1Fukuoka Industrial Technology Center, Biotechnology and Food Research Institute, Kurume, Fukuoka 839-0861, 2Fukuoka Fisheries and Marine Technology Research Center, Imazu, Fukuoka 819-0165, Japan
Previously, we reported on the seasonal variation of the mucilage polysaccharide content of Akamoku Sargassum horneri in the Chikuzen Sea (Fukuoka prefecture), and suggested a relationship between fucoidan content and sexual maturation of the alga. To confirm this finding, we conducted further investigations of the mucilage polysaccharide content depending on male-female difference and alga maturation stage, focusing on receptacles. It was found that most of the fucoidan is contained in receptacles, and the amount of fucoidan increases in the receptacle elongation stage, and decreases after the gamete releasing stage. These findings strongly suggest that fucoidan participates in the reproduction of Akamoku. Additionally, the sugar composition and the sulfated rate of fucoidans derived from Akamoku receptacles revealed that there is no notable difference in composition between male and female plants. Based on these results, we propose using the formation of receptacles as a criterion to decide the season for picking fucoidan-rich Akamoku alga.