Inhibition of glycosphingolipid biosynthesis does not impair growth or morphogenesis of the postimplantation mouse embryo.

Whole embryo culture (WEC) of organogenesis-stage mouse embryos was adapted for glycosphingolipid (GSL) metabolic studies to evaluate the hypothesis that de novo GSL biosynthesis is a prerequisite for growth and morphogenesis of the early postimplantation embryo. WEC supports the growth and development of postimplantation mouse embryos to stages that are indistinguishable from those achieved in vivo. N-Butyldeoxygalactonojirimycin (NB-DGJ) is an N-alkylated imino sugar that specifically inhibits biosynthesis of all glucosylceramide-based GSLs. NB-DGJ inhibited glucosylceramide and lactosylceramide biosynthesis nearly completely and inhibited ganglioside biosynthesis approximately 90% in both the embryo and visceral yolk sac. NB-DGJ also significantly reduced total ganglioside content in both the embryo and visceral yolk sac as estimated by the cholera toxin immunooverlay technique. A shift in expression from the structurally simple to the structurally complex gangliosides was also observed in NB-DGJ-treated embryos and yolk sacs. Despite causing major changes in GSL biosynthesis and composition, NB-DGJ had no effect on embryo viability, growth, or morphology. The findings suggest that de novo GSL biosynthesis may not be a prerequisite for the growth and morphogenesis of the organogenesis-stage mouse embryo.