Student Profiles Archive - Science Poster Day Dean's Prize Winners 2010
Here you will find information about past and present students funded through scholarships administered by the Undergraduate Research Center - Sciences. We are proud of the achievements of our research scholars.
Please click on the program year to get information about the supported students, their mentors and their research projects.
| Mr. Joseph Antonios
Mr. Joseph Antonios
Mentor: Michael Levine
Title: Effects of mTOR Modulation on the Physiology of Neocortical Neurons
Tuberous sclerosis, a disease caused by dysregulation of mTORC1, is characterized by seizures and dysplastic cortical neurons. The role that mTORC1 plays in the physiology of epilepsy is poorly understood. In this study, mTORC1 function was examined in normal neurons using rapamycin, an mTORC1 inhibitor. Electrophysiological recordings from prefrontal layer 2/3 cortical pyramidal neurons were obtained using whole slices from C57BL6/J mice using both voltage and current clamp recording techniques. Three conditions were examined: (1) Acute protocol: Slices were bathed 200nM, 2microM, or 10microM rapamycin for approximately 10 minutes; (2) Subacute protocol: Slices were incubated for one hour in 2microM rapamycin; and (3) Chronic protocol: Animals were injected every other day with 10mg/kg rapamycin intraperitoneally for 4 weeks prior to recording experiments. Acute application of rapamycin did not affect spontaneous excitatory postsynaptic current (sEPSC) or spontaneous inhibitory postsynaptic current (sIPSC) frequencies and kinetics. Subacute rapamycin resulted in an increase in sIPSC frequency, faster sIPSC and sEPSC kinetics, and a reduction in membrane excitability. Chronic rapamycin resulted in a hyperpolarized resting membrane potential and increased rheobase. In conclusion, mTORC1 inhibition increases synaptic inhibition and lowers membrane excitability. Exploring the role that mTORC1 plays in modulating cortical excitability will help to better understand the pathogenesis of pediatric epilepsy.
| Mr. Jeffrey Chuang
Mr. Jeffrey Chuang
Mentor: Amander T. Clark
Title: The Role of PRMT5 in Human Embryonic Stem Cell Self Renewal and Germ Cell Formation
There are many causes of infertility, with abnormal development of the germ line being one of the major causes of this disease. One protein that has been linked to germ cell development in model organisms is the protein arginine methyltransferase 5 (Prmt5). During murine primordial germ cell (PGC) development, Prmt5 is hypothesized to associate with the B-lymphocyte-induced maturation protein-1 (Blimp1) to symmetrically dimethylate arginine 3 of histone H2A and H4 tails [1,2]. We wish to model this in humans by generating in vitro-derived PGCs (iPGCs) from embryonic stem cells (hESCs). Our lab has found PRMT5 and BLIMP1 to be expressed in both undifferentiated hESCs as well as human fetal germ cells. We wish to investigate the role of PRMT5 in both cell types using a constitutive lentiviral short hairpin RNA (shRNA). As a positive control for the fidelity of the PRMT5 shRNA construct, human embryonic kidney 293T (HEK 293T) cells were first evaluated as knockdown of PRMT5 in these cells affects cell growth [3,4]. Consistent with previous reports, we show that HEK 293T cells transduced with PRMT5 shRNA are at a proliferative disadvantage compared to control-transduced cells. Comparing this to undifferentiated hESCS, we find that unlike HEK 293T cells, PRMT5 KD does not affect proliferation or self-renewal. In future studies, our goal is to evaluate the role of PRMT5 in hESC differentiation and formation of the germ line.
| Ms. Emma Deane
Ms. Emma Deane
Mentor: Patricia Phelps
Title: Long-term Care and Prevention of Urinary Tract Infection in Rats with Complete Spinal Cord Transection
Animal models are essential to the long-term evaluation of axonal regeneration after spinal cord injury and the reliability of the data collected heavily depends on the health of the research animals. The purpose of this study was to determine the most effective diet and preventative treatment plan for adult rats with a completely transected spinal cord at the mid-thoracic level (i.e. spinal rats) that are maintained for eight months. To prevent urinary tract infections (UTI) we tested two supplements added to the diet of the spinal rats: ammonium chloride to acidify the urine and inhibit bacterial growth and dried cranberries to reduce bacterial colonization. In addition to the diet supplementation, weekly urine tests were performed to monitor pH, specific gravity, nitrites and leukocytes. Data from these tests allowed us to treat rats in the earliest stages of UTI in an effort to improve the overall bladder and kidney health. The addition of ammonium chloride to the diet was effective at reducing urinary pH and increasing specific gravity but did not decrease inflammation or hyperplasia of the bladder. Surprisingly, it had a negative effect on bladders and kidney health. Cranberries did not show any effect on bladder and kidney health. Weekly testing and early treatment of UTI, however, significantly reduced the overall severity of bladder inflammation of adult spinal rats fed a control diet compared to spinal rats from a previous study (Kubasak et al., Brain 131: 264-276).
| Ms. Sarah Diringer
Ms. Sarah Diringer
Mentor: Rebecca Shipe
Title: Carbon Export by Diatom Blooms in Coastal Ocean Regions
Single celled marine primary producers may provide a possible sink for excess CO2 in the atmosphere caused by burning fossil fuels and changes in land use. However, it is unclear how effectively they can sequester carbon to depth, especially in coastal regions. Diatom (class Bacilliariophyceae) blooms represent a significant increase in ocean surface biomass during upwelling and increased nutrient events, and are the dominant primary producers in coastal upwelling regions such as the western US coastline. This study examines the extent to which diatoms (as indicated by biogenic silica concentrations) can contribute to carbon budgets, and their potential to export carbon by sinking to the bottom of the basin at >300 meters depth. Biogenic, lithogenic, and dissolved silica concentrations were determined at twelve depths approximately every two weeks between October 2003 and October 2009 from the UCLA Mooring Station in Santa Monica Bay, California. Although diatoms contribute greatly to local carbon budgets during spring and fall blooms in the upper water column, the data does not show significant sinking after diatom blooms. Diatoms and associated nutrients, instead, may dissolve and be recycled in the upper water rather than sinking and transporting carbon to the deep ocean basin.
