Biochemistry, Biophysics, and Structural Biology Commons^™

Sensing Rna’S Conformation With A Solid-State Nanopore Device At Various Ph And Temperature, Haopeng Li

Graduate Theses and Dissertations

This study uses solid-state nanopore technology to investigate the stability and dynamics of RNA molecules under thermal stress and pH fluctuations. Two distinct mRNA samples were analyzed: (1) heat shock protein (HSP)-encoding mRNA extracted from Sulfolobus solfataricus P2, a thermophilic archaeon inhabiting extreme environments such as geothermal sulfuric hot springs (pH < 4, temperature range: 65–90°C), and (2) total RNA extracted from White Leghorn chickens, which thrive under standard physiological conditions. ΦX174 virion single-stranded DNA (ssDNA) were included as a comparative reference. Nanopores, fabricated in silicon nitride membranes, were used to electrically characterize the structural properties of individual RNA molecules in solution, close to their native environments. The nanopore membrane separates two chambers containing salt buffer solution, where ionic current is the primary measurement parameter. When a voltage bias is applied across the membrane, ion flow and an ionic current can be measured. Charged RNA molecules driven translocation through the nanopore induces pore resistance changes, resulting in detectable current blockade events. Variations in these events provide insights into RNA secondary structure and conformational dynamics. By systematically altering pH and temperature, this study elucidates the effects of environmental stressors on RNA stability and structural integrity. The findings reveal distinct responses between thermophilic HSP-encoding mRNA and mesophilic RNA, underscoring the adaptive mechanisms of thermophilic RNA under extreme conditions. These results contribute to a better understanding of RNA behavior under stress and establish a foundation for future applications in RNA-based diagnostics and biotechnology development.

Maternal Inflammation Alters Nuclear And Mitochondrial Dna Methylation Patterns In Neonatal Brain Monocytes, Andrew Ebenezer, Jonathan Hicks, Brooke Hollander, Alexander Hone, Mona Batish, Robert Akins, Adam Marsh, Elizabeth Wright-Jin

Department of Medicine Faculty Papers

Neonatal hypoxic ischemic encephalopathy (HIE) is a common birth complication that can cause death or lifelong disabling conditions like cerebral palsy, epilepsy, and autism. It is well established that maternal infection and inflammation are significant risk factors for HIE but reasons for this increase in neurological risk to the offspring remain unknown. Inflammation or infection are associated with epigenetic changes and may contribute to the increased risk of neurodevelopmental disability in exposed offspring. Here, we analyzed and compared DNA methylation patterns in brain monocytes isolated from control, maternal immune activation (MIA), and an inflammation sensitized HIE (IS-HIE) CF-1 mouse model …

G-Quadruplex Dna-Driven Genomic Instability Under Ber Loss, Addison Belick, Claryssa Gutierrez, Joslynn Rosas, Andrea Vargas

Posters - 2026

Base Excision Repair (BER) is a cellular tool that can repair damaged DNA (Hindi et al., 2022, Cellular and Molecular Life Sciences). G-quadruplexes (G4s) are unique 4-stranded structures in DNA or RNA that are rich in guanine (Gray et al., 2023, Nat. Chem. Biol). The purpose of this study is to understand whether BER contributes to the removal of G4s in DNA. This will determine if the BER-deficient yeast is more sensitive to treatment with G4-binding drugs than the BER-proficient yeast. We will replace the APN1 gene in the yeast genome with the URA3 gene, because the wild type yeast …

Exploring Base Excision Repair Using Gene Knockout, Gregory Guantos, Cailyn Brock, Kamily Visser, Dylan Vargas

Posters - 2026

•             Base Excision Repair (BER) fixes damaged 3DNA bases throughout the cell cycle by removing damaged bases and replacing either one nucleotide in short-patch BER or a short stretch of nucleotides in long-patch BER. (Hindi, 2021, Cellular and Molecular Life Sciences:CMLS)

