Molecular cloning and expression pattern of the DjStag gene in the planarian Dugesia japonica during embryonic...

We examined STAG-related gene (DjStag) expression in the planarian Dugesia japonica. This species is common in Far Eastern countries. The DjStag cDNA includes 1362 bp and contains a 489-bp open reading frame corresponding to a deduced protein of 162 amino acids, with a 170-bp 5'-UTR and a 703-bp 3'-UTR. Phylogenetic analysis showed that DjStag is an STAG/STAG-like member. We examined the expression pattern of DjStag in this planarian during embryonic development by whole-mount in situ hybridization. DjStag was detected in embryonic cells in the germ band at early embryo stages. The number of DjStag-positive embryonic cells increased in stage 5. Later, it was mainly expressed in lateral region parenchyma. In juveniles, extensive expression of DjStag was observed not only in the head and tail regions, but also in the parenchyma between the epidermis and the gastrodermis. We conclude that DjStag is expressed in the cellular subset that will become the neoblast cells of the adult flatworm. DjStag may play an essential role in spatial and temporal regulation during planarian embryonic development.