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The Minority Access to Research Careers

2007-2008 Scholars

Mr. Alon Agua
Mr. Ryan Dosumu-Johnson
Mr. Rodrigo Gonzalez
Mr. Joseph Hargan Calvopina
Ms. Erin Jimenez
Mr. Kristopher Kennedy
Mr. Daniel Krauth
Ms. Lan Huong Lai
Ms. Ekeoma Nwadibia
Ms. Lena Pernas
Ms. Maylen Perez

        


          
       
 
       
        

 

Mr. Alon Agua
Mentor: Dr. Ohyun Kwon
Title: Systematic Structural Variation of a
Novel Class of Chiral Phosphines

(Christopher Henry, Alon Agua, Dr. Ohyun Kwon)

Alon Agua is a 1 st year MARC Trainee and a 4 th year undergraduate student majoring in Chemistry. He joined Dr. Ohyun Kwon’s lab group in Spring quarter of his 2 nd year at UCLA and is currently under the mentorship of graduate student Christopher Henry.

Recent efforts in organophosphine catalysis have resulted in the discovery of numerous useful heterocycle forming reactions. Formation of asymmetric variants of the reactions remains a challenge; therefore, synthesis of new chiral phosphine ligands is important. Stereoselective reactions are also useful in drug development because the resultant compounds need to be enantiomerically pure compounds. This project hopes to study the effects of systematic structural modifications on the ability of a chiral phosphine to catalyze annulations with high yield and stereoselectivity. In particular, Alon is trying to functionalize the amino position of a rigid azaphospha [2,2,1] bicyclic chiral phosphine catalyst. He has carried out the necessary synthetic route in the synthesis of the phosphine ligands. From trans-4-hydroxy proline, the route begins with N-sulfonylation or N-acylation of the amine followed by reduction of the acid. Di-O-sulfonylation prepares the compound for a ring closure with dilithium phenyl phosphine to synthesize the desired bicyclic chiral phosphine ligands. Systematic variation of the N-substituent will allow the synthesis of a collection of structurally related chiral phosphines. These phosphines will be evaluated in various annulations to determine the effects of catalyst structure on asymmetric induction.

 

 

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Mr. Ryan Dosumu-Johnson
Mentor : Stephanie A. White
Research Title : Stress Levels Associated with Routine Behavioral Experiments in Birdsong Research

(Ryan Dosumu-Johnson and Dr. Stephanie White)

Ryan Dosumu-Johnson is a senior majoring in Neuroscience and a 1st year MARC student. He recently transferred from Orange Coast College to UCLA during the fall of 2006. Ryan was introduced to laboratory research at UCI through the MSP’s Bridge to the Baccalaureate summer research program. Through the connections he made at UCI he was advised to apply for the MARC fellowship program at UCLA and to speak with Dr. Stephanie A. White about her research. Because of this he began working in Dr. White’s lab in the spring of 2007 and shortly after was accepted into the MARC fellowship program.

Ryan is currently working with zebra finches, which are a good model for studying learned vocalizations, similar to human speech. To do this his project is focused on genetically modifying the well-characterized songbird circuit in hopes of elucidating a better understanding of the function of cells in certain nuclei. The ultimate goal of the project is to express or inhibit the expression of molecules of interest, like FoxP2. FoxP2 is currently the only protein to be directly linked to speech. This is of interest because modification of this molecule in the songbird circuit could help solidify the songbird as a good model organism for studying speech and provide a deeper understand of FoxP2’s role in speech. Previous work done by Ryan on the effect of the effect of common experimental trials on stress levels has been submitted for publication.

 

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Mr. Rodrigo Gonzalez
Mentor: Dr. Giovanni Zocchi
Title:Stability of Polynucleotide Hairpin

(picture pending)

Rodrigo Gonzalez is a fourth year student majoring in Biophysics and is in his first year of the MARC program.  He is participating in a lab run by Giovanni Zocchi in the physics department. The lab is focused on the study of conformational changes of biological macromolecule.  Rodrigo began in the lab fall quarter of his junior year.

