Expression patterns of FoxA genes during embryonic development of the leech Helobdella

According to morphological and physiological characteristics of species to improve genetic relationship in early evolutionary study . Regionalization of gut into pharynx, foregut, midgut and hindgut in Bilateria embryonic development. In recent years, developmental biologists use genetic and molecular techniques to study the embryos development. Orthologs of regulatory genes that specify endomesoderm have different developmental roles in Metazoa. Polychaete annelids have conserved gene expression of transcription factors such as FoxA in endomesoderm. Therefore, study of molecular development can predict phylogenetic relationships and figure out gut formation in embryonic development. Transcription factor Forkhead box A (FoxA) is a Fox gene family member. Fox family regulates embryonic development in endoderm, liver, lung, and the formation of the ventral neural development. In protostomes, FoxA orthologs gene has conserved expression in pharynx, forgut, midgut and hindgut region. FoxA orthologs gene not only plays an important role in gut development, but also involved ventral nerve cord formation in deuterostomes. This study use a in situ hybridization to observe expression patterns of FoxA genes during embryonic development of the leech Helobdella. The results show that Hro-FoxA3 express in endomesoderm during cleavage stage. Hro-FoxA2 conservatively express in foregut and hindgut region. Hro-FoxA1 express in specific neuronal precursor cells and Hro-FoxA3 express in ventral nerve cord during late stage. It is means FoxA orthologs play different role during leech embryonic development.