Title: "The neural basis of temperature-driven host seeking in the human threadworm Strongyloides stercoralis”
Speaker: Astra Bryant, PhD
Assistant Project Scientist
Dept of Microbiology, Immunology, and Molecular Genetics
University of California, Los Angeles
Soil-transmitted parasitic nematodes infect over a billion people and cause devastating morbidity, primarily in the world’s most socioeconomically depressed communities. Many of these parasites have infective larvae that locate hosts in a poorly understood process that requires thermal cues, but virtually nothing is known about the neural basis of this behavior.
We investigated the neural basis of temperature-driven host seeking in parasitic nematodes using the skin-penetrating human threadworm Strongyloides stercoralis. We identified the primary thermosensory neurons in S. stercoralis and characterized their responses to thermal stimuli by applying single-cell genetic targeting, cell-type specific neural silencing, and calcium imaging techniques for the first time in an endoparasitic animal. These neurons display unique thermal response properties that support the ability of parasitic worms to engage in long-distance host seeking using body heat. We discovered a new component of the sensory strategy that guides parasitic worms to hosts: the ability to rapidly reverse an erroneous attraction to non-host heat sources. This novel behavior is generated by rapid sensory adaptation selectively triggered by exposure to sub-body heat temperatures. Finally, we identified the thermoreceptors that confer parasite-specific sensitivity to body heat, and used CRISPR-Cas9 mutagenesis of the downstream sensory transduction pathway to identify, for the first time in parasitic worms, a gene necessary for host seeking.
Together, these results are the first direct evidence that the sensory neurons of parasitic worms exhibit unique neural adaptations and sensory coding strategies that allow them to target humans, a finding with important implications for efforts to develop new therapeutic strategies for nematode control.
Bio: Dr. Astra Bryant is a neuroscientist and parasitologist currently working as an Assistant Project Scientist in the Department of Microbiology, Immunology, and Molecular Genetics at the University of California, Los Angeles. She received her B.A. in Biology from Bryn Mawr College, and a Ph.D. in Neuroscience from Stanford University.
During her scientific career, Dr. Bryant has worked on a wide array of topics in systems and circuits neuroscience, including the neural underpinnings of absence epilepsy and spatial attention, the central pattern generators that drive leeches to swim, as well as how brain hormones control the social status of African cichlid fish. In 2016, Dr. Bryant moved to UCLA for a postdoctoral fellowship in the lab of Dr. Elissa Hallem. In the Hallem lab, she uses an interdisciplinary approach combining expertise in neuroscience, parasitology, molecular biology, bioinformatics, and genetics to understand the neural mechanisms underlying sensory-driven host seeking by soil-transmitted parasitic nematodes.
Dr. Bryant is a 2017 A.P. Giannini Postdoctoral Fellow, and has received multiple awards for her research on parasitic worms, including the 2021 Boyer/Parvin Award for Excellence in Molecular Biology Research, the 2020 Arnold Scheibel Distinguished Postdoctoral Fellow Award, and the 2020 M. John Pickett Award for Outstanding Achievement in Postdoctoral Research.
Date: Monday, October 18, 2021
Time: 12-1 pm
Location: Hill Pavilion, Room 132
University of Pennsylvania School of Veterinary Medicine
380 S University Ave, Philadelphia, PA 19104
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