Endogenous beta-galactosidase activity in amphioxus: a useful histochemical marker for the digestive system

Endogenous beta -galactosidase activity has been shown in the digestive tra ct of amphioxus from the larval to the adult stage and it can be easily fol lowed as a histochemical marker. Enzymatic activity first appeared in 30-h larvae, became evident in 36-h larvae and remained in adults. In situ detec tion of beta -galactosidase activity was used to monitor morphological and functional differentiation of the digestive system and the posteriorization of the endodermal structures in retinoic-acid treated embryos. The endogen ous beta -galactosidase activity was distinguished from the bacterial lacZ reporter by incubation at low pH.