Identifying Axonal Guidance Factors in the Zebrafish Olfactory System

Shreyas at computer




Project Summary

Brain plasticity, and its innate relationship with the developing nervous system, is a fascinating subtopic within the larger neurobiological field of science. Uncovering the mechanisms and influential factors on growing neurons can result in medical advancements that would ultimately help benefit the world.


With the help of the PURM program, I was able to work on an ongoing project in Dr. Jonathan Raper’s lab which concerns trying to identify which gene modifications can alter the path of developing axons in zebrafish embryos. Specifically, the axons in focus are those in the zebrafish olfactory system, which originate in the olfactory pit (odor receptor) and terminate in the olfactory bulb of the brain (glomerulus). My job involved collecting the zebrafish which had already been injected with a guidance factor and subsequently immunostaining and imaging the zebrafish heads. This whole procedure takes 2-3 days to complete and involves the use of various enzymes, buffers, antibodies, stains, and GFP fluorescence. In this manner I collected data on over one hundred fish in an effort to find those images which clearly showed the axon travel from olfactory out to olfactory bulb. The guidance factors I was testing for were PCDH11 and LRRC4Bb, and the particular receptor cell axon that I was tracking was the OR11-7 cell. These OR11-7 receptor cell axons, in wild-type fish, terminate in the central zone of the glomerulus, whereas the guidance factors should (as hypothesized) redirect the OR11-7 cells to the dorsal zone of the glomerulus. This data collection phase is still continuing and the process is continually being refined to properly visualize the growing axons in the zebrafish embryos.


During my time in the lab, I learned the specificities of working practically with all the reagents I had to use in the immunostaining process. I learned the importance of effective usage of such materials as the lab has to buy all the materials themselves. In relation to my education, my understanding of genomics and microbiology greatly benefitted from spending time in a neurobiological lab (in addition to the obvious advancement of neuroscience knowledge). I hope to continue with this lab and illuminate which genetic factors can influence axon development.