Identification and characterization of globin genes from two lepidopteran insects, Bombyx mori and Samia cynthia ricini

We describe the characterization of hemoglobin-like genes from two lepidopteran insects, Bombyx mori (Bmglobin) and Samia cynthia ricini (Scglobin). Bmglobin and Scglobin are predicted to be intracellular proteins and contain amino acids required for heme and oxygen binding. Expression profiles of two lepidopteran globins, especially Bmglobin, were different from that of other insect globins. Although other insect globins are mainly associated with the tracheal system, Bmglobin was expressed almost exclusively in the Malpighian tubules, and the strongest signal for Scglobin was detected in the fat body. Furthermore, biochemical fractionation analysis revealed that both Bmglobin and Scglobin were localized in the cytoplasm. These results suggest that each lepidopteran globin has a distinct role in the tissues in which it is expressed and that the functions of insect globins are more divergent than previously thought.