Zebrafish are a powerful animal model for small molecule screening. Small molecule treatments of zebrafish embryos usually require that the chorion, an acellular envelope enclosing the embryo, is removed in order for chemical compounds to access the embryo from the bath medium. For large-scale studies requiring hundreds of embryos, manual dechorionation, using
forceps, can be a time-consuming and limiting process.
Pronase is a non-specific
protease that is widely used as an enzymatic alternative for dechorionating zebrafish embryos. However, whether
pronase treatments alter the effects of subsequent small molecule treatments has not been addressed. Here, we provide a detailed protocol for large-scale
pronase dechorionation of zebrafish embryos. We tested whether
pronase treatment can influence the efficacy of
drug treatments in zebrafish embryos. We used a zebrafish model for
Duchenne muscular dystrophy (DMD) to investigate whether the efficacies of
trichostatin-A (
TSA) or
salermide +
oxamflatin, small molecule inhibitors known to ameliorate the zebrafish dmd muscle degeneration phenotype, are significantly altered when embryos are treated with
pronase versus manual dechorionation. We also tested the effects of
pronase on the ability of the
anthracycline cancer drug doxorubicin to induce
cardiotoxicity in zebrafish embryos. When comparing
pronase- versus
forceps-dechorionated embryos used in these small molecule treatments, we found no appreciable effects of
pronase on animal survival or on the effects of the small molecules. The significant difference that was detected was a small improvement in the ability of
salermide +
oxamflatin to ameliorate the dmd phenotype in
pronase-treated embryos when compared with manual dechorionation. Our study supports the use of
pronase treatment as a dechorionation method for zebrafish
drug screening experiments.