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The cohort of early career scientists represents a promising future for biomedical science. The HHMI Hanna H. Gray Fellows Program provides each fellow with up to $1.5 million in support for up to eight years.
The cohort of early career scientists represents a promising future for biomedical science. The HHMI Hanna H. Gray Fellows Program provides each fellow with up to $1.5 million in support for up to eight years.

Today, the Howard Hughes Medical Institute (HHMI) announced the selection of the 2023 Hanna Gray Fellows, a cohort of 25 early career scientists who represent a promising future for biomedical science. These outstanding researchers will continue their postdoctoral training at 18 institutions across the United States.

The HHMI Hanna H. Gray Fellows Program provides each fellow with up to $1.5 million in support for up to eight years spanning postdoctoral training through transition to an early career faculty position. The program is designed to give fellows the freedom to explore new scientific territory and follow their curiosity, while seeking answers to challenging scientific questions. Members of the newest cohort include researchers who are working to design new therapies to treat Parkinson’s disease, advance understanding of the aging process, and bring to light how climate change affects animal-microbial interactions.

“We are thrilled to welcome these exceptional scientists into the HHMI community,” said Vice President and Chief Scientific Officer Leslie Vosshall. “Each of this year’s Hanna Gray Fellows has the expertise, talent, and ingenuity to make groundbreaking discoveries in the life sciences while developing and inspiring generations of scientists over their career.”

To date, HHMI has committed more than $180 million to the Hanna H. Gray Fellows Program, which currently includes 109 fellows (87 postdocs and 22 early career faculty). That investment continues expanding, with appointments of up to 25 fellows each year as part of HHMI’s broader commitment to advancing inclusion across key career stages in academic science.

The new cohort will join a close-knit community of Hanna Gray Fellows who participate in professional development, mentorship, and networking with their peers and the broader HHMI community of scientists.

In keeping with HHMI’s “people, not projects” philosophy, fellows have freedom to change their research focus in pursuit of their evolving interests at any point through the duration of the award.

The program is named for Hanna Holborn Gray, former chair of the HHMI board of trustees and former president of the University of Chicago. Under Gray’s leadership, HHMI developed initiatives that foster inclusion in science education. HHMI continues to carry forward this work on college and university campuses across the United States.  

The next open competition for the Hanna H. Gray Fellows Program will launch in early 2024. For more details about the program or to receive updates about the next competition launch, visit


HHMI is the largest private biomedical research institution in the nation. Our scientists make discoveries that advance human health and our fundamental understanding of biology. We also invest in transforming science education into a creative, inclusive endeavor that reflects the excitement of research. HHMI’s headquarters are located in Chevy Chase, Maryland, just outside Washington, DC. 


2023 Hanna Gray Fellows

Julia Belk, PhD

Stanford University
Mentor: Howard Y. Chang, MD, PhD

Julia Belk studies the swarms of “nano-robots” patrolling our bodies – sometimes known as the immune system – that can cause, prevent, or cure disease. As a doctoral student, Belk focused on reprogramming immune cells to fight cancer more effectively. Now, she is investigating whether these cells can be engineered to protect the aging brain. These studies could inform immunotherapeutic approaches to mitigate or pre-empt neurodegenerative diseases, including Alzheimer’s disease.

Ali Sina Booeshaghi, PhD

University of California, Berkeley
Mentor: Aaron Streets, PhD

Our DNA consists of a static set of base pairs that are dynamically influenced by lifestyle and environmental factors. These influences vary across populations and may confer differential risk for disease susceptibility. Sina Booeshaghi studies this variation within the historically overlooked non-protein-coding region of our genome. He works with chromatin accessibility and gene expression data in mouse models of obesity, cancer, and diabetes, aiming to produce robust genomics measurements that associate genomic variation with disease.

