Current Postdoctoral Research Associate Training (PRAT) Fellows

Theodore Busby

Theodore Busby is a PRAT fellow in the lab of Tom Misteli at the National Cancer Institute where he studies epigenetic regulation of genome organization. To do so he uses single-molecule fluorescence imaging to visualize and quantitate changes to genome structure on a single cell level. By taking snapshots of the DNA at specific genes, like those known to be important for cancer formation, new mechanisms can be uncovered to understand gene regulation in 3D space. Dr. Busby earned his Ph.D. at The University of Alabama at Birmingham in the laboratories of Drs. Hao Jiang and Quamarul Hassan where he studied interactions between epigenetic regulators during development and tumor formation to identify therapeutic targets. His long-term goal is to become an independent investigator at a research-intensive institute or university studying epigenetics and genome organization in tumor cells.

Jonathan Chow

Jonathan Chow is a PRAT fellow in the lab of Yavin Shaham at the NIDA IRP where he studies the neurobiological mechanisms associated with choice between nondrug rewards and drugs of abuse. The goal of Dr. Chow’s research is to understand how alternative rewards can compete with drugs of abuse, and possibly identify novel neurobiological mechanisms that may improve treatment. Dr. Chow earned his Ph.D. at the University of Kentucky in the laboratory of Dr. Joshua Beckmann where he studied decision-making. His long-term goal is to have his own lab and continue investigating decision-making and its associated neurobiology.

Luis Colón-Cruz

Luis R. Colón-Cruz is a PRAT fellow in the laboratory of Dr. Shawn Burgess at the National Human Genome Research Institute (NHGRI), where he studies the gene expression, chromatin structure, and chromosomal conformation regulating the regenerative capacity of hair cells in the adult inner ear of a non-mammalian vertebrate, the zebrafish. This could identify genomic features crucial to developing therapies to trigger hearing restoration in humans. Although there are modern devices that amplify sounds, such as hearing aids and cochlear implants, there is still no cure, and these do not restore hearing. Therefore, a better understanding of the regulatory programs of hair cell development and regeneration in the adult inner ear at a single-cell level can advance otolaryngology research and make sensory regeneration a possible reality. Dr. Colón-Cruz earned his Ph.D. in Anatomy and Neurobiology at the University of Puerto Rico - Medical Sciences Campus in the laboratory of Dr. Martine Behra. There, he investigated the interplay of neurogenetics and altered behaviors by generating several CRISPR/Cas9 loss-of-function zebrafish mutants involved in the central and peripheral nervous system development and function, particularly the cannabinoid receptors. His long-term goal is to lead a research program to define the foundations and consequences of genomic structural changes of the hair cells’ regenerative plasticity as a proxy to comprehend the broader field of wound healing and tissue regeneration.

Rachel Cosby

Rachel Cosby is a PRAT fellow in Todd Macfarlan’s lab in the National Institute of Child Health and Human Development. She obtained her Ph.D. in genetics, genomics, and development at Cornell University, where she studied how transposons, mobile genetic invaders that are highly abundant their host genomes, can be repurposed, or coopted, by natural selection to generate novel transcription factors and their associated regulatory networks. Her PRAT research builds on this foundation to understand the biological function of one such family of transcription factors, the THAP proteins, in vivo and how mutations in these genes lead to human disease. Specifically, she is investigating the role of THAP7 in vertebrate neurodevelopment and human intellectual disability using mice as a model organism. Her goal is to establish an independent research program investigating the spectrum of interactions between transposons and their host organisms, including conflict, cooperation, and cooption.

Ryan Cupo

Ryan Cupo is a PRAT fellow in the lab of Dr. Richard Youle at the National Institute of Neurological Disorders and Stroke where he studies mitochondrial nucleotides in Parkinson's Disease models. His current research spans from yeast, to drosophila, to mice, to human cells. Dr. Cupo completed his Ph.D. in Pharmacology in the Shorter Lab at the University of Pennsylvania, where he discovered the first human mitochondrial protein disaggregase, Skd3 (CLPB). Dr. Cupo's ultimate goal is to lead a robust research program studying mitochondrial biology in health and disease with an aim towards developing novel therapeutic strategies.

