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Research Interests

Our research focuses on the sensory behaviors of parasitic and free-living nematodes, and lies at the interface of neurobiology and parasitology. The goals of our research are to understand how human-parasitic worms use sensory cues to locate hosts to infect, how sensory circuits of parasitic animals differ from those of free-living animals to enable parasitic behaviors, and how sensory microcircuits generate flexible outputs. We use the skin-penetrating gastrointestinal parasitic nematodes Strongyloides stercoralis and Strongyloides ratti, as well as the free-living nematode C. elegans, as model systems. S. stercoralis is a human parasite that infects ~600 million people worldwide. Our research addresses fundamental questions of sensory circuit function and evolution in the context of human parasitism. In addition, human-parasitic worms are a major cause of morbidity worldwide, and a better understanding of their sensory behaviors may enable the development of novel strategies for preventing or treating infections. More information about our research program is available on our lab website, www.hallemlab.com.

Selected Recent Publications

Gang, S.S., Castelletto, M.L., Yang, E., Ruiz, F., Brown, T.M., Bryant, A.S., Grant, W.N., and Hallem, E.A. (2020) Chemosensory mechanisms of host seeking and infectivity in skin-penetrating nematodes. Proc Natl Acad Sci USA 117: 17913-17923.

Castelletto, M.L., Gang, S.S., and Hallem, E.A. (2020) Recent advances in functional genomics for parasitic nematodes. J Exp Biol 223: jeb206482.

Banerjee, N. and Hallem, E.A. (2019) The role of carbon dioxide in nematode behavior and physiology. Parasitology 147: 841-854.

Rengarajan, S., Yankura, K.A., Guillermin, M.L., Fung, W., and Hallem, E.A. (2019) Feeding state sculpts a circuit for sensory valence in Caenorhabditis elegans. Proc Natl Acad Sci USA 116: 1776-1781.

Bryant, A.S. and Hallem, E.A. (2018) Terror in the dirt: Sensory determinants of host seeking in soil-transmitted mammalian-parasitic nematodes. Int J Parasitol Drugs Drug Resist 8: 496-510.

Bryant, A.S. and Hallem, E.A. (2018) Temperature-dependent behaviors of parasitic helminths. Neurosci Lett 687: 290-303.

Bryant, A.S., Ruiz, F., Gang, S.S., Castelletto, M.L., Lopez, J.B., and Hallem, E.A. (2018) A critical role for thermosensation in host seeking by skin-penetrating nematodes. Curr Biol 28: 2338–2347.

Ruiz, F., Castelletto, M.L., Gang, S.S., and Hallem, E.A. (2017) Experience-dependent olfactory behaviors of the parasitic nematode Heligmosomoides polygyrus. PLoS Pathog 13: e1006709.

Gang, S.S., Castelletto, M.L., Bryant, A.S., Yang, E., Mancuso, N., Lopez, J.B., Pellegrini, M., and Hallem, E.A. (2017) Targeted mutagenesis in a human-parasitic nematode. PLoS Pathog 13: e1006675.

Guillermin, M.L., Carrillo, M.A., and Hallem, E.A. (2017) A single set of interneurons drives opposite behaviors in C. elegans. Curr Biol 27: 2630-2639.

Cevallos, J.A., Okubo, R.P., Perlman, S.J., and Hallem, E.A. (2017) Olfactory preferences of the parasitic nematode Howardula aoronymphium and its insect host Drosophila falleni. J Chem Ecol 43: 362-373.

Rengarajan, S., and Hallem, E.A. (2016) Olfactory circuits and behaviors of nematodes. Curr Opin Neurobiol 41: 136-148.

Gang, S.S. and Hallem, E.A. (2016) Mechanisms of host seeking by parasitic nematodes. Mol Biochem Parasitol 208: 23-32.

Lee, J., Dillman, A.R., and Hallem, E.A. (2016) Temperature-dependent changes in the host-seeking behaviors of parasitic nematodes. BMC Biol 14: 36.

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.

Castelletto, M.L., Gang, S.S., Okubo, R.P., Tselikova, A.A., Nolan, T.J., Platzer, E.G., Lok, J.B., and Hallem, E.A. (2014) Diverse host-seeking behaviors of skin-penetrating nematodes. PLoS Pathog 10: e1004305.