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Biomedical Sciences Seminar Series

Spring 2008 Poster Presentation
May 2, 2008 at 1 pm
Physical Sciences Lobby

Poster #1- Roxana Rangel Rodriguez

Cation-p Interaction in Small α-Helical Peptides
Roxana  Rangel-Rodriguez, Dr. Alison McCurdy.

Cation-p interactions have been shown to play an important role in biological systems. The objective of this research is to gain a better understanding of the stabilizing non-covalent cation-p interaction in model helical peptides. The cation-pi interaction in small alanine-based a-helical peptides has been studied by CD spectroscopy and the cation-pi interaction has been quantified by calculating the free energy of stabilization. Pairs of residues Cha/R, Cha/K, F/K and F/R were investigated with four and five residues in between. This data was added to previously determined data for pairs of residues Y/R, Y/K, W/K and W/R. The free energy of stabilization for all peptides was examined and the uncertainty on these values was found.

Poster #2-Monica Delgado

 Use of Site Directed Mutagenesis and Reverse Genetics to Create a Variant of Sendai Virus, RGV22, to Study the Effects of a Mutation in the
L Protein on the Rate of Virus Production
Monica Delgado
M.S Prospectus

            The emergence of new viral human pathogens from variants of viruses that infect other animals has highlighted the importance of investigations on the genetic basis of viral infections. The long-term goal of this lab is to understand how the structure and function of Sendai virus proteins relate to viral pathogenicity. Wild-type (wt) Sendai virus causes a localized respiratory tract infection in mice, while a mutant, F1-R, causes a systemic infection. We attributed he difference in type of infection to amino acid changes in the F and M proteins of F1-R. In tissue culture, wild-type virus consistently produces at least 10-fold more viruses than F1-R.  Since M is known to be a negative regulator of viral mRNA synthesis, we attributed the difference in virus production rate to the amino acid changes in the M protein of F1-R. However, studies with reverse genetics viruses generated to identify the amino acid substitutions necessary for the systemic behavior of F1-R proved that amino acid substitutions in F1-R M are not responsible for F1-R’s reduced rate of virus production.  RGV0, a reverse genetics virus that contains all F1-R F and M amino acid changes produced at least 10-fold more viruses in tissue culture than did F1-R.  In mice it caused a systemic infection and preliminary evidence suggests that it is more virulent than either F1-R or wild-type Sendai virus. We suggest that the increased virulence of RGV0 with respect to F1-R is due to the increased rate of virus production in the infected mice. F1-R has a single mutation in each of the P and L genes that encode the viral polymerase complex proteins.  Amino acid changes in either or both of those proteins are likely to be the cause of the decreased rate of virus production and decreased virulence of F1-R. This study will test the hypothesis that the mutation in the L gene of F1-R causes the decreased rate of virus production and decreased virulence of F1-R. To address this hypothesis, we will use reverse genetics to construct a virus, which we will call RGV22, containing the L gene mutation of F1-R.  The RGV22 production rate will be studied in tissue culture via a multiple cycle replication assay and the pathogenicity of RGV22 in mice will be studied using real-time PCR and plaque assays on organ homogenates from infected mice.


Poster #3- Mario Corona

Creating cysteine sulfinic acid in creatine kinase with hydrogen peroxide
Mario A. Gallardo and Jamil Momand

Cysteine thiols in proteins are susceptible to oxidation. One molecule that has been shown to oxidize proteins is hydrogen peroxide. Hydrogen peroxide is generated in biological systems and has been shown to oxidize protein cysteine thiols to disulfides, sulfenic acids and sulfinic acids. Oxidized proteins possess altered activities. One protein that is susceptible to hydrogen peroxide-mediated oxidation is muscle creatine kinase. It is possible that oxidized creatine kinase is a target for degradation or repair. To test this hypothesis an oxidized form of creatine kinase was created. Hydrogen peroxide treatment of creatine kinase decreased the pI of the protein from its natural pI of 6.1. Two more acidic forms of the protein were created after hydrogen peroxide treatment as determined by isoelectric focusing.