Rodrigo’s project consists of looking at the conformational changes of polynucleotide chains.  The self-complementary ssDNA and ssRNA sequences can fold into either a hairpin or random coil conformations. The hairpin conformation is composed of two separate parts, the stem and loop.  The loop exerts stress on the stem which is proportional to the length.  The loop is composed of paired nucleotides, the longer the stem the more stable the molecule. When the hairpin becomes unstable it changes into the random coil conformation. The change of the conformation is temperature sensitive, where the hairpin conformation is stable at lower temperatures.  The temperature at which the nucleotide sequence acquires the hairpin conformation and the other half the hairpin conformation is known as the melting temperature (Tm).  Both DNA and RNA have a maximum absorbance of approximately 260nm wavelengths.  The paired polynucleotide has a lower absorption than unpaired polynucleotide. A polynucleotide in the hairpin conformation will therefore have a lower absorbance than the random coil.  A use of UV Spectrophotometer with temperature control allows nucleotide absorbance measurements at different temperatures.  Stress induced on the stem by the loop will decrease hairpin stability, decreasing its melting temperature.  The goal of these experiments is to quantify this mechanical stress, in order to probe the mechanical response of DNA and RNA to sharp bends.  Studies are now underway to examine the effect of varying stem lengths on the stability of DNA and RNA hairpins.

 

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Mr. Joseph Hargan Calvopina
PI:  Dr. Hong Wu
Post Doc: Dr. Reginald Hill
Project:  Exploring the role of PTEN in pancreas tumorigenesis

(Dr. Hong Wu, Joseph Hargan Calvopina and Dr. Reginald Hill)

Joseph Hargan Calvopina is a third year student majoring in Microbiology, Immunology, and Molecular Genetics.  He is a first year MARC student and currently works in the department of Molecular and Medical Pharmacology.  Joseph entered the lab fall quarter of his junior year and is under the supervision of Dr. Hong Wu, and Dr. Reginald Hill.

The PTEN controlled signal pathway is responsible for regulating cellular processes crucial for normal development, including cell proliferation, soma growth, cell death, and cell migration.  It is a gene that has been found to be frequently mutated in human tumors.  Through the use of a mouse model containing a PTEN deletion along with the over expression of KRAS G12D, an oncogene, Dr Hill’s research deals with identifying possible pathways that lead to pancreatic tumorigenesis.  Through western blotting Joseph has been helping DR. Hill identify the possible over expression, or lack thereof of certain proteins that might be involved in the development of Pancreatic Ductal Adenocarcinoma(PDAC).  Through immunohistochemistry it has also been possible to identify certain markers, and proteins that could also be responsible for the development of PDAC, including the possible role of Cox-2 in the inflammatory response that can be responsible for creating a microenvironment suitable for pancreatic lesions.  The project seems to be moving in many different directions, including the possible role of immune response regulation playing a part in PDAC, as well as the possible role certain chemokines may have in metastasis.

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Ms. Erin Jimenez
Mentor: Dr. Carla Kohler
Title: AKT Localizes to the Intermembrane Space in Mammalian Mitochondria

(Dr. Susan Walsh and Erin Jimenez)

Erin Jimenez is a junior transfer student from El Camino College in Torrance, CA. She is a 1st Year MARC Trainee and is majoring in MCDB. She joined Carla Koehler’s lab in the summer of 2007 after participating in the Bridge Summer Program for Community College students. She is supervised by Dr. Susan Walsh.

