A preliminary gene expression analysis on Paracentrotus lividus embryos exposed to UVB, Cadmium and their combination

Paracentrotus lividus is a Mediterranean and Eastern Atlantic sea urchin species, very sensitive to chemical andphysical environmental changes and widely used in eco-toxicological studies. Here, we applied a highthroughput screening approach on P. lividus embryos exposed to UVB radiation (UV), Cadmium Chloride (Cd)and their combination (Cd/UV), to deeply characterize the molecular responses adopted by embryos to cope withthese stressors. in vitro eco-toxicological assays were performed by exposing embryos to Cd (10? 4 M) soon afterfertilization, to UV (200 and 400J/m2) at early stage of development, while in co-exposure experiments, Cdexposedembryos were irradiated with UV at 200 J/m2. By NanoString nCounter technology, custom-madeprobes were developed and hybridized on total RNA extracted from exposed embryos at 51h after fertilization.By in silico analyses, we selected and retrieved at the NCBI nucleotide database a panel of P. lividus transcriptsencoding for many regulatory and structural proteins that we ranked in categories, i.e., Apoptosis,Biomineralization, Defense, Development, Immunity, Signaling and Transcription Factors. The analysis of 127transcripts highlighted the dysregulation of many genes, some specifically activated to cope with stress agents,others involved in the complex molecular network of genes that regulate embryo development. We revealed thedownregulation of Biomineralization and Development genes and the upregulation of Defensive genes in Cd andCd/UV embryos. Our approach, using sea urchin embryo as an in vivomodel, contributes to advance ourknowledge about cellular responses to UV, Cd and their combination.