«Strengthening the Nation through Diversity, Innovation & Leadership in STEM San Antonio,Texas · October 3-6, 2013 Get Connected! Connect with the ...»
Burnout is a psychological syndrome based on one’s relationship with work, which consists of overwhelming exhaustion, feelings of cynicism and detachment, and a sense of ineffectiveness on the job. Although limited in number, past research studies have suggested fairly high levels of burnout among the general college student population. What is not clear from past studies is whether there are times during a student’s college career when burnout is more pronounced, and, given the homogenous nature of past samples, whether ethnic differences exist in the experience of burnout among college students. The current research is aimed at addressing these issues by investigating whether the self-reported experience of burnout differs by classification, transfer status, and ethnic identity in a predominantly Hispanic sample. An additional goal for this study is to explore how well selfreported academic motivational orientation (intrinsic vs. extrinsic) predicts burnout in this sample. Volunteers from the undergraduate student population at Texas A&M International University will complete self-report measures of burnout, academic motivational orientation, ethnic identity, and relevant demographic information. Students who are near the end of their current classification will be asked to complete the same survey once more during the following semester to assess any shift in their responses.
TRADITIONAL ECOLOGICAL KNOWLEDGE
CAN CULTURALLY BASED EDUCATION BE INTERMIXED WITH COMPUTING SCIENCES AND INCREASE
STUDENT PERFORMANCECalvin Pohawpatchoko, Clayton Lewis.
University of Colorado, Boulder, Boulder CO.
It is believed that culturally based education holds an answer to improving student performance, and studies have shown its power. However, can culturally based education be integrated with computing science to improve student performance and bring about a better understanding of historical influences on indigenous identity? This workshop provides a framework built on culturally based education principles. We integrate computing science in a holistic approach for building 21st century skills, understanding historical influence by addressing student’s educational needs in an integrated way that opens interest in the power of indigenous computing. This work will help build future intellectual capital to help Native Nations advance in education and sciences in a manner that is culturally appropriate.
TRANSFORMING NATIVE AMERICAN YOUTHS’ PERCEPTION OF GEOSCIENCE THROUGH A CONNECTION
TO CULTURE, NATURE, AND COMMUNITYJamie Ricci1, Eric Riggs1, Sara Unsworth2.
Texas A&M University, College Station, TX, 2University of California, San Diego, La Jolla, CA.
1 The importance of diverse perspectives in the geosciences has precipitated an active movement to find inclusive educational practices. As Indigenous people and geoscientists increasingly interact, it has become imperative that each gain fluency in both Indigenous knowledge and Western earth sciences. However, few earth science programs consider the cultural milieu from which students approach their studies. Sharing the Land (StL), a program for Native American youth in California, considers geoscience education from a culturally appropriate perspective. Throughout the program, the youth take part in activities that cultivate an understanding of geology, environmental science, and current geoscience issues by embedding each activity in local culture. Activities are guided by members of local Native American communities, professors, and students from various universities, and specialists in certain fields. StL
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has been shown to be effective in transforming youths’ perceptions of themselves and their culture through science.
The aim of this research is to determine which components of StL contribute to this shift. To accomplish this, a series of presurveys and postsurveys are used to explore the youths’ relationship with their culture, perception of their future identity, and connections with other people. Three to 4 youth are chosen from each program to participate in semistructured interviews, once before the program began and twice after. By understanding how StL is effective, we may be able to foster similar programs or classroom applications, thereby increasing Native American youths’ interest and literacy in science.
INTEGRATING TRADITIONAL ECOLOGICAL KNOWLEDGE INTO MAINSTREAM SCIENCE AND POLICY:
INTERNATIONAL HUMAN RIGHTS CONSIDERATIONSCynthia Boshell.
University of Tulsa College of Law, Tulsa OK.
Once viewed as folklore by mainstream science practitioners, traditional ecological knowledge (TEK) is increasingly heralded as a key for human populations to adapt and survive in a changing climate, as an alternative frontier of discovery for science research, or as a policy answer to federal land management consultation requirements with Indian Tribes. Such utilitarian approaches to TEK would extract deeply rooted intellectual knowledge from its customary keepers, who are responsible for stewardship of their traditional homelands and attempt to merge TEK into mainstream resource-management programs. This policy-oriented legal research project addresses evolving international human rights dimensions of integrating TEK with science and policy, and proposes alternative approaches for resolving the inevitable conflicts that arise when value systems collide.
POSOH-THE SUSTAINABILITY LEADERSHIP COHORTLaundi Keepsesagle, Kate Flick.
College of Menominee Nation, Keshena, WI.
POSOH (meaning hello in the Menominee language) is a partnership of University of Wisconsin-Madison researchers, the College of Menominee Nation’s Sustainable Development Institute (SDI), and educators in northern Wisconsin.
This partnership and project is funded by a $4.7 million grant from the US Department of Agriculture. The multicultural education model of POSOH will embrace learning both traditional (from Native American collaborators) and scientific ways of understanding sustainability. The goal is to ignite interest and broaden understanding in sustainability through STEM. POSOH’s mission is to develop strategies for preparing all learners, including typically underserved youth from nonmainstream cultures and to pursue bioenergy- and sustainability-related studies and careers. This is to be accomplished while simultaneously exploring the contributions of traditional and scientific ways of knowing to our understanding of ecosystems and sustainability. In partnership with POSOH, SDI introduces the Sustainability Leadership Cohort (SLC) to train the next generation of community leaders, especially those of indigenous heritage on or near the Menominee Reservation. The SLC aims to maintain cultural values and encourage holistic thinking.
The SLC provides a hands-on non-lecture style environment including trips to other Tribal Nations, film productions, science research retreats, and homework assignments that promote critical thinking and leadership skills. The students will be involved in this new, innovative program from early spring 2013 until late fall 2013. The goal is to empower students so they may one day serve as leaders and change agents in an era of climate change. As POSOH and SLC mature, their multicultural education models and the sustainability research that emerges will be disseminated nationally via presentations, publications, and online forums.
POSTDOCTORAL POSTER ABSTRACTS
BIO/AGR/ENV LIFE SCIENCES
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A HIGH-THROUGHPUT INHIBITOR SCREEN FOR THE PROTEIN DISAGGREGASE HSP104, A NOVEL
THERAPEUTIC TARGET AGAINST FUNGIMariana Torrente, James Shorter.
University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA.
