The Molecular Basis of Locomotion

Gene Editing

When Wayne Barnaby, a PhD candidate in Neuroscience and Behavior, first heard about a new technology that could “edit” genes, his curiosity was instantly piqued.  Although it sounds like something straight from a science fiction movie, this technique, known as CRISPR (short for Clustered Regularly Interspaced Short Palindromic Repeats), can indeed alter gene expression. Barnaby explained, “CRISPR can be used to either over-express or under-express a certain gene, and that allows scientists to better understand the role that gene has in the grand scheme of the functioning body.”  For example, if you turn a mysterious knob to the left and you start to see the lights dim, you could conclude that that particular knob regulates that light. 

As he was finishing his undergraduate studies, Barnaby recalled, “I was geeking out about [CRISPR], I couldn’t stop thinking about and reading about it.” CRISPR was an emerging technology when Barnaby was an undergraduate student at Westfield State University, and he believed it would soon be a major player in the future of science.   

When an opportunity arose to complete an internship at UMass with Dr. Gerald Downes on research involving CRISPR, Barnaby didn’t hesitate. “I had a really good connection with [Pr. Downes]”, he described. “I got to get a taste and understanding of what research looks like.”   

It wasn’t long before Barnaby officially joined the Downes lab as a PhD student in the Neuroscience and Behavior (NSB) Graduate Program. “I felt like I could really thrive here,” Barnaby recounted, adding “when I was interviewing for the neuroscience program, I really felt a strong sense of felt like a community of people who really cared about each other.”  

Over the past five years, Barnaby’s work in the Downes lab has focused on the molecular basis of locomotion, using zebrafish as an animal model. Barnaby is interested in how a particular class of receptor, a part of the brain and spinal cord which responds to stimuli, plays a role in locomotion. There are several of these receptors, called GABA receptors, present in all vertebrate animals, including humans. Barnaby wants to know which GABA receptors are driving and regulating locomotion, where they are located, and what neurons they are involved in.  

Zebrafish are an ideal animal model for this study, Barnaby explained, because they exhibit a characteristic swimming activity at the embryonic stage. In response to a tactile stimulus, the embryo will perform a “backflip” as an escape response and start to swim rapidly in the opposite direction of the disturbance.   

“If you think about a human embryo, we’re pretty useless at that time,” Barnaby remarked, “while  zebrafish, for multiple evolutionary purposes, have developed this escape mechanism, this flight response, at a really early age so that they may survive another day.”   

This characteristic swimming behavior is used as a baseline for normal behavior in the absence of genetic modifications, what Barnaby describes as a “wild-type” response. Barnaby can then use CRISPR to “turn off” different types of GABA receptors in different combinations and observe how this swimming activity changes. If the swimming behavior significantly changes after a particular receptor or group of receptors is downregulated, then these receptors are likely involved in regulating normal swimming behavior.   

Sure enough, this is what Barnaby found through his experiments, as demonstrated by the image showing both wild-type and mutant swim behaviors. After conducting numerous trials, Barnaby’s data shows that receptors containing gabra3 seem to be the most important GABA receptor class for locomotor response in zebrafish. These findings “might be a key to understanding how gabra3 GABA receptors are important for not only locomotor responses but more broadly for motor responses" Barnaby notes, adding that there is a wider application to this research.   

Other studies have shown that modification of the gabra3 gene “can lead to disruptive disorders in the brain like epilepsy and other diseases if not treated properly,” and that a deeper understanding of these systems can help with developing appropriate therapies. “If you don’t understand the basic mechanism, it’s really hard to understand or move towards a therapy. But if you have a target, if you know what is being disrupted...then you have a better idea of what to look for when it’s time to do different therapeutic screens.”   

Although his work doesn’t focus directly on medical interventions for humans, Barnaby says he is passionate about being “one small person contributing to the greater understanding of the natural world. I have a lot of pride in that...I think that we’re doing really good work.”  

As he has conducted these experiments during his doctoral program, Barnaby has felt empowered to be able to ask his own research questions. Graduate school is “a beautiful journey to scientific independence,” Barnaby remarked, adding, “the greatest skill that I’ve learned in grad school is not what I’ve learned, but how to learn.” Barnaby credits much of his success at UMass to his community of advisors, fellow scholars, and friends, insisting that “it has everything to do with the people around me.”    

Barnaby continued, “I think no matter what, having mentors and friends, people who you feel like have your best interests at heart and that you have their best interests at heart, is a really great way to grow scientifically and personally.”  

After his dissertation is finished and defended, Barnaby has big plans. He wants to leverage the information and skills that he has learned to answer questions about neuroscience and cancer using new technologies. “I feel really confident in my ability to try new things,” Barnaby remarked, adding “I think that grad students should feel empowered to do that when they get out of grad school.” He recently completed an internship with a biotechnology company in San Francisco that focuses on oncological research. Despite having a different specialization, Barnaby says “I was able to pick up this different field quickly because of the skills I learned in grad school.”   

As he reflected on his graduate school experience and his future endeavors, Barnaby echoed a proverb about the importance of community: “If you want to go fast, go alone, but if you want to go far, go together.” Perhaps he could have added, if you want to go in the right direction, don’t inhibit your gabra3 GABA receptor.  

Written by Stefanie Farrington, PhD student in Organismic & Evolutionary Biology, as part of the Graduate School's Public Writing Fellows Program.