The T-related gene (Trg), a Brachyury homologue in insects

Abstract

The T-related gene (Trg) of Drosophila is a member of the T-box gene family and displays a high degree of similarity to the vertebrate Brachyury genes. Trg acts down-stream of the terminal gap genes tailless and huckebein and is required for the development of a particular organ, the hindgut. It is expressed throughout embryogenesis, first at the end of the blastoderm stage in the primordium of the hindgut close to the posterior pole of the embryo, then in the differentiating hindgut during gastrulation and organogenesis. A corresponding expression pattern of Trg homologues in the developing hindgut of short germ insects implies that the function of Trg in gut development has been highly conserved during evolution. This conservation in insects and the high similarity between Trg and the chordate Brachyury genes allows speculations about a link between gut parts of insects and notochord of chordates.