Around a year ago I wrote about a study which showed that micro-RNAs from plants that were eaten could regulate genes in the animal that ate them.  It was an exciting and important finding.  The study claimed that the miRNAs survived passage through the digestive tracts of mice, got into their bloodstream and traveled to their liver, where they regulated genes involved in cholesterol metabolism.  This week I read a post on Virginia Hughes’ blog Only Human where she discusses several follow-up studies which haven’t been able to reproduce the original results.  That doesn’t necessarily mean the study was wrong, but it certainly raises doubts.  In her post, Virginia also links to a rebuttal letter she received from the author of the original study, so it looks like the debate is on!  I’ll try to keep an eye on the subject and report back about it as things develop, but in the meantime read Virginia’s excellent summary of the current state of affairs.  Showing that creatures can directly regulate genes in organisms of another kingdom of life would be a major finding, so I’m really glad that there’s debate about it.  That’s how science should work: we should try to repeat studies, remain critical and open-minded, and challenge each other.