its beginning stages, it has widespread fisheries and natural resource policy implications. Understanding the socioeconomic impact of policy decisions, especially in communities that depend on fisheries, is essential to creating innovative solutions to natural resource issues.
Ballroom C - 73
DECOLONIZING MEDICINE: THIRD-WORLD INDIGENOUS TECHNOLOGIES OF HEALING CONFRONTING THE
MEDICAL COLONIAL COMPLEXRico Chenyek, Paula Treichler.
Institute of Communications Research, University of Illinois at Urbana-Champaign, Urbana, IL.
Scholars have located the value of curandera (healer)-scholar-activist texts, authored by writers including, but not limited to, Gloria E. Anzaldúa, Ana Castillo, and Aurora Levins Morales, within the field of Chicana/Latina-Indigenous studies and cultural studies at large. Within literature and oral history fields, scholars have analyzed how these texts actively work to dismantle patriarchy, colonial legacies, compulsory heteronormativity, criminalization, militarization, and both physical and cultural borders. Within health and medical science, physicians and scholars have critiqued the medical-industrial complex and offer first-hand, scientific accounts of differential healing. Nurse-curandera (nursehealer) scholarship in particular has begun to bridge critical studies and health medicine science with Chicana/LatinaIndigenous healing philosophies and practices. This scholarship inherently threatens the Eurocentric, capitalist, and imperialist nature of the institutions of medicine and healthcare and thus serves as the basis for culturally conscious healthcare and medicine models. Decolonizing medicine situates itself within and develops on this decolonial vision for culturally conscious, democratic, egalitarian medicine by bridging Chicana/Latina-Indigenous studies with critical health and medicine science. It argues that love forms the basis of not only the curandera-scholar-activist texts and parallel oral histories, but also the philosophical underpinnings of a vision toward healing justice. Decolonizing medicine employs Chela Sandoval’s methodology of emancipation as a theoretical tool to analyze the curanderascholar-activist texts as well as the traditional healing oral histories, bridging scholar-activism, and community intellectualism. Decolonizing medicine demonstrates a transdisciplinary approach to dismantling supremacy in science and medicine, an urgency central to the legacy of traditional knowledge in the sciences.
GRADUATE ORAL ABSTRACTS
BIO/AGR/ENV LIFE SCIENCES
MODE OF ACTION STUDIES OF THE NATURAL PRODUCT SUBLANCIN 168
University of Illinois at Urbana-Champaign, Urbana, IL.
Infectious diseases are a continuous threat to human health, and the rapid development of bacterial antibiotic resistance not only decreases the effectiveness of known antibiotics but also increases the need for the discovery of novel drugs. A rapidly expanding class of such compounds is the ribosomally synthesized and post-translationally modified peptide (RiPP) natural products. Sublancin 168, produced by Bacillus subtilis 168, contains a glucose moiety linked to a cysteine residue, an unprecedented post-translational modification. In addition, sublancin 168 has been shown to be extremely stable and has a narrow spectrum of activity with an unknown mode of action. Its extreme stability and unique structure have led us to hypothesize that sublancin has a novel antimicrobial mechanism of action. We have employed the use of various biochemical, microbiological, and genomic tools to characterize sublancin’s activity. Data obtained from comparative genomic analysis and global gene expression using DNA microarrays has identified the PTS-glucose specific transport system as a possible mechanism by which sublancin could enter the cell. Current efforts include investigating sublancin’s localization in the cell by creating fluorescent sublancin analogues. In addition, we synthesized a sublancin analogue lacking the glycan to investigate the role of the sugar and are refining a solution NMR structure of sublancin for clues regarding its mechanism of action. A clear understanding of how this unique antibiotic exerts its antimicrobial activity may facilitate the development of new antibiotics. Ultimately, we will attempt to shed light on exploitable pathways to better understand, target, and treat bacterial infections.
USING SPECTROSCOPIC PROBES AS A TRACKING NUMBER: FOLLOWING COPPER(I) TRANSPORT AND
DELIVERY IN THE ASSEMBLY OF THERMUS THERMOPHILUS CUAKelly Chacón, Ninian Blackburn.
Institute of Environmental Health, Oregon Health and Sciences University, Beaverton, OR.
Copper is an essential but potentially toxic metal ion in all living organisms. To manage this metal, an army of metallosensors, chaperones, and efflux pumps are needed for copper homeostasis and delivery of the ion to its ultimate destination in the cell, but our knowledge of these processes is still limited. In particular, the mechanism of metallation of CuA, the binuclear copper center present in cytochrome c oxidase, is still incompletely understood.
In vivo, both Sco and PCuAC have been implicated in the transfer of copper to CuA. Because these putative chaperones bind copper in a mononuclear environment, yet the CuA center is dinuclear, the nuclearity of the transfer intermediates is an open question. Here we address this topic via investigations of the reaction between Cu(I)-loaded PCuAC and apo CuA from the thermophilic bacterium Thermus thermophilus. We use a technique based on labeling the chaperone or the target with selenomethionine and monitoring the transfer of copper by way of multiedge X-ray absorption spectroscopy (XAS). Here we present a variety of spectroscopic data that suggest that Cu(I) is transferred in a facile manner to form a mononuclear intermediate in CuA and also show progress in developing rapid kinetic approaches in examining this mechanism. These results allow for a more informed approach toward studying the role of Sco and other putative copper chaperones because of common threads in the underlying copper chemistry.