Fungi are a growing public health problem. These microorganisms can cause fatal infections in immunocompromised hosts such as transplant patients, AIDS patients, cancer patients, premature babies, and the elderly. Efficacious treatment of these infections is often difficult as medications that eradicate the fungus also harm human cells, becoming toxic to the human host. Thus, more specific antifungals that are able to bypass these problems are needed. Hsp104 is a ring-shaped hexameric yeast AAA+ATPase capable of restoring misfolded and aggregated proteins to their normal structure and function. This protein is essential for cell viability in challenging conditions when proteins tend to aggregate more readily. Interestingly, Hsp104 orthologues are found in all kingdoms of life except animals. Inhibition of Hsp104 would allow for therapies specifically targeted against fungi, which are dependent on Hsp104’s activity for survival, while producing little or no side effects. However, only one inhibitor of Hsp104’s activity is currently known. Here, by way of a high throughput colorimetric screen including over 16,000 compounds, we identified 20 small-molecule drugs capable of inhibiting Hsp104’s activity. These molecules inhibit Hsp104’s ATPase activity in a noncompetitive manner. Out of these, we mined molecules that interact with Hsp104 by mechanisms other than nonspecific colloidal effects and inhibit Hsp104 function both in vitro and in vivo. It is our hope that the results of this study can ultimately open the door to a new, more selective generation of antifungals with fewer side effects.
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INVESTIGATION INTO THE SUBSTRATE SPECIFICITY OF THE HALODURACIN SYNTHETASE HALM2Gabrielle Thibodeaux,1 Wilfred van der Donk2.
1University of Illinois at Urbana-Champaign, Urbana, IL, 2Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, Urbana, IL.
Lantibiotics are genetically encoded peptides that are produced by Gram-positive bacteria. Efforts to study and understand lantibiotics have been driven in part by a major problem the world is facing today: the emergence of pathogens that are resistant to common antibiotics. There has been an increasing interest in lantibiotic biosynthetic systems because of their potential for engineering peptides that contain enhanced antimicrobial activity and superior pharmacokinetics. A two-component class-II lantibiotic system was discovered in Bacillus halodurans C-125. In this organism, two lantibiotic synthetases, HalM1 and HalM2, were found to process two separate peptide substrates, HalA1 and HalA2, into mature lantibiotics. The importance of the core peptide was biochemically characterized by in vitro assays, in vivo production of chimeric substrates in E. coli, and determining the binding constants of HalM2 toward the leader and core independently using fluorescence polarization. Our results have shown HalM2 can process chimeric substrates, which contain HalA1 leader peptide and HalA2 core peptide and HalA2 leader peptide and HalA1 core. Until now, it was believed the leader peptide directed the lanthipeptide synthestase direction and activity, but these results provide evidence that the core peptide is also equally important in the maturation process.
The understanding of substrate specificity will enhance our ability to rationally design novel peptides and to generate compounds with improved therapeutic potential. In addition, the unique catalytic properties of lantibiotic synthetases hold great potential for the development of biotechnologies that can potentially impact many areas of basic and applied research.
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SYNTHESIS, CHARACTERIZATION, AND ANALYSIS OF BIOCOMPATIBILITY OF STAR-SHAPED GOLD
NANOPARTICLESGermán Plascencia Villa, Daniel Bahena, Arturo Ponce, Miguel José-Yacamán.
University of Texas at San Antonio, San Antonio, TX.
Engineered nanoparticles have diverse applications in biomedicine as diagnostics, image contrast agents, nanosensors, and drug delivery systems. Anisotropic metallic nanoparticles possess potential applications in cell imaging and therapy+diagnostics (theranostics). However, controlled synthesis and growth of these anisotropic or branched nanostructures have been challenging. Star-shaped, gold nanoparticles were obtained through a seed mediated route using 2-[4-(2-hydroxyethyl)-1-piperazinyl] ethane-sulfonic acid (HEPES) as a precise shapedirecting agent. Morphology of gold nanoparticles was obtained by ultra-high resolution FE-SEM (HITACHI S5500) and aberration-corrected atomic resolution TEM/STEM (JEOL ARM-200F) to obtain a detailed characterization of nanostructure and atomic arrangement. Nanoparticles showed absorbance centered in the NIR region (700nm) and dynamic light scattering. The zeta potential showed a narrow size distribution (80 nm), monodispersity, and high colloidal stability. Interaction of star-shaped, gold nanoparticles (35 - 350 µg/ml) with in vitro cultured macrophages showed that after 24 h there are no signs of cytotoxicity, as viability remained at 94 ± 1%, even at the highest concentration. FE-SEM imaging techniques helped to analyze adsorption and uptake of gold nanoparticles. Gold nanostars were shown to be biocompatible and efficiently adsorbed and internalized by cells, as revealed by advanced FE-SEM and backscattered electron imaging of complete, unstained, uncoated cells. Additionally, low voltage STEM and X-ray microanalysis revealed the ultrastructural location and stability of nanoparticles after endocytosis with high spatial resolution. Star-shaped gold nanoparticles have demonstrated their applications in biomedicine for SERS applications, thermal ablation, and nanotheranostics.
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BLOCKADE OF CD47 ENHANCES MACROPHAGE-MEDIATED CANCER CELL CYTOTOXICITY THROUGH THE
UPREGULATION OF AUTOPHAGYDavid Soto Pantoja, Gema Martin Manso, David Roberts.
Laboratory of Pathology, National Institute of Health, National Cancer Institute-Center for Cancer Research, Bethesda, MD.
Over two thirds of cancer patients in the United States will require ionizing radiation (IR) therapy as part of their course of treatment; however, achieving a curative response is limited in part by detrimental side effects on normal cells. We have previously demonstrated that therapeutic targeting of CD47 with antisense morpholinos confers radioprotection on normal tissue while enhancing radiation-induced tumor growth delay in murine models. One possible explanation for this observation is that CD47 blockade protects normal immune cells and preserves antitumor immunity. To test this, wild type or CD47-/- mice were injected with B16 melanoma cells to form subcutaneous tumors and exposed to local IR. Our results demonstrate that tumors on a CD47-deficient microenvironment in combination with IR treatment show reduction in tumor growth when compared to wild type. This was associated with an increase in tumor macrophage infiltrate. Moreover, targeting of CD47-enhanced macrophage mediated killing of melanoma cells and breast cancer cells. CD47 also protects macrophages from death from IR and enhances macrophage differentiation indicating that blockade of CD47 may selectively protect cytotoxic macrophages and increase citotoxic potential to reduce tumor growth. These effects are associated with upregulation of autophagy related genes ATG5, ATG7 and LC3. Therefore, CD47 blockade selectively activates protective autophagy in macrophages that in turn can target irradiated cancer cells and reduce tumor burden. These findings indicate that agents targeting CD47 may allow for more aggressive application of radiation in the treatment of cancer and increase the percentage of curative responses.
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MUTATION IN SPLICEOSOMAL PROTEIN SF3B1 INDUCES ERYTHROID MATURATION ARRESTOscar Ramirez Jr., Manoj Pillai.
University of Colorado, Anschutz Medical Campus, Northglenn, CO.
Myelodysplastic syndrome (MDS) is a group of clonal hematopoietic disorders characterized by ineffective production of blood cells by the bone marrow and a propensity to transform to acute leukemia. Over 14,000 new cases of MDS are reported each year in the US. Recently, whole-genome sequencing (WGS) of MDS patient samples revealed recurrent mutations in proteins of the splicing machinery. RNA splicing is the molecular process by which introns are removed from pre-mRNA in the nucleus. SF3B1 is the most commonly mutated spliceosomal protein in MDS.
