DEVELOPMENTAL BIOLOGY:
Mixed Messages in Early Development
Stephen M. Cohen and Julius Brennecke
MicroRNAs, molecules that repress gene expression, fine-tune early embryogenesis. Rather than expressing genetic information supplied in the egg from the mother, microRNAs direct the developing embryo to express its own genome instead.
The authors are at the European Molecular Biology Laboratory, Heidelberg, Germany. E-mail: cohen{at}embl.de