The role of a fatty acid hormone in the reproduction of the polychaeteArenicola marina(L.)

Abstract

Summary Reproduction in the lugworm Arenicola marina is annual and, for most populations, occurs in the late autumn or early winter. Oocyte maturation in females and sperm activation of males and spawning are under hormonal control. In males the polyunsaturated fatty acid, 8, 11, 14-eicosatrienoic acid, causes both activation of the spermatozoa (Bentley et al., 1990) and spawning (Pacey and Bentley, 1992). Dissociation of syncitial sperm masses occurs in response to the fatty acid. Active swimming of spermatozoa then follows on dilution in seawater (as a consequence of elevation of internal pH, pHi), and fertilization of the eggs takes place in the burrow of the female. Sperm activation can also be induced by arachidonic and 5, 8, 11-eicosatrienoic acids but not by the 11, 14, 17-isomer. This suggests a possible role for cyclooxygenases or lipoxygenases. Sperm activation by the PUFAs is inhibited by nordihydroguaiaretic acid (50 μM) and eicosatriynoic acid (13 μM) suggesting that 12-lipoxygenase acts during activation. Possible involvement of the fatty acid in coordination of reproduction between individuals is also discussed.