Comparative Receptor Study in Gamete Chemotaxis of the Seaweeds Ectocarpus siliculosus and Cutleria multifida

Abstract

Gamete fusion in phaeophytes is initiated by olefinic hydrocarbons as messenger substances. They are secreted by the female gametes and act on male gametes of gametangia. The sensitivity thresholds of the androgametes of E. siliculosus and C. multifida, 2 brown algae of different evolutionary stages, for ectocarpene, which is produced by either species, were 0.89 and 8.9 nmol/l seawater, respectively. The molecular recognition mechanism is shown to be identical for these 2 spp. and probably also for most other phaeophytes. The pheromones involved are structurally related and sometimes resemble each other in their overall .pi.-electron distribution (e.g., ectocarpene and multifidene). Knowing the specific messenger, the typical response behavior of each receptor involved, the pheromone productivity of the considered species as well as other biological parameters (phytogeographic distribution, the natural benthic habitat and times of fertilization), a method is presented to uncover possible interspecific cross-reactions of such algal communication systems as a chemical warfare device in their fight for living space.