| Ms. Anna Do
Ms. Anna Do
Mentor: Michael Teitell
Title: Role of Cox4 in Metabolism and Pluripotency of Human Embryonic Stem Cells
Human embryonic stem cell (hESC) mitochondrial respiration and pluripotency are closely interdependent. HESCs develop within the hypoxic environment of the inner cell mass of a blastocyst, thus it is not surprising that low O2 tension can enhance pluripotency in vitro. In hypoxia, a cytochrome c complex IV (COX4) isoform switch occurs to adjust to lower O2 levels. COX4, the final subunit of the electron transport chain (ETC), is expressed as COX4-1 in normoxia and as COX4-2 in hypoxia allowing higher ETC efficiency. This isoform switch was examined for involvement in enhanced hESC pluripotency in hypoxia. To examine the role of mitochondrial respiration and the COX4 isoform switch in hypoxia in maintaining pluripotency, mRNA and protein levels of pluripotency marker OCT4 were monitored in hESCs in normoxia and hypoxia over 10 weeks. Differentiation markers AFP, KDR, and NCAM1 were also measured. This was done for knockdown COX4-1, COX4-2 and control cells transduced with an empty vector. Oxygen consumption rates were measured to test if impaired ETC function affects pluripotency. Results show long-term hypoxia upregulates levels of pluripotency marker OCT4 and downregulates differentiation markers but not in knockdown constructs. Oxygen consumption decreased after hESCs were cultured in hypoxia or when ETC functions were altered. Thus, hESC pluripotency can be enhanced with hypoxia; and the COX4 isoform shift downregulates oxygen consumption, but does not directly affect pluripotency.
| Mr. Djuan Farmer
Mr. Djuan Farmer
Mentor: Luisa Iruela-Arispe
Title: Early Estrogen Disruption Results in Abnormal Placental Vasculogenesis
Placental hypoxia and vascular abnormalities can have dire consequences on both mother and fetus during pregnancy. Tamoxifen (TMX), a selective estrogen receptor modulator which is frequently used in breast cancer, functions as an antagonist in breast tissue but acts as a partial agonist in the endometrium, and has been linked to endometrial cancer. In our research, we investigate the role of tamoxifen on placentation in order to understand estrogenic effects on placental vasculature. Thus, at day 6.5 of gestation (24hrs after implantation), mice are injected with tamoxifen, and are evaluated at early to late gestation (days 9 to 18). To analyze the effects of estrogen modulation on placentation, we applied various forms of immunohistochemistry: pimonidazole for placental hypoxia, caspase-3 for cell death, estrogen receptor for expression analysis, progesterone receptor for expression analysis, and PECAM-1 for vasculogenesis. We found consistent placental hemorrhaging after TMX injection, suggesting a potential vascular abnormality. Investigating tamoxifen exposed placenta, we note abnormal placental vasculature with increased cell death, hypoxia, abnormal estrogen receptor expression, decreased progesterone receptor expression, and abnormal laminin expression. It appears that endocrine disruption in early pregnancy (by tamoxifen administration) may result in long-term vascular disturbances in the placenta throughout pregnancy. We plan to investigate how hormonal pathways intersect with placental vasculogenesis.
| Mr. Christopher Greer
Mr. Christopher Greer
Mentor: Xinshu Xiao
Title: Computationally Predicting Novel MicroRNAs in Long Non-Coding RNA
The human genome contains thousands of non-coding RNAs (ncRNA) with unknown function that are potentially important players in epigenetics. One possible function for these ncRNAs are microRNAs: small sequences of RNA that usually bind the 3' UTR of genes and suppress their expression. Recently, the understanding of the role that microRNAs play in genetic regulation has increased, and it will be important to identify where microRNAs originate. My research project aims to identify novel microRNAs within long non-coding RNA via a computational pipeline. The pipeline begins by filtering various sources of data to verify length and non-coding character. Each sequence is then checked for the following properties: conservation of a microRNA seed region, appropriate folding structure, and overall conservation of mature microRNA. Regions around known microRNAs have clusters of predictions, so predictions are filtered based on the amount of clustering. Small RNA and tissue-specific libraries are inspected for prediction matches. The pipeline successfully predicts known, conserved microRNAs with a true positive rate of 90.8 percent. One novel microRNA prediction (in the 9p21 region) has been successfully verified experimentally, and there are many other predicted microRNAs expressed in small RNA libraries that aren't reported in literature. Because microRNAs are implicated in various illnesses such as cancer and heart disease, discovering novel ones will help further elucidate disease mechanisms.
| Ms. Iris Claire Ha
Ms. Iris Claire Ha
Mentor: William Lowry
Title: Modeling Human Embryonic Development in Vitro Using Human Embryonic Stem Cells and Induced Pluripotent Stem Cells
Both human embryonic stem (ES) cells and human induced pluripotent stem (iPS) cells provide great promise for the advancement of regenerative medicine as well as a means for modeling human disease and embryonic development in vitro. However, a major challenge in both ES and iPS technology remains to isolate and characterize functionally distinct populations from the large, heterogenous pools formed in culture. In order to elucidate the molecular events required for germ layer specification during human embryonic development, we are currently using human ES and iPS cells to generate and characterize distinct cell types derived from all three germ layers: epidermal keratinocytes of the ectoderm, fibroblasts of the mesoderm, and hepatocytes of the endoderm. In doing so, we hope to identify candidate genes differentially expressed as human ES and iPS cells progress down various lineages and to ultimately discover mechanisms that can be exploited for the future development of patient-specific therapies.
| Ms. Vivian Hecht
Ms. Vivian Hecht
Mentor: Robin Garrell
Title: Optimizing Trypsin Immobilization on Superparamagnetic Nanoparticles for Proteomics Applications
Proteomics encompasses characterizing proteins based on their structure and function. An essential method in proteomics involves enzymatically digesting whole proteins into fragments, which are then identified by matching matrix-assisted laser desorption/ionization mass spectra to databases of known proteins. We have developed a method for immobilizing trypsin onto superparamagnetic nanoparticles to conduct these digestions. Covalently attaching enzymes to nanoparticles prevents a loss of activity over time due to autolysis. Moreover, trypsin immobilized to nanoparticles can be recovered with a magnet and reused. Previous studies demonstrated the feasibility of immobilizing trypsin onto epoxide-functionalized superparamagnetic iron oxide nanoparticles. The current work evaluates the effect of nanoparticle surface modification on trypsin loading and activity. Iron oxide nanoparticles were synthesized and then etched with acid, coated with oleic acid, or coated with tetraethyl orthosilicate, and finally coated with an epoxide to which trypsin was covalently attached. The activity of the immobilized trypsin was determined by digesting a model substrate and analyzing the cleaved product by spectrophotometry. Results show that both oleic acid and silica coated particles have higher loadings and activity than acid-etched particles. Oleic acid-coated particles were shown to digest both cytochrome c and carbonic anhydrase. In the future, the particles will be used to digest proteins on droplet-based microfluidic devices.