SF3B1 is a 155 kilo-Dalton (kD) protein that forms part of the U2 spliceosomal complex. A nonsynonymous mutation (K700E) is the most common SF3B1 mutation in MDS. As MDS patients with SF3B1 mutation have profound anemia, we hypothesized that expression of SF3B1-K700E in normal hematopoietic precursors will result in maturation arrest of the erythroid lineage. Wild type (SF3B1-WT) and mutant (SF3B1-K700E) were expressed in human CD34+ cells by means of retroviral vectors. Erythroid maturation was then effected by culture in two phases: a 7-day culture in hematopoietic cytokines IL3, stem cell factor, FLt3 ligand, IL6, and a subsequent 10-14-day culture in erythropoietin (EPO). Cells were assayed every 3 days for expression of erythroid maturation markers CD71, CD105, and CD235A.
At days 7 to 10 of erythroid induction, cells expressing SF3B1-K700E were found to express significantly lower levels of CD71 and CD105 when compared to SF3B1-WT expressing controls. Studies defining the molecular mechanisms of SF3B1-K700E in this maturation arrest are ongoing.
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VOLTAGE-GATED CALCIUM CHANNEL SPLICE VARIANTS IN SYMPATHETIC NEURONSArturo Andrade, Summer Allen, Diane Lipscombe.
Brown University, Providence, RI.
Voltage-gated calcium 2.2 (CaV2.2) channels control transmitter release at many synapses and in some neurons such as superior cervical ganglia (SCG). A large number of G-protein-coupled receptors inhibit presynaptic CaV2.2 channels. This property is used by neurotransmitters, drugs, and hormones to downregulate transmitter release. The properties of CaV2.2 channels and their inhibition by G proteins vary according to cell type and synapse. Several factors contribute to cell specificity, but we have evidence that cell-specific alternative splicing is critical. Cacna1b is the gene that encodes CaV2.2, and it contains several alternatively spliced exons. Here we analyze the actions of an alternatively spliced exon, e18a, which encodes a short, 21-amino-acid sequence in the II-III linker of CaV2.2. E18a is enriched in SCG neurons particularly in adults (90% of the total). To assess the function of e18a, we engineered two lines of mice that either expressed e18a-containing CaV2.2 mRNAs only or that expressed e18a-lacking CaV2.2 mRNAs (D18a) only. The mice were viable and had no gross behavioral differences. CaV2.2 current densities in SCG neurons were approximately 25% larger in +18a compared to D18a mice similar to our analyses of cloned channels expressed in cell lines. Total CaV currents were strongly inhibited by vasoactive intestinal peptide (VIP), and further analyses showed the majority of inhibited currents were CaV2.2. The form of CaV inhibition induced by VIP, membrane delimited or diffusible, was different in neurons of +18a compared to D18a mice, consistent with our studies of cloned channels.
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CADHERIN-11 REGULATES PULMONARY FIBROSIS IN BLEOMYCIN-INDUCED LUNG INJURYMesias Pedroza, Teresa George, Sandeep Agarwal.
Baylor College of Medicine, Houston, TX.
Idiopathic pulmonary fibrosis (IPF) is a progressive, irreversible pulmonary disorder with no known effective treatments and is generally lethal within five years from the time of diagnosis. Pathologically, IPF is characterized by an aberrant wound-healing mechanism leading to excessive fibroblast proliferation, myofibroblast differentiation, and extensive matrix deposition in the alveolar airways. Epithelial-to-mesenchymal transition (EMT) is the differentiation of fibroblast-like phenotype from epithelial cells that results in myofibroblast accumulation. Cadherin-11 (Cad11) expression on hyperplastic alveolar epithelial cells undergoing EMT is a novel finding in our lab. Hence, we formulated the hypothesis that Cad11 contributes to the development of pulmonary fibrosis through EMT. To test this hypothesis, Postdoctoral we proposed the following: determine the contribution of Cad11 deficiency and neutralization in the intraperitoneal bleomycin (IP-BLM) model of pulmonary fibrosis, which better resembles the chronic aspects of IPF; and assess the contribution of Cad-11 in alveolar epithelial cells through EMT. Preliminary findings show that deficiency and
369 POSTDOCTORAL POSTER ABSTRACTS
neutralization of Cad11 in the IP-BLM model is associated with attenuated pulmonary fibrosis in conjunction with reduced b-catenin expression. In this model of pulmonary fibrosis, Cad11 deficiency and neutralization revealed restored arterial oxygen saturation, diminished a smooth-muscle actin accumulation, reduced collagen deposition, and decreased TGF-b production. The novelty of this project will be the identification of mechanisms by which Cad11 regulates EMT and TGFb production. This project will support additional translational studies to develop Cad11 as a therapeutic target for pulmonary fibrosis.
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MIF PROMOTES RESISTANCE TO GLUCOCORTICOIDS IN EXPERIMENTAL AUTOIMMUNE
ENCEPHALOMYELITISNiannian Ji, Thomas Forsthuber.
University of Texas at San Antonio, San Antonio, TX.
Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with the unique property of being induced by glucocorticoids (GCs) and the ability to counter regulate their antiinflammatory effects. GCs are the standard treatment for acute attacks of multiple sclerosis (MS); however, they eventually lose efficacy and overall do not prevent progression of the disease. We wanted to determine whether MIF played a role in resistance to GC treatment in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We induced active EAE in both wild type and MIF knockout (MIF-KO) mice followed by the treatment with dexamethasone (Dex) before or at the onset of disease. Splenocytes and brain mononuclear cells were collected for cytokine ELISPOT assay, flow cytometry analysis, and immunofluorescence staining. Treatment of EAE with Dex in MIF-KO mice was substantially more effective as compared to wild-type mice in terms of delayed EAE onset and decreased disease severity.
Dex treatment suppressed inflammatory infiltration in the brains of both wild-type and MIF-KO mice; however, the suppression lasted longer in MIF-KO mice once the treatment was stopped. In contrast, antigen-specific cytokine production by T cells was partially suppressed by Dex and slightly affected by MIF deficiency. Importantly, Dex profoundly inhibited the upregulation of transcription factor T-bet in CD4+ T cells from the brains of MIF-KO mice as compared with wild-type mice. Our data suggest that MIF promotes EAE and possibly MS by antagonizing GC effects on T-bet, which implicates the pathogenic, autoreactive T cell in EAE.
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OXIDATIVE-STRESS MEDIATES APOPTOSIS IN A HUMAN MODEL OF DANON DISEASE AND HEART FAILURECynthia Perry1, Sangyoon Han1, Stacey Clegg2, Kunfu Ouyang1, Dekker Deacon1, Ju Chen1, Qiuming Gong2, Zhengfeng Zhou2, Neil Chi1, Eric Adler1.
University of California, San Diego, La Jolla, CA, 2Oregon Health Sciences University, Portland, OR.