Rodolfo Flores Garcia

Dr. Rodolfo Flores Garcia is a PRAT fellow in the Unit of Neuromodulation and Synaptic Integration led by Dr. Hugo Tejeda at the National Institute of Mental Health. He earned his Ph.D. Behavioral Neuroscience from the University of Texas at El Paso (2019) studying sex differences and the role of ovarian hormones in modulating the rewarding effects of nicotine and the aversive effects of nicotine withdrawal in rats. His PRAT research examines the neural circuits underlying motivational and affective processes, such as reward and aversion, and their role in approach-avoidance conflict decision-making. To achieve this, he will combine transgenic/viral approaches, single-cell Ca2+ imaging, optogenetics, and machine learning. He is interested in studying motivation and decision-making and would ultimately like to establish a program in an academic setting​.

Stefan Katharios Lanwermeyer

Stefan Katharios Lanwermeyer is a PRAT fellow in the lab of Dr. Anupama Khare at the National Cancer Institute where he studies polymicrobial interactions between bacteria that colonize the airways of people with cystic fibrosis. Stefan came to microbiology first by way of public health. After his MPH at the University of Michigan, he conducted epidemiological research of anthrax meningitis as an ORISE Fellow at the Centers for Disease Control and Prevention. Subsequent to this, he pursued his thesis work under George O'Toole at Dartmouth College where he studied the mechanisms that Pseudomonas aeruginosa uses to maintain biofilm. Stefan is broadly interested in how different bacterial species respond and adapt to another and the potential ecological and clinical implications of these interactions.

Amber Lockridge

Amber Lockridge is a PRAT fellow in the lab of Dr. John Hanover at the NIDDK where she studies the relationships between lipid metabolism and the nutrient-sensitive protein modification - O-GlcNAcylation. Her current project is focused on how the O-GlcNAc attachment/detachment enzymes help cells to utilize either glucose or fatty acids to produce energy. This type of “fuel switching” is important for the body to adapt to different nutrient conditions such as right after a meal, during an overnight fast or in response to a high fat diet. Metabolic fuel inflexibility has been implicated in heart disease, non-alcoholic fatty liver disease, obesity and type 2 diabetes. Dr. Lockridge earned her Ph.D. at the University of Minnesota in the laboratory of Dr. Emilyn Alejandro where she showed how the protein O-GlcNAc Transferase (OGT) is required for pancreatic beta cells to potentiate their glucose-stimulated insulin secretion in response to a high lipid environment. Her long-term goal is to become the PI of her own research lab, studying the amazing diversity of cellular memory and adaptation mechanisms in the context of systemic nutrient metabolism.

Ashira Lubkin

Ashira Lubkin headshot

Ashira Lubkin is a PRAT fellow in the lab of Dr. Michail Lionakis at the National Insti​tute of Allergy and Infectious Diseases. Ashira obtained her M.D./Ph.D. in immunology at New York University with Dr. Victor Torres, where she studied the role of leukocidins in Staphylococcus aureus pathogenesis. Her PRAT research in the Lionakis lab focuses on Candida albicans infection. C. albicans is the most common fungal pathogen causing human disease, but is also a commensal, living peaceably on several body sites. Oral candidiasis (or oral thrush) is worsened in the state of type II interferonopathy, where interferon-gamma levels are excessive, leading to barrier disruption. Ashira aims to understand how C. albicans responds to this environment to promote greater disease. This work may reveal mechanisms regulating the switch in C. albicans between commensal and pathogenic phenotypes, potentially leading to new therapeutic targets. Ashira's long-term goal is to lead an independent research group studying host-fungal interactions.