Poster #4-Maura Palacios

The influence of varying salinity on spatial patterns of larval settlement of the mussels Mytilus californianus and Mytilus trossulus in
Barkley Sound, British Columbia

Maura Palacios
M.S. Biology
Faculty Mentor: Dr. Torres/ Dr. Robles

A commonality seen along the pacific coast of North America is the alongshore segregation of closely related mussel species. Beds of Mytilus californianus are restricted to wave-beaten headlands, whereas M. trossulus aggregations occur on shores protected from wave action. As a classical topic that has challenged the Marine Ecology community for years, current theory refers to post-settlement mortality as the cause. M. californianus smothers M. trossolus on the headlands and in quiet bays the effects of siltation suffocate M. californianus eliminating  the overgrowth effect. The proposed method is applicable in certain regions of the pacific coast but irrelevant in the Pacific Northwest where silt accumulation is not observed.
The proposed theory for this study is salinity tolerance plays a crucial role in the observed phenomenon. Specifically, salinity tolerance for larvae of M. trossolus is wide but M. californianus isnarrow. Also, abundance in the water column and settlement rates of both types of larvae is high on open coastlines due to wave action and vertical mixing maintaining a constant salinity.
Field and laboratory experiments proposed would develop reliable identification based on morphology, confirm differential tolerance of the larvae, describe spatial patterns of incursions, and determine rates of survival during incursions.


Poster #5-Sergio Rivas

The study of expander graphs that are Ramanujan.
Sergio Orlando Rivas
MS Mathematics
Faculty Mentor: Dr. Shaheen, Anthony

The theory of expander graphs is a hot topic in mathematics and computer science, as these graphs have a wide range of applications.  One of these applications is to communications networks.  Think of a communications network as a graph where each vertex represents a computer in a network and two vertices are connected by an edge if they can communicate directly with one another.  When designing a communications network one wishes that any message originating from anywhere within the graph will propagate quickly.  
There are various measurements, which describe how well a graph spreads messages.  One such measurement is called the spectral gap of a graph.  A graph is k-regular if every vertex of the graph has k edges incident to it.  The spectral gap of a connected, k-regular graph X is given by k– λ1(X), where λ1(X) is the second largest eigenvalue of the graph X.
One wishes to construct infinite families of regular graphs where the spectral gap of each graph is bounded away from zero by a fixed amount.  That is, one wants to make λ1(X) as small as possible.  But at the same time one wishes to minimize the number of edges in each graph of the family.   Some of the best graphs that have the property of being highly connected are families of Ramanujan graphs.
In this study we will start by investigating the properties of Cayley graphs, Cay(G,S) , which encodes the structure of a group G when a generating set S is given.  We want to know what types of groups G, along with their generating set S, give rise to families of Ramanujan graphs.

Poster #6-Nadine Rodriguez

Response of Paneth Cells in Small Intestine of Mice to Salmonella enterica serovar Typhimurium

Nadine Rodriguez and Dr. Edith Porter

Innate mucosal immunity represents the first line of defense preventing most microbes from entering the gut lining and invading the bloodstream. Paneth cells (PC) located at the base of the small intestinal crypts contribute to the mucosal first line defense by the secretion of granules filled with antimicrobial polypeptides. Recently interleukin 17 (IL-17) has been discovered as inflammatory cytokine regulating epithelial cells in the intestine. Previous studies indicated that PC in mice infected with Salmonella enterica serovar Typhimurium (ST), one of the leading causes of gastrointestinal infections in humans, contain less granules than PC in control mice. Therefore, we undertook to enumerate the granules in PC in hematoxylin & eosin stained small intestinal tissue sections obtained from mice one and three days after inoculation with ST or buffer only. There was a statistically significant decrease in the number of granules per PC in ST infected mice after three days accompanied by an increase in the number of PC per crypt. The total number of granules within the crypts was not significantly altered. Furthermore, we observed an increase of mitotic events in ST infected tissue sections. In addition, we found one day after inoculation increased IL17 levels in the tissue extracts from mice infected with ST compared to tissue extracts from control mice. However, IL17 levels were reduced in ST infected mice three days after inoculation. These data suggest an accelerated production of PC with the reduced number of granules reflecting immaturity as part of the host response which may be mediated by IL17. Our study may contribute to a better understanding of the host response to Salmonella infections.