Recent studies have identified new pathways in the mitochondrial intermembrane space (IMS), including an oxidative folding pathway for the import of proteins and phosphorylation-dependent signaling. We are investigating the kinase AKT (also known as Protein Kinase B), a major serine/threonine kinase regulated by extracellular and intracellular signaling pathways and capable of inducing pro-survival and proliferative effects.  Substrates of AKT include a number of signaling proteins, such as transcription factors, apoptotic machinery, and components of glycogen metabolism.  Previously, it was reported that a fraction of the total cellular AKT localizes to the mitochondria in tissue culture.  We have shown that, though it is present in both mouse brain and liver tissue, AKT only localizes to mitochondria isolated from the brain.  Furthermore, the fraction of AKT in the mouse brain mitochondria is active, localizes to the IMS, and may be loosely membrane-associated facing the IMS.  This is in contrast to previously published data that suggests AKT localization to the mitochondrial membranes and matrix of tissue culture cells.  We are currently investigating the mechanism of AKT import into the mitochondrion and the mitochondrial substrates and interacting proteins of AKT.  This line of research will provide insight into AKT regulation and its cellular effects as well as a greater understanding of signaling pathways in the mitochondrial intermembrane space.

 

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Mr. Kristopher Kennedy
Mentor: Nicholas C. Brecha, Ph.D. and
Salvatore L. Stella, Ph.D.
Title: Development of thy-1.2 YFP positive mouse cone bipolar neurons in vitro

(Dr. Salvatore Stella, Kristopher Kennedy, Dr. Nicholas Brecha)

Kristopher is a junior majoring in Neuroscience. He recently transferred from Los Angeles Pierce College to UCLA during the Fall/2006 quarter. Kris received an excellent introduction to UCLA’s research through CARE’s Bridge Summer Research Program for community college students. While in Bridge he chose to study the vertebrate retina in Dr. Nicholas Brecha’s neurobiology lab, under the guidance of Dr. Salvatore Stella. Shortly after completing the Bridge Program, Kris was accepted in the MARC Fellowship Program. As a first year MARC trainee, he is now continuing his summer project in Dr. Brecha’s lab on cone bipolar cell development in vitro.

The Brecha lab is interested in characterizing the functional anatomy of the vertebrate retina, the neurosensory tissue of the eye involved with vision. Kris’s project is concerned with how a subset of mouse retinal bipolar cells develops in culture. The development of retinal neurons in culture provides a critical step in understanding their differentiation in culture, but is poorly understood. Insights into retinal cell development in culture may provide a way to isolate and harvest cultured retinal progenitor cells. The goal of Kris’s project is to characterize the morphological development of yellow fluorescent protein (YFP) expressive mouse cone bipolar cells using a novel culture technique. These transgenic mice express YFP in a subset of neurons in the retina, which includes bipolar cells. This provides a clear fluorescent reporter for easy cell identification in culture. Kris is involved in each step of this study. Once he finishes collecting and analyzing data, he hopes to embark on the rigorous challenge of preparing a publishable manuscript under the guidance of his lab mentors.

As a MARC trainee, Kristopher encourages his peers, especially transfer students, to engage in CARE’s research programs at UCLA. He deeply appreciates the support he has received from everybody involved with CARE and MARC including faculty, staff and fellow students. Kris’s academic goal is to take advantage of all the opportunities here at UCLA like the MARC Program to develop a skill set that will make him an outstanding applicant to Ph.D. programs. From there, he hopes to fulfill his career goal of uncovering mysteries of the human brain and becoming an influential and contributing member of the biomedical research community.

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Mr. Daniel Krauth
Mentor:Dr. Marie-Francoise Chesselet
Title:The Effects of Small Peptides Derived from Amyloids on Induced Cell Dysfunction

(Dr. Marie-Francoise Chesselet and Daniel Krauth)

Daniel Krauth is a 4th year student majoring in Neuroscience. As a first year MARC student in the lab of Dr. Marie-Francoise Chesselet, in the Department of Neurology, Daniel is examining the effects of various small peptides derived from amyloids, specifically, alpha-synuclein and amylin, along with their effect on induced cytotoxicity.

Prior investigations have described the presence of proteinaceous aggregates in several diseases such as Huntington’s, Alzheimer’s, Parkinson’s and other prion-related diseases. The role of these aggregates in cell dysfunction is the subject to much debate especially in diseases such as Huntington’s disease. These aggregates are amyloid in structure and recently the laboratory of Dr. Eisenberg (UCLA) has described the smallest sequences of these disease related proteins that are capable of forming amyloid fibers. In collaboration with the Eisenberg Lab, Daniel looks to examine the cytoxicity or cell dysfunction induced by these disease related peptides. To do this he will continue to examine LDH release, MTT formazan production, and Alamar Blue reduction following administration of these peptides in differentiated PC12 cell lines. Through these experiments, Daniel's work will shed light on how these disease-related proteins which form amyloid can cause cell dysfunction. His experiments will also help his lab further understand whether the cell dysfunction induced by these disparate peptides are related.

