Regulation of germline transcriptional repression by Popk-1.

<p>(A-D) Images of 16-cell stage embryos stained by WISH for <i>FoxD</i>.<i>a</i>. Shown are (A) 1000 pg of control MO-, (B) 1000 pg of <i>Popk-1</i> MO-, (C) 1000 pg of <i>Popk-1</i> MO and 50 pg of <i>LacZ</i> mRNA- and (D) 1000 pg of <i>Popk-1</i> MO and 50 pg of <i>Pem</i> mRNA-injected embryos. Vegetal views. Anterior is to the top. Arrows indicate germline B5.2 cells. Scale bar, 50 μm. The digits in the bottom right corner indicate the proportions of embryos with ectopic <i>FoxD</i>.<i>a</i> expression in the germline. The proportions are also shown in E. ** P<0.01, * P<0.05 (one-sided Fisher’s exact test). Although the numbers with the ectopic expression were low in B (24%) and in C (29%), 95% of embryos (n = 19) showed ectopic expression by injection of an increased amount of MO (1500 pg, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0196500#pone.0196500.s001" target="_blank">S1 Fig</a>). (F, G) Fluorescent images of the 16-cell stage embryos stained with anti-Pem antibody. (F) 1000 pg of control MO- and (G) 1000 pg of <i>Popk-1</i> MO-injected embryos. White arrows indicate the nuclear signals, and white arrowheads the CAB signals. Pem protein has been shown previously to be present both in the nucleus and CAB in the ascidian germline [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0196500#pone.0196500.ref008" target="_blank">8</a>]. Smaller panels in the top left corners show entire views of the embryos. (F’, G’) DIC images of F and G. White arrows indicate the nuclei. F and F’, and G and G’ are on the same focal planes, indicating that faint signals in the nuclei in G are not due to being out of focus for the nuclear level. The digits in the bottom right corner show the proportions of embryos with nuclear Pem signals. Scale bar, 50 μm. The proportions are also shown in H. ** P<0.01 (chi-square test).