•             4G-quadruplexes (G4s) are 4 stranded secondary DNA structures formed in guanine rich areas of DNA and RNA. (Rhodes, 2015, Nucleic Acids Research)

The URA3 plasmid was used as a PCR template to make a gene deletion construct, then yeast were transformed so APN1 was replaced by URA3. 2APN1 encodes a major DNA repair enzyme in yeast, and strains …

Investigating Rad14 Gene Nucleotide Excision Repair On G-Quadruplexes, Juan Pablo Olvera Rodriguez, Tyna Trevino, Yvette Gonzalez, Georgia Romike

Posters - 2026

DNA is typically found as a double-stranded helical structure; however, it can be found in different types of structures, such as G-quadruplexes (G4s). These are structures formed when DNA sequences are rich in Guanines, which interact with each other by hydrogen bonding, forming stacked G-tetrads. These guanine-rich structures are known for interacting with DNA during important cell processes, such as recombination and replication, leading to instability and DNA damage (Grey et al., 2014). If not treated properly, these structures may contribute to mutations and cancer development. To solve these issues, cells have developed maintenance pathways such as Nucleotide Excision Repair …

Nucleotide Excision Repair In Yeast, Kinleigh Mines, Larry Ramirez, Jacob Rodriguez, Delynda Gonzalez

Posters - 2026

DNA damage occurs constantly in cells due to environmental factors and normal cellular processes, making DNA repair pathways essential for maintaining genomic stability (Hindi et al., 2021). One major repair mechanism is Nucleotide Excision Repair (NER), which is responsible for recognizing and removing bulky DNA lesions that distort the double helix structure (Scharer, 2013). In Saccharomyces cerevisiae (yeast), the RAD14 gene plays a critical role in this pathway by helping identify and initiate repair of damaged DNA (Scharer, 2013). Another source of instability comes from the formation of G-quadruplex (G4) structures, which are secondary DNA configurations that can interfere with …

Multicomponent Deoxyribozyme Probes For Targeted Detection Of Cancer Associated Gene Insertions, Samuel R. Veleke

Honors Undergraduate Theses

Insertions and deletions (indels) in DNA sequences of genes are linked with cancers such as glioblastoma (GB). Thus, indels may be used as potential cancer biomarkers. In the NANOG gene, its pseudogene NANOGP8 has a 22 base pair insertion sequence for GB patients. In this work, the NANOG gene and the insertion sequence were detected in one sample using a dual-fluorescent assay containing two multicomponent split deoxyribozyme (Dz) probe complexes. One complex used TXR fluorescence to detect the gene regardless of the insertion’s presence. The other complex used fluorescein (FAM) fluorophore to detect the insertion. The probes were able to …

31p Solution Nmr Investigation Of Abasic Dna, Clarissa R. Krimmel

Graduate Theses/Dissertations

Base excision repair (BER) mechanisms fix single base lesions in DNA, such as T:G mismatches. During the base excision repair mechanism, an abasic site (AP site) is formed as an intermediate. AP sites are unstable and highly mutagenic; they can stop DNA replication. This research investigates how the conformational properties of abasic sites in DNA affect the binding recognition of enzymes involved in DNA repair mechanisms, including BER. Three different abasic sequences are being analyzed for this research project. A second project looks at the effects of a naturally occurring purine derivative, hypoxanthine, on the DNA backbone. These hypoxanthine lesions …

Dna Extrusion Size Determines Pathway Choice During Cag Repeat Expansion, Mayuri Bhatia, Ashutosh S. Phadte, Anna Lakhina, Anthony R. Monte Carloi Iii, Sarah Barndt, Anna Pluciennik

