The present study investigated the effects of dietary iron (Fe) exposure on physiological performance and homeostatic regulation of trace metals during development (5-28 days post-fertilization; dpf) in zebrafish (Danio rerio). The results demonstrated that whole body Fe content was increased in 14 dpf larvae fed a high Fe diet. Cumulative mortality was also significantly elevated during exposure to the high Fe diet. Using droplet digital PCR, we observed that high Fe-exposed larvae exhibited an increase in mRNA levels of the Fe-storage protein ferritin, which appeared to be associated with the elevated level of whole body Fe content. Further, the results indicated that dietary Fe exposure induced transient changes in the mRNA expression levels of various metal transporters, including the iron transporter dmt1, and the zinc transporters zip8 and zip14. The expression of the epithelial Ca channels (i.e., ecac) was also found to increase by high dietary Fe. Overall, our findings suggest that larval fish during the early nutritional transition period are sensitive to the effects of dietary Fe.
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