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Chem Senses

Title:		Inducible defences in Daphnia depend on latent alarm signals from conspecific prey activated in predators
Author(s):		Stabell OB; Ogbebo F; Primicerio R;
Address:		"Department of Natural Sciences, Faculty of Mathematics and Sciences, Agder University College, Kristiansand, Norway. ole.b.stabell@hia.no"
Journal Title:		Chem Senses
Year:		2003
Volume:		28
Issue:		2
Page Number:		141 - 153
DOI:		10.1093/chemse/28.2.141
ISSN/ISBN:		0379-864X (Print) 0379-864X (Linking)
Abstract:		"Some water fleas (Daphnia spp.) undergo phenotypic changes when exposed to chemical signals from predators. The chemical signals have been assumed to be of predator origin (i.e. kairomones), since juices of crushed Daphnia have been found ineffective. We speculated that latent alarm signals could be present in Daphnia, to be activated in predators following ingestion. Accordingly, fish predators were fed earthworms for 10 weeks to remove Daphnia remains from their gastro-intestinal tracts. Following another 6 days of earthworm feeding, water conditioned by fish induced no morphological changes in D. galeata. When fish were alternatively fed Daphnia for 6 days, changes were induced with fish-conditioned water. Extracts made from intestines of earthworm-fed fish, homogenized with earthworms, gave no morphological changes, but intestines of the same origin homogenized with Daphnia did. Similar results were found when earthworms and Daphnia were homogenized with fish liver. Freshly frozen extracts of homogenized Daphnia gave no detectable changes at first instar stage in test animals, whereas extracts of Daphnia that had been kept at room temperature did induce such changes. Our results suggest that Daphnia respond to latent conspecific alarm signals (i.e. 'dormant' pheromones) that are activated by intestinal or bacterial enzymes in predators or in the water"
Keywords:		Aggression/*physiology Animals Carps Cichlids Daphnia/anatomy & histology/*physiology Digestion/physiology Fishes/*physiology Humans Invertebrate Hormones/physiology Liver/physiology Odorants Oligochaeta Phenotype Predatory Behavior/*physiology Signal Tra;
Notes:		"MedlineStabell, Ole B Ogbebo, Fortune Primicerio, Raul eng England 2003/02/18 Chem Senses. 2003 Feb; 28(2):141-53. doi: 10.1093/chemse/28.2.141"