Department of Biochemistry and Molecular Biology Faculty Papers

DNA triplet repeat expansion causes several primarly neurological disorders like Huntington's disease, myotonic dystrophy type 1, and fragile-X related disorders. There is general consensus that recognition of extrahelical extrusions or hairpin-loop structures (formed by strand slippage) by the DNA mismatch repair protein MutSβ leads to repeat expansion by a mutagenic process. By contrast, the FAN1 nuclease attenuates triplet repeat expansion, the molecular basis of which was explained by our recent finding that FAN1 nuclease cleaves and initiates removal of extrahelical extrusions. Here we show that extrusions containing two or more triplet repeats are subject to recognition and processing by either …

The Effects Of Tfeα And Promoter Sequence On Early Events In Archaeal Transcription Initiation, Madolyn Toli

Dissertations and Theses

Expression of genes is dependent on promoter sequences in DNA, which direct transcription by RNA polymerase. Transcription factors interact with promoters and RNAP and are often conserved and are essential for proper gene expression. In this thesis, a functional region of archaeal TFEα, homologous to eukaryotic TFIIEα, has been identified, and specific amino acids in these regions have been determined to have significant importance in TFEα's ability to promote transcription in early initiation. All three Domains of life encode a 16S rRNA promoter, which is responsible for production of the 16S portion of ribosome. Transcription with this promoter is not …

Ion-Dna Interactions As A Key Determinant Of Uracil Dna Glycosylase Activity., Sharon N Greenwood, Alexis N Dispensa, Matthew Wang, Justin R Bauer, Timothy D Vaden, Zhiwei Liu, Brian P Weiser

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Because of their ubiquitous presence, ions interact with numerous macromolecules in the cell and affect critical biological processes. Here, we discuss how cations including Mg²⁺ alter the enzymatic activity of a DNA glycosylase by tuning its affinity for DNA. The response of uracil DNA glycosylase (UNG2) to Mg²⁺ ions in solution is biphasic and paradoxical, where low concentrations of the ion stimulate the enzyme, but high concentrations inhibit the enzyme. We analyzed this phenomenon by modeling experimental data with a statistical framework that we empirically derived to understand molecular systems that display biphasic behaviors. Parameters from our statistical …

Structural Basis For Intrinsic Strand Displacement Activity Of Mitochondrial Dna Polymerase, Ashok Nayak, Viktoriia Sokolova, Sirelin Sillamaa, Karl Herbine, Juhan Sedman, Dmitry Temiakov

Department of Biochemistry and Molecular Biology Faculty Papers

Members of the Pol A family of DNA polymerases, found across all domains of life, utilize various strategies for DNA strand separation during replication. In higher eukaryotes, mitochondrial DNA polymerase γ relies on the replicative helicase TWINKLE, whereas the yeast ortholog, Mip1, can unwind DNA independently. Using Mip1 as a model, we present a series of high-resolution cryo-EM structures that capture the process of DNA strand displacement. Our data reveal previously unidentified structural elements that facilitate the unwinding of the downstream DNA duplex. Yeast cells harboring Mip1 variants defective in strand displacement exhibit impaired oxidative phosphorylation and loss of mtDNA, …

Evaluation Of The Dnazyme Gr5 For The Determination Of Lead Speciation In Natural Waters, Gaganprit Gill

Theses and Dissertations (Comprehensive)

This thesis explores the development and application of a DNAzyme-based biosensor designed to detect labile metal species in environmental samples. Real time and on-site monitoring of labile metal fractions would make a valuable contribution to environmental management, as these fractions are the most bioavailable and pose significant toxicity risks to aquatic organisms. Conventional methods for detecting labile metals, while effective, are often burdened by high costs, complexity, and lengthy processing times, making them less ideal for rapid and widespread environmental assessments.

