A simple quantitative technique for testing behavioral responses of Schistosoma mansoni miracidia to chemicals.
We describe a new technique for testing responses of Schistosoma mansoni miracidia to chemicals. Miracidia in spring water were placed in a chamber shaped like the Greek letter phi. Small volumes of test chemicals were inoculated into one side of the chamber. After 30 sec a dam was inserted to bisect the chamber and the percentage of miracidia on the inoculated side was calculated. Reproducible quantitative results were obtained using the known miracidial stimulants, snail-conditioned water (Biomphalaria glabrata) and Mg2+; up to 80% of the miracidia were recovered on the inoculated side of the chamber. Other substances also stimulated miracidia: several inorganic cations, 4 neurotransmitters, 3 acetycholine antagonists, and 1 acetycholine agonist. Modifying the technique by testing stimulants in altered chemical "backgrounds" allowed us to test for inhibitors of miracidial responses. Assays of the Mg2+ content of several of the test solutions indicated that their stimulatory or inhibitory effects could not be ascribed to Mg2+ contamination. However, results obtained with neurotransmitters and drugs were not sufficiently consistent to implicate specific neurotransmitters in the mechanism by which miracidia detect and respond to stimulants in snail-conditioned water.
D000109:Acetylcholine / Q000037:antagonists & inhibitors; D000704:Analysis of Variance; D000818:Animals; D002412:Cations; D008124:Locomotion / Q000187:drug effects; D008274:Magnesium / Q000494:pharmacology; D008722:Methods; D018377:Neurotransmitter Agents / Q000494:pharmacology; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000502:physiology
D002412:Cations; D018377:Neurotransmitter Agents; D008274:Magnesium; D000109:Acetylcholine