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Biomedical Sciences Seminar Series

Spring 2007 Poster Presentation
May 4, 2007 at 1 pm
Physical Sciences Lobby

Poster #1- Caridad Wilson

Response of Breast Cancer Cell Proteome to Hydrogen Peroxide

Caridad Wilson, Shefali Sharma, Jamil Momand 


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. We hope to elucidate the function of the protein (with respect to hydrogen peroxide response) by RNA interference. Finally, cells will be analyzed for increased or decreased sensitivity to a knockout of the identified protein.

Poster #2-Albert Izarraraz

  Explicit Stochastic Models for the Population Dynamics of Tribolium 

Authors: Alberto Izarraraz and Robert Desharnais
California State University at Los Angeles

Abstract: Models that incorporate random chance are useful tools to study the dynamics of ecological populations.  Most stochastic models are phenomenological deterministic equations with an added random term representing “noise.”  However, noise does not explain the mechanistic nature of random processes within the population.  An explicit stochastic model provides insight on the mechanisms leading to randomness.  I propose to develop explicit demographic stochastic models for insects of the genus Tribolium, estimate parameters for the model using data from laboratory populations, and compare the predictive ability of the models using time series population data. The models will take into account a variety of potential sources of demographic stochasticity, such as a deviations in the sex ratio, different birth and survival rates among individuals, and different rates of development. This project can serve as a paradigm for the way one can model stochasticity explicitly and connect it to experimental data.


Poster #3- Laura Martinez

Identification of activities shared by MyoD and p53 by global expression analysis

Laura E. Martinez; Sandra B. Sharp, Ph.D.; Xiu Zhu Sun, M.D.; Mesfin GeweDepartment of Biological Sciences at the California State University, Los Angeles

MyoD is a muscle-specific transcription regulator and one of the earliest markers of myogenic commitment. It is transcribed from one of a family of four myogenesis determination genes, each of which has been shown to induce myogenesis when expressed from a transgene in cultured non-muscle cells.   P53, a tumor suppressor known to regulate cell cycle checkpoints and apoptosis, also contributes to skeletal muscle differentiation in cultured cells.  It does not, however, induce myogenesis. We and others propose that p53 acts as a backup for MyoD.  A corollary to this proposition is that p53 and MyoD must have some activities in common.  Several such activities have already been identified.  A specific aim for my study, in collaboration with a second student, is to identify a suite of genome-wide regulatory activities shared by p53 and MyoD in cultured cells.  In addition, I will determine whether or not p53 facilitates myogenesis initiated by MyoD in our cell culture system, as it has been shown to do in other systems.

To accomplish this, our lab is creating two cell lines that are genetically identical except that one is p53 null and MyoD positive, and the other is MyoD null and p53 positive. We are transfecting expression constructs for MyoD, p53, or both into p53/MyoD negative Balb 10(1) fibroblast cells.  Once the cell lines are constructed, we will induce differentiation and assay for myogenesis.  Microscopic examination will be used to look for myotube formation. To confirm MyoD activity if myotubes are not observed, expression for several genes known to be activated by MyoD will be analyzed by reverse transcriptase-PCR using RNA isolated from the cells.  Once activity of MyoD has been confirmed, we will use the RNA to prepare cDNA, which will be analyzed by commercial microarray service for transcripts that are up-regulated or down-regulated by activity of MyoD in the absence of p53. A parallel study will examine the role of p53 in the absence of MyoD.  Analysis of data acquired by the parallel studies will identify genes activated or repressed in common in the two cells lines. In this manner, we will identify candidates for combinatoric and non-combinatoric but redundant transcriptional regulation by p53 and MyoD.

Based on prior work by ourselves and others, we predict that in cultures transformed with MyoD alone, we will see upregulation of genes known to be upregulated during myogenesis, such as myogenin, p21, myosin heavy chain, and desmin.  The data should identify known and additional transcripts that are regulated in common by MyoD and p53.  The importance of the products of these transcripts to myogenesis can then be investigated by literature search, bioinformatically, and by experiment.  We expect the cell culture co-transfected with MyoD and p53 expression constructs to form myotubes more readily than cultures transformed with MyoD alone.   For the MyoD null/p53 null cell line we expect no myogenesis


Poster #4-Luis Gonzalez

Mutagenic Analysis of a Proposed Glycine Binding Site in
PEP Carboxylase from Maize

Luis Gonzalez
Department of Chemistry and Biochemistry
California State University, Los Angeles 90032 


