Chemical nature of the egg shell in helminths: II. Mode of stabilization of egg shells of monogenetic trematodes

Abstract

The chemical nature of the egg shells of the monogenetic trematodes Pseudomicrocotyle sp. and Pricea multae, parasitizing the gills of the marine fish Scomberomorus guttatus was studied with a view to understanding the mode of stabilization of the egg shells. The egg shells of the monogenetic trematodes appeared to contain dimers of tyrosine; a conclusion based on fluorescence properties, affinity to toluidine blue, methylene blue, and a positive test for aromatic amino acids. In addition, they are stabilized by -S-S- linkages as indicated by the positive reaction to tests for disulfides. This is also suggested by the shells being refractile to stain but which can be reversed after treatment with sodium thioglycollate. Absence of phenolic tanning in the egg shells of the monogenetic trematodes is indicated by the negative reaction to tests for quinones, the failure to develop color on incubation in catechol after heat treatment, and by the fluorescence in uv light. In these respects the egg shells of the monogenetic trematodes strongly resemble the egg shell of Fasciola hepatica.