Mice Inherit Gene Effects -- but Not Gene

Mice in a lab experiment inherited the effects of an aberrant gene without inheriting the gene itself, a bizarre-sounding result that may someday help scientists understand aspects of diabetes, infertility and other problems.

Although DNA is the stuff of genes in mice and men, the study indicates that DNA’s chemical cousin, RNA, produced the result.

In this case the result was mice with white-tipped tails.

For the study, reported in Thursday’s issue of the journal Nature, scientists produced mice that carried one normal copy of a particular gene and one aberrant copy.

When the mice were bred through several generations, researchers found that 24 out of 27 mice that did not receive a copy of the aberrant gene nonetheless showed the telltale white patches associated with it.

When scientists bred these mice to others that had only normal copies of the gene, most offspring with only normal gene copies still showed the distinctive coloring. Experiments showed the trait could be inherited through either the mother or father, and it went on for generations in absence of the abnormal gene.

How can this be? Researchers focused on sperm, which are simpler to analyze than eggs, and found evidence that RNA molecules there were carrying the hereditary signal. For example, when RNA from mice bearing the aberrant gene was injected into early embryos, about half the resulting mice showed the distinctive tail.

RNA normally delivers instructions from genes to a cell’s protein-making machinery, so it makes sense that it might be involved in transmitting a gene’s effect. Just how it’s operating in the mice is not clear, said lead study author Minoo Rassoulzadegan of the University of Nice, Sophia Antipolis, in France.

It’s not clear how common or important this kind of inheritance is, researchers said.