Evolutionary implications of morphogenesis and molecular patterning of the blind gut in the planarian Schmidtea polychroa.

摘要: The formation of a through-gut was key innovation in the evolution metazoans. There is still controversy regarding origin anus and how it may have been either gained or lost during different bilaterian taxa. Thus, study groups with blind gut great importance for understanding this organ system. Here, we describe morphogenesis molecular patterning sexual triclad Schmidtea polychroa. We identify analyze expression goosecoid, commonly associated foregut, GATA, ParaHox T-box genes, members which are regionalization. show that GATA456a expressed triclads, while GATA456b localized dorsal parenchymal cells. Goosecoid central nervous system, unique gene identified, Xlox, detected association not isolated any brachyury complement S. polychroa, consists one tbx1/10, three tbx2/3 tbx20. Furthermore, absence genes like caudal also present other Platyhelminthes. This suggests GATA456, combination foxA, gut-specific mechanism conserved gut-associated midgut hindgut markers absent. Based on these data deviations spiral cleavage found more basal flatworms, propose lack an be loss even loss.