Effects of polycyclic aromatic hydrocarbons on molluscan lysosomes and endoplasmic reticulum

Some effects of two isomeric polycyclic aromatic hydrocarbons, anthracene and phenanthrene, on the fine structure and cytochemistry of digestive cells in the marine mussel Mytilus edulis have been investigated. The cytochemical results show that increasing concentrations of anthracene and phenanthrene have different effects on the acid labilization time for latent beta-glucuronidase which is used to measure the stability of lysosomal membranes. At the ultrastructural level the limiting membranes of secondary lysosomes appear multilayered, with discontinuities and overlaps. Under the conditions of the experiment, only phenanthrene produces changes in this configuration. Both macroautophagic and microautophagic processes occur in the control and hydrocarbon treatments, and complementary data from other studies indicate that autophagic processes are enhanced by polycyclic aromatic hydrocarbons. Phenanthrene also causes proliferation of the smooth endoplasmic reticulum in the digestive cells, although cytochemical measurements of smooth endoplasmic reticulum-associated NADPH-ferrihemoprotein reductase show that anthracene stimulates activity over a greater range of concentrations than phenanthrene. The different effects of the two isomers is taken as evidence that the molecular configuration of the compound determines its reactivity with membranes and its subsequent effect on the physiology of the cells.