Amino acid flux in the sporocysts ofCercaria emasculansPelseneer, 1906in vitro

Abstract

Quantitative paper chromatography and radioactive tracers were used to study the flux of alanine through the sporocysts ofCercaria emasculans in vitro. The following evidence indicates that simple diffusion is the main mechanism of permeation: (1) the sporocysts cannot accumulate alanine against a concentration gradient; (2) the concentration of alanine in the sporocysts is a direct linear function of the concentration of alanine in the external environment; (3) addition of 10−2M glucose to the medium does not enhance permeation; (4) neither heat-killing the sporocysts nor treating them with 10−3M iodoacetate slows the rate of permeation; (5) theQ10's for the permeation are similar to those to be expected in a process involving simple diffusion; (6) the amino acid molarities in the parasite and host tissuesin vivoare strikingly similar. No utilization of alanine during the course of 3 h incubations could be detected by autoradiography.The dynamic nature of the equilibrium between the sporocysts and the external environment is emphasized by the exchange of alanine that occurred even under isotonic conditions.Fresh sporocysts leaked alanine and proline during 1 and 4 h incubationsin vitro. The significance of this is not known.