Poster #7-Elizabeth Alusha

What Turns People Off: A Descriptive Study of Sexually Repellent Features

Elizabeth Alusha, B.A. and Pamela Regan, Ph.D., Department of Psychology, California State University, Los Angeles, Los Angeles, CA.

One of the unfortunate truths of human existence is that we cannot always obtain the kind of partner we ideally desire. Yet compromise and choice, which are important aspects of any mating relationship, generally are not considered by theorists or researchers in the areas of attraction and mate selection.  Rather, the majority focus on what people ideally seek to obtain in a potential partner (i.e., on their unmoderated, unadulterated desires).  The present descriptive study addressed this limitation by exploring beliefs about sexually undesirable partner attributes (that is, those features that exclude someone from the field of potential short-term mates).  Adults (N = 900; 450 men and 450 women) indicated in a free response format the features that they definitely would not want in a short-term sexual partner.  Participants specified a number of sexually undesirable partner attributes related to appearance (e.g., body weight, poor skin; 80.1%), personality (e.g., emotional instability, lack of intelligence; 70.1%), hygiene (e.g., poor general hygiene; 45.3%), sexuality (e.g., inexperience, aggression; 39.8%), social status (e.g., illiteracy; 21.0%), relational status (e.g., committed to another; 14.8%), bad habits (e.g., drug or alcohol use; 14.2%), and health (e.g., AIDS; 12.0%).  This result pattern indicates that the characteristics that men and women find sexually repellant (e.g., unattractiveness, emotional instability, stupidity) are the opposite of those they find particularly sexually appealing, and lends support to social contextual and evolutionary models of human mating.  In addition, few sex differences were found.  In particular, the strong and equal emphasis that men and women placed on undesirable physical attributes supports a growing body of evidence that appearance attributes play an important role in the short-term mating decisions of both sexes (see Gangestad, 1993; Regan, 2003).  Interestingly, although men and women specified similar characteristics, women generated significantly more repellant features than did men (p < .001).  This finding is in accord with theory and research that suggests that women have higher standards than men in the context of short-term mating relationships (Regan, in press).


Poster #8- Cindy Barlan

Alteration of Serum Enzyme Kinetics by Dietary Jojoba Oil Maintains Normal High Density Lipoprotein Cholesterol Concentration in Cholesterol-Fed Rabbits

Cindy Barlan, Susie Rascon, Christine Do, and Raymond E. Garcia

Most cardiovascular diseases (CVD) are caused by the formation of atherosclerotic plaques in the arteries. High density lipoprotein total cholesterol concentration [HDL-C] is considered an anti-atherogenic determinant in diagnosing the risk for CVD. New Zealand White (NZW) rabbits fed a cholesterol-rich diet exhibit a decrease in [HDL-C], whereas those fed a cholesterol-rich diet supplemented with jojoba oil maintain normal [HDL-C]. The objective of this project is to determine the mechanism behind these observations by studying the kinetics of the enzymes involved in the reverse cholesterol transport pathway. We hypothesize that dietary jojoba oil in the presence or absence of dietary cholesterol increases lecithin:cholesterol acyltransferase (LCAT) and decreases cholesteryl ester transfer protein (CETP) activities. Blood samples were obtained before and after feeding NZW rabbits either normal (N), 3% jojoba oil (J), 1% cholesterol (C), or, 1% cholesterol + 3% jojoba oil (CJ) diet for 7 days. Total cholesterol (TC) and free cholesterol (FC) concentrations were determined using enzymatic assays. LCAT rate was determined by measuring the disappearance of FC over a three hour period. LCAT rates in μmol/dL/h were: CJ = 217.8 ± 14.2 > C = 157.3 ± 22.8 > (J = 37.9 ± 2.3 ≈ N = 40.4 ± 2.9). CETP rates in μmol/dL/h were: C = 63.9 > (CJ = 45.4 ≈ J = 41.1 ≈ N = 34.3). These results indicate that dietary jojoba oil stimulates LCAT and inhibits CETP whenever cholesterol is present in the diet. (Supported by NIH MBRS-RISE Grant R25 GM61331.)


