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Vitamins change colour of baby mice

7 August 2003: US researchers have altered the colour and disease susceptibility of newborn mice by feeding their mothers extra vitamins during pregnancy.

The study is the first to find a clear mechanism for the effect of maternal nutrition on disease development in mammals without mutating the offspring's genes.

The implications for cloning, nutrition and disease research are huge, says Rob Waterland of Duke University Medical Centre in North Carolina. "For decades, there has been research linking prenatal diet to diseases like diabetes, obesity and cancer but the explanation was missing," he says.

Waterland and his colleague Randy Jirtle worked with Agouti yellow mice, they report in this month's Molecular and Cell Biology. The mice have an extra piece of DNA, making them obese and yellow. When fed the vitamin B12, folic acid, choline and betaine before, during and after pregnancy, the animals gave birth to thin, brown babies. The control animals' offspring were fat and yellow. The nutrients had silenced the Agouti gene, but had not altered its sequence, Waterland and Jirtle found. Molecules containing carbon and hydrogen had been attached to the gene. Cells often use this process, called DNA methylation, to switch genes on or off during development.

The study presents a valuable model system and underlines the influence of outside factors on gene expression, says geneticist Wolf Reik of the Babraham Institute in Cambridge. "It highlights the fact that external events are important," he says. But more data is needed before humans can benefit, Reik warns. The Agouti mice received three to 20 times their required daily levels of the nutrients. Scaled up to humans, such doses would be huge.