Katherine Deets, PhD

The University of Utah
Mentor: Nels Elde, PhD

Aquatic environments contain a wealth of hidden host-pathogen interactions that can teach us about the evolution of eukaryotic immunity. To uncover some of these interactions, Katherine Deets is studying antiviral responses in ciliates – single-celled eukaryotes that play an important role in moving nutrients throughout aquatic ecosystems. She is also developing a new model system to determine how these ciliates might concentrate and transmit viruses or other pathological microbes between fish.

Marty Douglass, PhD

Vanderbilt University
Mentor: Eric Skaar, PhD, MPH

Martin Douglass is interested in studying Clostridioides difficile, the leading cause of hospital-acquired intestinal infections. To establish infection, the bacterial pathogen must outcompete a host’s gut microbiota and immune system for limited nutrients. Understanding how C. difficile scavenges essential nutrients will lay the foundation to develop alternative strategies to treat this urgent public health threat.

Kow Akaa Essuman, MD, PhD

Massachusetts General Hospital
Mentor: Christopher A. Walsh, MD, PhD

Mutations accumulate in both normal and diseased tissues with age and are thought to drive increasing risk of cancer. Kow Essuman is interested in better understanding how mutations accumulate in the human brain, and how mutations drive brain tumor growth. Using single cell sequencing technologies on brain tissues from normal individuals and from individuals with the brain tumor predisposition syndrome NF1, Essuman hopes to uncover genetic drivers and therapeutic targets for brain cancer.

Alexis Gibson, PhD

Oregon Health & Science University
Mentor: Isabella Rauch, PhD

Alexis Gibson is studying how the epithelial cells that line our intestines play a central role in defense against infections and chronic conditions like inflammatory bowel disease. Using organoids – effectively, miniature intestines derived from biopsies taken from human patients or mice – she wants to examine how cell death is coordinated to maintain the epithelial barrier through the process of extrusion. Studying extrusion will help us to understand and manipulate key differences between homeostasis and inflammation.

Emily Heckman, PhD

University of Michigan
Mentor: E. Josephine Clowney, PhD

How are brains built for learning? By studying the brains of diverse insect species with a range of learning abilities, Emily Heckman aims to uncover the building blocks for learning and how their organization has been shaped by evolution. Through identifying brain circuit adaptations, she hopes to define how circuit structure influences the learning process and to test whether certain evolutionary innovations are sufficient to improve learning performances.

Christina Homer, MD, PhD

University of California, San Francisco
Mentor: Anita Sil, MD, PhD

Challenging fungal infections, including Valley Fever, are on the rise. Valley Fever is caused by the fungus Coccidioides, which forms a unique and mysterious structure during infection – the spherule. Christina Homer is a physician-scientist who discovered that a family of Coccidioides protease enzymes is required to make spherules. She aims to unlock the role of these proteases in spherule formation and infection, and ultimately develop a protease inhibitor to treat Valley Fever.

Ryan E. Hulett, PhD

Carnegie Science
Mentor: Phillip A. Cleves, PhD

Climate change, perhaps the greatest challenge of our lifetime, is having an impact on animal-microbial interactions, a fundamental feature of animal biology. Ryan Hulett is using symbiotic marine invertebrates, like anemones and corals that take up algae into their own cells, to understand how intracellular microbes reprogram host cell fate decisions during heat stress. This work will illuminate fundamental cellular and molecular mechanisms underlying animal resilience in response to global warming.

Maia Kinnebrew, PhD

Stanford University
Mentor: Rajat Rohatgi, MD, PhD

Primary cilia are solitary cell-surface organelles that act as “cellular antennas.” By sensing the extracellular environment, they play critical roles in human metabolic homeostasis. Maia Kinnebrew is a biochemist investigating how the lipid composition and organization of the ciliary membrane regulates its sensory and signaling functions. This work will reveal new principles of membrane biology and uncover strategies to correct human developmental and metabolic diseases.

