In silico analysis using profile-based database searches identified 33 candidate globins in the complete genome sequence of C. elegans which can be aligned so as to fit determinants of the globin fold. All putative globins display a remarkable structural diversity with lengths ranging from approximately 150 to 540 aa residues, some of them featuring N- or C-terminal and internal extensions of unusual length. Evolutionary analysis of the core globin domains shows that the majority of these globins are very divergent from each other, suggesting a long evolutionary history. The putative globin genes are distributed over all 6 chromosomes and analysis of the gene structures revealed that absolutely no conservation could be observed in the number of exons and introns or in the intron insertion positions. All putative globins have orthologs in C. briggsae and C. remanei and some display significant sequence similarity to vertebrate myoglobin, neuroglobin and cytoglobin. Highly synchronous cultures of C. elegans were studied to establish the temporal pattern of globin gene expression throughout its life cycle. Results indicate that nearly every globin is expressed in all stages of development with significant differences in expression levels between particular life cycle stages. Real-time quantitative PCR amplifications demonstrate that several of them display upregulation in WT worms upon exposure to oxygen deprivation. Additionally we evaluated globin gene expression in
daf-2 worms, which are known to be hypoxia resistant. Results show that the majority are expressed at lower levels compared to WT worms and that the expression level of ZK637.13 is induced significantly by 4-fold. Expression cloning and determination of physical characteristics is in progress for a subset of putative globins, selected on deviations from the globin template. Preliminary results indicate that the canonical globin ZK637.13 exhibits normal ligand binding properties whereas T22C1.2 displays remarkable functional characteristics.