Tracking the evolutionary loss of hemoglobin expression by the white-blooded Antarctic icefishes.

摘要: Abstract The blood of Antarctic icefishes (family Channichthyidae, suborder Notothenioidei) is completely devoid hemoglobin. Icefishes have developed compensatory adaptations that reduce oxygen demand and enhance transport. Oxygen delivery to tissues occurs by carrying the gas physically dissolved in plasma. To evaluate evolutionary pathway leading icefish hemoglobinless phenotype, adult embryonic/juvenile gene complexes from a closely related, red-blooded notothenioid species were isolated characterized. hybridization pattern globin cDNAs showed genomes three retain transcriptionally inactive α1-globin-related DNA sequences, which are identical truncated variants α1-globin fish, containing part intron 2, all exon 3, 3′-untranslated region. no β-globin genes. Furthermore, Southern blots genomic red- white-blooded (two species) notothenioids, probed with fragments genes flanking ends complex, indicated also lost It proposed inability express hemoglobin arose single, large-scale deletional event, removed exception 3′ end α1 .