caa a22 4500 475767632 CHVBK 20180406123610.0 cr unu---uuuuu 170329e20000101xx s 000 0 eng 10.1007/PL00008184 doi (NATIONALLICENCE)springer-10.1007/PL00008184 Ectopic expression of Xenopus noggin RNA induces complete secondary body axes in embryos of the direct developing frog Eleutherodactylus coqui [Elektronische Daten] [Hung Fang, Yusuke Marikawa, Richard P. Elinson] Abstract : We tested the effects of noggin RNA from Xenopus laevis on axis induction in embryos of a direct developing frog, Eleutherodactylus coqui. We microinjected noggin RNA into one blastomere of 4-cell embryos at the site close to the animal pole, and found that overexpression of noggin RNA is not only sufficient to induce additional axes but also induces heads with eyes. We also injected noggin RNA into 8-cell or 16-cell embryos in various sites, including the marginal zone, above the marginal zone, and the vegetal pole, and found the formation of a complete secondary axis in all three types of injection. These effects of X. laevis noggin RNA on the E. coqui embryo are remarkably different from those found in the X. laevis embryo itself. It has been shown previously that overexpression of noggin RNA on the ventral side of the normal X. laevis embryo induces only a partial axis, with no head structures. We show here that the failure of noggin induction of a complete axis when overexpressed on the ventral side of the X. laevis embryos is not due to an insufficient amount of RNA injected. Also, the failure is unlikely due to inhibition from the primary axis since noggin RNA can induce duplicated head structures on opposite sides of UV-irradiated X. laevis embryos. There appear to be fundamental differences in the responses of E. coqui and X. laevis embryos to exogenous noggin RNA. We propose that these differences stem from an alteration in cytoplasmic arrangements that occurred during evolution of this large egg. Springer-Verlag Berlin Heidelberg, 2000 Key words Noggin nationallicence Direct development nationallicence Egg evolution nationallicence Head development nationallicence Body axis nationallicence Fang Hung Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada e-mail: hfang@zoo.utoronto.ca Tel.: +1-416-9783678 Fax: +1-416-9788532, CA aut Marikawa Yusuke Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada e-mail: hfang@zoo.utoronto.ca Tel.: +1-416-9783678 Fax: +1-416-9788532, CA aut Elinson Richard P. Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada e-mail: hfang@zoo.utoronto.ca Tel.: +1-416-9783678 Fax: +1-416-9788532, CA aut https://doi.org/10.1007/PL00008184 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/PL00008184 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Fang Hung Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada e-mail: hfang@zoo.utoronto.ca Tel.: +1-416-9783678 Fax: +1-416-9788532, CA aut NATIONALLICENCE 700 1- Marikawa Yusuke Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada e-mail: hfang@zoo.utoronto.ca Tel.: +1-416-9783678 Fax: +1-416-9788532, CA aut NATIONALLICENCE 700 1- Elinson Richard P. Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada e-mail: hfang@zoo.utoronto.ca Tel.: +1-416-9783678 Fax: +1-416-9788532, CA aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer