Physiology

Reduced-Fat Milk

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Science  10 Jan 2003:
Vol. 299, Issue 5604, pp. 167
DOI: 10.1126/science.299.5604.167a

Sometimes the most natural of events presents the most unnatural problems. Breastfeeding might be considered such an event, and about 5% of women experience lactation problems.

Vorbach et al. describe their work on mice that have only one copy of the gene for xanthine oxidoreductase (XOR). These mice appear normal and fertile but are incapable of nursing successfully, and hence their pups die of starvation within about 2 weeks of birth. Haploinsufficiency of XOR in mice results in a defect in the enveloping of milk fat droplets, preventing their secretion into the lumen of the mammary alveoli. The involvement of XOR appears to be unrelated to its enzymatic function in purine catabolism; instead, it appears to contribute to the structural packaging of milk fat within the epithelial cells. — BAP

Genes Dev. 16, 3223 (2002).

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