title: Navigation within host tissues: cues for orientation of Diplostomum spathaceum (Trematoda) in fish towards veins, head and eye.
abstract: Cercariae of Diplostomum spathaceum penetrate the skin of fish, and then migrate along blood vessels and tissues towards the head and the eye-lens. We studied their orientation behaviour in tail fins of guppies and in chemical concentration gradients within agar-filled choice chambers. In fins, they entered veins and orientated cranially, independent of the blood flow and living cells. In choice chambers, they were attracted by a small molecular fraction of fish serum, D-glucose (at 1, 10, and 1000 microM), D-mannose, D-maltotriose and Cl-ions, whereas D-glucosamine repelled them (even at 1.0 nM). Amino acids were not attractive, but arginine in tetrapeptides attracted at concentrations as low as 1 microm and melatonin at 0.4-4.3 PM. We suggest a preliminary model for the behaviour of diplostomula in fish fins and attracting (+) or repelling (-) host cues: (1) migration towards deeper skin layers and avoidance of skin surface, cues: Cl-ions (+ and -), glucose (+), glucosamine (-), light radiation (-); (2) orientation in cranial direction, cue: Cl-ions (+); (3) localization of blood vessels, cues: glucose (+), arginine-residues (+); (4) localization of the retina, cue: melatonin (+). A comparison with the navigation mechanisms of tissue-migrating schistosomules and hookworm larvae reveals an enormous diversity of strategies.
authors.affiliation: Institute for Zoology I, University Erlangen-Nuernberg, Staudtstrasse 5, D-91058 Erlangen, Germany. whaas@biologie.uni-erlangen.de
authors.forename: W
authors.initials: W
authors.lastname: Haas
authors.forename: C
authors.initials: C
authors.lastname: Wulff
authors.forename: K
authors.initials: K
authors.lastname: Grabe
authors.forename: V
authors.initials: V
authors.lastname: Meyer
authors.forename: S
authors.initials: S
authors.lastname: Haeberlein
mesh_terms: D000818:Animals; D003463:Cues; D005123:Eye / Q000469:parasitology; D005260:Female; D005393:Fish Diseases / Q000469:parasitology*; D006790:Host-Parasite Interactions / Q000502:physiology; D007814:Larva / Q000502:physiology; D011036:Poecilia / Q000469:parasitology*; D044967:Serum / Q000737:chemistry / Q000502:physiology; D013623:Tail / Q000469:parasitology; D014200:Trematoda / Q000502:physiology*; D014201:Trematode Infections / Q000469:parasitology / Q000662:veterinary*; D014680:Veins / Q000469:parasitology