Ian Morgan

Ian L. Morgan is a PRAT fellow in the lab of Keir C. Neuman at the NHLBI where he uses state-of-the-art biophysical tools to study the molecular mechanism of antimicrobials. According to the World Health Organization, antimicrobial resistance is one of the top ten global health threats facing humanity. By better understanding the mechanism of current antimicrobials, we can help improve current treatments and/or guide the development of new antimicrobials. Dr. Morgan earned his Ph.D. at the University of California, Santa Barbara in the laboratory of Omar A. Saleh where he developed new single-molecule tools for studying the structure of intrinsically disordered proteins. His long-term goal is to better understand the molecular mechanisms of enzyme-drug interactions in order to improve human health.

Melesse Nune

Melesse Nune headshot 

Melesse Nune is a PRAT fellow in the lab of Dr. Susan Buchanan at the NIDDK where he studies the Structural basis for Rcs phosphorelay cascade. One of the key factors that contributes to Klebsiella pneumoniae’s pathogenicity is its ability to produce extracellular polysaccharide capsule in response to environmental stress. Capsule production is regulated by the Rcs regulatory phosphorelay cascade. Rcs cascade is inactive by default but becomes significantly activated when the bacteria experience environmental changes such as the presence of antimicrobials. Mechanisms underlying the activation/inhibition process are incompletely understood. Dr. Nune is dedicated to elucidating the molecular structures of pivotal proteins within the Rcs phosphorelay signaling cascade, employing cutting-edge techniques such as CryoEM and X-ray crystallography. The findings from this study lay the foundation for understanding the regulation of capsule synthesis in Klebsiella and may offer potential pathways for drug target studies. Dr. Nune earned his Ph.D. at Johns Hopkins School of Medicine in the laboratory of Dr. Cynthia Wolberger where he studied the roles of FACT and Ubp10 in histone deubiquitination and chromatin organization. His long-term goal is to lead an independent research group dedicated to investigating the structure and function of vital bacterial membrane proteins, particularly those implicated in nutrient and drug transport.


Nune, M.​, Morgan, M.T., Connell, Z., McCullough, L., Jbara, M., Sun, H., Brik, A., Formosa, T., and Wolberger, C. (2019). FACT and Ubp10 collaborate to modulate H2B deubiquitination and nucleosome dynamics. Elife 8. pii: e40988. doi:10.7554/eLife.40988.

Stoudenmire, J.L., Schmidt, A.L., Tumen-Velasquez, M.P., Elliott, K.T., Laniohan, N.S., Walker Whitley, S., Galloway, N.R., Nune, M., West, M., Momany, C., et al. (2017). Malonate degradation in Acinetobacter baylyi ADP1: operon organization and regulation by MdcR. Microbiology 163, 789-803.

Yang, J., Nune, M., Zong, Y., Zhou, L., and Liu, Q. (2015). Close and Allosteric Opening of the Polypeptide-Binding Site in a Human Hsp70 Chaperone BiP. Structure 23, 2191-2203.

Galloway, N.R., Toutkoushian, H., Nune, M., Bose, N., and Momany, C. (2013). Rapid Cloning For Protein Crystallography Using Type IIS Restriction Enzymes. Crystal Growth & Design 13, 2833-2839.

John O'Malley

Dr. John (JJ) O’Malley is a PRAT fellow in the lab of Dr. Mario Penzo at the NIMH where he studies the role of inhibition of the midline thalamus. Specifically, how thalamic inhibition shapes the selection of defensive behaviors such as avoidance or freezing in response to a threat. These defensive behaviors are important for an organism’s survival but can be come maladaptive resulting in neurological disorders such as anxiety-related disorders. Understanding the how the brain governs the selection of these behaviors can help us understand the underlying cause or causes to neurological disorders which may provide key insights to new treatments for those disorders. Dr. O’Malley earned his Ph.D. at the University of Texas Health Science Center in Houston in the laboratory of Dr. Michael Beierlein where he studied the cellular and circuit mechanisms in the thalamic reticular nucleus that generate slow oscillations. His long-term goal is to continue researching how thalamic inhibition shapes anxiety-related behaviors while teaching neuroscience to the next generation of scientists.

