FOCAL POINT  (Left to right) Sandy Oas, Richard Cripps, and Anton Bryantsev found that the protein Arrest, which controls alternative splicing, helps spur the differentiation of Drosophila flight muscles. The two sets of panels show the flight muscle myofibrils end on (TS) and lengthwise (LS). In a normal fly (top panels), the myofibrils are cylindrical and show regular striations. But in a fly with reduced levels of Arrest (bottom panels), the myofibrils are misshapen and sometimes hollow (arrows).

PHOTO COURTESY OF LUBA UDALOVA