Daniel would like to thank Dr. Elma Gonzalez, Dr. Miriam Hickey, and Dr. Marie-Francoise Chesselet in their encouragement towards his ideas and research.

 

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Ms. Lan Huong Lai
Mentor: Miguel Garcia-Garibay
Research Title: Crystalline Molecular Machines: Design Influences on Solid-State Dynamics in Amphidynamic Materials

(Lan Huong Lai and Dr. Miguel Garcia-Garibay)

Lan Huong Lai was born in Saigon, Vietnam and moved to the US in 1994. She grew up in La Puente, California. She works in Professor Miguel Garcia-Garibay’s lab, a physical organic chemistry lab. One of the major focuses of the Garcia-Garibay lab is the study of structural influences on amphidynamic crystals, materials with both dynamic and static parts. Ms. Lai hopes to attain a BS in biochemistry and then go on to attain a PhD in organic chemistry.

Abstract: The purpose of our research is to study the solid-state dynamics of molecular gyroscopes in hopes of understanding how different topologies affect motion in the solid state. Previous studies in our group have shown that the dynamics of rotation of molecular gyroscopes becomes more favorable (i.e. faster) with decreasing packing coefficients, which can be achieved by increasing the steric bulk of the stator, the static portion of the molecule.  In an effort to explore the effects of increased stator size and shape on the solid-state dynamics of these crystalline molecular machines, a molecular gyroscope with much larger “exploded” stators was synthesized by a series of Grignard (72.1%), Sonogashira cross coupling (47.5%), and organolithium (70.8%) reactions. We are currently attempting to synthesize deuterated analogues of the target gyroscope in order to study the dynamics in solid-state.

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Ms. Ekeoma Nwadibia
Mentor: Joan Valentine
Research Title: The Effect of Zinc-Binding on Human Wild-type SOD1 Reduction Kinetics

Ekeoma Nwadibia is a junior Chemistry major who started as a freshman at UCLA in fall 2005. She is a past participant in the PEERS program and BISEP. She joined Dr. Joan Valentine’s lab in the summer of 2007. 

Abstract: Copper-zinc superoxide dismutase (CuZnSOD1) is a metal-bound dimeric antioxidant protein that catalyzes the disproportionation of superoxide anions. Copper is the catalytic site for dismutation of superoxide anion, while zinc provides structural stability. Though, SOD1 is present in the reducing environment of the cytosol, it has two oxidized cysteines that form an intermolecular disulfide bond, in addition to two reduced cysteines. Metal occupancy, oligomeric status, and the status of the disulfide bond, are tightly coupled in SOD1, and recent studies have shown that the binding of even one equivalent of zinc to SOD1 stabilizes the protein. Hence, I am studying both the rate of reduction and the reduction potential of the disulfide bond in SOD1. This study involved the use of metal-free (apo) SOD1 in optimizing the methods for which the quantification of disulfide bond reduction in SOD1 could be made. Metal-free SOD1 was reduced using dithiothreitol (DTT), and alkylated using 4-acetamido-4’-maleimidylstilbene-2,2’-disulfonic acid (AMS), which reacts with free thiols (reduced cysteines). Both reverse phase high-performance liquid chromatography (RP-HPLC) and SDS-PAGE were used to monitor the rate of disulfide bond reduction and thus quantitate the amounts of reduced and oxidized forms of SOD1. Alkylation with AMS seems effective in the quantification of reduced and oxidized SOD1, as indicated by mass spectrometry, and so will be standardized for future studies. Quantification of reduced and oxidized SOD1 will allow continued studies of zinc binding on the reduction kinetics and reduction potential of the disulfide bond in human wild-type SOD1, as well as mutant SOD.

