Colchicine, nocodazole and trifluralin: different effects of microtubule polymerization inhibitors on the uptake and migration of endosymbiotic algae in Hydra viridis.

Hydra viridis (= Chlorohydra viridissima) the freshwater coelenterate, is symbiotic. Each individual animal harbours Chlorella sp. in its endodermal cells. The symbiosis may be disestablished, the partners grown independently, and then re-established experimentally. The most effective method to produce alga-free hydra was developed by Pardy (1976). In this study algae from homogenized H. viridis, English (= European) strain, were either used directly or first grown in pure culture and then injected to re-establish the symbiosis. The uptake of algae grown in culture was compared with that of algae released directly from fresh hydra. Fewer cultured algae were taken up. Four strains were tested: English, Carolina, Frome, and Jubilee. Each takes up a characteristic number of Chlorella when injected in excess. Colchicine, nocodazole and trifluralin, were tested for their effects on either uptake or migration. Colchicine had no effect. Nocodazole and trifluralin reduced both the number of algae taken up and the rate at which they were transported to the distal region of the hydra digestive cell. The effects of these drugs tended to be proportional to the concentration between 10(-8) and 10(-5) M.