| Mr. Charlie Ho
Mr. Charlie Ho
Mentor: Kenneth Bradley
Title: Identification and Characterization of a Novel Anthrax Toxin Inhibitor
Bacillus anthracis is a Gram-positive, spore forming bacterium that causes the disease anthrax. The virulence of B. anthracis is in large part due to a secreted binary toxin, lethal toxin (LT), which consists of the cell-binding subunit protective antigen (PA) and the catalytic subunit lethal factor (LF). While LF is known to target most mitogen-activated protein kinase kinases (MKK), it is not fully understood how LT causes death in animals and dysfunction in various immune cells (Agrawal, 2004). Utilizing a chemical genetic approach, we screened the Biomol library of biologically active compounds for inhibitors of LT-induced macrophage death. Among the compounds identified in the screen was the JAK3 inhibitor, ZM449829. The JAK-STAT signaling pathway regulates cellular proliferation, differentiation, and apoptosis in response to extracellular stimuli, but no role has been reported for the pathway in LT sensitivity. The effect of ZM449829 is not recapitulated by other JAK-STAT inhibitors, suggesting that ZM449829 may have an alternative target. ZM449829 was shown to stimulate host-mediated proteolytic processing of MKK2 and partially inhibit LF-mediated cleavage of MKK2. It also stimulates the phosphorylation of MKK2 targets ERK1 and ERK2, though reversing this effect does not ablate protection. A current hypothesis is that ZM449829 protects macrophages from LT by targeting a kinase other than JAK3, but further experimentation is required to determine the specific mechanism by which it protects cells from LT.
| Ms. Christina Hong
Ms. Christina Hong
Mentor: Karen Lyons
Title: Roles of Inhibitory Smads in Chondrocyte Differentiation
The bone morphogenetic protein (BMP) and transforming growth factor-beta (TGF-beta) signaling pathways are important in normal endochondral ossification. However, the role of intracellular regulation of these pathways by the inhibitory Smads (I-Smads), Smad6 and Smad7, is unclear. We hypothesized that Smad6 and Smad7 are essential throughout development for normal endochondral bone formation. To determine whether Smad6 is required for normal bone development, we examined the spatial and temporal expression of Smad6 in the developing mouse embryo (E. 13.5 and E15.5) via whole mount X-gal staining. The effects of Smad7 on early chondrocyte differentiation were determined through Alcian blue staining of limb bud micromass cultures of Smad7+/+ and Smad7-/- prechondrogenic cells treated or untreated with TGF-beta 1. Finally, postnatal phenotypes of Smad7-/- growth plates were examined via Alcian blue and nuclear fast red staining to determine the effects of Smad7 on chondrocyte differentiation in the growth plate. We found Smad6 expression in the mid-femur, tibia region immediately below the knee cap, and bone marrow during E15.5, indicating the importance of Smad6 in bone formation. The results of the aforementioned Smad7 studies confirmed that Smad7 inhibits TGF-beta signaling, which delays early chondrocyte differentiation and alters postnatal phenotype of growth plates. Understanding the roles of the I-Smads in chondrocyte differentiation is essential to developing treatments of skeletal disorders, such as osteoarthritis.
| Mr. Jenny Huang
Ms. Jenny Huang
Mentor: Timothy Lane
Title: Elucidating the Role of Wnt10b on Pericyte and Astrocyte Recruitment and Proliferation in the Neural Retina
Loss of vision due to retinal damage is a problem that many people encounter with the onset of old age or as a side effect of medical conditions such as diabetes. Retinopathy, or damage to the retina, can be caused by a variety of issues, one of which is the destruction of cells known as pericytes. Pericytes, along with astrocytes, line the endothelial cells of small blood vessels and capillaries. These cells aid in the formation of the tight junctions between the endothelial cells of neural tissue and are required for the formation of the blood-brain and blood-retina barriers. Wnt10b is a canonical Wnt ligand which has been implicated in the maintenance of mesenchymal progenitor cells. Pericytes have many features in common with mesenchymal progenitors and may represent a repository of mesenchymal progenitor activity in adult tissues. Utilizing retinal dissection from wild type or Wnt10b-deficient mice, we use whole mount immunohistochemistry and confocal microscopy to examine the effect of Wnt10b on the association of pericytes and astrocytes with the vasculature of retinal tissue. Analysis of retinal morphology and quantification of pericyte and astrocyte coverage of the vessels indicate an age dependent loss of pericyte and astrocyte association with the retinal vasculature. These findings may lead to a greater understanding of vascular maintenance in the retina and effective treatments for vision loss.
| Mr. Samuel Irving
Mr. Samuel Irving
Mentor: Carla Koehler
Title: Characterizing Mitochondrial Protein Import in Mammalian Cells Using Small Molecule Modulators
Mitochondria contain thousands of proteins that are crucial for cellular function. Most are encoded in the cellular genome, translated in the cytosol and targeted to different compartments of the mitochondrion. There exists another novel redox regulated pathway in the intermembrane space that mediates import of small Tim and cysteine rich proteins. Two key proteins, Erv1 and Mia40 participate in forming transient disulfide bonds with the newly imported reduced proteins, accepting and passing electrons to the electron transport chain. Recently a mutation in GFER, the human homolog to the yeast protein Erv1, has been associated with human disease, although the molecular basis of the disease is not understood. To facilitate mechanistic studies, we used a chemical biology approach to identify small molecules that abrogate Erv1 activity. To this end, recombinant Erv1 was cloned into an inducible system in Escherichia coli, column purified and screened against small molecule libraries using a high throughput assay. Those molecules identified as affecting recombinant Erv1 function were further screened using secondary assays in our model system, Saccharomyces cerevisiae. S. cerevisiae contain mitochondrial import proteins homologous to human proteins, making this a model system for studying human mitochondrial myopathies. One such molecule identified, MitoBloCK-6 inhibited oxidation of model substrates such as Tim13 and Cmc1 in in vitro reconstitution assays and altered the ability of Erv1 to assemble with its partner proteins.