Graduate Oral Room 211
STRUCTURAL STUDIES OF AN ER AND MITOCHONDRIAL TETHERING COMPLEXAndrew Ah Young, Pascal Egea.
University of California, Los Angeles, Los Angeles, CA.
In the highly compartmentalized eukaryotic cell, many cellular processes require communication and cooperation between organelles. One of the best-characterized models of interorganellar communication is the intimate liaison
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between the endoplasmic reticulum (ER) and mitochondria at sites called mitochondrial-associated membranes (MAMs). MAMs are implicated in the transport of calcium, maintenance of mitochondrial morphology, and the exchange of phospholipids. Deficiencies that alter the association of ER and mitochondria at MAMs are associated with several neurodegenerative disorders including Alzheimer’s disease and Charcot Marie Tooth Type-IIA. Despite the biological and medical relevance of MAMs, the molecular mechanisms that govern membrane tethering at these sites are poorly characterized. The goal of this research is to establish a structural understanding of the membranetethering reactions that link the ER and mitochondria. A powerful system to study this is the ER-mitochondria encounter structure (ERMES) complex. ERMES is a multimembrane protein complex that tethers the ER and mitochondria. It is composed of the cytoplasmic subunit Mdm12, ER-resident protein Mmm1, and outer-mitochondrial membrane proteins Mdm34, Mdm10, and Gem1. To determine the structure of ERMES, we will use X-ray crystallography, electron microscopy, and mass spectrometry. We have already obtained crystals of Mdm12, which we are optimizing in order to solve the crystal structure. Despite the challenges associated with the crystallization of membrane proteins, we have successfully expressed, purified, and crystallized a stable complex between Mdm12 and the cytoplasmic domain of Mmm1. Soluble domains of Mdm34 and Gem1 have been purified and are currently being screened for crystallization and association into higher order complexes.
BINDING TO BCOR DEFINES A SUBFAMILY OF PSC ORTHOLOG-MEDIATED POLYCOMB GROUPCOMPLEXES Sarah Junco, Renjing Wang, Alexander Taylor, P. John Hart, Chongwoo Kim.
The University of Texas Health Science Center at San Antonio, San Antonio, TX.
Polycomb group (PcG) proteins form transcriptionally repressive complexes that mediate epigenetic modifications of histones. The Drosophila polycomb group (PcG) protein Psc has 6 human orthologs: NSPC1/PCGF1, MEL18/PCGF2, PCGF3, BMI1/PCGF4, PCGF5, and MBLR/PCGF6. Each of these proteins contains 2 main structural domains: an N-terminal RING finger domain and a C-terminal RAWUL domain for protein-protein interactions. Binding studies suggest the presence of at least 2 distinct functional classes of Psc orthologs: Class I, (BMI1 and MEL18) that binds Ph, and Class II (PCGF3, NSPC1, and likely PCGF5) which binds BCOR and its homolog, BCOR-like1 (BCOR-L1).
We believe existence of different classes of Psc homologs demonstrates the evolution of the PcG in order to diversify its silencing function. We solved the crystal structure of the minimal binding regions of both BCOR and BCOR-L1 in complex with the RAWUL domain of PCGF1 to 2.1 Å and 1.9 Å, respectively. Analysis of the crystal structures reveals unique contacts made by residues not conserved in BMI1 and MEL18. The minimal binding regions of BCOR and BCOR-L1 to NSPC1 contain a novel domain, which we have named PCGF ubquitin-like fold discriminator (IPUD).
Comparison of the solution structure of the IPUD region of BCOR with the crystal structure of this region bound to NSPC1 reveals a conformational tightening of the IPUD on binding. This conformational tightening may be necessary to bind other proteins in the repressive BCOR complex, such as KDM2B. These observations lead to the hypothesis that PcG repressive complexes may form in a hierarchical manner.
USING BIOMOLECULAR NMR AND BIOPHYSICAL TECHNIQUES TO INVESTIGATE PROTEIN-RNA
INTERACTIONSRoderico Acevedo, Scott A. Showalter.
Pennsylvania State University, University Park, PA.
MicroRNAs are critical post-transcriptional regulators of gene expression, and their precursors have an A-form helical geometry that prevents proteins from identifying the sequence-determining hydrogen bonding groups on the nucleobases. This suggests that global structural features such as bulges or mismatches play a central role in specific double-stranded RNA (dsRNA) selection from cellular dsRNA pools by double-stranded RNA binding domain (dsRBD)- containing proteins. Furthermore, the processing enzymes in the maturation pathway require tandemdsRBD cofactor proteins for optimal function, suggesting a mechanistic role for cooperative, intrachain binding of dsRNA between domains. Here, we focus on one tandem-dsRBD, TRBP, which has been shown to tightly bind perfect dsRNA duplexes. It is our hypothesis that, although dsRBDs bind dsRNA in a nonsequence-specific manner, their presence is essential for the enzymes in the maturation pathway to efficiently locate the proper cleavage sites along the RNA. We present a combination of circular dichroism, electrophoretic mobility shift assays, and isothermal titration calorimetry-based assays demonstrating that TRBP binds dsRNA cooperatively because of intra-chain interactions.