Poster #9- Ann Marie Valenzuela

Parental marital conflict and divorce, parent-child relationships, social support, and relationship anxiety among Latinos in young adulthood

Ann Marie Valenzuela & Heidi R. Riggio, Ph.D.

Previous research indicates that attributes of the family unit are related to quality of relationships in young adulthood, including relationships with parents and siblings, and overall perceptions of social support (Riggio, 2001, 2004).  Parental divorce and the experience of parental marital conflict are especially likely to influence features of relationships with parents and beliefs about the self in relationships with others, including feelings of anxiety in relationships (Amato & DeBoer, 2005; Riggio, 2004).  The current study investigates the harmful consequences of parental conflict and divorce for adult Latino offspring.  A sample of 180 young Latino adults from divorced and intact families completed self-report measures of parental conflict (Peterson & Zill, 1986), quality of parent-adult child relationships (Kenny, 1987), anxiety in relationships with others (Snell, 1998), and perceptions of social support from others (Sarason, Levine, Basham, & Sarason, 1983).  I hypothesize that divorce and conflict will have negative effects on the quality of relationships with both mother and father, perceived social support from others, and anxiety in personal relationships.  In addition, based on previous research (Riggio, 2004), I expect parental divorce to be associated with higher quality relationships with mothers and lower quality relationships with fathers.


Poster #10-Angelina Hernandez


Angelina Hernandez and Amelia Russo-Neustadt

            Chronic stress is known to have detrimental effects on the structure and function of the hippocampus.  This brain region plays an important role in spatial learning tasks.  Furthermore, glucocorticoids, or corticosterone in rats, are hormones secreted during times of stress that impair spatial learning (Roozendaal et al., 2003).  In addition, it has been suggested that exercise can prevent the damaging effect of stress on the hippocampus.  This may occur through one mechanism involving an upregulation of brain derived neurotrophic factor (BDNF) during exercise (Russo-Neustadt, 2003).  In this study, it is hypothesized that stress impairs spatial learning and that this impairment can be prevented by the use of exercise.  The model for stress used in this experiment is the chronic unpredictable stress model that consists of seven stressors: 24 hr illumination, 4 ºC forced swim, 24 hr food deprivation, 5 min tail suspension, 24 hr water deprivation, 20 min footshock, and 2 hr restraint.  Animals will receive a different stressor each day for three weeks.  Stressed and control rats will be tested on spatial learning ability using the Barnes circular platform maze.  This maze is a circular maze with 18 evenly spaced holes around the edges.  Under one hole, there will be a dark escape chamber with new bedding.  Rats will use spatial cues, including bright posters and boxes, in a brightly lit room to locate the dark escape chamber hole.  On the next part of this experiment, exercise will be implemented on a new cohort of control and stressed rats.  The same behavioral test will be used to measure spatial learning ability.  In support of the hypothesis, results displayed a longer latency time during testing to reach the escape chamber in the stressed rats compared to the control group.  Furthermore, exercise improved latency times in the new cohort of stressed rats.  In conclusion, the learning ability of stressed animals was impaired; however, with the use of exercise, the impairment in spatial learning was absent in stressed animals.  These preliminary results can advance the knowledge of mechanisms involved in preventing neurodegenerative effects due to chronic stress.