Maiko Kitaoka, PhD

Whitehead Institute for Biomedical Research
Mentor: Yukiko Yamashita, PhD

Genome quality is paramount for our cells, especially for those that pass genetic information to the next generation. Yet, sperm genomes face unique and long-lasting challenges to their DNA integrity as they mature. Maiko Kitaoka seeks to uncover how these vulnerable sperm genomes are safeguarded and filtered to ensure sperm quality and fertility. Her research will shed light on the intersections between DNA damage responses, genome architecture, and sperm developmental dynamics as she untangles crucial quality control mechanisms that guard genomes across generations.

Linnea M. Lemma, PhD

Princeton University
Mentor: Ned Wingreen, PhD

Cells harness internal activity to organize their components and perform incredible feats, such as plants turning CO2 into sugar. To understand activity-driven phase transitions in living cells, Linnea Lemma studies the pyrenoid, a membrane-less organelle in photosynthetic algae. This organelle concentrates CO2 to enhance photosynthesis. Combining concepts from active matter physics and tools from molecular biology, she is uncovering physical principles for pyrenoid formation and function. These insights will advance our understanding of how cells use energy to bring about organization and life.

Lisandro Maya Ramos, MD, PhD

The University of Texas Southwestern Medical Center
Mentor: Joseph A. Hill, MD, PhD

Lisandro Maya Ramos is investigating how adipose-tissue-derived signals affect cardiovascular pathophysiology. Maya Ramos, a scientist and cardiology fellow, plans to unravel how endotrophin, a peptide originating in adipose tissue, drives heart failure with preserved ejection fraction, a type of heart failure associated with ventricular stiffness. His results could unravel novel mechanisms underlying adipose tissue signaling to the heart as well as potential new therapies for heart failure.

Saria A. McKeithen-Mead, PhD

Stanford University
Mentor: Kerwyn Casey Huang, PhD

Perturbations such as inflammation and antibiotics often lead to disruption of the gut microbiome, with profound impacts on human health. Underlying gut bacterial interactions is the movement of discrete DNA fragments between species, which facilitates their adaptation to the environment. Saria McKeithen-Mead seeks to develop methods for measuring and disentangling molecular mechanisms driving horizontal gene transfer within the human gut. This work will accelerate our understanding of how bacterial adaptation and evolution influence health outcomes.

Jose M. Orozco, MD, PhD

Dana-Farber Cancer Institute
Mentor: Lewis C. Cantley, PhD

Diets high in sugar and carbohydrates trigger an orchestra of adaptations throughout our bodies. If the orchestra is out of tune, diseases such as diabetes can wreak havoc on metabolism, with dire consequences for our health. Jose Orozco is interested in understanding the fundamental mechanisms of how our bodies sense and adapt to sugar and carbohydrates. A better understanding of these adaptations will lead to improved care for metabolic diseases of aging.

Carolina Ortiz Cordero, PhD

Massachusetts Institute of Technology
Mentor: Laura L. Kiessling, PhD

Cell types within the human body display unique signatures of sugar molecules called glycans on their surfaces. In human diseases such as cancer and neuromuscular disorders, cell glycan signatures are significantly altered. Carolina Ortiz Cordero is developing tools to study novel glycan components to discover how changes in glycans affect protein function. Ortiz Cordero hopes that understanding novel glycans will help us gain insight into their function in health and disease, leading to new treatments.

James Osei-Owusu, PhD

Harvard Medical School
Mentor: Andrew Kruse, PhD

Many drugs approved by the US Food and Drug Administration target cell membrane receptors. These receptors transduce extracellular signals into key physiological effects such as neurotransmission, taste, vision, and immune responses. However, abnormal receptor signaling can lead to various diseases. James Osei-Owusu wants to understand the molecular basis of how cell membrane receptors are activated and inhibited. He hopes to exploit these underlying mechanisms to improve drug development and disease treatments.

Louis Parham, PhD

Salk Institute for Biological Studies
Mentor: Christina Towers, PhD

Cellular recycling is intimately linked to the pace of aging in many species. Using a light-regulated tool, Louis Parham aims to manipulate recycling processes in C. elegans – a worm having many genes in common with humans – to determine when, where, and how they control aging. By detailing the mechanisms by which cellular recycling dictates age, Parham will pave the way for the development of therapeutics promoting longer and healthier lives.