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Ms. Maylen Perez
Mentor : Peggy Fong
Research Title : Drag and sediment scouring by tidal flow limit Enteromorpha intestinalis bloom formation in Carpinteria Salt Marsh






(Maylen Perez and Dr. Stephanie White)

Maylen Perez is a junior Biology major. While in high school Maylen volunteered at a lab at  Cal State Los Angeles. She started as a freshman at UCLA in fall 2005. She joined Dr. Peggy Fong’s lab in 2007.

Abstract:The biodiversity and dynamics of estuaries are greatly affected by eutrophication (the excessive accumulation of organic matter).  Although we know excessive nitrogen loading stimulates algal blooms, other factors that limit algal blooms are poorly understood.  Previous work suggested that water flow might limit Enteromorpha intestinalis blooms that occasionally obstruct habitat quality for other species in estuaries.  We hypothesized that 1) water flow removed algae from the surfaces they attached to, 2) tall filaments would be dragged and removed more than short filaments and 3) E. intestinalis removal was due to sediment scouring by water flow as well as drag.  We tested the effect of the two water flow regimes on short and tall algae attached to tiles (drag only) and to sediment cores (drag + scouring).  Tiles and cores were photographed before and after each experiment and analyzed digitally for initial and final percent algal cover.  We calculated percent removal as final percent cover minus initial percent cover.  Sediment cores showed greater percent removal than tiles, demonstrating both drag and scouring of sediments are important in limiting algal blooms.  In both tiles and cores, there was greater removal of short filaments than long filaments, suggesting both drag and scouring were more important in the initial stages of algal bloom development than in the later stages when algae are stronger and thus more resistant to both scouring and drag.  Identifying the role of water flow speed on algal removal is important in understanding algal blooms.

 



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Ms. Lena Pernas
Mentor: Dr. Kent L. Hill
Title: Characterizing the subcellular localization of TbCMF 63 and TbCMF 70 in Trypanosoma brucei

(Dr. Kent Hill and Lena Pernas)

A first year MARC student, Lena Pernas is a third year Microbiology, Immunology, and Molecular Genetics major. She began her undergraduate research career working in Dr. Hill’s lab in Fall 2006 under the mentorship of 5th year Katharine S. Ralston, and has since decided to pursue a PhD in a field that fascinates her: parasitology.

Her current research is on flagellar motility in the protozoan parasite Trypansoma brucei, the causative agent of the African Sleeping Sickness. Little is known about the T brucei flagellum on a molecular level, but motility is hypothesized to play a major role in disease pathogenesis by allowing the parasite to spread into vital host tissues. In order to further characterize the role of the flagellum, the lab has used a comparative genomics approach to identify a core group of 50 genes that are conserved in motile flagella, referred to as the T. brucei components of motile flagella (TbCMF). To validate this approach, 41 of these genes have been targeted for RNAi knockdown in T. brucei, and the majority of these knockdown mutants had defective motility. The lab will now further characterize several of these genes by raising antibodies to allow the examination of protein localization and to identify interacting proteins, and by performing site-directed mutagenesis to identify key residues. To begin this process, Lena has selected two putative flagellar genes, TbCMF 63 and 70. TbCMF 63 is of particular interest because it contains a calcium-binding EF hand, and calcium concentration has been shown to affect motility in several organisms. To raise antibodies to these proteins, Lena has cloned these genes into a plasmid with a 6x His marker for protein purification by nickel affinity chromatography. These proteins were expressed in Escherichia coli, purified, and used to immunize mice. Subsequent steps will involve immunofluorescence to determine the subcellular localization of the recombinant protein, and co-immunoprecipitation to identify interacting proteins. To better characterize the role of the calcium binding EF-hand in TbCMF 63, Lena will be probing the function of this putative domain. This will be done by mutagenizing key amino acids and examining mutant phenotypes in collaboration wtih Dr. Springer's lab at Mount Holyoke College.

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Profiles of Students