2,2′,3,5′,6-Pentachlorobiphenyl (PCB-95) is an environmental neurotoxicant. There is accumulated evidence that some neurotoxic effects of PCB-95 are caused by increased spontaneous Ca 2+ oscillations in neurons resulting from modifying ryanodine receptors (RyR) in calcium-releasing channels. However, there are large gaps in explaining brain and other developmental malformations on embryonic PCB-95 exposure. In the present study, we address those deficiencies by studying the toxic effects of PCB-95 using zebrafish as an ontogenetic model. To characterize these effects, zebrafish embryos with intact chorions were exposed to 4 different concentrations of PCB-95 (0.25, 0.5, 0.75, and 1 ppm) for 3 consecutive days. The controls were maintained in 0.5 × E2 medium or egg water and in 0.1% (v/v) dimethyl sulfoxide (DMSO)/0.5 × E2 medium or egg water. PCB-95-treated groups showed dose-dependent decreases in survival and hatching rates, with increased rates of developmental malformations when compared to controls. These include morphological malformations, brain cell necrosis, and smaller eye sizes at 5 d post fertilization. These data suggest potential mechanisms underlying the abnormal behavior observed in a visual stimulus assay. The present study provides insight into PCB-95induced developmental toxicity and supports the use of the zebrafish model in understanding the effects of PCB-95 exposure. Environ Toxicol Chem 2020;39:162-170. © 2019 SETAC The Tg(elavl3:EGFP) line, maintained at Brown University, expresses enhanced green fluorescent protein and was utilized wileyonlinelibrary.com/ETC © 2019 SETAC Embryonic PCB-95 exposure and developmental malformations-Environmental Toxicology and Chemistry, 2020;39:162-170 Zhang XQ, Yang L, Zhang M, Guo X, Chi X. 2015. PCB1254 exposure contributes to the abnormalities of optomotor responses and influence of the photoreceptor cell development in zebrafish larvae. Ecotoxicol Environ Saf 118:133-138.

2,2',3,5',6-Pentachlorobiphenyl (PCB-95) is an environmentally significant chiral PCB, of which enantioselective toxicity, biodegradation and chiral stability studies have been limited to date, as no commercially available enantiomers exist for PCB-95 and due to the lack of an efficient preparatory chiral separation method. A selective, sensitive, and rapid high-performance liquid chromatography with UV detection (HPLC-UV) method has been developed and validated for the chromatographic separation and quantitation of PCB-95 enantiomers. In this study, we resolved enantiomers of PCB-95 using a cellulose tris (4-methylbenzoate) Chiralcel OJ-H column. After evaluating mobile phase compositions and temperatures, optimum separation and detection were obtained with isocratic 100% n-hexane as the mobile phase, a column temperature of 20°C, a flow rate of 1 mL/min, and a detection wavelength of 280 nm. The total run time was 8 minutes. Enantiomer purity was confirmed using enantioselective gas capillary chromatography-electron capture detection. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to limit of detection, limit of quantification, precision, linearity, robustness and ruggedness.

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