UCLA UCLA Electronic Theses and Dissertations Title Investigating the Neural Circuit for Carbon Dioxide Avoidance Behavior in Caenorhabditis elegans Permalink https://escholarship.org/uc/item/70m1v28x Author Carrillo, Mayra Publication Date 2015 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Investigating the Neural Circuit for Carbon Dioxide Avoidance Behavior in Caenorhabditis elegans A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Microbiology, Immunology, and Molecular Genetics by Mayra Alejandra Carrillo 2015 ABSTRACT OF THE DISSERTATION Investigating the Neural Circuit for Carbon Dioxide Avoidance Behavior in Caenorhabditis elegans by Mayra Alejandra Carrillo Doctor of Philosophy in Microbiology, Immunology, and Molecular Genetics University of California, Los Angeles, 2015 Professor Elissa A. Hallem, Chair Carbon dioxide (CO2) is a byproduct of oxidative metabolism that can be sensed by different species including mammals, insects, and nematodes and can lead to both physiological and behavioral responses. In the free-living nematode Caenorhabditis elegans the behavioral response can be either avoidance or neutral to CO2, indicating that the behavior is flexible. In this thesis, I investigated the neural basis of behavioral flexibility. We found that the CO2 circuit can be modulated by diverse sensory neurons that respond to ambient oxygen (O2), temperature, and food odor. Additionally, we identified two interneurons downstream of the CO2- sensing BAG neurons, AIY and RIG, that have opposing roles in CO2-evoked responses. A decrease in AIY activity and an increase in RIG activity promote appropriate avoidance behavior to CO2 levels. Our results show that just like thermosensory and oxygen circuits, the CO2 circuit can exhibit a network of multisensory integration to enable animals to generate flexible behaviors to changing environments. ii The dissertation of Mayra Alejandra Carrillo is approved. David G. Brooks Peter J. Bradley Alvaro Sagasti Elissa A. Hallem, Committee Chair University of California, Los Angeles 2015 iii DEDICATION I dedicate this dissertation to my parents Pedro and Aurora Carrillo, and to all my friends and family. I thank them for all their support during graduate school. I would also like to dedicate this to all my past mentors and science teachers who inspired me to pursue a career in science. Mike Reynolds, Kent Smith, Victor and Brenna Tam, Robb Pagarigan, Raymond Wong, Brian Weist, and others. Thank you guys for giving me the opportunity to learn from you. iv TABLE OF CONTENTS Chapter 1: Introduction: Gas Sensing in Nematodes 1 Chapter 2: O2-sensing neurons control CO2 response in C. elegans 15 Chapter 3: Identifying the downstream interneurons required for CO2 response 27 Chapter 4: The immune response of Drosophila to entomopathogenic nematodes 37 Discussion 53 References 65 v LIST OF FIGURES Figure 2-1: Loss of AIY function in ttx-1 mutants rescues CO2 avoidance behavior 25 Figure 2-2: Expression of flp-19 in URX rescues npr-1 phenotype 26 Figure 3-1: Neural circuit connecting BAG and URX 28 Figure 3-2: Responses of RIG and AIY-ablated animals across CO2 concentrations 29 Figure 3-3: Increasing synaptic transmission in AIY and RIG reveal antagonistic 30 roles in CO2 response Figure 3-4: Ablation of AIY interneurons rescues CO2 avoidance in npr-1 mutants 31 Figure 3-5: RIG interneurons show CO2-evoked activity that is BAG-dependent 31 Figure 3-6: AIY shows CO2-evoked inhibition that is BAG-dependent 32 Figure 3-7: Presence of isoamyl alcohol restores CO2 avoidance in npr-1 mutants 33 Figure 3-8: Ablation of AWC neurons restores CO2 avoidance in npr-1 mutants 34 Figure D-1: A distributed network of sensory neurons regulate the CO2 circuit 53 Figure D-2: Antagonistic roles by RIG and AIY mediate CO2 avoidance behavior 53 Figure D-3: Model for CO2-evoked locomotor activity 56 vi ACKNOWLEDGMENTS First, I would like to acknowledge my PI Elissa Hallem for being a wonderful and excellent mentor. I hope I can inspire younger generations to become excited about science as she has inspired me. I would also like to acknowledge Manon L. Guillermin, my partner in crime, for equally contributing to this work, especially generating transgenic lines and calcium imaging data. This project would not be close to where it is now if it wasn’t for her contributions. I would like to acknowledge my funding sources, the NSF Graduate Research Fellowship and the Eugene Cota-Robles Fellowship for supporting me throughout graduate school. I would also like to thank the Hallem lab members for the feedback on this project and overall being the best group of people with restricted dietary needs anyone can ever work with. Thank you guys for being so awesome. I especially like to extend my gratitude to the members of my committee for giving valuable feedback on my progress and on this project. Chapter 1 is a version of Carrillo, M.A. and Hallem, E.A. (2015) Gas sensing in nematodes. Mol. Neurobiol. 