Retinoblastoma binding protein 6 and crystallin lambda 1 are cadmium-responsive genes in zebrafish embryos and adults retinae

Nonessential metal cadmium is widely used and released in the environment, causing cell toxicity and posing a severe threat to wildlife. Zebrafish (Danio rerio) is one of the most commonly used animals in the investigation of environmental cadmium toxicity in vertebrates. In this study, we identified two cadmium-responsive genes, RBBP6 and CRYL1, in the early phases of zebrafish development, at the gastrula stage. The retinoblastoma binding protein 6 is associated with increased protein degradation and cell proliferation; crystallin-lambda 1 is a lens protein with redox activity. In situ hybridization analysis performed on adult zebrafish exposed to 1.5-40 μM cadmium for 30 days confirmed the ability of cadmium to up-regulate the expression of both genes in retinal cells in a dose-dependent manner. The over-expression was transient, being switched off when cadmium was removed. The involvement of RBBP6 and CRYL1 in the onset of cadmium-induced morphological alterations in adult zebrafish retina is discussed.