Embryogenesis and substratum adhesion in the brown algaHormosira banksii(Turner) Decaisne

Abstract

Following fertilization Hormosira zygotes rapidly acquire an adhesive surface coating that firmly attaches them to the substratum. It is not until 14–16 h after fertilization that rhizoids appear and these attach both by mucopolysaccharides and by physical interaction with the microtopography of the substratum surface. Histochemistry of the adhesive material indicates that it is probably a sulphated ester of fucose. This appears in the wall 3–4 h after fertilization, and up to this stage the adhesive materials contain large amounts of a carboxylated polyuronide alginic acid. Electron microscopy suggests that adhesive materials are generated within the Golgi apparatus and vesicles containing these substances are liberated into the walls closest to the substratum as well as into the actively growing rhizoids. There is also an accumulation of polyphenolic material in the tip of the developing rhizoid. Such compounds have been implicated in suppressing the growth of competitors for space on the intertidal rock platform.