The photosynthetic enzyme PEP carboxylase is activated by glucose-6-phosphate, and in monocot plants the enzyme is also activated by glycine.  Previously, we have created a number of individual mutations whose regulatory properties suggest that the activators glucose-6-phosphate and glycine bind near each other at the subunit interface of the maize enzyme.  Here we describe the effects of several new mutants in the vicinity of this subunit interface region that further delineate the location of the glycine binding site.  G937 and K927 are two residues that line a pocket near the subunit interface that we propose to be the glycine binding site. This pocket is approximately 10 Å deep and includes multiple negative charges at its base and positive charges at its surface.  Lysine 927 is one of these positive charges, and when mutated to glutamine (K927Q) the enzyme shows much less activation by glycine.  Similarly, when glycine 937 is converted to aspartate (G937D) the enzyme loses most of its sensitivity to glycine activation.  This latter change mimics one of the structural features of PEP carboxylase from dicot plants and may partially explain why dicot enzymes are unresponsive to glycine.  Mutation of the nearby lysine 940 (K940Q) also reduced the response to glycine.  Other mutations in the vicinity of this pocket, including E932Q, N933G and C335S, did not significantly reduce the enzyme’s response to glycine. 



Poster #5-Kim Lien

Studies of Amyloid-β Aggregation at the Air-Water Interface

Kim Lien T. Dinh, Nakul Maiti, Dianlu Jiang, Yi Zhang, Feimeng Zhou

Alzheimer’s disease (AD), one of the most fatal neurodegenerative disorders in senior citizens, is characterized by the formation of insoluble plaques and fibrils aggregates of amyloid-β (Aβ) protein in the brain.  Aβ belongs to a group of 39- to 43-amino acid residue long peptides that undergo misfolding from the soluble to the insoluble state with high β-sheet content.  Although extensive studies have been performed to understand the morphologies of the aggregates on different substrates and in different solution environments, their mechanisms and structures are still not well understood.  In this study, we utilize the Langmuir-Blodgett technique to investigate the assembly of Aβ.  The amphiphilic nature of Aβ can enable it to freely aggregate at this interface, without little steric hindrance.  In a Langmuir-Blodgett trough, Aβ is allowed to assemble at the interface for different lengths of time, and the final assemblies were transferred onto hydrophobic and hydrophilic substrates as the film of Aβ is compressed at a constant pressure.  Atomic force microscopy is then used to image the resulting samples.  Small globular structures to large ones that are over 200 nm in height are detected.  Attached along the edges of these large globular structures are short fibrils and a layer of tightly packed oligomers.  By utilizing this interface to study the aggregation of Aβ, we are able to gain fundamental insight into the Aβ aggregation, a process purported to be crucial in the development of AD.


Poster #6-Vanessa Gonzalez

Molecular Phylogeny of Cypridinid Ostracods.

Sequence information from the 16s rRNA and 12s rRNA mitochondrial gene sequences were used to reconstruct the evolutionary relationships within the family Cypridinidae (Ostracoda: Myodocopida) in order to study the evolution of bioluminescence within this group. Bioluminescence is described as the production of light by any living organism and is proposed to have developed first as an anti-predatory behavior in cypridinids and, second as a courtship ritual performed by
males of some Caribbean species of the family Cypridinidae. This project combined the 12s rRNA mitochondrial gene sequences from Caribbean Cypridinidae species with information from the 16s rRNA gene from a previous study. A more robust molecular phylogeny was generated and evolutionary relationships were resolve d within the Cypridinidae,
than with previous molecular data. Molecular gene sequence information
from this project, supports the previous hypothesis of the evolution
of bioluminescence in this group, in which bioluminescence did indeed
evolve once, and the luminescent signaling, used for courtship in male
ostracods of the Caribbean evolved later and only once. Information
from this project is helpful in gaining an understanding of how an
adaptation of a behavior is affected by evolution, in this case the
ability to luminesce.


Poster #7-Angela Venegas

Expression of the Serine / Threonine Kinase LKB1 in Rat Granulosa Cells

Angela L. Venegas
Faculty Mentor: Dr. Philip S. LaPolt 

LKB1 has been identified as a tumor suppressor kinase that directly activates adenosine monophosphate-activated protein kinase (AMPK).   AMPK is known to regulate metabolic pathways involved in fatty acid and cholesterol synthesis.  In the ovary, cholesterol is required as a substrate for estradiol (E2) production from granulosa cells.  E2 synthesis in granulosa cells is induced by follicle-stimulating hormone (FSH), which acts through a cyclic AMP-dependent pathway.  Our preliminary findings suggest that AMPK is required for FSH-induced E2 production.  There is also evidence that cyclic AMP phosphorylates LKB1, activating it.  These findings suggest roles of LKB1 and AMPK in regulating granulosa cell function. However, there is little information available regarding the expression and regulation of total LKB1 protein levels during FSH-induced granulosa cell maturation.  Immunoblot analysis was used to confirm the presence of LKB1 protein levels in cultured rat granulosa cells.  However, treatment of granulosa cells with FSH did not affect LKB1 levels, indicating that LKB1 expression is not hormonally regulated.  Since LKB1 is post-translationally activated by phosphorylation, our findings suggest that LKB1 may be activated during FSH-induced granulosa cell maturation, but that LKB1 expression does not change.  Further studies are required to examine the control of LKB1 activation in granulosa cells.


