Zebrafish stocks (Danio rerio) were kept and used according to Home Office regulations (UK) at the University of Birmingham. For these experiments wild-type fish (AB* strain) were used. Adults were crossed pairwise and eggs were collected 10-15 minutes after fertilization. Microinjection solutions contained 30 ng/μl of plasmid DNA, 0,2% of phenol red (Sigma) and 15 ng/μl of Tol2 mRNA transcribed in vitro from pCS2:Tol2 plasmid using mMESSAGE machine SP6 Kit (Ambion). Injections were performed through the chorion and into the cytoplasm of zygotes using an analogue pressure-controlled microinjector (Tritech Research). More than 200 eggs were injected per construct and experiments were replicated at least three times. Embryos were kept according to65 in E3 Medium containing 50 ng/ml of gentamicin (Fisher Scientific) and 0,03% phenylthiourea (PTU, Sigma) in an incubator at 28.5°C.
