Selenium is an essential micronutrient found in selenoproteins.These proteins have selenocysteine residues, also known as the 21st amino acid, which encode for UGA, a STOP codon. Although they have remained dismissed for many years, they play essential roles in redox signaling, antioxidant defense, thyroid hormone metabolism and immune response, being crucial for the proper functionality of the organism (22).

    The aim of this study is to determine the selenoproteome in Xiphophorus Couchianus genome, including its selenoproteins, cysteine homologues and machinery genes, involved in their synthesis.

    It was performed by using a variety of bioinformatic tools, which have enabled a comparison analysis between the genome of interest and Zebrafish genome. This comparison was made as these species are closely related in terms of evolution and homology based analysis were possible due to high degree of conservation between them.

    This study is supposed to contribute in the identification of selenoproteins in the different organisms, as they are largely widespread through kingdoms. Therefore, a better understanding of the different evolutionary mechanisms among the years and between species can be achieved.