Effects of chlorinated benzenes on diatom fatty acid composition and quantitative morphology. III. 1,2,3-Trichlorobenzene.

Cells of the diatom Cyclotella meneghiniana were exposed in a closed system to 0.245 ppm 1,2,3-trichlorobenzene. Response of the diatom was measured by quantitative ultrastructure and fatty acid percent composition over a 5-day period. During that time, 35 significant morphological and 12 fatty acid percent composition changes occurred. The most pronounced morphological change that occurred was a significant increase in lipid volume. In addition, changes were observed in vacuolar relative volume, suggesting that the tonoplast became more permeable. Fewer significant changes were observed in fatty acid percent composition upon exposure to this isomer. However, there was a consistent increase in oleic acid (C18:1). The observed changes in morphological and fatty acid percent composition were uniformly distributed with time after the first hour of exposure. Results support the hypothesis that increased lipid stores may alter the timing of response to lipophilic toxicants.