Cloning, expression and functional study of translation elongation factor 2 (EF-2) in zebrafish.

We have identified translation elongation factor 2 (EF-2) in zebrafish (GenBank Accession No. AAQ91234). Analysis of the DNA sequence of zebrafish EF-2 shows that the 2826 bp cDNA spans an open reading frame between nucleotide 55 to 2631 and encodes a protein of 858 amino acids. Zebrafish EF-2 protein shares 92%, 93%, 93% and 92% identity with the corresponding amino acid sequence in human, mouse, Chinese hamster and Gallus EF-2, respectively. Whole-mount in situ hybridization showed that zebrafish EF-2 was a developmentally regulated gene and might play important roles during the early development of zebrafish embryos. Therefore, we further studied the function of EF-2 during early embryogenesis. Using morpholino antisense oligo knockdown assays, anti-MO injected embryos were found to display abnormal development. The yolk balls were larger than normal and the melanophores spreading on their bodies became fewer. Furthermore, their tails were incurvate and their lenses were much smaller than those of the normal embryos. However the EF-2 overexpression data showed that extra EF-2 protein had no obvious effect on zebrafish embryonic development.