The first manuscript of this thesis (chapter 2) establishes the fundamental capabilities of the Pb²⁺-specific DNAzyme GR5 …

The C-Terminal 4cxxc-Type Zinc Finger Domain Of Cdca7 Recognizes Hemimethylated Dna And Modulates Activities Of Chromatin Remodeling Enzyme Hells, Akeo Shinkai, Hideharu Hashimoto, Chikako Shimura, Hiroaki Fujimoto, Kei Fukuda, Naoki Horikoshi, Masaki Okano, Hitoshi Niwa, Erik W Debler, Hitoshi Kurumizaka, Yoichi Shinkai

Department of Biochemistry and Molecular Biology Faculty Papers

The chromatin-remodeling enzyme helicase lymphoid-specific (HELLS) interacts with cell division cycle-associated 7 (CDCA7) on nucleosomes and is involved in the regulation of DNA methylation in higher organisms. Mutations in these genes cause immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome, which also results in DNA hypomethylation of satellite repeat regions. We investigated the functional domains of human CDCA7 in HELLS using several mutant CDCA7 proteins. The central region is critical for binding to HELLS, activation of ATPase, and nucleosome sliding activities of HELLS-CDCA7. The N-terminal region tends to inhibit ATPase activity. The C-terminal 4CXXC-type zinc finger domain contributes to CpG …

Computational Analysis Of O6-Methylated Guanine And Thioguanine Complexes, Kirsten Stinson, Michael Bowman

Lux et Fides: A Journal for Undergraduate Christian Scholars

DNA methylation occurring on the O⁶ position of guanine has been linked to the formation of cancer. DNA complexes with O⁶-methylated guanine have been studied experimentally, yet questions remain concerning the carcinogenic properties of O⁶-methylguanine. This present research explored the interaction between O⁶-methylguanine and its potential nucleobase pairs of cytosine and adenine in hopes of elucidating the mutagenic characteristics of O⁶-methylguanine. A variety of computational methods including Density Functional Theory (DFT), Symmetry Adapted Perturbation Theory (SAPT), Noncovalent Interaction (NCI) analysis, and Natural Bond Orbital (NBO) analysis were employed to comprehensively probe …

Identification Of Potent Pan-Ephrin Receptor Kinase Inhibitors Using Dna-Encoded Chemistry Technology, Chandrashekhar Madasu, Zian Liao, Sydney E Parks, Kiran L Sharma, Kurt M Bohren, Qiuji Ye, Feng Li, Murugesan Palaniappan, Zhi Tan, Fei Yuan, Chad J Creighton, Suni Tang, Ramya P Masand, Xiaoming Guan, Damian W Young, Diana Monsivais, Martin M Matzuk

Faculty, Staff and Students Publications

EPH receptors (EPHs) are highly sought-after drug targets owing to their essential roles in maintaining appropriate cellular functions in both physiological and disease conditions. However, limited potency and specificity pose significant obstacles to the development of small-molecule inhibitors for EPHs. Here, using high-throughput DNA-encoded chemical library screenings, we developed potent and selective inhibitors of the EPH receptor kinase family. Our results also emphasize the therapeutic potential of our EPH inhibitors in cancer and endometriosis, a global health concern that causes chronic pain and often leads to infertility in women. This study showcases the robust pipeline of using DNA-encoded chemistry technology …

Structural Basis Of Dna Crossover Capture By Escherichia Coli Dna Gyrase, Marlène Vayssières, Nils Marechal, Long Yun, Brian Lopez Duran, Naveen Kumar Murugasamy, Jonathan M Fogg, Lynn Zechiedrich, Marc Nadal, Valérie Lamour

Faculty, Staff and Students Publications

DNA supercoiling must be precisely regulated by topoisomerases to prevent DNA entanglement. The interaction of type IIA DNA topoisomerases with two DNA molecules, enabling the transport of one duplex through the transient double-stranded break of the other, remains elusive owing to structures derived solely from single linear duplex DNAs lacking topological constraints. Using cryo–electron microscopy, we solved the structure of Escherichia coli DNA gyrase bound to a negatively supercoiled minicircle DNA. We show how DNA gyrase captures a DNA crossover, revealing both conserved molecular grooves that accommodate the DNA helices. Together with molecular tweezer experiments, the structure shows that the …