Poster #11- Abebayehu N Yilma

Human bronchioepithelial cell culture model to test the antimicrobial role of cholesteryl esters in innate host defenseµ

Abebayehu N Yilma and Edith Porter

Respiratory infectious diseases continue to be among the leading causes of illness and death world wide. A better understanding of natural host defense against microbial invasion may provide alternative strategies to prevent and treat infectious diseases. Previous research in our laboratory showed that host-derived lipids contribute to the inherent antibacterial activity of nasal fluid. In this study, we wish to demonstrate that cholesteryl esters contribute significantly to the inherent antibacterial activity of respiratory secretions employing an in vitro cell culture system with human bronchioepithelial cells. Our overall goal is to block the expression of Acyl-coenzyme A:cholesterol acyltransferase one (ACAT-1), a key enzyme of cholesteryl ester synthesis, and assess the effect on the antibacterial activity of these cells. Here, we report on the establishment of HBE4-E6/E7-C1 cells, the initial lipid analysis of their secretions and preliminary XTT assays targeted to evaluate the cytotoxicity of externally added lipids.   We collected the supernatants from four day old submerged cultures and, for control, of unused culture medium. Total lipid extracts performed according to Bligh & Dyer were analyzed by TLC and rpHPLC. Our preliminary data suggests that HBE4-E6/E7-C1 cells secrete cholesterol and, importantly, cholesteryl esters in the low µg/ml range. Our preliminary cytotoxicity assays indicate that liposomal formulations of cholesteryl linoleate did not exert cytotoxic activity toward HBE4-E6/E7-C1cells. If successful this study may entail better treatment of chronic infectious diseases through manipulation of cholesteryl ester production.

Poster #12-Lori Tallorin

Effects of Oxidative Addition via Singlet Oxygen on Pt (II) Thiolato Complex:
A Model System Elucidating Nephrotoxicity by cis-Platinum Antitumor Drugs

Lori Tallorin*, Dong Zhang*, and Matthias Selke*

Keywords: Photooxidation; Persulfoxide; Metal Thiolate; Singlet Oxygen; Peroxide

Effective treatment of nephrotoxicity by recognized cis- platinum antitumor drugs requires a mechanistic understanding of how these drugs initiate toxicity upon binding to cysteine-rich residues of metallothionein (MTs), a protein that is predominant in liver and kidneys and responsible for the detoxification of heavy metals. A study by Saryan et al. (1992) has shown that binding to cysteine-rich residues on MTs is cis-Pt(II) dependent implying that these Pt(II) cysteinato complexes are mainly responsible for nephrotoxicity. The exact mechanism of how these antitumor drugs induce toxicity is unclear. It is believed that oxidation of these metal bound MT cysteine residues may be one of the processes leading to severe side effects of cis-platinum drugs. The goal of this study is to determine whether short- lived peroxidic intermediate(s) are causing some of the damage. Studies by Gray et al. (1997) indicate the formation of the sulfinite product implying an intramolecular oxygen atom transfer upon photooxidation of a Pt(II) thiolate complex, implying intramolecular oxidation and no intermolecular oxygen atom transfer by the peroxidic intermediate. However, studies currently being conducted by our group indicate that peroxidic intermediates involved in the oxidation of the Pt-S-cys motif are in fact capable of intermolecular oxygen atom transfer and may therefore be involved in oxidative damage. The mechanisms of the peroxidic intermediate(s) produced by these Pt (II) cysteinato complexes may provide clues to understanding the mechanistic intricacies involved in the nephrotoxicity of these cis- platinum drugs.


Poster #13- Michelle Flores

Examining Interracial Interactions through a Mixed-Methods Approach

Kohatsu, Eric; Victoria, Rudolfo;
Vasquez, Jason; Salazar, Andrea and Flores, Michelle

Ongoing conflicts between Latinos and Asians in the U.S. contradict the much-adopted view that race relations in this country are harmonious and diversity-driven. This type of interracial interaction is best analyzed through a mixed methods approach in order to gain both a quantitative as well as a qualitative perspective (Kohatsu, 2007). The purpose of this study was to examine interracial interactions between Latinos and Asians using a mixed-methods approach. Participants were recruited from a culturally diverse west coast university and surveyed with established measures as well as an open-ended question. A thematic analysis revealed emerging themes through which participants identified their racial/ethnic group membership. Results further validated the use of mixed-methods in understanding the racial experiences of Asian Americans and other People of Color.


