Biological effects of Ni and Chlorpyrifos in the form of single chemicals and mixture. The wire charts depict the biomarker outcomes obtained in tissues of animals challenged with Ni, Chlorpyrifos and their mixtures at nominal equitoxic levels for lysosomal membrane stability. A. Digestive gland lysosomal membrane stability (LMS) determined as residual N-acetyl-B-hexosaminidase activity (% labilization time) in cryostat section; 100% activity was obtained in control samples at 20 min of incubation in acidic-citrate buffer. B. Digestive gland lysosome/cytoplasm ratio in same sections. C. Digestive gland lysosomal lipid accumulation (fold change) evaluated by red oil staining and digital image analysis in cryostat section. D. Gill acetylcholinesterase residual activity (%) evaluated in S10 supernatant; 100% activity was calculated in control samples as 60.3 μmoles/min/mg. Legend (blue square, 0 TU, control; red diamond, 0.25 TU; yellow inverted triangle, 0.50 TU; green triangle, 1 TU). Symbols marked with a color other than grey depict a difference with respect to control (Mann Whitney U-test, p < 0.05).