title: Schistosoma mansoni and S. haematobium: miracidial host-finding behaviour is stimulated by macromolecules.
abstract: The miracidia of Schistosoma mansoni and S. haematobium approach their host snails by increasing their rate of change of direction (RCD) in increasing gradients of snail-conditioned water (SCW), and they perform a turnback response in decreasing gradients. After contact with the host "repeated investigation" is the typical host-specific response. Both species show no significant directed chemotactical orientation towards their snail hosts. All three host-finding responses (increased RCD, turnback response, and "repeated investigation") seem to be stimulated in both species by a similar component of SCW, a macromolecular glycoconjugate with a molecular weight > 30,000. The saccharide chains seem to be O-glycosidically linked via serine and N-acetylgalactosamine. The glycoconjugate is sensitive to lysozyme which may suggest that muramic acid as a gastropod-specific component is involved in the recognition process. Small molecular components of SCW, as well as magnesium chloride offered as pure chemical, may cause a moderate increase in the RCD. Therefore a minor contribution of these components to the host-finding response of schistosome miracidia cannot be excluded. That schistosome miracidia respond to complex macromolecules as host cues may indicate an adaptation to avoid interference of the host-finding with ubiquitous small molecular mud components and it might enable the miracidia to achieve a high degree of host-specificity in their host-finding.
authors.affiliation: Institut für Zoologie 1, Universität Erlangen-Nürnberg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Haberl
authors.forename: M
authors.initials: M
authors.lastname: Kalbe
authors.forename: H
authors.initials: H
authors.lastname: Fuchs
authors.forename: M
authors.initials: M
authors.lastname: Ströbel
authors.forename: G
authors.initials: G
authors.lastname: Schmalfuss
authors.forename: W
authors.initials: W
authors.lastname: Haas
mesh_terms: D000818:Animals; D001700:Biomphalaria / Q000737:chemistry / Q000469:parasitology*; D002633:Chemotaxis; D006001:Glycoconjugates / Q000737:chemistry* / Q000302:isolation & purification; D006790:Host-Parasite Interactions; D008970:Molecular Weight; D012548:Schistosoma haematobium / Q000502:physiology*; D012550:Schistosoma mansoni / Q000502:physiology*; D014867:Water / Q000737:chemistry
chemical_list: D006001:Glycoconjugates; D014867:Water