Research Assistants, Associates, Aides & Graduate Students

Research Assistants

Aakriti Bhandari, B.S.

I joined the John Lab in 2018 as a research intern after receiving my B.S in Biochemistry and Neuroscience from Centenary College of Louisiana. I have experience with animal husbandry and genotyping, physiology, immunohistochemistry, and microscopy.




Logan Horbal, B.S.

I joined the John lab in September of 2018 as a research assistant. I earned my BS in Physiology & Neurobiology from the University of Connecticut in 2017. I have experience with behavioral assays, ocular phenotyping of mice, immunohistochemistry, data visualization with R, and computer-aided design.


Research Associate I

Sally Zhou, B.S.

I joined the John Lab as a research assistant after I graduated from Northeastern University in May of 2021 with a B.S. in Biology. In my previous research experience, I studied the mutational frequency of mice treated with NDMA, a water contaminant that is known to cause DNA adducts that contribute to the development of cancer in mouse models. During the pandemic, I worked at Massachusetts General Brigham’s COVID-19 Diagnostic Accelerator Lab to validate alternative COVID-19 diagnostic devices. At the John Lab, I am excited to be exposed to working with animals models, studying mechanisms of ocular disease, and various molecular and physiological techniques such as IHC, ISH, dissection, and genotyping. I believe this experience will enhance my foundation in science and support my journey to pursue a career in medicine. In my free time, I enjoy cooking meals from various cultures and I plan to adopt a cat soon.

Research Associate II

Felicia Juarez, B.S.

I received my Bachelor of Science in Neuroscience with a concentration in Molecular and Cellular Biology from the Johns Hopkins University in 2017. My main research interests are genetics and neuroscience. As an undergraduate, I worked in Seth Blackshaw's lab on a project entitled "Investigating the role of Lhx2 in the development of the ciliary body." Since graduating college, I have worked in several labs ranging from studying blood diseases to building a library of nuclear constructs to study the phase separation of nuclear proteins in vivo. I am experienced in tissue culture, mouse husbandry, cloning, and various molecular biology techniques. I joined the John lab in June of 2020 as a Research Associate. During my free time I enjoy reading, exploring new areas in New York, and spending time with my dog, Nova.

Research Aide

Tracy Preko, B.S.

I joined the John Lab as a research aide after I graduated from the University of Notre Dame in May of 2021 with a B.S. in Neuroscience and Behavior along with a minor in Poverty Studies. During my time here I am excited to gain in-depth knowledge into the development of glaucoma and how it is investigated in mice models while gaining experience in various techniques and procedures like genotyping, animal husbandry, and immunohistochemistry. My hobbies include exploring new recipes and dishes while catching up on my favorite shows and movies.

Graduate Student

Nicholas Tolman B.A., Ph.D student

I received my B.A. in Behavioral Neuroscience from Connecticut College . During my time at Connecticut College, I worked on several different research projects. We studied whether Ceftriaxone and other β-lactam antibiotic compounds could attenuate morphine reward in rats by enhancing the reuptake rate of excitatory amino-acid transporters. For my honors thesis, I examined the effects of developmental lead exposure on working memory performance in rats after manipulating several elements of the animal’s developmental environment.

I started my Ph.D. in the John lab in 2016. I am studying the roles of a LIM domain transcription factor , LMX1b, in ocular development and adult-onset glaucoma. This has allowed me an unusually broad graduate training including clinical, molecular, genetic, genomic and other computational/statistical approaches using R, Seurat and other software . Beyond immunohistochemistry and other standard molecular techniques, I have mastered various delicate dissections (retina, optic nerve, brain regions and ocular drainage tissues) and precise ocular physiological measurements (including intraocular pressure and ocular fluid drainage or outflow). My projects have also involved clinical and histologic examination of mouse eyes and Mendelian and complex genetics including the diversity outbred mouse population. I have been involved with several other exciting projects, including the screening for and characterization of high IOP mutants and in a collaboration with engineers towards developing new treatment tools. Currently, I am focusing on the developmental biology of ocular development in Lmx1b mutants as well as the gene expression networks controlling ocular development and IOP elevation (using single cell sequencing, bulk RNA sequencing and other approaches). Dr. John has facilitated my interaction with collaborators and exposed me to grant writing, lab. management decisions and strategic planning. This diverse training along with his mentorship and the lab's environment are putting me in a strong position for my future career as a PI.

Being from coastal Maine, I was used to being an outdoor person at our lab's initial location next to Acadia National Park. The exciting and fast paced environment at our new location, Columbia University, is an amazing experience with the opportunity to learn from many first rate scientists.