Neutral glycolipid abnormalities in a t-complex mutant mouse embryo

The content of neutral glycolipids was studied in normal and twl/twl mutant mouse embryos at embryonic day 11 (E-11). The twl mutation is part of the T/t complex on chromosome 17 and causes embryonic lethality from defects in the developing neural tube. Previous studies suggested that the mutation could involve a defect in ganglioside biosynthesis. Although the total neutral glycolipid content was similar in the normal and mutant whole embryos (approximately 80 nmol glucose/100 mg dry weight), marked differences were detected for the distribution of specific glycolipids. The content of lactosylceramide, globotriaosylceramide, and globotetraosylceramide was significantly higher in the mutant than in the normal embryos, whereas that of glucosylceramide was significantly reduced. The Forssman glycolipid was slightly elevated. The neutral glycolipid composition was similar in embryonic head and body regions of normal embryos, suggesting that the glycolipid abnormalities observed in the mutants are expressed in most embryonic cells and tissues. These and the previously reported ganglioside abnormalities in the twl/twl mutants could result from an inherited defect in glycolipid biosynthesis.