Usuy David Leon Tolosa
Researcher and educator with 2 years of experience, passionate microscopist, a dreamer for diversity, open science, and open software. Focused on biological mechanisms underlying pattern formation and regeneration of tissues and structures.
Email: Udleont(a)unal.edu.co -
ORCID: 0000-0001-7868-9934 -
GitHub: Usuaryo
Education
National University of Colombia, Bogotá, DC, Colombia
Bachelor in Biology, Jan 2016 - Dec 2022
Honors: 2023 Best Bachelor Thesis of the Year Award | Top 10% Undergraduate Performance| 2023 Top Performance University-Level Saber Pro National Exam |
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Research Experience
University of Maryland, Faculty Assistant
Juan Angueyra’s Laboratory, College Park, MD, U.S.A
May 2023 – Jan 2025
- Characterized effects of thrb modulation on photoreceptor subtypes of Astatotilapia Burtoni (preliminary NSF grant data)
- Induced CRISPR mutagenesis on Foxq2 transcription factor; sparse neuron labeling to evaluate synaptic connectivity in Danio rerio
- Assembled a custom electrophysiology rig and multi-wavelength stimulator for ERG recordings
- Recorded electroretinograms and optokinetic responses during early visual development of Astatotilapia Burtoni
- Explored horizontal cell diversity across species using DII staining and confocal microscopy (Snakes, Geckos, Cichlids, Mongolian Gerbil, Zebrafish)
- Proficient in retina microdissection and zebrafish aquaculture and maintenance
National University of Colombia, Research Assistant
Neurophysiology Research Group, Bogotá, Colombia
May 2021 - July 2023
- Established protocols to isolate functional photoreceptors from Schmidtea mediterranea planaria for patch clamp and calcium imaging
- Labeled phototransduction cascade elements by immunohistochemistry on planarian ocelli
- Skilled in planarian ocelli dissection and tissue dissociation; culture maintenance
University of Pennsylvania, Research Trainee
Summer Undergraduate Internship Program (SUIP), Philadelphia, PA
Summer 2020
- Applied machine learning (DeepLabCut) to analyze behavioral effects from optogenetic manipulations in mice ventral striatum
- Co-authored a review on olfactory and non-olfactory brain network connections
National University of Colombia, Research Trainee
Neurophysiology Research Group, Bogotá, Colombia
Jan 2019 - Dec 2020
- Trained in cellular electrophysiology, immunocytochemistry, chicken eye dissection, electrophoresis, Western blot, and neuroblastoma cell culture
National University of Colombia, Research Trainee
Protein Research Group, Bogotá, Colombia
Feb 2018 - Dec 2018
- Purified lectin protein from Salvia bogotensis to test insecticidal activity against Tecia solanivora
Teaching Experience
Neurophysiology Laboratory 405, Teaching Assistant
University of Maryland, College Park, MD, U.S.A
Jan 2024 - May 2024
- Supervised weekly 4-hour labs (~20 students) on extracellular/intracellular electrophysiology with crayfish, crickets, and worms
- Guided students in experiment design and poster presentations of pharmacology on sensory trasduction data
High School Volunteer Teacher
Bogotá, DC, Colombia
Feb 2017 - Dec 2018
- Mentored low-resource community students preparing for National University of colombia entrance exam.
Publications
Bhattarai, J.P., Etyemez, S., Jaaro-Peled H., Janke, E., Leon Tolosa, U.D., Kamiya, A., Gottfried, J.A., Sawa, A., Ma, M. (2021).
Olfactory modulation of the medial prefrontal cortex circuitry: implications for social cognition. Seminars in Cell and Developmental Biology.
DOI
Presentations and Posters
- Leon, U., Forero, J. (2025). El Observatorio Solar de Bacatá: Nuevas perspectivas arqueo astronómicas en el centro histórico de Bogotá. V Workshop de Astronomia de los Andes, Universidad de Nariño, Pasto. (Principal presenter)
- Leon, U., Angueyra, J. (2024). Waiting for godot? Unveiling the rules for synaptic connectivity of horizontal cells. Mid Atlantic Zebrafish Meeting (MARZ), Rutgers University, NJ. (Principal presenter)
- Leon, U., Ma, M. (2020). Contribution of the olfactory system to social cognition in mice. Undergraduate Internship Program, University of Pennsylvania, Philadelphia, PA. (Principal presenter)
- Puerto, P., Leon, U., Zuluaga, M., Gomez, P. (2023). Planaria eye as a study model of phototransduction. XIII Seminario Nacional de Neurociencia (COLNE), Cali, Valle del Cauca. (Principal presenter)
Skills & Others
Techniques:
- Lipid tracing (DII), Immunocytochemistry, Golgi staining
- Whole-cell patch clamp, Electroretinograms (ERG), Calcium imaging (GCamp6, Fluo4AM)
- Confocal, Light sheet, Confocal live, and Expansion microscopy
- PCR, cell transfection, Western blot
Software:
- Python, FIJI-ImageJ, μManager, Linux, OpenSCAD, Inkscape, Nikon Elements, Zeiss Zen
Hardware:
- Soldering circuits, Arduino basics, Raspberry Pi
Relevant Coursework:
- Cellular Biophysics, Molecular Biology, Genetics, Cell Biology, Animal Physiology I & II, Electricity and Magnetism, Biochemistry I & II
- Graduate courses in Neurobiology of Sensory Transduction, Membrane Biophysics, Fundamentals of Light Microscopy
Languages:
- Spanish (Fluent), English (Fluent), German (Beginner)
References
Juan Angueyra, M.D., Ph.D.
Assistant Professor, Department of Biology, University of Maryland – College Park
angueyra@umd.edu
Maria del Pilar Gomez, M.D., Ph.D.
Associate Professor, Department of Biology, National University of Colombia
mpgomzco@unal.edu.co
Karen Carleton, Ph.D.
Full Professor, Department of Biology, University of Maryland - College Park
kcarleto@umd.edu
Minghong Ma, Ph.D.
Associate Professor, Department of Neuroscience, University of Pennsylvania
minghong@pennmedicine.upenn.edu
Enrico Nasi, Ph.D.
Full Professor, Genetics Institute, National University of Colombia
enasil@unal.edu.co
Citizenship: Colombia
Last updated: October 2025