Discovery Of A Small-Molecule Inhibitor That Traps Polθ On Dna And Synergizes With Parp Inhibitors, William Fried, Mrityunjay Tyagi, Leonid Minakhin, Gurushankar Chandramouly, Taylor Tredinnick, Mercy Ramanjulu, William Auerbacher, Marissa L Calbert, Timur Rusanov, Trung Hoang, Nikita Borisonnik, Robert Betsch, John Krais, Yifan Wang, Umeshkumar Vekariya, John Gordon, George Morton, Tatiana Kent, Tomasz Skorski, Neil Johnson, Wayne Childers, Xiaojiang Chen, Richard Pomerantz

Department of Biochemistry and Molecular Biology Faculty Papers

The DNA damage response (DDR) protein DNA Polymerase θ (Polθ) is synthetic lethal with homologous recombination (HR) factors and is therefore a promising drug target in BRCA1/2 mutant cancers. We discover an allosteric Polθ inhibitor (Polθi) class with 4-6 nM IC₅₀ that selectively kills HR-deficient cells and acts synergistically with PARP inhibitors (PARPi) in multiple genetic backgrounds. X-ray crystallography and biochemistry reveal that Polθi selectively inhibits Polθ polymerase (Polθ-pol) in the closed conformation on B-form DNA/DNA via an induced fit mechanism. In contrast, Polθi fails to inhibit Polθ-pol catalytic activity on A-form DNA/RNA in which the enzyme binds in …

Parp2 Promotes Break Induced Replication-Mediated Telomere Fragility In Response To Replication Stress, Daniela Muoio, Natalie Laspata, Rachel L Dannenberg, Caroline Curry, Simone Darkoa-Larbi, Mark Hedglin, Shikhar Uttam, Elise Fouquerel

Department of Biochemistry and Molecular Biology Faculty Papers

PARP2 is a DNA-dependent ADP-ribosyl transferase (ARTs) enzyme with Poly(ADP-ribosyl)ation activity that is triggered by DNA breaks. It plays a role in the Base Excision Repair pathway, where it has overlapping functions with PARP1. However, additional roles for PARP2 have emerged in the response of cells to replication stress. In this study, we demonstrate that PARP2 promotes replication stress-induced telomere fragility and prevents telomere loss following chronic induction of oxidative DNA lesions and BLM helicase depletion. Telomere fragility results from the activity of the break-induced replication pathway (BIR). During this process, PARP2 promotes DNA end resection, strand invasion and BIR-dependent …

Chemical Synthesis Of Sensitive Dna, Komal Chillar

Dissertations, Master's Theses and Master's Reports

Over the past decades, researchers have tried various chemical methods to synthesize modified oligodeoxynucleotides (ODNs, i.e. short segments of DNAs). Traditional ODN synthesis methods require strong basic, and nucleophilic conditions for the deprotection and cleavage of the ODN from the solid support. However, the sensitive ODNs containing labile functionalities are vulnerable to such harsh conditions. Sensitive ODNs have a wide range of applications in research and pharmaceuticals. To synthesize sensitive ODNs, researchers devised different strategies but no practical methods have been developed. To overcome these challenges, we developed alkyl Dim alkyl Dmoc technology. This innovative technology uses weakly basic and …

Structural Basis For Dna Proofreading, Gina Buchel, Ashok Nayak, Karl Herbine, Azadeh Sarfallah, Viktoriia Sokolova, Angelica Zamudio-Ochoa, Dmitry Temiakov

Department of Biochemistry and Molecular Biology Faculty Papers

DNA polymerase (DNAP) can correct errors in DNA during replication by proofreading, a process critical for cell viability. However, the mechanism by which an erroneously incorporated base translocates from the polymerase to the exonuclease site and the corrected DNA terminus returns has remained elusive. Here, we present an ensemble of nine high-resolution structures representing human mitochondrial DNA polymerase Gamma, Polγ, captured during consecutive proofreading steps. The structures reveal key events, including mismatched base recognition, its dissociation from the polymerase site, forward translocation of DNAP, alterations in DNA trajectory, repositioning and refolding of elements for primer separation, DNAP backtracking, and displacement …