1 Emerging evidence has highlighted the importance of autophagy, an intracellular recycling pathway, in regulating cardiomyocyte bioenergetics, function, and survival. However, the mechanisms responsible for cellular dysfunction and death in cardiomyocytes with impaired autophagic flux remain unclear. Danon disease is a familial cardiomyopathy associated with impaired autophagy due to mutations in the gene encoding lysosomal-associated membrane protein type 2 (LAMP-2). To investigate the pathogenesis of Danon disease, we created iPS cells from a patient with a mutation in LAMP-2 who expired from heart failure. Danon induced-pluripotent-cells (iPS)-derived cardiomyocytes recapitulated key features of the disease in vitro, including impaired autophagic flux, increased cell size, abnormal calcium handling, and increased expression of natriuretic peptides. Danon cells were noted to have significant amounts of mitochondrial oxidative stress and apoptosis, both of which could be abrogated by treatment with the antioxidant N-acetylcysteine. These results implicate mitochondrial oxidative stress and apoptosis in the pathogenesis of Danon disease. They also provide the basis for the use of antioxidants for Danon disease and other autophagy-related human diseases such as heart failure, diabetes, cancer, and neurodegenerative disorders.
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ROLE OF 11-HYDROXYSTEROID DEHYDROGENASE TYPE 1 IN LEUKEMIA CELL LINESAdaris Rodriguez Cortes, Fatima Rivas, Taotao Ling.
St. Jude Children’s Research Hospital, Memphis, TN.
Glucocorticoids (GC) are steroid hormones that regulate physiologic functions such as gluconeogenesis, cell differentiation, and apoptosis in a tissue-specific manner. The prodifferentiation and proapoptotic effects of GCs are central in the treatment of childhood leukemia, particularly in the treatment of the most common childhood cancer, acute lymphoblastic leukemia (ALL). GCs are known to rapidly reduce ALL tumor burden without hindering bone
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marrow activity (myelosuppression). The initial response of a tumor to GC treatment is used as a key prognostic indicator. Resistance to GC treatment is observed in 10% to 30% of patients with untreated ALL and in relapse ALL.
Multiple factors influence GC resistance, but its etiology and development remain vague. Recently, a clinical study found that mRNA levels of a GC signaling enzyme, 11β-hydroxysteroid dehydrogenase (11β-HSD1), differ between GC-sensitive and GC-resistant ALL primary cells. The GC-sensitive cells contained more 11β-HSD1 mRNA than the GC-resistant cells. This enzyme is bidirectional, with both oxidase and reductase activities, primarily converting cortisone to cortisol and amplifying intracellular GC signaling. The role of 11β-HSD1 in leukemia cells is still unclear.
Our studies aim at exploring the role of 11β-HSD1 in the development of GC resistance in ALL. Herein, we disclose preliminary data from our studies on the presence and function of 11β-HSD1 in both B and T leukemia cell lines.
We used various molecular techniques, including RT-qPCR, western blots, and drug-induced inhibition studies. Our findings offer a platform to evaluate 11β-HSD1 as a potential therapeutic target to treat GC resistant ALL. Our current efforts and future studies will be discussed.
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NATURAL VARIATION AND COVARIATION IN THE MODEL ALGA CHLAMYDOMONAS REINHARDTIIKyle Hernandez, Jacob Malcom, Tom Juenger, Raquel Likos, Nathan Wisnoski.
The University of Texas at Austin, Austin, TX.
Variation is the lifeblood of ecological and evolutionary dynamics, and wild-type accessions provide a vital resource for studying the causes and consequences of variation. We quantified genome-wide genetic variation, phenotypic variation, and fitness variation and covariation in 40 environments for 18 wild-type Chlamydomonas reinhardtii lines and six F3 crosses between 2 of the wild-type lines. Patterns of genetic variation among polymorphic loci from RAD genotyping reflected the patterns uncovered in a resequencing project with many of these same lines. In addition, we found substantial phenotypic variation in fitness, cell cycle, cell size, and phototaxis among lines. Currently, we are exploring patterns of phenotypic plasticity and genotype-environment interaction in these wild-type lines across environments varying in nutrient availability, trace element concentrations, contaminant concentrations, pH, light, and temperature regimes. The natural variation of C. reinhardtii wild-type accessions, ease of crossing, abundance of inexpensive genetic markers, and speed of assays highlight an ideal resource for studying the molecular basis of variation.
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NANOMATERIAL CONTAMINATION IN AGRICULTURAL CROP SPECIES: INTERACTION WITH COEXISTING
CHEMICALS AND TROPHIC TRANSFER POTENTIALRoberto De La Torre Roche, Joseph Hawthorne, Jason White.
Connecticut Agricultural Experiment Station, Hamden, CT.
Although the use of engineered nanomaterials (NM) has increased, the fate and effects of these substances in the environment are poorly understood. As an emerging class of contaminants, there is significant potential for NM interactions with coexisting chemicals, as well as for bioaccumulation and biomagnification of these materials through food webs. A study currently underway involves corn, soybean, zucchini, and tomato being grown in soil containing weathered pesticides (chlordane and DDE) amended with nanoparticles (NP) of C60 or multiwalled carbon nanotubes (MWCNT). The accumulation of DDE by zucchini, soybean, and tomato grown in C60-amended vermiculite increased by 30-65% compared to controls. However, in a soil containing weathered DDE, C60 coexposure had little impact on DDE accumulation. MWCNT suppressed the pesticide accumulation by 20% to 67%. The finding that engineered nanomaterials can significantly alter the accumulation of pesticides in plants may have significant implications for food safety as well as for the movement of pesticides and other organic contaminants through the environment. To Postdoctoral determine NMs’ trophic transfer potential, studies have been initiated by exposing zucchini to cerium-amended or control soils. Fresh shoot tissue that had been exposed to 0 - 1000 mg/kg bulk or cerium oxide NPs will be used to feed Acheta domesticus (cricket) populations for up to 28 days. Live crickets that had consumed zucchini shoots will
be used to feed predator Tenodera sinensis (mantid) populations. The cerium content and nanoparticle translocation in plant and animal populations will be determined.
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HUMAN HEALTH RISK ASSESSMENT OF METALS IN PRIVATE AND PUBLIC GROUNDWATER SUPPLIES INARIZONA Roberto Marrero-Ortiz, Kelley R. Riley, Charles Gerba, Kelly Reynolds.
University of Arizona, Tucson, AZ.
The United States Environmental Protection Agency (USEPA) promulgated the final Groundwater Rule and the revised Arsenic Rule in 2006 to reduce the risk of exposure to contaminants in public groundwater water supplies.
The rules however do not regulate chemical contaminants in private, domestic-use wells. Approximately 5% of the Arizona population (300,000 persons) obtains its drinking water from one of 95,000 private household wells. The present study evaluated the occurrence and associated human health risk of arsenic and others metals in 39 private household wells and 10 small public-drinking groundwater supplies in Arizona. The determination of metals present in water samples was carried out by inductively coupled plasma mass spectrometry. Human health impacts related to arsenic and other metal concentrations found in the drinking water supplies were assessed using a quantitative toxic risk assessment approach. In a number of cases, the concentration of metals including As, B, Mo, Mn, Se, and U in groundwater were above the permissible levels for drinking-water quality recommended by the USEPA and WHO.
