Hormonal Coordination of the Processes Leading to Cell Fusion in Algae: A Glycoprotein Hormone from Red Algae

Abstract

In a number of algae and fungi, sexual reproduction, including the induction of sexuality, the meeting of gametes, and gamete fusion, have been shown to be coordinated by specialized morphogenetic substances. These substances differ widely in their chemical composition. Among the fungi, substances which induces sexual morphogenesis include oligopeptides in some Ascomycete and Basidiomycete yeasts [1, 9, 12], steroids in the watermold Achlya [6], and carotenoids in Mucoralean fungi [2]. In the water mold Allomyces, a cyclic sesquiterpenediol has been identified as a sexual attractant [5]. Among the algae, inducers of sexual morphogenesis have only been identified in the colonial green alga Volvox. Within this genus, a glycoprotein male inducer has been characterized from V. carteri [3, 10], while in V. capensis a single amino acid, L-glutamic acid, has been shown to trigger sexual development [11]. Among the brown algae a number of simple volatile hydrocarbons have been shown to act as species-specific sexual attractants; in some cases these may also serve as inducers of sperm release [4, 7, 8].