(full paper is archived in the Miller Library)
Title: Analysis of putrescine in the egg case of Loligo opalescens: potential roles in predator deterrence
Student Author(s): Hoerner, Michelle
Faculty Advisor(s): Epel, David
& Kaufman, Melissa
Location: Final Papers Biology 175H
Date: June 1996
Abstract: The squid Loligo opalescens deposit their egg cases in conspicuous masses on the floor of Monterey Bay. These egg masses remain largely undisturbed by predation during the 30 days until embryo hatching. A reproductive gland of the adult female squid contains bacteria of predominantly one species which the female includes in the egg case during spawning. These bacteria are of the genus Shewenella, closely related to Shewenella putrefaciens, a putrefying marine bacteria which is characterized by the production of extremely large quantities of the polyamine putrescine. In this study, bacteria isolated from the squid gland and egg sheath were examined by HPLC to deetermine the quantity of putrescine. The bacteria contained amounts of putrescine comparable to S. putrefaciens. The possible role of the putrescine was then examined in a chemotactic response assay utilizing the starfish Pisaster ochraceus, a common predator at the depth of the egg masses. S. putrefaciens, the squid bacteria and a solution of putrescine were found to be significant deterrents to the P. ochraceus while a control strain, Vibrio harveyi, with low levels of putrescine showed no deterrence. These results suggest a role for putrescine in the protection of the L. opalescens egg cases from predation.