| Ms. Jessica Jimenez
Ms. Jessica Jimenez
Mentor: Carlos Portera-Cailliau
Title: Fate of Cajal'Retzius Neurons in the Postnatal Mouse Neocortex
Determining the mechanisms by which cortical circuits are assembled in the brain during normal development is essential to understanding various neuropsychiatric disorders. Cajal-Retzius (CR) neurons play a crucial role in neuronal migration and cortical lamination. In mice, after cortical layers are properly assembled, CR neurons gradually disappear for reasons that remain unclear. Still, a small fraction of these neurons remain into adulthood and continue to extend axons. Therefore, some CR neurons may have other functions in cortical development beyond the period of neuronal migration, perhaps playing a role in the structural maturation of pyramidal neurons, or in their integration into functional cortical circuits. To examine the fate of CR neurons during postnatal mouse development, in vivo two-photon microscopy was used to chronically image CR neurons from postnatal day 3 to adulthood in transgenic mice that express the green fluorescent protein selectively in CR neurons. Time-lapse imaging revealed that CR neurons die by apoptosis, while <3& survive into adulthood and appear to be stable. CR neuron density was shown to decrease drastically from ~500 neurons/ mm3 in the first postnatal week to ~25 neurons/ mm3 in the third postnatal week. The largest drop appears to occur between postnatal days 7 to 14 (540 to 57 cells/ mm3). These data confirm that the vast majority of CR neurons die during early postnatal development, and that the surviving population appears to be stable in the adult cortex.
| Ms. Danielle Kay
Ms. Danielle Kay
Mentor: Rachelle Crosbie
Title: Myogenic Akt Overexpression Ameliorates Muscular Dystrophy and Improves Myofiber Regeneration in Mdx Mice
Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy and is caused by X-linked inherited mutations in the dystrophin gene. Dystrophin deficiencies result in the loss of the dystrophin-glycoprotein complex (DGC) which reduces sarcolemmal stability and results in cycles of myofiber degeneration and regeneration. Pathology in the mdx mouse model of DMD begins at 3 weeks of age and severity peaks at 6 weeks of age. We have previously shown that Akt overexpression in mdx mice at pre-necrotic (<3.5 weeks) ages upregulates proteins of the utrophin-glycoprotein complex to confer protective effects against contractile induced stress. Here, we delayed treatment of mdx mice with exogenous Akt after the onset of peak pathology at 6 weeks of age. We show that transgenic Akt overexpression can rescue mdx pathology after the onset of necrosis by enhancing endogenous compensatory mechanisms. We observed improvements in histological measures of mdx pathology including reduction of mononuclear cell infiltration and a decrease in blood serum albumin infiltration. We attribute improved sarcolemmal stability to an increased abundance of the utrophin-glycoprotein and integrin complexes in extrasynaptic compartment of the membrane. This improvement of pathology is associated with improved grip strength muscle function of mdx mice treated with Akt. These findings provide further rationale for investigating the therapeutic activation of the Akt pathway to counteract muscle wasting seen in congenital muscular dystrophies.
| Mr. Yong Hoon Kim
Mr. Yong Hoon Kim
Mentor: Ren Sun
Title: A Recombinant Reporter Murine Gamma Herpesvirus-68 for ORF73 Identifies a Subpopulation of Latency-Permissive Epithelial Cells
The gamma-herpesviruses family includes several pathogenic human viruses such as Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV), which are associated with mononucleosis, Burkitt's lymphomas, nasopharyngeal carcinoma (NPC), and many other diseases. The gamma-herpesviruses are characterized by their ability to undergo either robust lytic infection or lifelong latent infection. While both EBV and KSHV establish latency in B-cells, they also establish latency in epithelial and endothelial cells, respectively. In our laboratory, we exploit murine gamma-herpesvirus-68 (MHV-68) as a model to study human gamma-herpesviruses. MHV-68 is known to establish latency in B-cells and epithelial cells. In order to identify and isolate latently infected cells, we generated a recombinant latency-reporter MHV-68 where a reporter gene is co-expressed with a latency-associated viral gene via IRES. Using this reporter virus, we infected various cell lines and found that it was able to establish latency in a subpopulation of human epithelial cells, A549. This data indicates that the latency-reporter virus is a viable approach. In the future, we will use another latency-reporter virus based on a surface marker and test whether the infected cells can be isolated by magnetic beads conjugated with the antibody against the surface marker. This approach will allow us to study viral and cellular gene expression in the infected cells and gain insights to the mechanisms by which the virus establishes and maintains latency.
| Mr. David Kirakossian
Mr. David Kirakossian
Mentor: Aleksey Matveyenko
Title: Role of Pulsatile Insulin Secretion in Expression of Genes Involved in Hepatic Glucose and Lipid Metabolism
Type 2 diabetes mellitus (T2DM) is marked by excessive hepatic glucose and lipid production leading to hyperglycemia and hyperlipidemia. T2DM develops due to a failure to maintain adequate numbers of insulin-producing beta-cells and secretory function in the context of insulin resistance. In health, insulin secretes into the hepatic portal vein in 4 minute interval pulses. Deficiency in insulin secretion in T2DM is manifest by reduction in insulin pulse size and amplitude, leading to inadequate exposure of the liver to insulin pulses. However, the role of pulsatile insulin secretion in regulation of hepatic glucose and lipid metabolism is largely unknown. A HIP rat model of T2DM, characterized by reduction of beta-cells and impaired pulsatile insulin secretion, closely recapitulates T2DM in humans. We applied Q-PCR to this novel rat model to examine patterns of hepatic glycolytic, gluconeogenic, and lipogenic gene expression from fasted and fed wild-type (WT) and pre-diabetic and diabetic HIP rats. Our data show a progressive decline in glycolytic gene expression as HIP rats develop T2DM with glucokinase mRNA expression levels having the greatest decline (~28 fold vs. WT, p<0.01). Also, examination of the gluconeogenic enzyme glucose-6-phosphatase reveals a failure to suppress its activity in HIP rats. Conversely, no significant changes were observed in lipogenic gene expression. Thus, progressive decline in pulsatile insulin secretion in a HIP rat model of T2DM leads to aberrant glycolytic and gluconeogenic gene expression.
