HEMOGLOBINS OF KIEFFERULUS, SISTER GENUS OF CHIRONOMUS (DIPTERA, INSECTA) - EVOLUTION OF THE HB VIIB CLUSTER

A genomic clone containing hemoglobin genes was isolated from a specie s of the chironomid genus Kiefferulus. Eight genes, including an appar ent pseudogene, were sequenced and the amino acid sequences of the put ative proteins were determined. By comparison to the previously descri bed hemoglobins in the sister-genus Chironomus, they were identified a s members of the dimeric Hb VIIB group. The results indicate that the existence of clusters of hemoglobin genes may be a common feature in c hironomids and not just confined to Chironomus. The Kiefferulus genes show greatest similarity of amino acid sequence to Hb VIIB-7 from the Chironomus cluster. The results suggest that the ancestral cluster con tained at least two gene types, one of which gave rise to VIIB-7 and t he Kiefferulus genes while the other gave rise to the other Chironomus VIIB genes. Both clusters appear to have increased in size by duplica tion or unequal crossing over since the separation of the genera. It a lso appears that an unrelated gene present in the Chironomus cluster, Hb-Y, arose from a completely independent origin with no apparent equi valent gene anywhere in the genome of Kiefferulus or some other Chiron omus species.