In two papers in this week's Science, researchers in the laboratory of Albert Einstein College of Medicine's Robert Singer, Ph.D., focused on beta actin, an essential protein found abundantly in neurons (nerve cells). The Einstein researchers developed a mouse in which all molecules of messenger RNA (mRNA) that code for beta actin were labeled with green fluorescent protein. After stimulating cultured neurons and brain tissue of the mouse, they were able to observe fluorescently tagged molecules of beta actin mRNA within the living neurons. In the first study, led by Hye Yoon Park, Ph.D., the researchers observed beta-actin mRNA being transcribed by the beta actin gene and then traveling within the neuron's branched projections, or dendrites, to sites where synthesis of beta actin protein would occur. This movie shows beta-actin mRNA molecules traveling within the dendrites of a cultured live hippocampal mouse neuron.