Poster #8- Cinthya Ramirez

 Career Identity Formation among Latino College Students


Career identity is important to identity formation. Research has found that youth from working class backgrounds face different career identity challenges. The current study sought to identify development in Latino college students. 55 Latino college students
(43 women & 12 men) participated in a structured career identity interview and were assigned to a career identity status (achieved, moratorium, foreclosed, diffuse). Those who were achieved reported the most support. Those in moratorium were most likely
to mention someone who inspired them in their career. Those in diffusion were most likely to report being discouraged by obstacles they faced. The context that
most facilitates career exploration is one in which supportive individuals are available to provide help, information, and inspiration, and role models.


Poster #9- Ronald Martinez

The pebbling number of C5 × C5

ABSTRACT: Chung has defined a pebbling move on a graph G to be the removal of two pebbles from one vertex and the addition of one pebble to an adjacent vertex. The pebbling number, f(G), of a graph is the least number of pebbles such that any distribution of f(G) pebbles on G allows one pebble to be moved to any specified, but arbitrary, vertex. Graham’s Conjecture states: for any graphs G and H, f(G * H) ≤ f(G)f(H). Herscovici and Higgins showed that Graham’s conjecture holds when G=H=C5. I will give details of a shorter – and hopefully generalizable – proof of this results 


Poster #10-Orquidia Rogers

Cloning of Bacterial Essential Genes and Purification of Encoded Products

 O. H. Rogers and H. H. Xu  
Department of Biological Sciencess
California State University, Los Angeles

Background: With the continued emergence of antibiotic resistant pathogens, there is an urgent need for the study and discovery of novel antibiotic compounds.  While advances in technology, such as high throughput screening, have facilitated the discovery of antibiotics, the study of the potential cellular targets for these antibiotics remains sluggish.  In this study, several Escherichia coli essential genes were cloned and the encoded proteins were over-expressed and purified.  Methods: Targeted essential genes in E. coli were PCR amplified and the resultant amplified gene segments were then inserted into a pET-30Ek/LIC vector from Novagen.  pET-30Ek/LIC, a ligation independent cloning vector, allows for high efficiency cloning to generate a His-tagged fusion protein to facilitate purification of protein product.  After gene cloning, the essential proteins were subsequently over-expressed in E. coli cells with the aide of ITPG induction.  The resultant over-expressed His-tagged proteins were purified using a metal chelation chromatography kit from Nogaven.  Results:  Three essential genes from E.coli: fabB, def, and murG were successfully cloned into vector pET-30Ek/LIC and transformed into host strain BL21 (DE3) as confirmed by restriction digest and agarose gel electrophoresis.  The resultant clones were over-expressed with overnight induction with ITPG and confirmed via SDS-PAGE gel electrophoresis.  SDS-PAGE gel electrophoresis showed the migration of over-expressed protein bands to areas consistent with the expected protein size encoded by each essential cloned gene.  His-tagged proteins were purified with the aid of a nickel metal chelation column.  Impurities were then removed via dialysis and centrifugation.  The purity of each over-expressed protein was then confirmed via gel electrophoresis.  Conclusion: The use of an LIC vector allowed for the high efficiency cloning and effective over-expression and purification of three essential E. coli proteins.    These over-expressed and purified proteins are valuable for future screening of novel enzyme inhibitors and mechanisms of action studies.


Poster #11- Carlos Ibarra

Solving the extension of the integers mod(2) by the integers mod(4) 

Carlos Ibarra

If K and Q are groups, then an extension of K by Q is a group having a normal subgroup K1 isomorphic to K with G mod K isomophic to Q. The objective of this presentation is to solve the extension problem for the integers mod(2) by the intergers mod(4) by means of Group Cohomology.

Poster #12-Jonathan Charles

Functional Brain Activation During Anticipation of
Visceral Pain in Conscious Non Restrained Rats

Jonathan Charles

One experimental medical approach in patients suffering from functional gastrointestinal disorders (e.g. irritable bowel syndrome) consists in the evaluation of brain regions activated during visceral stimulation, during anticipation of the pain and the effect of drugs on this response (Naliboff et al, Psychosom Med (2001)63:365-375). This study is aimed to characterize the brain regions that are activated during painful visceral stimulation and its anticipation by using fear conditioning in freely moving rats.  This approach is to make preclinical studies more relevant to the human condition and provide a valid model for the testing of drug candidates for the treatment of visceral pain. Our focus will be on how to characterize differences in the behavior and regional functional brain activation during anticipation of visceral pain.  The experimental design will consist in applying a visceral stimulus (distension of the distal part of the colon by using a removable inflatable balloon inserted via the rectum into the colon). The rats will be trained to receive distension of the colon paired with an auditory tone, in order to develop fear for the painful stimulation when the auditory tone is presented by itself. This procedure is called fear conditioning. We will then assess brain activation in response to the auditory tone after exposure to fear conditioning, mimicking anticipation of the stimulus. Another approach will consist in training rats to receive distension of the colon when stepping down a platform. Rats at the time of anticipation receive an intravenous injection of a perfusion radiotracer, followed by rapid euthanasia. Brain activation is assessed by measurement of regional changes in brain perfusion using autoradiography of the sectioned brain. The overall objective is to characterize the central pain pathways involved in conditions associated with enhanced visceral pain, such as irritable bowel syndrome, providing new targets for the development of new drugs.


Poster #13- Cynthia Nelly Carrion

Allometry of Pisaster ochraceus populations in Bamfield, British Columbia

Cynthia Nelly Carrion
Mentor: Carlos Robles

Seminal studies in benthic ecology demonstrate the sea star Pisaster ochraceous influences the abundance of its prey, Mytilus californianus. How the growth rates and terminal size of P. ochraceous are influenced in turn by varying abundance of M. californianus also has received some study. Yet our understanding of the effects of indeterminate growth in this important species remains incomplete. If growth rates are under environmental control, sea star populations from prey-scarce locations should show chronically low growth rates, which could lead to distinct allometric differences relative to populations in energetically rich locations. Occurrences of sea stars with different allometry have been reported for the shores of Bamfield, British Columbia, Canada. However, a rigorous quantitative analysis has not been done. This study aims to characterize the presence of alternative growth morphologies using allometric comparisons of two spatially extensive shorelines with contrasting prey abundances. A preliminary analysis of photographs of 319 sea stars is presented. Results indicate a distinctive morph of sea stars from prey depleted areas.


Poster #14- Eduardo Gonzalez Jr

Quality of Service in Wireless Local Area Networks

My research analyzes and compares different mechanisms for providing Quality of Service in Wireless Local Area Networks. Quality of Service is important to be able to support real time data, such as Video and Audio in Wireless Local Area Networks. Specifically, in IEEE 802.11 Wireless LANs, I have evaluated the Point Coordinating Function, Distributed Coordinating Function, Distributed Fair Scheduling, Blackburst, Deng and Chang, and Priority Queuing. For the new standard 802.11e I have also evaluated the Enhanced DCF and Hybrid Coordinating Function.  Performance of these mechanisms is provided by a WLAN simulator and those resources listed in the bibliography. My research illustrates medium utilization, access delay, and the ability to support high priority mobile stations performance with regard to the above metrics. The research focuses on an infrastructure mode in a Basic Service Set.

Poster #15- Jorge Osuna

X,Y - Methylene Bisphosphonates; X, Y = H, Cl, F, Br, CH3.
Understanding the kinetics and fidelity of human DNA polymerase â

Pol â is an important repair enzyme involved in base excision repair during DNA synthesis. Malfunctions of this enzyme are linked to disease and tumorigenesis. In order to understand the kinetics and fidelity of human DNA polymerase â the triphosphate chain of nucleotides was changed by replacing the -O- “linker” with a halogenated methylene groups to affect the chemistry of the enzyme.


Poster #16- Diane Scaduto

Analysis of protein expression in prostate cancer cells following
siRNA transfection

Analysis of Protein Expression in Prostate Cancer Cells Following siRNA Transfection

By: Diane I. Scaduto

BACKGROUND:  Prostate cancer is the third most common cause of death from cancer in men of all ages and can be divided into two clinical categories; androgen abalation dependent and castrate resistant (a.k.a. androgen abalation independent).  Two proteins, Grp78 (78-kDa glucose-related protein) and survivin have been shown to be over expressed in prostate cancer.  Grp78 belongs to the family of ~70 kDa stress response proteins and is a protein resident to the endoplasmic reticulum which associates transiently with a variety of newly synthesized secretory and membrane proteins [1,2,3]. Grp78 may also interact with mutant and misfolded proteins, marking them for degradation [4,5].  Survivin, a member of the inhibitor-of-apoptosis protein (IAP) family, is over expressed by androgen abalation dependent cancer cells and inhibits Fas-mediated apoptosis induced by immune cells [6].  Both proteins act in an anti-apoptotic manner and may provide prostate cancer cells a potential means of resistance when treated with androgen ablation.  The purpose of these experiments was to treat prostate cancer cells in vitro with siRNA against Grp78 and survivin and to observe the effects of this forced down regulation.

