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Evolutionarily conserved developmental pathways

Determination of endodermal and ectodermal portions of the digestive system - Transcription factors required for development of the gut

Forkhead is not required in Drosophila for the development of gut endoderm but instead for ectodermal gut derivatives. forkhead expression marks both the anterior and posterior gut primordia. Anterior derivatives include the foregut (pharynx and esophagus); the posterior derivative consists of the hindgut (proctodeum). In vertebrates there is a bewildering array of forkhead derivatives, many involved in mesoderm determination, and some expressed in anterior gut derivatives. The C. elegans Forkhead homolog, like Drosophila Forkhead, is expressed in ectodermal gut derivatives.

HNF-4 is required in Drosophila for gut formation. The vertebrate homolog plays a pivotal role in gut differentiation and expression of genes expressed in gut and other endodermal derivatives.

Serpent, the GATA homolog required for endodermal gut differentiation, is also required in mesoderm for hemocyte formation. This dual requirement is evolutionarily conserved. As many as six vertebrate GATA factors are involved in gut and/or erythrocyte determination and differentiation.

Drosophila                        Homologs in other species 
----------                        ----------------------------


Forkhead                          C. elegans: Ce-fkh-1
                                  Xenopus: XFKH1/Pintallavis/XFD1
                                  Mammalian: HNF-3

HNF-4                             Xenopus: HNF-4 alpha and beta
                                  Mammalian: HNF-4 

Serpent                           Xenopus: GATA-4, -5 and -6
                                  Mammals: GATA-4, -5 and -6

date revised: 24 FEB 97

Developmental Pathways conserved in Evolution

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