Evaluation Of Potential Role Of R-Loop And G-Quadruplex Dna In The Fragility Of C-Myc During Chromosomal Translocation Associated With Burkitt's Lymphoma, Nitu Kumari, Kohal Das, Shivangi Sharma, Sumedha Dahal, Sagar Sanjiv Desai, Urbi Roy, Anju Sharma, Meghana Manjunath, Vidya Gopalakrishnan, S T Retheesh, Saniya M Javadekar, Bibha Choudhary, Sathees C Raghavan

Faculty, Staff and Student Publications

t(8;14) translocation is the hallmark of Burkitt's lymphoma and results in c-MYC deregulation. During the translocation, c-MYC gene on chromosome 8 gets juxtaposed to the Ig switch regions on chromosome 14. Although the promoter of c-MYC has been investigated for its mechanism of fragility, little is known about other c-MYC breakpoint regions. We have analyzed the translocation break points at the exon 1/intron 1 of c-MYC locus from patients with Burkitt's lymphoma. Results showed that the breakpoint region, when present on a plasmid, could fold into an R-loop confirmation in a transcription-dependent manner. Sodium bisulfite modification assay revealed significant single-strandedness …

Rna World And The Development Of Rna Protocells, Benjamin C. Mayfield

PANDION: The Osprey Journal of Research and Ideas

Origins of life research, also known as pre-biotic chemistry or astrobiology, aims to unravel the mystery of the first cell’s origin on Earth. This interdisciplinary field encompasses biology, chemistry, and physics, with the primary goal of understanding the conditions necessary for life to emerge from abiotic environments. The RNA world hypothesis suggests that early life initially used RNA instead of DNA to store genomic information and for enzymatic functions. Protocells, membrane-bound entities with metabolic processes and self-replication capabilities, likely preceded the emergence of true cells. The challenges associated with RNA world is currently an active field of research. Advancements in …

Structural Underpinnings Of Mutation Rate Variations In The Human Genome, Zian Liu, Md Abul Hassan Samee

Faculty, Staff and Students Publications

Single nucleotide mutation rates have critical implications for human evolution and genetic diseases. Importantly, the rates vary substantially across the genome and the principles underlying such variations remain poorly understood. A recent model explained much of this variation by considering higher-order nucleotide interactions in the 7-mer sequence context around mutated nucleotides. This model's success implicates a connection between DNA shape and mutation rates. DNA shape, i.e. structural properties like helical twist and tilt, is known to capture interactions between nucleotides within a local context. Thus, we hypothesized that changes in DNA shape features at and around mutated positions can explain …

Advancing Asms With Lc-Ms/Ms For The Discovery Of Novel Pdcl2 Ligands From Dna-Encoded Chemical Library Selections, Qiuji Ye, Hassane Belabed, Yong Wang, Zhifeng Yu, Murugesan Palaniappan, Jian-Yuan Li, Stacey A Kalovidouris, Kevin R Mackenzie, Mingxing Teng, Damian W Young, Yoshitaka Fujihara, Martin M Matzuk

Faculty, Staff and Students Publications

BACKGROUND: A safe, effective, and reversible nonhormonal male contraceptive drug is greatly needed for male contraception as well as for circumventing the side effects of female hormonal contraceptives. Phosducin-like 2 (PDCL2) is a testis-specific phosphoprotein in mice and humans. We recently found that male PDCL2 knockout mice are sterile due to globozoospermia caused by impaired sperm head formation, indicating that PDCL2 is a potential target for male contraception. Herein, our study for the first time developed a biophysical assay for PDCL2 allowing us to screen a series of small molecules, to study structure-activity relationships, and to discover two PDCL2 binders …

