The sea lamprey is an ancient, parasitic fish that invaded the Great Lakes a century ago, where it triggered the collapse of many fisheries. Like many fishes, this species relies on chemical cues to mediate key aspects of its life, including migration and reproduction. Here we report the discovery of a multicomponent steroidal pheromone that is released by stream-dwelling larval lamprey and guides adults to spawning streams. We isolated three compounds with pheromonal activity (in submilligram quantities from 8, 000 l of larval holding water) and deduced their structures. The most important compound contains an unprecedented 1-(3-aminopropyl)pyrrolidin-2-one subunit and is related to squalamine, an antibiotic produced by sharks. We verified its structure by chemical synthesis; it attracts adult lamprey at very low (subpicomolar) concentrations. The second component is another new sulfated steroid and the third is petromyzonol sulfate, a known lamprey-specific bile acid derivative. This mixture is the first migratory pheromone identified in a vertebrate and is being investigated for use in lamprey control.
Bibliographical noteFunding Information:
We thank the staffs of the Hammond Bay Biological Station, Ludington Biological Station, Marquette Biological Station and Sea Lamprey Control Centre at Sault Ste. Marie for collecting the sea lamprey. NMR instrumentation was acquired with funds from the US National Science Foundation (BIR-961477), the University of Minnesota Medical School and the Minnesota Medical Foundation. Access to MS instrumentation was provided through the courtesy of the University of Minnesota Mass Spectrometry Consortium for the Life Sciences. This research was supported by the Great Lakes Fishery Commission (P.W.S. and T.R.H.), the Minnesota Agricultural Experiment Station (P.W.S.) and the US National Institutes of Health (T.R.H., GM65597).