Algae. 1999; 14(3): 155-160.

Chemotactic Effects of Nutrients and Thallus Extracts on Gametes of a Green Alga, Ulva pertusa Kjellman

Byeong Jik Park, Taejun Han

Department of Biology, University of Inchon

Gametes of a green alga, Ulva pertusa Kjellman exhibited chemotactic responses to a variety of concentrations of the chemical nutrients and thallus extracts. Chemotaxis was measured by counting the number of gametes that swam into glass capillary tubes with artificial seawater containing the chemical or biological agents relative to the number of that swam into control tubes with artificial seawater only. Similar chemotactic effects were observed between one and four day-okd preparations of U. pertusa gametes. Positive chemotaxis has been observed with nitrate concentrations of 0.01, 0.1 M and with posphate concentration of 1 mM. Low concentrations of nitrate (0.001 M) and phosphate (0.01 M) elicited negative chemotaxis. There was no significant chemotactic response at 0.1 mM of phosphate. When different concentrations of maternal thalli extracts (5,10,25,50, 100 g FW/500 ml ASW) were given gametes showed negative chemotactic responses except for concentration of 0.5 g FW/500 ml ASW where there was no effect. All concentrations of thallus extracts (0.5,5, 50 g FW/500 ml ASW) of the red alga Pachymeniopsis sp. had no effect on chemotactic responses of U. pertusa gametes.

Keywords : chemotaxis, gametes, nitrate, Pachymeniopsis sp., phosphate, thallus extracts, Ulva pertusa