HYPOTHESIS:  We hypothesize that by treating prostate cancer cells with siRNA against Grp78 and survivin separately and in combination, the corresponding protein levels will be decreased.  Additionally, it is predicted that the down regulation of Grp78 and survivin will contribute to increased apoptosis.

MATERIALS & METHODS:  Using immunohistochemistry, formalin-fixed paraffin embedded prostate tumors were immunostained for survivin.  Additionally, LNCap prostate cancer cells were immunostained for Grp78 and survivin.  As an in vitro model, the established androgen abalation dependent LNCap cell line was treated with siRNA specific to Grp78 and survivin. After transfection, the cells were collected, lysed, and used to perform a western blot analysis. 

RESULTS: Immunostaining of the primary tumors in comparison to the corresponding surrounding normal prostate tumor was more intense when detected by the survivin antibody.  Similarly, the LNCap prostate cancer cells revealed a higher intensity of Grp78 and survivin following immunostaining.  Upon western blot analysis of LNCap cells following Grp78 siRNA transfection, substantial knockdown of the protein expression was seen. Targeting survivin also significantly down regulated the protein as previously hypothesized.  Grp78 and Survivin in combination also showed a decrease in protein levels.  Finally, we saw an increased effect on apoptosis in treated cells compared to cells not treated with siRNA of both proteins.

DISCUSSION:  The results of immunohistochemistry confirm that Grp78 and survivin are over expressed in primary prostate tumor tissue [1,2].  Additionally, our findings suggest that prostate cancer cells transfected with siRNA targeted against Grp78 and survivin are susceptible to down regulation of the mRNA and therefore exhibit a decrease in protein expression.  These results indicate the potential therapeutic value of siRNA approach in prostate cancer.


[1] Pootrakul L, et al., Expression of stress response protein Grp78 is associated with the development of castration-resistant prostate cancer. Clin Cancer Res. 2006; 12(20 Pt1); 5987-93.

[2] Shariat, S. F. et al., Survivin expression is associated with features of biologically aggressive prostate carcinoma. Cancer, 100: 751-757, 2004.

[3] Haas IG, Wabl M. Immunoglobulin heavy chain binding protein. Nature 1983; 306; 387-9.

[4] Little E, Ramakrishnan M, Roy B, Gazit G, Lee AS., The glucose-related proteins (GRP78 and GRP94): function, gene regulation, and applications. Crit Rev Euk Gene Expr 1994; 4:1-18.

[5] Lee AS. The ER chaperone and signaling regulator GRP78/BiP as a monitor of endoplasmic reticulum stress.  Methods 2005; 35; 373-81.

[6] Asanuma K, et al., Survivin enhances Fas ligand expression via up-regulation of specificity protein 1-mediated gene transcription in colon cancer cells. J Immunol. 2004; 172(6):3922-9.


Poster #17- Jose Lepe

Syntheses and NMR Characterization of

Group VB Transition Metal Pentahaptotetraphenylcyclopentadienyl Compounds

J. Bernardo Lepe and Wayne Tikkanen, Ph.D.
Department of Chemistry and Biochemistry
California State University, Los Angeles, CA 90032-8202

Two group 5 transition metal compounds, η5-C5H(C6H5)4)NbCl4 (1) and  η5-C5H(C6H5)4)TaCl4 (2)  synthesized and characterized by 1H and 13C-NMR. The purple-brown niobium product 1 and the tantalum homologue 2 were synthesized in 46% and 50% unoptimized yields, respectively. Complexes 1 and 2 display identical 1H-NMR, δH(CD3CN): 6.36 – 7.51 ppm (20H, m) and 4.68 ppm (1H, s) and similar 13C-NMR, δC(C6D6): 145.4 (s), 145.1 (s),144.4 (s), 143.9 (s), 137.3 (s), 136.8 (s), 136.6 (s), 136.1 and 129.4 ppm (m). The Lewis acid catalysis of the silylcyanation of butyraldehyde using  1 was monitored via 1H-NMR.


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