Indeed, 82% of groundwater wells were positive for some level of arsenic with 90% (9/10) of small public systems and 15% (6/39) of private household wells exceeding federal standards for acceptable risk. The results of this study support the need for consumer safety improvements in Arizona groundwater, particularly for private well owners who may be at greater risk of exposure and adverse health outcomes due to a lack of drinking-water monitoring and controls.
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ANTIMICROBIAL EFFECTS OF NOVEL NITRO-SUBSTITUTED BENZAZOLO[3,2 A]QUINOLINIUM DRUGS
AGAINST MULTI-DRUG-RESISTANT BACTERIAL STRAINSGloricelys Rivera, Beatriz Zayas.
Universidad Metropolitana, San Juan, PR.
Benzazoloquinolinium salts (BQs) have shown previously cytotoxic affects in diverse cancer cell lines such as the human epidermoid carcinoma (A431), non-Hodgkin’s B cell lymphoma (Toledo), and, more recently, in colorectal adenocarcinoma (Colo 320DM). However, there is no evidence of its potential antimicrobial activity against bacterial strains. To test the antimicrobial potential of these salts, we selected five nitro-substituted benzazolo[3,2-a]quinolinium chlorides that have demonstrated strong activity as anticancer agents: NBQ-2, NBQ-48, NBQ-51, NBQ-95, and NBQTo perform the analysis, we selected five bacterial strains based on the multiple drug-resistant criteria previously published by the Infectious Diseases Society of America (IDSA) and revised literature: S. aureus, K. pneumoniae, P. aeruginosa, E. coli, and S. typhimurium. Susceptibility tests were examined using the disk-diffusion (Kirby-Bauer) method. Zones of inhibition were compared with the broad-spectrum antibiotic tetracycline. Evaluations of the minimum inhibitory concentration (MIC) of the drugs were performed in triplicate using different concentrations in a 3-microtiter plate of 96 wells. Preliminary screening showed that 4 drugs were effective against all bacterial stains.
NBQ-51 exhibited the highest activity with an average of 30 mm diameter of inhibition zone at a 3 mM concentration.
Conversely, NBQ-95 at the same concentration did not show any bactericidal activity in the chosen strains. Results of this study exhibited inhibition activity of these compounds and their potential use as antimicrobial agents, especially against multi-drug-resistant bacterial strains. Further analysis of the synergistic effect of NBQs with additional compounds will elucidate the clinical aspect of these drugs.
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EVALUATION OF ANTIGEN-PRESENTING CELLS IN HUMAN, DISTAL COLONIC MUCOSA SUGGESTS
A POSSIBLE ROLE FOR RECTAL CD209+ MACROPHAGES AS TARGETS IN HIV INFECTION AND
TRANSMISSIONGloria Preza, Karen Tanner, Julie Elliott, Peter Anton, Otto Yang, Maria-Teresa Ochoa.
University of Southern California, Los Angeles, CA.
The most common route for HIV-1 infection is sexual transmission across colorectal mucosa. It is 20 to 200 times more vulnerable to infection per sex act then that of the female genital tract. Mucosal CD4+ T lymphocytes are believed to be the earliest cells infected, and viral access to activated CD4+ T lymphocytes appears to be a major limiting factor for HIV-1 transmission. However, activation of CD4+ T lymphocytes is dependent on antigen-presenting cells (APCs) such as dendritic cells (DCs) and monocyte/macrophages. Mucosal surfaces are the first line of defense against pathogens but APCs, key regulators of innate immunity and determinants of adaptive immunity, are not well defined in this tissue. We hypothesize that differences in APCs in the mucosa that favor less T lymphocyte activation could contribute to target cell limitation for HIV-1 transmission. Here, we sought to characterize APCs in human colorectal tissue. Using immunohistochemistry, Langerhans cells (LC), which express Langerin, known to bind HIV-1, were detected in the periphery of glands. Unexpectedly, the largest population was a macrophage-like cell expressing CD68 and CD163. Confocal microscopy revealed colocalization of CD209 (DC-SIGN), a DC marker shown to have a role in HIV transmission, with this macrophage-like population. These results demonstrate the unconfirmed presence of LCs in these compartments and a predominance of macrophage-like APCs that express DC-SIGN. This study evaluates the microenvironment in normal human, distal colonic mucosa, describes the potential HIV target cells in these microcompartments, and suggests a possible role for rectal macrophages in early HIV-1 infection and transmission.
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OBESITY PROMOTES AEROBIC GLYCOLYSIS IN PROSTATE CANCER CELLSDavid Cavazos, Matthew deGraffenried, Laura Bowers, Meredith Marlett, Shruti Apte, Linda deGraffenried.
University of Texas at Austin, Austin, TX.
Obesity is the leading preventable comorbidity associated with prostate cancer-related recurrence and mortality.
As obesity becomes more prevalent, the contribution to prostate cancer progression and mortality is expected to rise. Obesity may promote a worse outcome through the induction of metabolic abnormalities that stimulate cellular proliferation and genotoxic stress. Preclinical and clinical studies indicate that a BMI 30 is associated with increased oxidative DNA damage and shorter time to PSA failure; however, the mechanisms are multivariate and relatively unresolved. Previous studies in our lab indicate that blood serum derived from obese mice maintained on a 60% calories-from-fat (DIO) diet may promote the proliferative potential of human prostate cancer cell lines ex vivo.
Further, we have shown that a 1-hour exposure of LNCaP cells to DIO mouse serum enhanced tumor volume and metastasis for up to 12 weeks after xenograft into immunodeficient mice. Here we show that a 1-hour exposure of LNCaP or PacMetUT1 prostate cancer cell lines to 2% DIO mouse serum results in increased aerobic glycolysis relative to those exposed to serum from control-weight mice. This metabolic change was correlated with accumulation of reactive oxygen species (ROS) and increased frequency of DNA double-strand breaks. Interestingly, N-tertbutylhydroxylamine, a common food preservative with antioxidant properties, significantly inhibited aerobic glycolysis in the DIO-serum treated cells, suggesting that ROS contributes to a metabolic shift toward glycolysis. Here, we describe one potential mechanism by which obesity contributes to prostate cancer progression and explore the potential role of antioxidants in ameliorating these effects.
PHYSIOLOGY/PATHOLOGYBallroom C - 102
SPHINGOLIPID PATHWAY MAPS FROM METABOLIC BIOSIMULATIONS REVEAL INCREASES IN
PROGRESSIVE STAGES OF ALZHEIMER’S DISEASEGilbert Centeno Jr., George Perry, Clyde Phelix.
University of Texas at San Antonio, San Antonio, TX.
