QUANTITATIVE-EVALUATION OF EROTACTIN SECRETION IN EGGS OF HORMOSIRA-BANKSII (FUCALES, PHAEOPHYCEAE)

The release of the C-11-hydrocarbon spermatozoid attractant hormosiren e by eggs of the Australian fucoid Hormosira banksii has been determin ed quantitatively using a closed-loop extraction technique. The eggs s ecrete erotactin for more than 2 weeks with an exponentially decreasin g rate. The initial secretion rate was estimated to be 7 5 fmol h-1 eg g-1 and the total amount of hormosirene produced per egg to be 2.35 pm ol (0.35 ng). The results were used to calculate the threshold range f or spermatozoid chemotaxis in the pheromone gradient around eggs.