Poster #14- Yessenia K. Velazco

Antimicrobial activity of liposomes against Neisseria gonorrhoeae

Yessenia K. Velazco, Annie Cheung, Molecular Express, Inc., and Edith Porter.

HIV infections continue to be of major concern worldwide. Previous studies have shown that sexually transmitted infections increase the HIV infectivity.  We have recently shown that human defensin 5 HD5) is up-regulated during infection with Neisseria gonorrhoeae (NG), a fastidious gram-negative bacterium and one of the common causes of STIs. Our collaborators have subsequently shown that HD5 enhances the infectivity of HIV. Thus, prevention and better treatment of STIs may help to stem the HIV epidemic. Increasing resistance of NG to currently used antibiotics has been reported. In our laboratory we have developed novel antibacterial liposomes and our goal is to explore the activity of theses liposomes against NG. In this study, we describe our preliminary work to establish NG in our lab and to develop the best assay to determine anti-NG activity of antibacterial liposomes. We found that routine Mueller-Hinton media, routinely used for antibiotic activity testing, can be utilized for NG provided that the media s supplemented with isovitalex, a vitamin cocktail. We also found that we can use standard MIC testing with a modified read out to accommodate the particulate nature of liposomes. In MIC turbidity is used to measure bacterial proliferation. Instead we modified the read out introducing Syto 9, a quantitative DNA-binding fluoroprobe. Our next steps are to perform activity testing with our antibacterial liposomes.  


Poster #15- Joey Contreras

Chronic Unpredictable Stress reduces BDNF/mRNA Expression in the Rat Hippocampus

Joey Contreras
M.S. Biology
Faculty Mentor: Dr. Amelia Russo-Neustadt

It has been found that when the body is put under a chronic unpredictable stress it can lead to considerable neuronal damage.  It does so by reducing the expression of Brain Derived Neurotropic Factor (BDNF) located in the hippocampus.  This protein is known for supporting the survival of existing neurons and promoting the growth of new neurons (Altar, 1999; Lindsay et al., 1994). To combat this neurodegeneration, our study set out to determine if a neuron enhancing effect could be observed in experimental conditions using a chronic unpredictable stress model paired with physical exercise.  Male rats will be split into a control group and two experimental groups.  The two experimental groups will be subjected to various stressful situations (tail suspension, food/water deprivation, prolonged exposure to light, submergence in water, whole body restraint, etc).  One experimental group will be allowed voluntary wheel running so that we can observe whether there is a supported growth in BDNF as a result of the exercise. Using In Situ Hybridization to analyze BDNF/mRNA levels, our results are expected to show some neuronal degeneration in the hippocampal area (C1, C2, CA3 and dendate gyrus) amongst the stress-only rat group.  We also expect to see supported growth in BDNF amongst the rats that received exercise as a treatment.


Poster #16- Jeré Wilson

Cloning of bacterial essential genes using a modified vector with Ligation-independent cloning (LIC) strategy

Jeré Annette Wilson, Lilian J Real, H. H. Xu

Novel antibiotics are needed in order to combat increasing spread of multi-drug resistant strains of bacteria, as well as the threat of bioterrism.  Recent advances in microbial genomics and functional genomics have identified sets of essential genes from a number of bacterial species. Most essential genes encode protein product, which could be potential targets of new antibiotics. Our laboratory has been able to clone essential genes from Escherichia coli to study functions of essential proteins encoded by these genes and to identify cellular targets of antibacterial compounds. Previous results in our laboratory indicated that over-expression of E. coli essential genes led to enhanced resistance of E. coli host cells toward inhibitors specifically targeting the expressed proteins.  Ligation-independent cloning (LIC) is an efficient cloning approach that is used for directional cloning of PCR products without the use of conventional restriction enzyme digestions or ligation reactions. Currently, however LIC cloning kits are only available from commercial vendors and do not provide enough flexibility for controlled expression of native polypeptide encoded by cloned genes. In this project, our objective is to modify pLEX5BA into an LIC vector, pLEX5BA/LIC/kan. This poster describes progress of this. 
Methods: Five of E. coli essential genes have been PCR amplified and cloned into an expression vector pLEX5BA/LIC/kan, under the control of an ITPG-inducible promoter.  Over-expression of cloned essential proteins was obtained from E. coli cells of these clones under appropriate inducing conditions.
Results: In this study a total of five essential genes were cloned into pLEX5BA/LIC/kan           
(murE, nusA, yacE, fabB, secE ). Over-expression of their encoded proteins was confirmed via polyacrylmide gel electrophoresis.
Conclusions: We have validated the usefulness of an LIC vector constructed in our laboratory. The pLEX5BA/LIC/kan provides an inexpensive alternative to commercial LIC cloning kits. In the future I plan to clone foreign essential genes of A. baumannii, using pLEX5BA/LIC/kan, followed by over-expressing encoded essential proteins and determine if inhibitor-specific resistance will be observed.