Sphingolipid metabolism plays a role in cell death through progressive stages of Alzheimer’s disease (AD). In this study, we tested the hypothesis that both levels of metabolites and flux of reactions in the sphingolipid pathway would increase in a simulated hippocampus as AD advanced. We used computational biology on integrated metabolic systems networks to perform predictive biosimulations. Transcriptomes from the human hippocampus (NCBI GEO GSE1297) from subjects of age-matched controls (AMC), incipient, moderate, and severe AD, were used to derive parameters for a deterministic kinetic model of 28 metabolic pathways. Transcriptome-To-Metabolome(TTM)™ biosimulation was performed using COPASI running time-course simulations and reporting metabolite levels and reaction flux values. Percent differences were calculated for gene expression and metabolite levels and reaction flux between each stage of AD versus AMC and each stage versus the prior stage. NodeXL software was used to generate network maps of the sphingolipid pathway where nodes represented metabolites and color and size the percent difference in level. Edges were directional arrows where size represented percent difference in flux and color indicated percent difference in gene expression levels. Results were easily assessed by the sizes and colors of nodes and edges on the network maps. Sphingolipid metabolites increased in AD as reported by others on direct measurements from human brain tissues. These differences were not progressive or linear. Such comprehensive datasets on levels and reactions are not possible with in vivo studies. This TTM™ method and pathway mapping will generate new hypotheses on AD pathophysiology.
EDUCATION RESEARCH/ADMINISTRATION (EXCEPT EDUCATIONAL/SCHOOLPSYCHOLOGY) Ballroom C - 52
PROMOTING CHANGE IN UNDERGRADUATE BIOLOGY CURRICULA BY INCORPORATING SCIENTIFIC
TEACHING TRAINING IN AN IRACDA POSTDOCTORAL PROGRAMDesirée L. Salazar1, Shannon Seidel2, Kelly S. Doran1, JoAnn Trejo2, Ricardo M. Zayas1, Laurence L. Brunton2.
San Diego State University, San Diego, CA, 2University of California, San Diego, La Jolla, CA.
1 The Institutional Research and Academic Career Development Awards (IRACDA) is funded by NIGMS at 19 sites, with the goal of providing mentored postdoctoral training and promoting diversity for the next generation of professors of biomedical sciences. The San Diego IRACDA couples a research-intensive institution, University of California, San Diego (UCSD), with a minority-serving institution, San Diego State University (SDSU). The IRACDA fellows conduct most of their research at UCSD and engage in mentored teaching at SDSU. Here, we discuss recent efforts to incorporate the principles of scientific teaching into the teaching experiences of IRACDA fellows to 1) train future faculty to build student-centered classrooms, 2) help promote a culture of scientific teaching at SDSU, and 3) improve the learning experience for undergraduate students. To provide an opportunity for IRACDA fellows to use scientific teaching skills, we implemented a project to revamp an upper-division cell and molecular biology course at SDSU.
We hypothesize that we can improve learning outcomes and decrease the minority/majority achievement gap by incorporating active learning and scientific teaching methods into the course. We created learning outcomes for the course and generated a pre/post-test, which we administered to assess student learning in the current course being offered in traditional lecture format. We will use the same pre/post-test to measure student learning in our revamped course, using student demographic information from the school registrar to assess characteristics of the student
population. We believe that involving our IRACDA fellows in a mentored teaching experience along with training in scientific teaching methods is a unique and effective way to enact change in biology curricula.
OTHER EDUCATIONBallroom C - 109
SPECTRUM: BUILDING PATHWAYS TO BIOMEDICAL RESEARCH CAREERS FOR GIRLS AND WOMEN OFCOLOR Audrey Parangan-Smith, Rebecca Garcia, Gloriana Trujillo, Kimberly Tanner.
San Francisco State University, San Francisco, CA.
Women of color (WOC) are still largely absent from the biomedical research community. Few materials or models exist that are designed specifically to attract girls of color to these careers. The Science Education Partnership and Assessment Laboratory (SEPAL) in the Biology Department at San Francisco State University (SFSU) has developed the Spectrum effort to address the dearth of WOC in biology. Through Spectrum, SFSU biomedical scientists who are WOC – including undergraduate and masters students, alumni in local doctoral and biotechnology positions, and biology faculty – with middle and high school teachers, collaborate to engage girls of color in science through
1) co-sponsoring after-school science clubs targeted at girls of color in high-need public schools, 2) developing a mentoring community of WOC biomedical research trainees, and 3) developing video resources highlighting the research programs of WOC biologists. During its initial 4 years, Spectrum engaged 456 girls (45% Latina, 13% African American, 22% Asian, 11% unknown, and 7% White) across 9 club sites, including 2 field trips to the laboratories of
SFSU WOC biologists. We report an increased number of participating girls who agreed with the following statements:
1) I have heard a woman scientist talk about why she likes science, and 2) I have met a woman scientist who is like me. Spectrum has also developed two video resources highlighting WOC, which are available on the SEPAL website and have been distributed nationally. (Spectrum is supported by the National Institutes of Health through #1R25RR024307, Supplement #3R25RR024307-05S, and Supplement #3R25RR024307-03S1.) Ballroom C - 60
TEACHING INTRODUCTORY BIOLOGY TO NON-MAJORS AT A TRIBAL COLLEGEOlivia George1, Leyma De Haro1, Gloriana Trujillo1, Summer Raines,1, Salina Torres1, Dorothy Wester2, Christopher Harrington2, William Adams2, Nader Vadiee2.
University of New Mexico, Albuquerque, NM, 2Southwestern Indian Polytechnic Institute, Albuquerque, NM.
1 Introductory biology for students with little or no background in biology has its challenges in colleges and universities across the country. Instructors teaching biology at tribal colleges face the same challenges as well as additional unique ones. Science education research has suggested that incorporating active learning into the curriculum enhances the student learning experience. As current Institutional Research and Academic Career Development Awards (IRACDA) fellows, we are paired with several minority-serving institutions. One such institution is a national tribal college, Southwestern Indian Polytechnic Institute. Because under-represented minority students tend to leave science, technology, engineering, and math (STEM) disciplines early in their education, we sought to restructure the current biology curriculum at SIPI from traditional lecture into a more active learning environment with more dynamic classes and culturally relevant topics. Our approach was to co-teach the subjects, while keeping the course structure identical for every unit with reading quizzes, clicker questions, and in-class active learning activities. In addition, we also created various low-risk assessments including multiple-choice and group exams, and the students created a final project on a current science topic of their choice instead of having a final exam. We found that students enjoyed working in groups and the incorporation of clickers in class. Our results from surveys and pre- and post-tests on content showed that the incorporation of active learning exercises into the curriculum can indeed increase student learning and retention of the material covered, especially within the Native American student population.
ENGINEERING/BIOENGINEERING/BIOMEDICAL ENGINEERINGBallroom C - 4
MICROBIAL POLY(GAMMA-GLUTAMIC ACID): PRODUCTION AND BIOMEDICAL APPLICATIONSJose Portilla-Arias1, Dulce Ma. Barradas-Dermitz2, Maria Guadalupe Aguilar Uscanga2.
Nanomedicine Research Center, Cedars Sinai Medical Center, Los Angeles, CA, 2Technological Institute of Veracruz, 1 Veracruz, MX.
