Tissue-expression pattern of elovl4 genes in Sparus aurata and Solea senegalensis: from larvae to adult

Very long-chain (˃ C24) fatty acids (VLC-FA) play critical roles during early development of vertebrates, since these compounds are accumulated in the rapidly forming neural tissues, ensuring their normal function. The functionality of VLC-FA has aroused scientific interest, focusing on the study of elongases protein 4 of very long chain fatty acid (Elovl4), which are responsible for their biosynthesis from shorter fatty acids (precursors). For a better understanding of the metabolism and the potential tissue-specific requirements of VLC-FA in marine teleosts, the present study aimed to determine the tissue-expression pattern of the genes that encode for Elovl4 isoforms, i.e. elovl4a and elovl4b, in different windows of development (larval and adult stages) of Gilthead seabream Sparus aurata and Senegalese sole Solea senegalensis. The results indicated that in S. aurata larvae, elovl4a is widely expressed in the head, while elovl4b is strongly focused in the eyes. Interestingly, in S. senegalensis larvae an opposite tissue-expression pattern was observed for both elovl4 isoforms. In adults of both fish, although elovl4 transcripts were detected in most tissues analyzed, elovl4a and elovl4b genes were strongly expressed in brain and eyes, respectively. Importantly, the differential tissue-expression pattern of both elovl4 isoforms associated to the pre- and post-metamorphic stage of S. senegalensis could be indicative of the VLC-FA particular needs linked to neural tissues functionality in each development stage. These findings can contribute to a better understanding of the species-specific VLC-FA metabolism in marine teleosts.