Poster #17- Ricardo Sanchez

Cysteine Oxidation Prediction Algorithm (COPA): Predicting cysteine oxidation Susceptible Thiols from Protein Structure.

Ricardo Sanchez1, Megan Riddle1, Dr. Jongwook Woo2, Dr. Jamil A. Momand1
1Chemistry and Biochemistry, 2Computer Information Systems, CSU, Los Angeles     5151 State University Drive, Los Angeles, CA, 90032

   Under oxidizing conditions a sulfhydryl group can be oxidized into sulfenic acid (S-OH), sulfinic acid (SO2H), sulfonic acid (SO3H) and, most commonly, disulfide bond (S-S). Oxidizers can increase or decrease the function of target proteins by oxidizing protein sulfhydryl groups. It is believed that certain thiols on the surfaces of proteins are susceptible to oxidation because of two major factors: the solvent accessibility of the sulfur atom, and the presence of atoms that can stabilize the thiolate ion created by deprotonation of the thiol. Our goal is to utilize these factors and other physicochemical parameters to create an algorithm that predicts which protein thiol groups are susceptible to oxidation. With a program we created that takes PDB files as input, we extracted 10 physicochemical parameters for each target thiol to form a decision table. An 11th parameter was used as a label (1/0) to indicate whether the thiol moiety is susceptible to oxidation. Using a classification program (the C4.5 decision tree classifier re-implemented as the J48 classifier), a decision tree was obtained.  The classifier selected three parameters critical for prediction of thiol oxidation susceptibility: (1) distance to the nearest cysteine sulfur atom, (2) solvent accessibility, and (3) pKa. The classifier was optimized to correctly predict 136 of the 161 cysteine thiols susceptible to oxidation. Leave-one-out cross validation analysis showed that the percent of correctly classified cysteines was 80.1% and that 16.1% of the oxidation-susceptible cysteine thiols were incorrectly classified. The algorithm developed from these parameters, named the Cysteine Oxidation Prediction Algorithm (COPA), is presented. COPA-mediated prediction of oxidation-susceptible sites can be used to locate protein cysteines susceptible to redox-mediated regulation and to identify possible enzyme catalytic sites with reactive cysteine thiols.


Poster #18- Cari Wilson

Response of Breast Cancer Cell Proteome to Hydrogen Peroxide

Caridad Wilson, Shefali Sharma, Jamil MomandDepartment of Chemistry and Biochemistry, California State University Los Angeles