Jong Park

Jong Park headshot 

Jong Park is a PRAT fellow in the laboratory of Dr. Brant Weinstein at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), where he studies the specialized gas-exchange endothelium of the zebrafish gill. Dr. Park's research aims to use the experimentally accessible zebrafish gill endothelium to establish a comparative vertebrate model for mammalian lung endothelium. Dr. Park earned his Ph.D. at the University of Maryland Baltimore County in the laboratory of Dr. Rachel Brewster, where he investigated the functional role of a hypoxia-responsive gene, ndrg1a, in the zebrafish embryonic kidney. His long-term goal following the PRAT fellowship is to lead his own lab investigating the mechanisms of physiological and pathological responses to hypoxia.

Julian A. Rey

Julian Rey headshot 

Julian A. Rey is a PRAT fellow in Peter Basser's lab at the Eunice Kennedy Shriver​ National Institute of Child Health and Human Development where he develops techniques to estimate the mechanical properti​es of brain tissue and biomimetic hydrogels noninvasively with MRI. Mechanical property fields (e.g., tissue rigidity, interstitial flow, internal stresses, etc.) are an exciting class of imaging biomarkers with the potential to inform early detection and treatment of brain cancer and neurodegenerative disease. His focus is investigating how structural and fluid components of the brain determine its bulk mechanical response in order to derive mechanical properties of these components from MRI measurements of brain motion. Dr. Rey earned his Ph.D. at the University of Florida in Malisa Sarntinoranont's lab where he developed computational mechanical models to 1) predict internal stresses and interstitial flows in rat brain tumors and to 2) evaluate mechanisms that may explain glymphatic flow and amyloid-beta clearance in the rat brain. His long-term goal is to lead an independent research group that will advance imaging and computational modeling methods to analyze mechanical changes in the brain, methods which will ulti​mately translate into novel diagnostic and therapeutic approaches for brain cancer and neurodegenerative disease.

Stephanie Sarbanes

Stephanie Sarbanes is a PRAT fellow in the lab of Dr. Antonina Roll-Mecak at the NINDS where she studies how cells sense and respond to damage of the microtubule cytoskeleton. When cells perceive microtubule damage they buffer the level of the subunits that make up microtubules by rapidly destroying the mRNA transcripts encoding those subunits. This process termed “tubulin autoregulation” is still poorly understood. However, a key protein in this pathway has been recently linked to intellectual disability suggesting this feedback pathway may be important in neurons where construction and regulation of the microtubule cytoskeleton is particularly critical. Dr. Sarbanes earned her Ph.D. at The Rockefeller University in the laboratory of Dr. Charles Rice where she studied how viruses navigate and hijack the cell for their own ends. Her long-term goal is to lead a research group studying the response of the cytoskeleton to pathogens and damage while promoting scientific education and engagement.

Elisha Segrist

Elisha Segrist headshot 

Elisha Segrist is a PRAT fellow in the lab of Dr. Yasmine Belkaid in the Laboratory of Host Immunity and Microbiome at NIAID. Elisha obtained her Ph.D. in Cellular and Molecular Biology with an emphasis in Microbiology, Virology, and Parasitology at the University of Pennsylvania under the mentorship of Dr. Sara Cherry. Her dissertation research focused on understanding how the gut microbiota shaped viral acquisition through interacti​ons with innate immune sensors in the intestinal epithelium. In the Belkaid lab, Elisha's work has focused on understanding how endogenous retroviruses shape immunity and function of the female reproductive tract. Her long term goal is to have her own research program to uncover how local factors alter immunity and disease susceptibility of the female reproductive tract.

Rilee Zeinert

Rilee Zeinert is a PRAT fellow in the lab of Dr. Gisela Storz at the NICHD where he studies small protein regulators of protein degradation. Given small proteins are found in all domains of life and are known to regulate various biological processes it is likely these proteins could serve as novel therapeutic targets. Dr. Zeinert earned his Ph.D. at the University of Massachusetts Amherst in the laboratory of Dr. Peter Chien where he studied bacterial protein degradation. His long-term goal is to run his own lab at a university.