MOLTING IN A PARASITIC NEMATODE, PHOCANEMA-DECIPIENS - ROLE OF WATER-UPTAKE

Davey K. G. 1979. Molting in a parasitic nematode. Phocanema decipiens: the role of water uptake. International Journal for Parasitology 9: 121-125. The rate of uptake of 3H2O increases in Phocanema decipiens between 8 and 13 h after it has been activated by exposure to 37°C in 0.9% Nacl containing juvenile hormone (0.4 μl/ml), while worms incubated in the absence of the hormone show no such increase. The exchange volume of an activated worm is greater than that of an unstimulated worm, but direct measurement by dry weight determination shows that both stimulated and unstimulated worms have a similar water content. The uptake of 3HO into the excretory cell is more rapid in stimulated worms, although there is no increase in uptake into the pseudoceolomic fluid. Moreover, there is an increase in water content of the excretory cell in activated worms. These observations are best explained by postulating that in an unactivated worm two compartments exist and in only one of these is water freely available for exchange. In an activated worm, the water in both compartments is available for exchange. © 1979.