| Ms. Teodora Kolarova
Ms. Teodora Kolarova
Mentor: Gottfried Konecny
Title: PD 0332991, a Selective CDK 4/6 Inhibitor, Preferentially Inhibits Growth of Ovarian Cancer Cells with High Rb and Low p16 (CDKN2A) Expression
Cell cycle dysregulation is a common molecular finding in ovarian cancer and the cyclin-D kinases (CDK) represent an attractive target in this pathway. PD 0332991 (Pfizer Inc.) is a highly selective inhibitor of CDK4 and CDK6 kinases in the low nanomolar range. Forty human ovarian cancer cell lines were treated with PD 0332991 using two-fold dilutions over 12 concentrations and dose response curves were generated using a cell count assay. These data were then analyzed against baseline gene expression data to identify genes associated with sensitivity to PD 0332991. Western blot analysis was performed to validate these markers and to study the effects of PD 0332991 on pRb phosphorylation. Cell cycle analysis was performed using flow-cytometry. Combination studies were performed to analyze the interaction between PD 0332991 and paclitaxel or carboplatin chemotherapy. Tissue microarrays were constructed from 324 ovarian cancer patients and IHC was performed for p16 and Rb expression. The effects of PD 0332991 were highest in cell lines with high Rb expression and low p16 expression as evident by gene expression array and Western blot analyses. Cell lines treated with PD 0332991 showed clear G0/G1 arrest and a decrease in S-phase fraction. IHC for Rb and p16 allows the identification of ovarian cancer patients most likely to benefit from this molecule. These studies suggest that a subgroup of ovarian cancers may be more likely to benefit from treatment with the PD 0332991 CDK4/6 inhibitor than others.
| Ms. Gretchen Lam
Ms. Gretchen Lam
Mentor: Daniel Kamei
Title:Genetically Engineered Transferrin As a Drug Delivery Vehicle For Treating Glioblastoma Multiforme
Due to the nonspecific side effects associated with chemotherapy, researchers have been investigating the targeted delivery of cytotoxins for several years. One such target is the transferrin (Tf) receptor, since it is overexpressed on many cancer cells. However, the ability of Tf to deliver its payload is limited by the short time it spends inside the cell (~5 minutes). The Kamei lab therefore developed a mathematical model to identify decreasing the iron release rate as an approach to increasing the time Tf spends with the cell. Tf mutants with slower iron release kinetics were generated using site-directed mutagenesis, and found to increase the association of Tf with cells, which translated into increased drug delivery efficacy in HeLa cells. We have now extended this approach to treating glioblastoma multiforme, a lethal form of brain cancer. This presentation summarizes our in vitro glioma cell line data, as well as our in vivo mouse model data, which clearly demonstrates that our mutant Tf proteins are more effective in delivering diphtheria toxin than wild-type Tf.
| Ms. Van Mai
Ms. Van Mai
Mentor: Dolores Bozovic
Title: Spontaneous Oscillations of Inner Hair Cells Coupled to an Artificial Membrane in the Bullfrog Sacculus
Spontaneous otoacoustic emission (SOAE) is the hallmark of an active process that is utilized by the inner ear to achieve amplification of low-level input. One possible mechanism that may underlie SOAE is the spontaneous oscillation of hair bundles, which are stereocilia projecting from the hair cells. Hair bundles in the bullfrog sacculus spontaneously oscillate with independent phase and frequency when the otolithic membrane, an extracellular matrix overlying the hair bundles, is removed by enzymatic digestion. This study tests the hypothesis that synchronization in spontaneous oscillation of hair cells in certain regions of the epithelium vibrates the overlying membrane, giving rise to otoacoustic emission. The first step is development of transparent and flexible micron-sized artificial membranes that can couple several hair bundles in a region. 5& agarose-gel squares with dimensions of 63 by 63 micrometers were coated with Cell-Tak, a biological adhesive extracted from Mytilus edulis (marine mussel), and their adhesive properties were tested by mechanically stimulating the membrane with a piezoelectrically activated probe and recording responses of hair bundles underneath with a fast camera. Preliminary findings indicated that the artificial membrane was able to couple a total of 81 hair bundles. This artificial membrane, in conjunction with the bullfrog sacculus, can be used in future research as a model for studying hair bundle oscillation and spontaneous otoacoustic emission in human and other species.
| Ms. Isabella Niu
Ms. Isabella Niu
Mentor: Andrew Diener
Title: Role of Tryptophan Biosynthesis in Promoting Plant Resistance to Fungal Diseases
Fungal infections decrease the yield and quality of numerous agricultural crops worldwide. One specific soil borne fungus, Fusarium oxysporum, threatens the cultivation of cotton and date palms here in southern California. Defense genes, including the tryptophan biosynthesis pathway, are induced when plants are infected. Paradoxically, mutation of a gene (TRP1) in the tryptophan pathway of the plant Arabidopsis thaliana increases resistance to Fusarium wilt disease. In addition to having only one percent of normal tryptophan synthesis activity and an accumulation of the substrate anthranilate, the trp1 100 allele is highly resistant to Fursarium infection. We propose three experiments to study the pathogen resistance of trp1 100: (1) We are examining whether trp1 100 is resistant to either root infection or shoot symptom development, by making grafts between wild type and trp1 100 shoot scions and rootstocks. (2) We are supplementing plants with tryptophan and auxin during infection to see whether exogenous tryptophan, or its downstream metabolite auxin, will suppress the resistance of trp1 100. (3) We are crossing trp1 100 with two upstream mutations in ASA1 and ASB1 that should affect anthranilate accumulation in the trp1 100 mutant. If anthranilate accumulation were responsible for resistance, we expect that a trp1 100 double mutant with asa1 or asb1 will have a suppressed resistance to Fusarium wilt disease.
| Ms. Iylene Patino
Ms. Iylene Patino
Mentor: A.V. Balakrishnan
Title: Determination of Flutter Speed for the Helios Unmanned Aerial Vehicle with Varying Parameters
Aircraft flutter occurs when aerodynamic forces excite the natural frequency of an aircraft's wing to produce increased vibrations. Depending on the energy of the induced vibration, this may cause a harmful periodic motion called self-exciting oscillation. This oscillation in the aircraft's wing increases rapidly with time and may result in structural failure. Such was the cause of the mishap of NASA's Helios Prototype aircraft. Since changing a wing's properties can induce flutter, the goal of the project was to conclude how the number of engines of this aircraft affects its flutter speed. A mathematical model which takes into account the aerodynamic forces acting on a flexible wing with spatially separated engines was used. Additionally, a program was created that calculates the aeroelastic modes, or frequencies, of the Helios aircraft at different speeds. From here the flutter speed was determined by observing the speed at which the real part of the mode becomes positive, corresponding to the induced vibration overcoming damping. For the modes that were observed, preliminary results suggest that the more masses the Helios aircraft has, the lower the flutter speed, and thus the greater the likelihood of experiencing self-excited oscillation and ensuing structural problems. This problem is further exacerbated at higher speeds. With these ideas taken into account, engineers are able to design this and other aircraft with the best parameters such that they may meet their mission objectives while remaining structurally sound.
