Gene structures of Branchiostoma floridae DIs and Trichoplax adhaerens DIs. A. Gene clusters of Bf.DI_a, Bf.DI_b and Bf.DI_c. The schematic position (under the coordinate) of Bf.DI_b indicates that this gene is on the minus strand. Two strong SECIS elements are located downstream of Bf.DI_b. B. Gene cluster of 6 Ta DIs. Ta.DI_h, Ta.DI_i and Ta.DI_j on the minus strand. A strong SECIS element is located downstream of each of Ta.DI_g, Ta.DI_i and Ta.DI_j.