Evolution and expression of the amphioxus AmphiHMGB gene encoding an HMG-box protein

Amphioxus HMGB gene, AmphiHMGB, encoding a high mobility group (HMG) protein was identified from the gut cDNA library of Branchiostoma belcheri tsingtauense. Primary structural examination indicates that it is a member of HMGB family. Molecular phylogenetic analysis suggests that AmphiHMGB represents the archetype of chordate HMGB genes including HMGB1, HMGB2 and HMGB3 although it may have lost its C-terminal domain during evolution. Northern blotting revealed that AmphiHMGB expression was restricted mainly to guts in the adult, and AmphiHMGB transcripts were in greater abundance in gastrula and neurula though they were markedly low in 1-day larva.