Suitability Of Double-Stranded Dna As A Molecular Standard For The Validation Of Analytical Ultracentrifugation Instruments, Maduni Ranasinghe, Jonathan M Fogg, Daniel J Catanese, Lynn Zechiedrich, Borries Demeler

Faculty, Staff and Students Publications

To address the current lack of validated molecular standards for analytical ultracentrifugation (AUC), we investigated the suitability of double-stranded DNA molecules. We compared the hydrodynamic properties of linear and circular DNA as a function of temperature. Negatively supercoiled, nicked, and linearized 333 and 339 bp minicircles were studied. We quantified the hydrodynamic properties of these DNAs at five different temperatures, ranging from 4 to 37 °C. To enhance the precision of our measurements, each sample was globally fitted over triplicates and five rotor speeds. The exceptional stability of DNA allowed each sample to be sedimented repeatedly over the course of …

Effects Of Group Ii Metal Binding On The Stability Of Dna I-Motif Structures, Charlotte Powers

Honors Theses

B-form DNA can adopt alternative structures while in superhelical duress. Alternative DNA structures are favored when there is an asymmetric distribution on complementary DNA strands. Cytosine rich strands may utilize cytosine-cytosine base pairing to form a four-stranded structure known as the i-motif (iM). The stability of iMs is affected by several factors such as DNA sequence, temperature, pH, ionic strength of the solution, and crowded conditions. While the effects of temperature, pH, and crowding conditions on iM stability have been well documented, the effects of ion presence in a solution has been less studied. Hence, those studies are the basis …

Exploring The Interaction Of Minor-Groove-Binder Netropsin With Dna Using Optical Tweezers, Irbazhusain Shaikh

Honors Program Theses and Projects

Netropsin is an antibiotic that binds in the minor grooves of DNA, which also exhibits anticancer properties. There have been many previous studies that explored the binding of this drug to DNA using traditional methods where an ensemble averaging is used. In this study we explore the interaction of Netropsin with DNA at a single molecule level using dual beam optical tweezers. We trapped and stretched a single DNA molecule using optical tweezers to measure the force experienced by the DNA as a function of extension in the absence and presence of various concentrations of Netropsin. Our results show the …

Dna Supercoiling-Induced Shapes Alter Minicircle Hydrodynamic Properties, Radost Waszkiewicz, Maduni Ranasinghe, Jonathan M Fogg, Daniel J Catanese, Maria L Ekiel-Jeżewska, Maciej Lisicki, Borries Demeler, Lynn Zechiedrich, Piotr Szymczak

Faculty, Staff and Students Publications

DNA in cells is organized in negatively supercoiled loops. The resulting torsional and bending strain allows DNA to adopt a surprisingly wide variety of 3-D shapes. This interplay between negative supercoiling, looping, and shape influences how DNA is stored, replicated, transcribed, repaired, and likely every other aspect of DNA activity. To understand the consequences of negative supercoiling and curvature on the hydrodynamic properties of DNA, we submitted 336 bp and 672 bp DNA minicircles to analytical ultracentrifugation (AUC). We found that the diffusion coefficient, sedimentation coefficient, and the DNA hydrodynamic radius strongly depended on circularity, loop length, and degree of …

Role Of Cdx4 And Sp5l In Zebrafish Development, Wesley Tsai

Honors Theses

The Caudal Type Homeobox transcription factors cdx are a family of genes found in vertebrates that regulates body regionalization and anterior-posterior patterning. They are also responsible for regulating axial elongation, but the mechanisms behind this behavior are not known. Previous studies in mouse embryonic stem cells have shown that the cdx genes are necessary for upregulating the gene sp5 which may be linked to axial elongation. Sp5 is a zinc-finger transcription factor belonging to the specificity protein (sp) family. Our group has used in-situ hybridization experiments on zebrafish embryos to show that sp5-like (sp5l) is transcribed within tailbud tissues that …