Lab Members

Principal Investigators

The Holt / Géléoc Lab operates with a non-conventional model.  We have one lab run by two principle investigators,

Jeffrey R. Holt and Gwenaelle, S.  Géléoc.  The arrangement works well as maintenance of a single lab helps to minimize expenses, while having two PIs facilitates scientific output.   Furthermore, while one PI is busy writing grants or manuscripts, the other can be in the lab doing experiments or working with lab members.  

Jeffrey R. Holt, Ph.D., Professor

I earned my doctorate from the Department of Physiology at the University of Rochester in 1995.  For my thesis work I studied inward rectifier potassium currents in saccular hair cells in Ruth Anne Eatock's lab.  I went on to a post-doctoral position with David Corey in the Neurobiology Department at Harvard Medical School, where I characterized transduction and adaptation in vestibular hair cells and developed an adenoviral vector system to transfect cultured hair cells.  My first faculty position was at the University of Virginia.  In July, 2011 the lab moved to Boston Children’s Hospital / Harvard Medical School. I am currently a Professor in the Departments of Otolaryngology and Neurology in the F.M. Kirby Neurobiology Center where I am involved with graduate and medical student teaching; I am a member of the Harvard Medical School, Program in Neuroscience and the Harvard/MIT Program in Speech and Hearing Bioscience and Technology.  As one of two principle investigators for the lab, I write grants and manuscripts for publication, supervise and mentor lab members and make time to work on my own research project.  I am currently working on several projects:  1) I am investigating the function of TMC genes in hair cells using viral vectors to deliver wild-type and mutant channel genes and 2) I am interested in identifying other genes and proteins required for hair cell mechanosensory transduction, and 3) I am working to develop inner ear gene therapy for patients with genetic hearing loss. 

Hobbies:  Working late, sailing, playing with my kids, kite surfing, red wine, soccer, astrophotography.                                            Jeff's CV:


Gwenaelle S. Géléoc, Ph.D., Assistant Professor

I was born in France and moved to the United States in Fall of 1999.  My passion for inner ear research began as an undergraduate student at the University of Montpellier (France) when I first saw a sensory hair cell under the microscope!  During my graduate and post-graduate studies, I was fortunate to train with some wonderful scientists including Corne Kros (Sussex University, UK), Guy Richardson (Sussex University, UK), Jonathan Ashmore (UCL, UK) and David Corey (HHMI, Harvard Medical School, USA). During my graduate work I developed a preparation which allowed me to record the first mechanotransduction currents from vestibular hair cells of the mammalian inner ear (Géléoc et al. 1996, 1997).  I realized that there was much to be learned by analyzing the pattern of functional developmental of inner ear hair cells around the time of birth. An obvious prerequisite for understanding vestibular and auditory disorders is knowledge of how hair cells develop in the normal state. Hair cells of the inner ear have the critical role of converting sound and head movement information into electrical signals which are transmitted to the brain.  Precisely how and when hair cells acquire mechanosensitivity is a major focus of my ongoing research. As an Assistant Professor at Boston Children’s Hospital I am also interested in the functional disruptions that are caused by mutations in hair cell genes, particularly those that cause congenital auditory and vestibular disorders in humans.  Armed with a better understanding of hair cell function and dysfunction, I aim to identify methods to protect or restore function in the sensory cells of the inner ear.                                   


Hobbies: Doing art work, cooking (and eating), sailing, hiking and skiing.


Olga Shubina-Oleinik, Ph.D., Post-Doctoral Fellow

I was born and grew up in Belarus. In 2011, I graduated from the International Sakharov Environmental University with a Bachelor's Degree in Biomedical Science. I received my Ph.D. degree at the Institute of Genetics and Cytology NAS of Belarus in 2015.  My Ph.D. project was dedicated to studying the genetics of non-syndromic hearing loss caused by both nuclear and mitochondrial mutations. I’ve also participated in developing a complex program of audiological and genetic testing of sensorineural hearing loss in children.  During this work I realized how complicated deafness can be, and how important it is to find treatment for hearing loss and improve people's lives.  In the spring of 2016, I had  the great opportunity to join the Holt/Géléoc Lab and continue my specialization in the field of hearing problems with a focus on developing  approaches to treat hearing impairment by gene therapy.
Hobbies: reading, dancing, yoga, writing sketches and traveling.


Irina Marcovich, Ph.D., Post-Doctoral Fellow

I was born and raised in Argentina. I got my Biology degree in 2014 at the Universidad de Buenos Aires and did my Ph.D. in the Laboratory of Physiology and Genetics of Hearing, led by Dr. Belen Elgoyhen (INGEBI-CONICET). My project aim was to study the evolutionary history of nicotinic cholinergic receptor subunits, particularly of the α9 and α10 nicotinic subunits which are expressed in the hair cells of the vertebrate inner ears. I became fascinated by the variety of mechanisms displayed by living organisms which allowed them to expand their hearing range, fine tune and amplify sound stimuli. I joined the Holt/Geleoc lab during the summer of 2019 to study evolution of mechanotransduction in the inner ear.


