Salamander

沒想到連續兩年冬春交替時期曾來我們家泳池拜訪的嶸螈親族竟然因其再生能力登上了這一期的[自然]雜誌, 令人羨慕. 照片上的這隻今年一月中還在泳池產下不少的小嶸螈, 可惜因為照顧不周而犧牲了, 轉載期刊摘要算是紀念這些犧牲掉的小生命吧.

Nature 460, 60-65 (2 July 2009)

Cells keep a memory of their tissue origin during axolotl limb regeneration

Martin Kragl1,3,5,6, Dunja Knapp1,3,5, Eugen Nacu1,3, Shahryar Khattak1,3, Malcolm Maden4, Hans Henning Epperlein2 & Elly M. Tanaka1,3
Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108,
Institute of Anatomy, Medical Faculty, University of Technology Dresden, Fetscherstrasse 74,
Center for Regenerative Therapies, University of Technology Dresden, Tatzberg 47/49, 01307 Dresden, Germany
The Regeneration Project, McKnight Brian Institute, University of Florida, Rm 326 Bartram Hall, Gainesville, Florida 32611, USA
These authors contributed equally to this work.
Present address: Institute of Metabolic Physiology, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.
Correspondence to: Elly M. Tanaka1,3 Correspondence and requests for materials should be addressed to E.M.T. (Email: elly.tanaka@crt-dresden.de).

Abstract

During limb regeneration adult tissue is converted into a zone of undifferentiated progenitors called the blastema that reforms the diverse tissues of the limb. Previous experiments have led to wide acceptance that limb tissues dedifferentiate to form pluripotent cells. Here we have reexamined this question using an integrated GFP transgene to track the major limb tissues during limb regeneration in the salamander Ambystoma mexicanum (the axolotl). Surprisingly, we find that each tissue produces progenitor cells with restricted potential. Therefore, the blastema is a heterogeneous collection of restricted progenitor cells. On the basis of these findings, we further demonstrate that positional identity is a cell-type-specific property of blastema cells, in which cartilage-derived blastema cells harbour positional identity but Schwann-derived cells do not. Our results show that the complex phenomenon of limb regeneration can be achieved without complete dedifferentiation to a pluripotent state, a conclusion with important implications for regenerative medicine.
(copy from http://www.nature.com/nature/journal/v460/n7251/abs/nature08152.html)