Parental exposure to CdSe/ZnS QDs affects otolith development and locomotor behavior in rare minnow (Gobiocypris rarus) offspring

Quantum dots (QDs) influence otolith development and locomotor behavior, although the underlying mechanism remain unclear. This study evaluated the toxicity of CdSe/ZnS QDs on otolith development and locomotor behavior in the next generation (F1) using rare minnows (Gobiocypris rarus) as model organisms. The sexually mature parents of rare minnows (F0) were exposed to varying concentrations of CdSe/ZnS QDs (0, 100, 200, 400 and 800 nmol/L) for four days, after which embryos were collected through artificial insemination. The results indicated that exposure to varying concentrations of QDs inhibited the growth of utricular and saccular otoliths in F1 larvae, evidenced by a decrease in otolith lateral area. Furthermore, an increase in malformations and mortality rate were observed, alongside reductions in swimming speed, movement distance and overall calcium content, ultimately resulting in loss of balance control in F1 larvae. Exposure to CdSe/ZnS QDs also suppressed the transcript expression of the atp2b1a, stm and sparc genes, while promoting the transcription of cahz, ecac and omp1 genes. Notably, the adverse effects of CdSe/ZnS QDs on otolith growth and swimming behavior could be mitigated by supplementing Ca²⁺ in the environment. Following calcium supplementation, the damage to otolith development in larvae was alleviated to some extent, and locomotor behavior returned to normal. Overall, the results suggest that CdSe/ZnS QDs can adversely affect otolith development and locomotor behavior in F1 larvae of rare minnows at both individual and molecular levels, ultimately leading to impaired swimming abilities and balance control.