The duration of the effectiveness of vitamin A at causing proximodistal duplication in regenerating limbs of the axolotl,Ambystoma mexicanum, in relation to whole body retinoid levels

✍ Scribed by Johnson, Keith J. ;Scadding, Steven R.

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 711 KB
• Volume: 264
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402640211

✦ Synopsis

Abstract

Urodele amphibians regenerate their limbs after amputation. Normally, only those parts of the limb distal to the plane of amputation are regenerated. However, retinoids are capable of inducing proximodistal (PD) duplication such that structures already present proximal to the plane of amputation are duplicated in the regenerating limb. PD duplication can be induced by retinoids even if amputation occurs some time after the retinoid treatment. Thus, the purpose of this investigation was to determine for how long after administration, retinoids were effective at inducing PD duplication, and to determine whether this persistent effectiveness was due to some change in the cells of the limb or to residual levels of retinoids in the body. Thus, forelimbs of larval axolotls, Ambystoma mexicanum, were amputated at various times in relation to retinol palmitate (RP) treatment to investigate the relationship between the induction of proximodistal duplications and the timing of the retinoid treatment. RP induced PD duplications when amputation was delayed for up to 2 weeks after cessation of the retinoid treatment. To measure the levels of retinoids actually present within the body, axolotls were treated with RP, and whole body retinoid levels were colorimetrically assayed during and after the RP treatment. Since high levels of retinoids were present for several weeks after the cessation of the treatment, we conclude that the induction of PD duplications, when amputation is delayed until after the RP treatment, is due to the persistence of retinoids in the axolotl body. © 1992 Wiley‐Liss, Inc.