Effects of Vitamin A on Limb Regeneration in the Larval Axolotl, Ambystoma Mexicanum
Vitamin A is known to cause both proximodistal and anteroposterior duplication of parts of the limb during limb regeneration in amphibians. The objective of this study was to investigate the nature and location of the cellular changes induced by vitamin A when it causes these duplications in the larval axolotl, Ambystoma mexicanum. A variety of experimental techniques were employed to try and determine where and when vitamin A was acting when it induced changes in the pattern of the regenerate. Overall, the results were consistent with the hypotheses: that a) vitamin A acts at the gene level by switching on or increasing the expression of some gene or set of genes, that b) this leads to synthesis of some protein, likely a glycoprotein, which c) modifies certain as yet unknown cell activities leading to a change in the positional coding, such that proximodistal duplication occurs, as well as other characteristic histological changes, and that d) this change persists for some weeks after the cessation of the vitamin A treatment, but that eventually the cells revert to their normal positional coding, implying that the vitamin A induced gene expression is reversed.
KeywordsRetinoic Acid Limb Regeneration Cellular Retinoic Acid Binding Protein Ambystoma Mexicanum Positional Code
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