Dayna C. Patterson, PhD

Northwestern University
Mentor: Amy C. Rosenzweig, PhD

Metalloenzymes are biological machines that can construct small molecules. Among these small molecules are natural products released from bacteria that harbor insecticidal activity against disease-carrying mosquitoes. Considering the adverse effects of commonly used insecticides on human health, it is imperative to seek safer alternatives. Taking on this challenge, Dayna Patterson aims to characterize a novel bacterial product with insecticidal properties and its primary iron-based metalloenzyme. This research will contribute to the development of safer insecticides.

Raul Arturo Ramos-Garcia, PhD

University of California, Berkeley
Mentor: Ellen Lumpkin, PhD

Raul Ramos is investigating the neural mechanisms that underlie distortions of touch perception, including persistent alterations seen in sensory processing disorder (SPD) and reversible distortions induced by psychedelics. His research will use a combination of genetics, electrophysiology, imaging, and behavioral tests to define the effects of psychedelics on touch neuron signaling and tactile behaviors. The work will provide new insights into the cause of SPD and the potential therapeutic benefits of psychedelics.

Yara Rodriguez Zabala, PhD

Dana-Farber Cancer Institute
Mentor: Kimberly Stegmaier, MD

Cancer cells have an Achilles heel – a vulnerability in the form of a gene or biological pathway that they rely on for survival. Yara Rodriguez is working to identify such vulnerabilities in the most aggressive type of blood cancer: acute myeloid leukemia (AML). Using sophisticated molecular biology and gene editing techniques to interrogate AML cells, she aims to uncover targets for their disruption. Identifying these genes or pathways can lead to potential therapies to treat AML patients.

Tulika Singh, PhD, MPH

University of California, Berkeley
Mentor: Eva Harris, PhD

Over our lifetimes we experience multiple viral infections. Some infections are similar to ones we have fought earlier. In the best-case scenario of secondary infection, our pre-existing immunity will jumpstart and neutralize the new, but related, virus. Tulika Singh wants to uncover the immune pathways that remember and reactivate such broadly neutralizing antibodies. She is pioneering tools to measure the parts of our immune response that encompass diversity towards multiple viruses. Singh hopes this work will improve vaccine design to protect the world from emerging viruses.

Simón(e) Sun, PhD

Cold Spring Harbor Laboratory
Mentor: Jessica Tollkuhn, PhD

Simón(e) Sun studies how gonadal hormones contribute to sex-variable neurobiology, with the broad goal of improving sex- and gender-related mental healthcare. The steroid hormones – progesterone, androgens, and estrogens – shape the expression of different sex variable social behaviors such as aggression, mating, and parenting. These behaviors emerge during adolescence, but the mechanisms that direct these hormone-mediated effects are poorly understood. To reveal these mechanisms, Sun is investigating adolescent development in mice at three levels: genomics, neurophysiology, and neurocircuitry.

Anthony Venida, PhD

Stanford University
Mentor: Michael Bassik, PhD

Anthony Venida is interested in understanding the mechanisms that lead to death of dopaminergic neurons, a major pathological hallmark of Parkinson’s disease. He is studying how protein and organelle quality control mechanisms in the brain become dysfunctional and lead to buildup of toxic factors that cause disease. Using CRISPR-based technology to manipulate gene function and investigating the interplay between neurons and glial cells, he hopes to identify disease-modifying therapies that can prevent neuronal cell death.

Alexandra Wells, PhD

The University of Texas Southwestern Medical Center
Mentor: John W. Schoggins, PhD

Viral infections ignite a powerful immune pathway, sounding the alarm within the body about foreign invaders. The proteins induced by this cascade possess remarkable antiviral potential, fueling Alexandra Wells’ mission to uncover how they combat viral infections. Through whole animal approaches, she seeks to discover new antiviral proteins and shed light on their crucial role in countering viral pathogenesis, paving the way for improved models to test therapeutics.