Precision in fly patterning

The mechanism that sets up the basic body plan of the developing fly is surprisingly precise, according to two papers in this week's Cell. The finding contradicts earlier studies that suggested that expression levels of the key protein were only loosely controlled."The way they've done this analysis is really spectacular," said Nipam Patel of the University of California, Berkeley, who was not involved in the work. "They're getting down to the physics level of what's going on."Researchers twenty years ago identified the transcription factor Bicoid, which controls the temporal and spatial expression of a cascade of genes that determine the anterior/posterior axis of the fly body plan. The transcription factor forms a concentration gradient across the embryo - high Bicoid levels at the fly's anterior end activate anterior-specific genes while low Bicoid levels at the posterior end activate posterior-specific genes. Scientists have considered Drosophila a model system for studying...