Poly(gamma-glutamic acid) (PGGA) is an edible polypeptide excreted by certain bacteria that is presently accessible on a semi-industrial scale by both chemical synthesis and prepared by biosynthesis in the laboratory in up 90 g/L yields. Chemically, it is a nylon 4 derivative bearing a carboxylic side group attached to the fourth carbon of the repeating unit. Although this biopolymer is being exploited in the food, agriculture, and cosmetic sectors, its use in massive applications as packaging or coating is still unknown, mainly due to its instability in wet environments and unsuitability to be processed by common techniques. Chemical modification of PGGA involving esterification or amidation of the carboxylic group is the approach explored the most to obtain materials with potential interest as fibers, films, or hydrogels. PGGA is receiving increasing attention in biomedicine because it combines a wellproven nontoxicity with the possibility of conjugating diverse active agents and drugs via the carboxyl side group. Of particular interest is its potential as a drug delivery system due to the capacity of PGGA derivatives to form structured nanoparticles. Partial amidation with hydrophobic amino acids renders stable nanospheres able to efficiently encapsulate proteins that are conveyed by mechanisms appropriate for the design of vaccine delivery systems.
Modification by ionic coupling with organic cations constitutes another option to generate PGGA derivatives with new potential applications. Complexes with polycationic polymers such as poly (epsilon-lysine) or chitosan are suitable for building drug and protein carrier systems able to respond intelligently to pH changes.
ENGINEERING SCIENCES/MECHANICS/PHYSICSBallroom C - 97
EXPERIMENTAL STUDY OF THE DISCHARGE IN ATMOSPHERIC PRESSURE PLASMA JETS GENERATED INAR AND AR/O2 MIXTURE Cosmina Nicula1, Magesh Thiyagarajan2, Abdollah Sarani1.
College of Science & Engineering, Texas A&M University-Corpus Christi, Corpus Christi, TX, 2Plasma Engineering 1 Research Lab (PERL), Texas A&M University-Corpus Christi, Corpus Christi, TX.
Low temperature atmospheric plasma jets are investigated in argon and argon/oxygen mixtures; the effects of oxygen content in the various plasma emissions have been examined. In order to probe the plasma properties, electrical characterization has been performed. As a result, the electrical properties of the plasma jet show that we have higher peaks in the case of electrical current for Ar/O2 mixtures compared to pure argon plasma. During the experiment, it can be seen that by adding O2 to the argon plasma, the system shows a power decrease. The chemical species presented in the plasma jet were identified by optical emission spectroscopy in the spectral range from 200 to 900 nm, and it was found that plasma generated in argon has the highest emission intensity. Space-resolved emission spectroscopy with a resolution of 0.8 nm was performed. Assuming that the rotational temperature of the diatomic molecules is equal to the gas temperature under atmospheric pressure conditions, the rotational and vibrational temperature of the plasma has been determined by fitting the experimental spectra obtained from the spectrometer (with a very high resolution from 306 to 311 nm) with the simulated spectrum achieved from Lifbase software. The interpretation of temperature results show that the increase of oxygen concentration in argon plasma leads to an increase in the gas temperature. Finally, perspectives on using plasma jets in biomedical applications are presented.
(Supported by the US Army Medical Research & Materiel Command and the Telemedicine & Advanced Technology Research Center and Texas Research and Development Fund.)
376 POSTDOCTORAL POSTER ABSTRACTS
Ballroom C - 91
DEVELOPMENT OF STERILIZATION DEVICE USING NON-THERMAL PLASMA JETS INDUCED BY
ATMOSPHERIC PRESSURE DIELECTRIC BARRIER DISCHARGEAbdollah Sarani1, Magesh Thiyagarajan2.
College of Science & Engineering, Texas A&M University-Corpus Christi, Corpus Christi, TX, 2Plasma Engineering 1 Research Lab (PERL), Texas A&M University-Corpus Christi, Corpus Christi, TX.
Non-thermal atmospheric pressure plasma jets have been verified to be a tremendous source because of their novel applications. In this work, an innovative sterilization device is developed that uses helium, argon, and a helium/ argon mixture with an oxygen plasma jet induced by an atmospheric pressure dielectric barrier discharge. Because the sterilization is performed by the plasma reactions of active species at atmospheric pressure, the system does not require any expensive vacuum chambers. To obtain a fundamental understanding of the plasma sterilization process, the reactive plasma species, and the temperature of the plasma jet are investigated. Plasma density has been estimated from current measurement and is in order of 1013 cm-3. The gas temperature has been determined by fitting the experimental spectra and using the Boltzmann plot method. The gas temperature is below the temperature required to kill bacteria, e.g., Streptococcus pneumoniae. Plasma gas temperature is near room temperature (300 K) in the active zone between the electrodes and was found to increase in the afterglow. In the second part of the work, sterilizations are performed by applying the plasma jet for 15 s to several samples of bacteria. From this test, it is found that complete deactivations of bacteria are obtained by applying the plasma jet for 15 s. Our results show that a non-thermal plasma jet is an efficient source for biomedical applications, where yield of radicals and plume length can be controlled by variation of gas flow rate and discharge parameters.
PUBLIC HEALTH (INCLUDING ENVIRONMENTAL HEALTH/EPIDEMIOLOGY)Ballroom C - 13
GENETIC POLYMORPHISMS IN SLC2A4 AND SCD ARE ASSOCIATED WITH VARIATION IN OBESITY-RELATED
PHENOTYPES IN YUP’IK PEOPLEDominick Lemas1, Howard Wiener2, Diane O’Brien3, Scarlett Hopkins3, Kimber Stanhope4, Peter Havel4, David Allison2, Jose Fernandez2, Hemant Tiwari2, Bert Boyer3.
University of Colorado Denver, Aurora, CO, 2University of Alabama at Birmingham, Birmingham, AL, 3Center for 1 Alaska Native Health Research, University of Alaska Fairbanks, Fairbanks, AK, 4University of California, Davis, Davis, CA.
Regular consumption of n-3 polyunsaturated fatty acids (n-3 PUFAs) has been associated with protection from obesity-related diseases, in part, by altering the activity of genes involved with lipid and glucose metabolism. Stearoyl CoA desaturase (SCD), insulin sensitive glucose transporter (SLC2A4), and steroyl regulatory element binding protein (SREBF1) are obesity candidate genes that are transcriptionally regulated by n-3 PUFA intake. Although polymorphisms in SCD, SLC2A4, and SREBF1 have been associated with obesity-related phenotypes, the extent to which these genetic associations are modified by interactions with n-3 PUFA intake remains unknown. Obesity and lipid-related phenotypes were measured in a cross-sectional sample of Yup’ik individuals (n = 1080) enrolled in the Center of Alaska Native Health Research (CANHR) study. A comprehensive list of 33 single nucleotide polymorphisms within or near SCD, SLC2A4, and SREBF1 were tested for association with outcomes of interest in linear models accounting for familial correlations. Dietary intake of n-3 PUFAs was estimated using nitrogen stable isotope ratios (δ15N) of red blood cells (RBC). SCD (rs11190480 and rs2167444) polymorphisms were positively associated with ApoA1 levels (p = 0.006 and p = 0.004, respectively). SLC2A4 polymorphisms (rs5415 and rs5435) were associated with lower fasting HDL-cholesterol (p = 0.001 and p = 0.003, respectively) as well as increased hip circumference Postdoctoral (p = 0.005 and p = 0.027, respectively). Although our results indicate that polymorphisms in SCD and SLC2A4 are associated with obesity-related phenotypes in Yup’ik people, we did not detect significant n-3 PUFA interactions between SNPs in SCD, SLC2A4, and SREBF1 that modified genetic associations with obesity phenotypes.
