title: Chemical defense in ascidians of the didemnidae family.
abstract: Fluorescent analogues (DB1 and TA1) of the secondary metabolites didemnin B (DB) and tamandarin A (TA) were synthesized to investigate the potential chemical defense mechanisms of tunicates in the family Didemnidae. These compounds were found to alter predator-prey relations. Five species of freshwater fish and one marine fish, the damselfish Amphiprion ocellaris, were acclimated to a diet of mosquito larvae. Fish showed an immediate, negative reaction to mosquito larvae treated with >/=5 ng of DB1 or TA1, with consumption of larvae resulting in regurgitation. Both freshwater and marine fish learned to avoid tainted prey by associating species of larvae with "distaste". Distaste for a given organism also arose when depsipeptides DB1 or TA1 were transferred to the fish from the surrounding medium. Fluorescence microscopy in fish indicated that a similar processing and localization followed ingestion and absorption of DB1 or TA1. Fluorescent labeling of DB or TA provided an ideal tool to conduct short-term studies of predator-prey relationships between fish and marine invertebrate larvae.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA. mjoullie@sas.upenn.edu
authors.forename: Madeleine M
authors.initials: MM
authors.lastname: Joullié
authors.forename: Michael S
authors.initials: MS
authors.lastname: Leonard
authors.forename: Padma
authors.initials: P
authors.lastname: Portonovo
authors.forename: Bo
authors.initials: B
authors.lastname: Liang
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Ding
authors.forename: James J
authors.initials: JJ
authors.lastname: La Clair
mesh_terms: D000818:Animals; D001362:Avoidance Learning; D002455:Cell Division / Q000187:drug effects; D009033:Culicidae; D047630:Depsipeptides; D005247:Feeding Behavior; D005399:Fishes / Q000502:physiology; D005764:Gastroesophageal Reflux / Q000139:chemically induced; D006801:Humans; D007814:Larva; D010456:Peptides, Cyclic / Q000008:administration & dosage / Q000494:pharmacology*; D014176:Protein Biosynthesis / Q000187:drug effects; D014407:Tumor Cells, Cultured; D014561:Urochordata / Q000737:chemistry*
chemical_list: D047630:Depsipeptides; D010456:Peptides, Cyclic; C409142:tamandarin A; C030051:didemnins