Hydrogen peroxide is a natural signaling molecule generated by oxidases and mitochondria during respiration and has been shown to mediate apoptosis in cells. This project is aimed towards investigating the molecular response of human breast cancer cells to hydrogen peroxide. One way to analyze the response is to determine which proteins are up- or down-regulated upon hydrogen peroxide treatment. Previous investigations used two-dimensional (2-D) gel electrophoresis to separate and analyze the proteome response to hydrogen peroxide treatment in the MCF-7 human breast cancer cell line. One protein exhibited a 3.2 fold increase in the presence of H2O2. The identity of the protein, determined by mass spectrometry, is either THO complex 3 or SLAP (Src-like adaptor protein). THO complex 3 is a more likely candidate since its molecular weight and pI most closely matched the unknown protein. It was found to be part of the TREX (transcription/elongation) complex which is involved in the transport of mRNA from the nucleus to the cytoplasm. THO complex 3 has also been suggested to be involved in protein-protein interactions and molecular evidence suggests that it is required for transcription elongation. SLAP is predicted to be involved in DNA replication and recombination, suggesting that hydrogen peroxide may trigger its overexpression in order to repair DNA damage. The goal of our project is to confirm the identity of the upregulated protein and determine if it helps the cells survive H2O2-mediated apoptosis. The identity of the protein (with respect to hydrogen peroxide response) will be elucidated by Western Blot analysis. Finally, cells will be analyzed for increased or decreased sensitivity to a knockout of the identified protein. 


Poster #19- Suzi Sanchez

Using a gene knockout approach to elucidate essential genes in Acinetobacter baumannii

Authors: Suzi Sanchez# and H. Howard Xu

The recent emergence of multi-drug resistant strains of bacterial pathogens has revived the imminent need for the development of novel antibiotics. Most currently used classes of antibiotics all target the products of essential genes. Consequently, identification and validation of essential genes from bacterial species are critical to discovery of novel antibiotics. Acinetobacter baumannii epitomizes the current trend, being documented in multiple sources as the causative agent in an array of nosocomial infections. It is believed that A. baumannii dedicates a large portion of its genome to pathogenecity and that it has acquired a considerable amount of foreign DNA through horizontal gene transfer conferring multi-drug resistance. We propose to use a recombination based gene knockout method to identify essential genes. The A. baumannii ATCC 17978 chromosome contains homologous copies of the fabB gene known to be essential in related organisms. This gene codes for the b-ketoacyl-acyl carrier protein synthase I, an essential enzyme in bacterial type II fatty acid synthesis. In order to determine whether one or both copies of the fabB genes are essential, a suicide vector construct will be used to knockout both copies of the gene, either individually or in sequence.middle region of each gene as a suicide vector to conduct knockout experiments within this strain.

Poster #20- Ivy Donaldson

Factors predicting child obesity in an ehtnically diverse community sample

Ivy C. Donaldson and Fary Cachelin, Ph.D.

Childhood obesity has become a major health concern in the United States, particularly among ethnic minority youth. Research has identified several factors that may potentially increase the risk of childhood obesity including parental feeding attitudes and practices, socioeconomic status, maternal weight status, amount of fast food consumption and television watching. Most studies to date have focused on European American and African American populations. The purpose of this study was to examine predictors of childhood obesity in a large, ethnically diverse community-based sample. Participants were 563 mothers with a child between the ages of 2 and 11 (306 Hispanic American, 76 Asian American, 36 African American, 145 European American/White). Mothers completed questionnaires assessing demographic information (maternal height, weight, age, occupation, education, ethnicity, generation status), child characteristics (gender, age, height, weight), child eating and activity patterns (times per week eat fast food, hours per week watch T.V.), and the Child Feeding Questionnaire (Birch et al., 2001) composed of the following subscales: perceived responsibility for child feeding; concern about child weight and eating; restriction of child eating; pressure on child to eat; monitoring of child eating. Multiple linear regression indicated that in this model (R2 = .14, p < .000) significant predictors of child’s body mass index (BMI) were hours per week child watches T.V. (p = .02), mother’s concern about child weight and eating (p = .002), pressure on child to eat (p = .01), socioeconomic status (p = .03), and ethnicity (p = .02). Specifically, higher child BMI was associated with more hours of television watching, more concern with child eating and weight, less pressure on child to eat, lower socioeconomic status, and being African American. The remaining variables (mother’s BMI and generation status, times per week child eats fast food, perceived responsibility for child feeding, restriction of child eating, monitoring of child eating) were not significant predictors of child BMI. Findings point to the need to consider a number of demographic and attitudinal factors in the prevention of childhood obesity.

Poster #21-
Poster #17-
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