ASTRONOMY/ASTROPHYSICSBallroom C - 36
MYSTERIES AND DISCOVERIES FROM THE CHANDRA PLANETARY NEBULAE SURVEY (CHANPLANS)Rodolfo Montez Jr.1, Joel Kastner2.
Vanderbilt University, Nashville, TN, 2Center for Imaging Science, Rochester Institute of Technology, Rochester, NY.
1 Planetary nebulae (PNe) are the ejected shells of glowing material formed during the late stages in the evolution of sun-like stars. Observations of PNe taken by NASA’s Chandra X-ray satellite observatory have ushered in a new wave of discoveries and mysteries in this class of evolved stars. The X-ray emission detected from PNe comes in 2 flavors: compact sources in the vicinity of the central star and extended sources that fill the nebular cavities. The latter variety, called hot bubbles, are chemically enriched with helium-shell burning products (C, O, and Ne), and their temperatures seem to be regulated by heat conduction across the bubble-nebula interface. Perhaps more exotic are the unexpected compact sources at PNe central stars. Their relatively hard X-ray spectral energy distributions cannot be explained by blackbody-like emission from the hot central stars but, instead, suggest the presence of even hotter thermal plasmas. The origin of this plasma emission may be coronae of binary companions, NLTE photospheric emission from the central proto white dwarfs, low-level accretion, or shocks in the chemically enriched stellar wind.
We are uncovering and investigating all of these phenomena via the Chandra planetary nebulae survey (ChanPlaNS), a volume-limited archival and multiyear survey of planetary nebulae in the solar neighborhood. We present the highlights from our analysis and results and the promising prospects afforded by ChanPlaNS.
Ballroom C - 45
HOW DO BLACK HOLES GET THEIR GASJillian Bellovary1, Alyson Brooks2, Fabio Governato3.
Vanderbilt University, Nashville, TN, 2Rutgers University, Piscataway, NJ, 3University of Washington, Seattle, WA.
1 Using a set of zoomed-in cosmological simulations of massive high-redshift galaxies, we isolate and trace the history of gas accreted by central, supermassive black holes. We determine the origins of the accreted gas in terms of whether it entered the galaxy during a merger event or was smoothly accreted. Furthermore, we designate whether the smoothly accreted gas is accreted via a cold flow or is shocked on entry into the halo. For moderate-mass (106
- 107 solar masses), black holes at redshift z4, there is a slight preference for accreting cold flow gas over gas of shocked or merger origin. However, this result is a consequence of the fact that the entire galaxy has a higher fraction of gas from cold flows. In general, each black hole tends to accrete the same fractions of smooth- and mergeraccreted gas as is contained in its host galaxy, suggesting that once gas enters a halo it becomes well mixed, and its origins are erased. We find that the angular momentum of the gas on halo entry is a more important factor: black holes preferentially accrete low angular momentum gas regardless of whether it was accreted smoothly or through mergers.
CHEMISTRY (EXCEPT BIOCHEMISTRY)
Ballroom C - 29
MONODISPERSE GOLD NANOPARTICLES SUPPORTED BY RICE HUSK SILICA FOR HETEROGENEOUSCATALYSIS Yan Li, Davontae Habbit, Luyi Sun.
Texas State University-San Marcos, San Marcos, TX.
Gold nanoparticle (Au NPs)-based catalysts have received more and more attention in the past 2 decades because of unique catalytic properties for many important industrial processes. Both the experimental findings and theoretical predictions demonstrate that the size of Au NPs plays a crucial role in governing the catalytic activity, and the smaller Au NPs exhibit higher catalytic activity. Here, we report an operationally simple method to synthesize Au NP-based heterogeneous catalyst using silica from rice husks (RHs) as a support. Although silica-supported Au NPs have been
378 POSTDOCTORAL POSTER ABSTRACTS
extensively studied, the chemical TEOS was usually used as the silica precursor. Notably, in this study, silica from RHs, byproducts from rice production, were first used as the silica source. Silica obtained by calcining HCl-treated RHs was first modified by (3-aminopropyl)triethoxysilane (APTES), which was found to play a dual role: absorb the Au precursor (AuCl4-) to the silica surface and stabilize the resultant Au NPs obtained by reducing AuCl4- using sodium borohydride (NaBH4). Characterizations of the nanostructures reveals that Au NPs are formed with a uniform, narrowsize distribution around 1 - 5 nm, which is very critical for essential catalytic activities. The catalyzed reduction of 4-nitrophenol with NaBH4 was also studied.
PHYSICS (EXCEPT BIOPHYSICS)
Ballroom C- 37
MODELING LASER-TISSUE INTERACTIONS: IMPLEMENTING THE HEAT DIFFUSION EQUATION AND WAVE
EQUATION TO SIMULATE THERMAL INTERACTION OF ABSORBER DISTRIBUTIONS IN BIOLOGICALTISSUES Frederick Barrera, Elharith Ahmed, Patrick Nash, Dhiraj Sardar.
University of Texas at San Antonio, San Antonio, TX.
The tracking of photons through turbid media (e.g., tissues) has been studied extensively from an experimental vantage point. These turbid media are difficult to characterize since their components are exceedingly variegated and present many challenges to clinicians who require models that precisely predict the location and time evolution of energy deposition. Furthermore, the interaction of the turbid media sample with the source of radiation typically involves many dynamic mechanisms (e.g., photothermal). Using diffuse light transport and an electromagnetic wave approach (i.e., Maxwell’s equations), an analysis of thermal energy distribution in tissues is performed. Assuming a highly absorbing chromophore model of melanosomes in tissues, a comparison of the variation of thermal energy by temperature profiles is determined for different collections of melanosome spatial distributions.
Ballroom C - 85
STRUCTURE ANALYSIS OF NATURAL COMPOSITE BIOMATERIALSFrancisco Ruiz Zepeda, Miguel Jose Yacaman.
University of Texas at San Antonio, San Antonio, TX.
Natural self-assembled structures are the inner layer of many species of mollusc shells. The primary purpose is protecting the mollusc’s soft bodies from their predators. The structures are made from an arrangement of aragonite crystal platelets separated by an organic matrix. In this work, a characterization of the structure and morphology of seashell samples is done by electron microscopy. The samples are prepared by mechanical polishing and ion milling. The aim of this study is to understand the biomineralization mechanism that nature uses to generate the selfassembled nanocomposite.
Psychological & Behavioral Sciences & Education