Carbonic anhydrases in development: morphological observations and gene expression profiling in sea urchin embryos exposed to acetazolamide.

Carbonic anhydrases (CANs) are conserved metalloenzymes catalysing the reversible hydration of carbon dioxide into protons and bicarbonate, with important roles in cells physiology. Some CAN-coding genes were found in sea urchin genome, although only one involved in embryonic skeletogenesis was described in Paracentrotus lividus . Here, we investigated gene expression patterns of P. lividus embryos cultured in the presence of acetazolamide (AZ), a CAN inhibitor, to combine morphological defects with their molecular underpinning. CAN inhibition blocked skeletogenesis, affected the spatial/temporal expression of some biomineralization-related genes, inhibited embryos swimming. A comparative analysis on the expression of 127 genes in control and 3 h/24 h AZ-treated embryos, using NanoString technology, showed the differential expression of genes encoding for structural/regulatory proteins, with different embryonic roles: biomineralization, transcriptional regulation, signalling, development and defence response. The study of the differentially expressed genes and the signalling pathways affected, besides in silico analyses and a speculative 'interactomic model', leads to predicting the presence of various CAN isoforms, possibly involved in different physiological processes/activities in sea urchin embryo, and their potential target genes/proteins. Our findings provide new valuable molecular data for further studies in several biological fields: developmental biology (biomineralization, axes patterning), cell differentiation (neural development) and drug toxicology (AZ effects on embryos/tissues).