A cluster of four globin genes from the Antarctic fish Notothenia coriiceps.

The blood of Channichthyidae, the most phyletically derived notothenioid family, is devoid of haemoglobin (Hb). Three of the 15 channichthyid species retain inactive genomic remnants of the major adult notothenioid alpha-globin gene, but have lost the gene encoding adult beta-globin. In an attempt to understand the mutational events leading to loss of globin expression in channichthyids, the organisation of globin genes in red-blooded notothenioid species was examined. Globin genes in fish are often organised as alpha/beta pairs linked in 5’ to 5’ orientation, and the major adult alpha- and beta-globins of the Antarctic yellowbelly rockcod Notothenia coriiceps have this organisation. A second globin gene cluster from N. coriiceps contains two sets of linked alpha- and beta-globin genes but the deduced amino acid sequences of the globins differ from those of the adult globins. To test the hypothesis that the globins may be expressed at different stages of ontogenesis, total RNA from head kidney and erythrocytes of adult and juvenile N. coriiceps were probed for transcripts corresponding to the four globin genes. The data suggest that the globin genes of this cluster are transcribed maximally in the early phase of development. Southern analysis of the genomes of red- and white-blooded notothenioids revealed that the genes of this complex are absent in Hb-less icefish.