Perfluorooctane sulfonate (PFOS) and ZnO nanoparticles (ZnO-NPs) are frequently detected in the environment, but few studies have assessed their joint toxicity. In this study, the acute toxicity and chronic toxicity to zebrafish (Danio rerio) induced by PFOS in the presence of ZnO-NPs were investigated, including developmental toxicity and DNA damage. The embryos were exposed to PFOS (only) (0.4, 0.8, and 1.6 mg/L) and PFOS plus ZnO-NPs (0.4 + 50, 0.8 + 50, and 1.6 + 50 mg/L) solutions to evaluate mortality (96 h), body length (96 h), hatch rate (72 h), heart rate (48 h),and malformation rate (96 h). The results revealed that the co-treatment could cause more severe developmental toxicity compared with the control and single-treatments, and the toxic effects generally increased in a dose-response manner. In addition, adult zebrafish were exposed to single and mixed solutions of PFOS and ZnO-NPs (at the concentrations mentioned above) for 30 days. DNA damage to zebrafish was evaluated by the comet assay and micronucleus test. We found that the PFOS single-treatment at all doses (0.4, 0.8, and 1.6 mg/L) could strongly induce DNA damage to peripheral blood cells and that ZnO-NPs could aggravate the formation of DNA damage in co-treatments. Histological examination of liver, testicle, and ovary showed that the presence of ZnO-NPs (50 mg/L) could also cause more serious histological damage to adult zebrafish than PFOS alone. As a result, the synergistic effects played an important role during joint exposure. Our observations provide a basic understanding of the joint toxicity of PFOS and ZnO-NPs to aquatic organisms.

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Angiotensin-I converting enzyme (ACE) has an important function in blood pressure regulation. ACEinhibitory peptides can lower blood pressure by inhibiting ACE activity. In this investigation, water-soluble proteins were extracted from yeast (Saccharomyces cerevisiae) and hydrolyzed by yeast protein extraction enzyme to isolate ACEinhibitory peptides. Peptides with ACE-inhibitory activity were further separated and purified by ultrafiltration and fast protein liquid chromatography (FPLC). A hexapeptide, Thr-Pro-Thr-Gln-Gln-Ser, with a calculated molecular weight of 660Da, was purified and identified by MALDI-TOF-MS. The hexapeptide showed remarkable ACE-inhibitory activity, with an IC 50 of 73.25 μg/mL. The level of ACE-inhibitory activity of the hexapeptide indicated that it is a good candidate for development of a hypotension drug or functional food.

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