51: 919-931. Permission was granted by publisher for use in this thesis Chapter 2 is a version of Carrillo, M.A., Guillermin, M.L., Rengarajan, S., Okubo, R.P., and Hallem, E.A. (2013). O2-sensing neurons control CO2 response in C. elegans. J. Neurosci. 33, 9675–9683. Chapter 3 is in preparation for publication. Chapter 4 is a version of Peña, J.M., Carrillo, M.A., and Hallem, E.A. (2015) Variation in the susceptibility of Drosophila to different entomopathogenic nematodes. Infect. Immun. 83, 1130- 1138. vii VITA Education: Bachelor of Science in Biological Sciences from University of California, Irvine, Irvine, CA. September 2007 - June 2010 Associate of Arts in Liberal Arts from Los Angeles Mission College, Sylmar, CA September 2000 - June 2003. Academic Honors and Awards: National Science Foundation Predoctoral Fellowship, 2010 Eugene Cota-Robles Fellowship, 2010 Sigma Xi Poster Presentation Award in Cell Biology, 2009 Dean’s Honor List, University of California Irvine, 2008 Publications: Peña, J.M., Carrillo, M.A., and Hallem, E.A. (2015) Variation in the susceptibility of Drosophila to different entomopathogenic nematodes. Infect. Immun. 83, 1130-1138. Carrillo, M.A. and Hallem, E.A. (2015) Gas sensing in nematodes. Mol. Neurobiol. 51: 919-931 Carrillo, M.A., Guillermin, M.L., Rengarajan, S., Okubo, R.P., and Hallem, E.A. (2013). O2- sensing neurons control CO2 response in C. elegans. J. Neurosci. 33, 9675–9683. Smith, K.A., Meisenburg, B.L., Tam, V.L., Pagarigan, R.R., Wong, R., Joea, D.K., Lantzy, L., Carrillo, M.A., Gross, T.M., Malyankar, U.M., et al. (2009). Lymph node- targeted viii immunotherapy mediates potent immunity resulting in regression of isolated or metastatic human papillomavirus-transformed tumors. Clin. Cancer Res. 15, 6167–6176. Wong, R.M., Smith, K.A., Tam, V.L., Pagarigan, R.R., Meisenburg, B.L., Quach, A.M., Carrillo, M.A., Qiu, Z., and Bot, A.I. (2009). TLR-9 signaling and TCR stimulation co- regulate CD8(+) T cell-associated PD-1 expression. Immunol. Lett. 127, 60–67. Presentations: Peña, J.M., Carrillo, M.A., and Hallem, E.A. Immune response of Drosophila to entomopathogenic nematode infection. Presented at the Southern California Eukaryotic Pathogens Symposium, UC Riverside 2014. Carrillo, M.A., Guillermin, M.L., Rengarajan, S., Okubo, R.P., and Hallem, E.A. O2- sensing neurons control CO2 response in C. elegans. Presented at the 19th International C. elegans meeting, UCLA 2013. Carrillo, M.A. Investigating the regulation of carbon dioxide response in C. elegans. Worm Club Meeting, UCLA 2013. Carrillo, M.A. Investigating the regulation of carbon dioxide response in C. elegans. Synapse to Circuit seminar, UCLA 2012. Carrillo, M.A., Sharp, K., Bardwell, L. The role of docking sites in yeast MAPK cascade signaling specificity. Sigma Xi Annual Meeting and International Research Conference, Houston 2009 ix Chapter 1: Introduction 1 Mol Neurobiol DOI 10.1007/s12035-014-8748-z Gas Sensing in Nematodes M. A. Carrillo & E. A. Hallem Received: 11 April 2014 /Accepted: 7 May 2014 # Springer Science+Business Media New York 2014 Abstract Nearly all animals are capable of sensing changes ambient O2 or CO2 levels can signal the presence of food, in environmental oxygen (O2)andcarbondioxide(CO2) pathogens, conspecifics, predators, or hosts. Moreover, levels, which can signal the presence of food, pathogens, prolonged exposure to hypoxia, hyperoxia, or hypercapnia conspecifics, predators, or hosts. The free-living nematode can result in cell damage, altered neural activity, and ultimate- Caenorhabditis elegans is a powerful model system for the ly death [1–4]. Thus, the ability to respond appropriately to study of gas sensing. C. elegans detects changes in O2 and changes in environmental O2 and CO2 levels is essential for CO2 levels and integrates information about ambient gas survival. Caenorhabditis elegans is a powerful system for the levels with other internal and external cues to generate study of the neural basis of gas sensing. It displays robust context-appropriate behavioral responses. Due to its small responses to both O2 and CO2. Moreover, it has a small nervous system and amenability to genetic and genomic anal- nervous system composed of 302 neurons and approximately yses, the functional properties of its gas-sensing microcircuits 6,500 synaptic connections [5, 6], and is amenable to precise can be dissected with single-cell resolution, and signaling circuit manipulation due to its optical transparency, stereo- molecules and natural genetic variations that modulate gas typed anatomy, and extensive genetic and genomic toolkits. responses can be identified. Here, we discuss the neural basis The molecular pathways that regulate circuit function and the of gas sensing in C. elegans, and highlight changes in gas- general principles of circuit design are in many cases con- evoked behaviors in the context of other sensory cues and served between mammals and nematodes [7–9].