Nonmuscle myosin II and tension are required for molecular actin ordering during myofibril initiation.

<p>(A) Actin molecular disorder angles ΔΨ for <i>kon</i> and <i>sqh</i> knock-down muscles at 32-h and 90-h APF, relative to wild-type 90-h APF. Error bars represent SD. Note the higher actin disorder ΔΨ after <i>kon</i> or <i>sqh</i> knock-down at 32-h APF; however, notice the largely preserved actin order buildup at 90-h APF. <i>p</i>-values: **<i>P</i> < 0.01; ***<i>P</i> < 0.001 (nonparametric Mann-Whitney U test; see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2004718#pbio.2004718.s003" target="_blank">S1 Data</a>). Error bars represent SD. (B) Molecular actin order angle profiles along the averaged sarcomere length for <i>kon</i> knock-down (light blue), <i>sqh</i> knock-down (slate blue), and wild-type control (black) at 90-h APF. Values are relative to the minimum of the wild-type profile. See <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2004718#pbio.2004718.s003" target="_blank">S1 Data</a> for primary data. APF, After Puparium Formation; <i>kon</i>, <i>kon-tiki</i>; <i>sqh</i>, <i>spaghetti-squash</i>.