Penn Veterinary Medicine | University of Pennsylvania

Description of Research Expertise

Research Interests
Human Strongyloidiasis: Model Development.
Haemonchus contortus: Neuronal Control of the Infective Process.

Key words: Parasitic nematodes, Neurobiolgy, Developmental biology, Infective process, Behavior.

Description of Research
I am interested in neurological aspects of the developmental biology of parasitic nematodes using the freeliving nematode, Caenorhabditis elegans, as a model. Parasitic nematodes of primary interest include the threadworm of humans, Strongyloides stercoralis, the hookworm of dogs, Ancylostoma caninum and the stomach worm of ruminants, Haemonchus contortus. Using these species as experimental tools, ongoing research attempts to identify the specific chemosensory neurons that are involved in host-finding behavior, host penetration and infection and in controlling alternative developmental pathways both during within-host development and in development occurring before host-invasion.

Rotation Projects for 2006-2007
Identification of specific neuron classes involved in host-finding behavior, host invasion and intra-host development and migration by various nematodes of medical and veterinary medical importance.

Lab personnel:
Mario Brenes, Research Specialist
Tom Nolan, Adjunct Associate Professor of Parasitology
Francis Ashton, Senior Research Investigator

Selected Publications

Ashton, F.T, Zhu, X., Boston, R., Lok, J.B., Schad, G.A. : Strongyloides stercoralis: amphidial neuron pair ASJ triggers significant resumption of development by infective larvae of under host-mimicking in vitro conditions. Exp. Parasitol. 115: 92-97, 2007.

Safer, D., Brenes, M., Dunipace, S. and SCHAD, G.A.: Urocanic acid is a major chemoattractant for the skin- penetrating parasitic nematode Strongyloides stercoralis. PNAS 104: 1827-1630, 2007.

Artis D, Wang ML, Keilbaugh SA, He W, Brenes M, Swain GP, Knight PA, Donaldson DD, Lazar MA, Miller HR, Schad GA, Scott P, Wu GD: RELMbeta/FIZZ2 is a goblet cell-specific immune-effector molecule in the gastrointestinal tract. Proc Natl Acad Sci USA 101(37): 13596-600, Sept 14 2004.

Ketschek AR, Freeman AS, Boston R, Habecker PL, Ashton FT, Schad GA: Vertical migratory behavior of the infective third-stage larvae of Oesophagostomum dentatum Vet Parasitol 123(3-4): 215-21, Sept 2 2004.

Forbes WM, Ashton FT, Boston R, Zhu X, Schad GA: Chemoattraction and chemorepulsion of Strongyloides stercoralis infective larvae on a sodium chloride gradient is mediated by amphidial neuron pairs ASE and ASH, respectively Vet Parasitol 120(3): 189-98, March 25 2004.

Freeman AS, Nghiem C, Li J, Ashton FT, Guerrero J, Shoop WL, Schad GA: Amphidial structure of ivermectin-resistant and susceptible laboratory and field strains of Haemonchus contortus Vet Parasitol 110(3-4): 217-26, January 2 2003.

Forbes WM, Ashton FT, Boston R, Schad GA: Chemotactic behaviour of Strongyloides stercoralis infective larvae on a sodium chloride gradient Parasitology 127((Part 2)): 189-97, August 2003.