Hobbies: acting, singing, yoga, music and travel.​


Stephanie Mauriac, Ph.D., Post-Doctoral Fellow

I grew up in Bordeaux, France. In 2015, I received my undergraduate degree from the University of Bordeaux in cellular biology and physiopathology. My interest for the inner ear began when I join the lab of Dr. Mireille Montcouquiol and Dr. Nathalie Sans in Bordeaux as a PhD student.  During my PhD, I studied a very rare pathology, called the Chudley McCullough Syndrome, characterized by early onset sensorineural deafness and brain anomalies. During this project, I learned different technics including biochemistry, Immunocytochemistry, surgery and dissection that permit us to clarify the etiology and identify a new molecular basis of this pathology. During this exciting project, I realized how this work is essential to find a treatment for these patients in order to improve their lives. After receiving my PhD degree in June, 2019, I had the great opportunity to join the lab of Dr. Jeffrey Holt and Dr. Gwenaelle Geleoc in October 2019 to continue in hearing research. My goal is to discover and develop approaches to restore auditory function by gene therapy in models of human deafness.


Hobbies : traveling, cooking, sewing, reading, music, movies


Wang Zheng, Ph.D., Post-Doctoral Fellow

I was born and grew up in the central part of China and graduated from Beijing Institute of Technology (BIT) with a B.A. in Biotechnology in 2008. Then I went to Wuhan University for a master’s degree in Microbiology, during which I developed a strong interest in ion channel proteins. In 2011, I moved to Canada and joined Dr. Xing-Zhen Chen's lab at University of Alberta to study gating mechanisms of polycystin ion channels, which were mutated in human autosomal dominant polycystic kidney disease. After receiving my PhD degree in 2017, I continued to pursue my interests in ion channels by joining Slav Bagriantsev's lab at Yale University where I studied inactivation mechanisms of mechanosensitive Piezo ion channels and how their inactivation processes are regulated by temperature. My research interests then drove me to join the Holt/Geleoc group in 2019 to explore mechano-electrical transduction (MET) apparatus in the inner ear. My goal is to figure out how the MET channels convert mechanical force into electrical signals, which would establish a foundation to develop therapeutic treatment for hearing loss.


Hobby: Skiing, fishing, hiking, traveling, music, reading



John Lee, Graduate Student

I was born in Illinois and graduated from Northwestern University in 2012 with a B.A. in Genetics & Molecular Biology and a minor in Communication Sciences & Disorders. Having grown up with cochlear dysplasia and complete deafness in my right ear, I developed a passion for inner ear research at a young age and earned my Au.D. (Doctorate of Audiology) from the Vanderbilt University School of Medicine in 2016. As an Au.D. student, I had the opportunity to serve a diverse group of patients with hearing/vestibular loss and develop several clinical research projects. I entered the Speech and Hearing Biosciences & Technology Ph.D. Program at Harvard University in 2016 to compliment my clinical experiences with a more molecular understanding of the inner ear. My translational interests have brought me to the Holt/Géléoc lab, where I hope to study the physiology of vestibular hair cells and vestibular end organs.


Hobbies: basketball, hip hop dancing, eating, kayaking, hiking



Carl Nist-Lund, Graduate Student

In 2015, I received my undergraduate Chemistry degree from Princeton University with a minor in Materials Science and Engineering. While my undergrad thesis work was in the development of magnesium-ion battery systems, since joining the Holt/Geleoc Lab in the summer of 2016, I have switched my research interests to various mechanochemical aspects of the gene therapies studied in this lab. Currently I am involved in performing and analyzing auditory brainstem responses (ABRs) to evaluate behavioral level hearing ability, as well as data analysis to evaluate hair cell electrophysiology data. I am also involved in the dissection and imaging of older stage inner ear tissue for immunocytochemical protein localization and expression. Outside of lab, I am involved in outreach activities with patients at Boston Children’s Hospital to help maintain academic contact during treatment. Although I was born and raised in Fort Myers, Florida, I am loving my time here in the Boston area!


Hobbies: Running, coffee, reading, baking treats for the lab


Nicole Russell, Research Assistant

I was born and raised right outside of Boston. I graduated from Clemson University in 2019 with a B.S. in human nutrition and minors in biology and chemistry. While my undergraduate research was on the use of stem cell therapies and oncology, I took an interest in the Holt- Geleoc Lab for the work being done in gene therapies. I was hired in the Holt- Geleoc Lab in 2019 as a Research Assistant, providing me with experience in genetics, animals used in research, and various lab techniques.


Hobbies: Anything outdoors, reading, cooking, traveling, and hanging out with my dog (pictures available upon request). ​ 



Nikko Baer, Research Assistant

I graduated from Carleton College in 2020 with a B.A. in Biology and minors in Biochemistry and Neuroscience. After studying the development of the cranial nerves ‒ first at Carleton and then in the Engle Lab at Boston Children’s Hospital ‒ I moved downstairs to Holt/Geleoc Lab in the summer of 2020. I am now characterizing novel mutant mouse lines with the hope of developing gene therapies to treat hearing loss. Outside of the lab, I am working on an FM Kirby Center Equity, Diversity, and Inclusion initiative to increase faculty diversity at BCH.


Hobbies: Hiking, reading, baking, board games

For a list of previous lab members please visit:  

 2018 by Holt/Géléoc Lab