| Ms. Danielle Perrot
Ms. Danielle Perrot
Mentor: Greg Okin
Title: Quantifying the Effects of the Mountain Pine Beetle on Melt Morphology and Timing in the Colorado River Basin, USA
The recent mountain pine beetle epidemic in the Colorado River Basin has resulted in widespread tree mortality in lodgepole pine stands across the Colorado Plateau. Arguably one of the most important issues of this epidemic involves the hydrologic impacts of changes in vegetation distribution and forest management practices. In particular, the complex interactions between vegetation and snow largely determines the hydrologic impacts of vegetation change as snow represents the dominant input of water into these water-limited forests. A reasonable hypothesis is that the affected stands will have a change in meteorologic factors and snow albedo (due to litter), which play a large role in determining sub-canopy melt. The result of these impacts on the basin scale hydrology is largely unknown given the complexity of these micro-scale interactions. We have developed a mechanistic approach toward understanding these impacts using distributed hydrologic instrument clusters, hyperspectral snowpack characterization techniques, a detailed distributed snowpack model (SNTHERM), and hemispherical photography. This measurement and modeling approach is able to resolve the spatio-temporal evolution of snow accumulation and melt at the micro-scale (i.e. < 10 cm) for green, red, and grey phase stages of beetle-related mortality. With the aid of remotely sensed snow and vegetation information, these results will provide the basis for larger scale simulations of the hydrologic impacts of beetle infestation across the Colorado River Basin.
| Mr. Matthew Pimentel
Mr. Matthew Pimentel
Mentor: Lily Wu
Title: Tumor-Associated Macrophages Regulate Stress-Enhanced Metastasis in Breast Cancer
Macrophage infiltration has been associated with poor prognosis in solid cancers by promoting angiogenesis and suppressing anti-tumor immune responses. Using a mouse model of breast cancer, we have shown that chronic stress increases infiltration of macrophages in the primary tumor by activating the sympathetic nervous system (SNS), which is associated with enhanced metastasis to distant tissues. Previous studies have shown that colony stimulating factor-1 (CSF-1) deficient mice display reduced macrophage infiltration and decreased metastasis in mouse models of breast cancer. In the current study, we show that stress increases levels of CSF-1 in primary tumors, along with other factors that regulate angiogenesis and tumor progression. To investigate the role of macrophages infiltration in stress-enhanced metastasis, we blocked CSF-1 signaling using a selective small molecule inhibitor of CSF-1 receptor (CSF1R), GW2580, in stressed vs. control tumor-bearing mice. We used bioluminescent optical imaging to track tumor growth over time and to quantify levels of metastasis in distant tissues. There was a 22-fold increase in metastasis (p=0.05) in stressed mice compared with controls, which was significantly reduced by 4.9-fold with GW2580 treatment. Our results suggest that macrophage infiltration mediates a causal effect of stress on breast cancer metastasis. Future studies are aimed at elucidating the signaling pathways required for macrophages to induce primary tumor cell dissemination.
| Mr. Ryan Ponec
Mr. Ryan Ponec
Mentor: Luisa Iruela-Arispe
Title: Vascular Remodeling of the Vitelline Artery Initiates Extra-Vascular Emergence of Hematopoietic Clusters.
Over the course of development, hematopoietic stem cells (HSCs) with the potential to differentiate into each type of blood cell bud out of endothelial vasculature in specific locations. Early descriptions of these vascular sites include clusters of hematopoietic cells lining the vessel wall within the luminal space, emerging around E10. In addition to these intraluminal clusters, groups of cells resembling blood islands were observed within the mesenchyme (E10). Our initial investigation of the vitelline artery reveals that some HSC aggregates appear to leave the vasculature and enter the surrounding tissues from E10 to E11.5. Due to similarities in location and appearance, we have speculated that these budding derivatives of the vitelline artery may contribute to the previously described blood islands. We have tracked the emergence and migration of these cells with live fluorescent imaging using a VE-Cadherin Cre mouse line crossed to an EYFP reporter line, taking advantage of the endothelial origin of HSCs. Time lapse imaging of E10 explants has revealed the behavior of vitelline artery HSCs and should elucidate their possible role in populating the fetal liver. In addition to these studies, we have shown that the mesenteric blood islands are, in fact, viable and that they likely derive from a common lateral plate mesoderm population that may contribute to all of the hemogenic sites contributing to the formation of the definitive hematopoietic system.
| Ms. Catherine Pourdavoud
Ms. Catherine Pourdavoud
Mentor: Peter Bradley
Title: Proteolytic Maturation and Host Targets of a Novel Rhoptry Effector Protein in Toxoplasma gondii
Toxoplasma gondii is an opportunistic pathogen that causes severe central nervous system disorders in immunocompromised individuals as well as death or birth defects in congenitally infected neonates. As an obligate intracellular parasite, T. gondii invades and hijacks the nucleated cells of its warm-blooded host in order to survive. To this end it has evolved a specialized set of secretory organelles that are intimately involved in the invasion process. One of these organelles, the rhoptries, secretes proteins into the host cell that are involved in facilitating invasion and intracellular survival. Proteomic analysis of the rhoptries has previously identified a novel secretory protein, 10072, that is conserved in the related malarial pathogen, Plasmodium falciparum. Localization of 10072 to the rhoptries and its presence within the host cytosol during invasion indicate that it is a parasite effector protein that serves some function in the invasion and intracellular survival of this important human pathogen. Identification of host targets will reveal key insight into how this protein enables T. gondii to co-opt its host cell. Additionally, SDS-PAGE analysis of 10072 from parasite lysates shows that it undergoes proteolytic maturation like other rhoptry effector proteins; however, MS/MS analysis indicates that this maturation is via a novel rhoptry maturase. Identification and mutagenesis of the maturase recognition site will reveal any salience of processing to the proper trafficking and function of 10072.
