I would like to thank SOT and the FUTURE Committee for the Undergraduate Faculty Research Grant that supported two undergraduate students, Arina Kazakova and Kevin Bayingana, in my group at Swarthmore College for the 2021–2022 school year. Their project aimed to dissect how circadian rhythm and melatonin levels influence planarian behavior and the adverse effects of neurotoxicants on neural function. The planarian Dugesia japonica is a promising invertebrate system for rapid chemical screening of potential neurotoxicants using a robotic platform developed in my group. I supported the students in following their research interests as the project and their involvement developed, generating new directions and results. Both students had productive and fulfilling research experiences.
Arina became interested in the computational aspects of the data analysis and focused on optimizing our image analysis for one behavioral endpoint (“scrunching”) that is a characteristic response of planarians to noxious heat. By fully engaging with this endpoint, Arina also became interested in understanding the molecular basis of noxious heat sensation in planarians—which would allow us to connect behavior with neural pathways. She decided to identify the receptors for noxious heat sensation using a chemical screening approach for her neuroscience thesis. A literature search led Arina to test two candidate pathways using chemical inhibitors: (1) a cocktail of three inhibitors targeting three transient receptor potential (TRP) channels previously identified and characterized individually in planarians and (2) mefloquine, an inhibitor of the calcium-activated chloride channel anoctamin 1 (ANO-1). She found that both the triple TRP inhibitor cocktail and mefloquine eliminated scrunching in response to noxious heat, suggesting that both pathways are involved in heat sensation. Interestingly, crosstalk between ANO-1 and certain TRP channels (e.g., TRPV1) has been found in mammalian systems, and her data suggests that a similar situation may exist in planarians. This is an exciting finding that further supports the relevance of the planarian model for neurobiology and neurotoxicity studies and one that we will pursue in more detail in the coming months.
Kevin, along with another undergraduate student, studied the effect of the photoperiod and different concentrations of melatonin on planarian behavior. He compared three groups of planarians that were entrained for several weeks in different photoperiods: planarians that were always kept in the dark, always in the light, or in a 12-hour dark, 12-hour light rotation. These planarians were then screened on our robotic behavioral platform, either after acute or sub-chronic exposure to melatonin. Based on our analysis of the acute data, melatonin had the most effects on thermotaxis, inducing decreased thermotaxis at several concentrations and in almost all entrainments. We also observed changes in other endpoints, with some effects being concentration independent. Interestingly, acute melatonin exposure did not have any significant effects on planarians kept in constant light. We are still in the process of analyzing the results from the sub-chronic exposure. Kevin also studied the effect of sub-chronic exposure to common drugs, and we are currently writing up the results. Kevin is learning how to write an original research paper and make publication quality figures.
I consider the project a success, not only because it will lead to student co-authored manuscripts, but it really helped shape the trajectory of two students. Arina loved the computational work so much that
she decided to major in computer science in addition to her original major in neuroscience. She
took an extra load of courses, in addition to self-study, and successfully completed both majors! Kevin got so excited about the work that
he plans to continue as an honors student in my group and do his honors thesis with me, building upon this project.#Communique:ScienceNews#Communique:SOTNews#Awards#FUTURE#Undergraduateeducation#Members#ResearchandGrantFunding