Transcriptional analysis of tyrosinase gene expression during development.

Tyrosinase (EC.1.14.18.1.) is a widespread enzyme, in the phylogenetic scale, that produces melanin, from bacteria to man, by using as substrates monophenols, o-diphenols and molecular oxygen. In this work we have confirmed and demonstrated that during development tyrosinase activity and gene expression first occur at developmental stages 17-18 (tail bud-muscular response) as detected by a spectrophotometric assay and qRT-PCR. As expected, also during development tyrosinase gene is expressed after the late gastrula (stage 12), differently from development when tyrosinase mRNA appears at the neural plate stage and enzyme activity at stage 20 (gill circulation). We have cloned and sequenced the tyrosinase cDNA in order to prepare tyrosinase cDNA specific primers (forward and reverse). Tyrosinase mRNA cloning has been performed by using degenerate primers prepared according to the anuran tyrosinase gene sequence coding for the copper binding sites. The expressions of tyrosinase gene and enzymatic activity during development support that until the developmental stage 17, embryo melanin is of maternal origin and at this stage can start embryo melanin synthesis. A correlation exists between tyrosinase expression and O consumption during development.