| Mr. Jason Scapa
Mr. Jason Scapa
Mentor: Luisa Iruela-Arispe
Title: Exploring the Contributions of Jagged1 to Vascular Homeostasis and Disease
Deletion of beta1 (b1) integrin in vascular smooth muscle cells (VSMCs) leads to apoptosis in the vessel smooth muscle layer. The vascular system compensates through the proliferation of fibroblasts that produce excess extracellular matrix in the adventitia. PDGFR-B was shown to be upregulated in this fibrotic event, suggesting a possible mechanism to the fibrosis. It has been demonstrated that jagged1 (jag1) can lead to an increase in expression of PDGFR-B through the Notch pathway. We hypothesized a potential link between jag1 and fibrosis through PDGFR-B in b1 integrin deficient VSMCs. First, we verified smooth muscle specific deletion of jag1 by PCR, beta-gal staining, and IHC. We characterized the jag1 knockout mouse histologically and demonstrated that the inducible deletion of jag1 displayed no observable differences between knockout and wildtype vascular morphology, and therefore does not show a confounding phenotype in the jag1 and b1 integrin double knockout. We described the jag1 and b1 integrin double knockout in order to explore the links between b1 integrin, jag1, and PDGFR-B in vivo. Contrary to our hypothesis, we did not observe reduction in vascular fibrosis in the tissues examined, demonstrating that VMSC jag1 does not mediate fibrosis through the PDGF pathway. Vascular fibrosis may play a role in Raynoud's syndrome and Hutchinson-Gilford progeria, and while the pathway causing fibrosis remains unclear, understanding the gene links may provide insight to the common mechanisms that initiate these conditions.
| Ms. Monica So
Ms. Monica So
Mentor: Benjamin Schwartz
Title: How Do Novel Fullerene Derivatives Affect Plastic Solar Cells? Investigating Effects of Structural Factors on the Performance of Polymer Based Photovoltaics
Recent increases in the cost of fossil fuels have generated a strong interest in harvesting solar energy using photovoltaic (PV) devices. These devices, fabricated with a blend of light-absorbing conjugated polymers and electron-accepting fullerene derivatives, are more cost effective than their inorganic counterparts. However, the polymer-based PV devices to date have not overcome efficiencies of 8&, so they are not yet economically viable. Since previous studies indicated that the network of electron acceptors hinder device performance, we have synthesized novel fullerene derivatives, called shuttlecocks, which resemble badminton birdies, and blended them with semiconducting polymers to fabricate PV devices. We then measured the photovoltaic performance of these devices, examined the degree of fluorescence quenching, and determined the morphology of the active materials using atomic force microscopy (AFM) and x-ray diffractometry (XRD). We find that some shuttlecocks exhibit dramatic phase segregation, which may occur due to a decrease in free energy arising from the crystallization of polymer and fullerenes. Even though different chemical substitutions do not significantly affect the energy transfer on the fullerenes, synthetic modifications to the shuttlecock periphery do yield dramatic differences in the nanoscale morphology of the blend film. Additional investigations will be conducted to help us understand the role of shuttlecocks and their effects on charge transport within solar cell devices.
| Mr. Tanuj Thapliyal
Mr. Tanuj Thapliyal
Mentor: Jacob Schmidt
Title: Automated Lipid Bilayer and Ion Channel Measurement Platform
Ion channels and transmembrane proteins play key roles in a wide range of physiological processes. Engineered ion channels have been explored as highly sensitive single molecule sensors. Scientific and sensing measurements of ion channel conductance often utilize artificial lipid bilayers, which have shortcomings limiting their application. We describe a fully automated lipid bilayer formation system that integrates the measurement electronics within the fluidic controls. Unattended operation of this system resulted in highly reproducible automatic bilayer formation and ion channel measurement over dozens of consecutive trials. The fully automated, closed-loop control algorithm enabled autonomous operation of the platform, a step toward applications of ion channel measurements for remote sensing and pharmacological studies requiring minimal operator involvement.
| Ms. Allison Truong
Ms. Allison Truong
Mentor: Robert Modlin
Title: Stimulation of Innate Immune Responses by Mycobacterium leprae Short Tandem Repeat DNA
The innate immune system is the body's first line of defense against microbial pathogens. The innate immune system utilizes germ-lined encoded receptors to recognize groups of pathogen-associated molecular patterns (PAMPs) that are conserved among families of microbial pathogens. These ligands are components of pathogens, including foreign DNA and RNA. Some subsets of innate immune cells respond to foreign DNA by producing inflammatory cytokines, including IFN-alpha and IFN-beta. The two most widely studied DNA for triggering innate immune activation via cytosolic DNA pathways are poly(dA:dT), heterogeneous arrangement of dA and dT bases, and IFN-stimulatory DNA (ISD), dsDNA with blunt ends. Recent characterization of polymorphic DNA sequences known as short tandem repeats (STRs) in Mycobacterium leprae genome may provide a biological link to the role of nucleic acid sensors in a human disease model due to its close resemblance to experimentally identified ISD and poly(dAdT). Human monocytes from peripheral blood of healthy donors were collected and differentiated into mature dendritic cells or macrophages using GM-CSF or GM-CSF and IL-4 stimulated with ISD, dAdT, or M. leprosy STRs, then analyzed for cytokine production and gene expression. The morphology-physiology relationship between DNA structure and immune response may provide greater understanding as to whether different types of DNA ligands are recognized by similar receptors or whether they are part of distinct cytosolic DNA recognition pathways.
| Ms. Allison Wong
Ms. Allison Wong
Mentor: Paula Diaconescu
Title: Differential Ligand Effects on Lanthanide Reactivity Towards N-Heterocycles
A homogeneous catalyst which could remove N-heterocycles from currently unusable alternative fuel sources could facilitate their industrial use. Previous communications from our group have reported the ring-opening of imidazoles facilitated by a scandium benzyl complex supported by a silylated ferrocene 1,1-diamide ligand, but have shown mixed results regarding pyridines. We hypothesized that variation of the nitrogen-donor substituent might allow more favorable reactivity. Lutetium benzyl complexes supported by 1,1-bis((2,4,6-trimethylphenyl)-amino)ferrocene, 1,1-bis((2,4,6-triisopropylphenyl)-amino)ferrocene and 1,1-bis(adamantylamino)ferrocene were synthesized and their reactivity toward various N-heterocycles was studied. The metal benzyl complexes were further analyzed by X-ray crystallography, XANES, and Mossbauer spectroscopy. These metal benzyl complexes were found to mediate the ring opening of 1-methylimidazoles, C-C coupling of pyridines, and alkyl transfer to isoquinoline. Product identities were confirmed by proton and carbon nuclear magnetic resonance spectroscopy and elemental analysis. We found the iron-lutetium distance varied between the lutetium benzyl complexes, suggesting different electronic interactions of iron with the lutetium center. Diverse reactivity of the complexes with pyridines further supports this observation. This study suggests that variation of the nitrogen-donor substituent on ferrocene diamide ligands may be used to affect the reactivity of the supported metal benzyl complex.
