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 ad apted for glycosphingolipid (GSL) metabolic studies to evaluate the hy pothesis that de novo GSL biosynthesis is a prerequisite for growth an d morphogenesis of the early postimplantation embryo. WEC supports the growth and development of postimplantation mouse embryos to stages th at are indistinguishable from those achieved in vivo. N-Butyldeoxy-gal actonojirimycin (NB-DGJ) is an N-alkylated imino sugar that specifical ly inhibits biosynthesis of all glucosylceramide-based GSLs. NB-DGJ in hibited glucosylceramide and lactosylceramide biosynthesis nearly comp letely and inhibited ganglioside biosynthesis similar to 90% in both t he embryo and visceral yolk sac, NB-DGJ also significantly reduced tot al ganglioside content in both the embryo and visceral yolk sac as est imated by the cholera toxin immunooverlay technique. A shift in expres sion from the structurally simple to the structurally complex ganglios ides was also observed in NB-DGJ-treated embryos and yolk sacs. Despit e causing major changes in GSL biosynthesis and composition, NB-DGJ ha d no effect on embryo viability, growth, or morphology. The findings s uggest that de novo GSL biosynthesis may not be a prerequisite for the growth and morphogenesis of the organogenesis-stage mouse embryo.