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ABSTRACT

Callopanchax toddi is a tropical fish species we know very little about. Here, we characterize its selenoproteome -i.e. all its selenoproteins- as well as the machinery it needs to be translated. Selenoproteins contain at least one selenocysteine (Sec) amino acid, which is encoded by the UGA codon. Specific elements- i.e. selenocystine insertion sequences (SECIS) - are required for this codon to codify a Sec, otherwise protein translation would be interrupted. In this study, the homology between Danio rerio and Callopanchax toddi is used by an algorithm running tblastn, exonerate, Seblastian, T-coffee and phylogeny.fr to map the selenoproteome and its machinery on the genome of C. toddi. Results show that the selenoproteome of C. toddi has 28 selenoproteins, one of which is part of selenoprotein machinery. There are also 13 cysteine-containing homologues, 6 of which are part of the selenoprotein machinery, too. These amount of selenoproteins and selenoprotein machinery is doubled if we compare it to the selenoproteome of mammals, like humans, due to Teleosts’ whole-genome duplication. In addition, we have found that SelenoO1 selenoprotein and MSRB3 machinery protein from C. toddi appear to have suffered a duplication when compared to Danio rerio. Unfortunately, some selenoproteins hasn’t been characterised here because of the unexpected proximity between predicted SECIS and the gene end. In future studies, interdisciplinary research, together with state-of-the-art bioinformatics, will be very useful to discover the unknown biology of C. toddi.