Developmental expression and cDNA cloning of globin genes from the brine shrimp, Artemia

The brine shrimp, Artemia, is unusual in having large (130 kD) extracellular hemoglobins composed of two globin chains, each of which is a polymer of at least eight myoglobin-like domains. Hemoglobin first appears at the time of naupliar hatching apparently as a result of a physiological switch. Globin gene expression is induced at this time, indicating transcriptional control of hemoglobin synthesis during early development. From a globin partial cDNA clone constructed by a primer extension strategy, we have derived the amino acid sequence of a region that links two of the myoglobin-like domains together. The post H region of the myoglobin-like domain has adapted to accommodate the fusion of these domains. We used the partial cDNA to isolate two classes of large clones containing globin cDNA, and thus established that there are at least two distinct hemoglobin genes in Artemia.