| Ms. Paowen Wong
Ms. Paowen Wong
Mentor: Richard Kaner
Title: A Novel Scheme for Synthesis, Characterization, and Thin-Film Deposition of Poly(3-hexylthiophene) and Polyaniline Nanofibers
The synthesis of poly(3-hexylthiophene) (P3HT) and polyaniline (PANI) nanofibers was carried out using a chemical initiator during polymerization. The oligomeric additive leads to large quantities of intrinsic conducting polymer nanofibers by accelerating the reaction kinetics, and polymerization at the interface of two immiscible solvents suppressed the formation of agglomerates. Monolayer films of P3HT and PANI nanofibers were deposited by engineering the extrusion of nanofibers out of the interface of immiscible binary fluids. The interfacial spreading of nanofibers due to a spontaneous surface tension gradient leads to a thin film of nanofibers that grows within seconds and deposits at ambient conditions onto a variety of substrates. Large substrate areas are homogeneously covered with a continuous and conducting film of P3HT and PANI nanofibers with a transparency greater than 60&, thus affording a readily scalable solution process for these films. Scanning electron microscopy images show reproducible film morphology of aforementioned P3HT and PANI nanofibers films, and atomic force microscopy of these films indicates a thickness of 75 nm. Poly(3-hexylthiophene) and PANI has been intensely used and studied as the active material in organic solar cells and chemical sensor, respectively. Therefore, a simple synthetic scheme coupled with the homogeneous deposition of thin film of P3HT and PANI nanofibers affords an efficient and cost-effective technology for organic electronics fabrication.
| Ms. Kristina Woodruff
Ms. Kristina Woodruff
Mentor: Michael Carey
Title: Heterochromatin Protein 1-Alpha Inhibits Recruitment of Transcription Components
Transcription in eukaryotes is a well studied process, with multiple chromatin modifications and recognition proteins influencing the formation of an activator-dependent preinitiation complex (PIC). One such recognition protein is Heterochromatin Protein 1-alpha (HP1-alpha), which binds to the modified Histone H3 tail. HP1-alpha has been shown to promote the formation of transcriptionally silent chromatin, yet a detailed mechanism for how HP1-alpha blocks transcription remains elusive. We hypothesized that the binding of HP1-alpha to chromatin would prevent several PIC components from associating with gene promoters. Recombinant HP1-alpha was expressed in E. coli, purified by GST affinity chromatography, and quantified. Concurrently, chromatin arrays were synthesized and immobilized on paramagnetic beads. HP1-alpha-mediated inhibition of PIC assembly was analyzed in vitro on methylated chromatin arrays. The templates were incubated with an activator, HP1-alpha, and nuclear extracts containing PIC components. Proteins which bound to the chromatin arrays were eluted and detected by SDS-PAGE and immunoblotting. Our results reveal that several elements of the PIC were blocked by HP1-alpha, representative of transcriptional repression. Further investigation will yield a more detailed understanding of HP1-alpha mediated inhibition of transcription. Knowledge of this basic tenant of gene regulation has far-reaching implications in many fields including development, stem cell biology, and cancer biology.
| Ms. Lei Xu
Ms. Lei Xu
Mentor: Joan Valentine
Title: Abnormalities in Glucose-Repressible Regulatory Pathways in CuZnSOD-Deficient Yeast Saccharomyces cerevisiae
Yeast lacking the antioxidant enzyme, CuZn superoxide dismutase (CuZnSOD), exhibit several metabolic phenotypes, including elevated mitochondrial mass and oxygen consumption rate when aerobically grown on glucose. In the presence of glucose, yeast typically generate ATP via fermentation and undergo glucose repression, a process in which they downregulate the expression of genes necessary for cellular respiration and mitochondrial biogenesis. To examine the cause of the metabolic phenotypes of CuZnSOD null yeast, glucose repression was investigated by measuring growth in the presence of 2-deoxyglucose (2-DOG), a toxic glucose analogue that induces glucose repression, but is not itself metabolized by glycolysis. Wildtype yeast exhibit higher sensitivity to 2-DOG than CuZnSOD null yeast, suggesting a glucose repression defect in the mutant. To characterize this defect, the activities of four transcription factors were studied using beta-galactosidase reporter assays. Of the two main transcriptional activators involved in mitochondrial biogenesis, CuZnSOD null yeast have increased Hap2p/3p/4p/5p, but not Hap1p, activity. They also show increased Adr1p and/or Cat8p activity. Since the activities of Hap2p/3p/4p/5p, Adr1p, and Cat8p, but not Hap1p, are normally glucose repressed, this further suggests that CuZnSOD null yeast suffer from a glucose repression defect. This weaker glucose repression may be a significant contributing factor to the increased mitochondrial mass and cellular respiration phenotype of CuZnSOD null yeast.
| Ms. Yue Zhao
Ms. Yue Zhao
Mentor: Xianjie Yang
Title: Role of DNMT1 in Mouse Retina
DNA methylation is essential for embryonic development, and is involved in a number of roles including regulation of gene expression, genomic imprinting, chromatin modification, and chromosomal stability. Maintenance DNA methyltransferase 1 (DNMT1) is one of four DNA methyltransferases, and the only known to copy DNA methylation onto the new strand during replication. As knockouts of DNMT1 result in embryonic lethality, studies have used conditional knockouts to discover the role of the transferase. Condition knockouts of DNMT1 in zebra fish eyes showed retinal disorganization and loss of dorsal retinal pigmented epithelium. In the brain, DNMT1 conditional knockouts appeared to cause neuronal cell death and consequently promote astroglial differentiation. Apoptosis of neurons began at the height of embryonic neurogenesis and continued through postnatal development. Using the cre-lox system, we examined the effects of conditional DNMT1 knockout in chx10 positive cells. Preliminary data suggested while many of the differential cell markers were decreased at postnatal day 3, photoreceptor markers seemed more sensitive to the condition knockout, and progenitor cell markers were up-regulated. By day 7 all differentiated cell markers were down-regulated, and at day 30, few retina cell layers remained. DNMT1 appeared to have a profound effect on retinal development, similar to that found in the brain.