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#axolotl

2 public questions tagged with this topic.

Regeneration -lll

FGFs alone in axolotl limb regeneration promote:

In axolotl limb regeneration studies, fibroblast growth factors supplied alone via beads or transgenes promote distal outgrowth. FGF8, FGF10 secreted by apical epidermal cap and nerves maintain distal blastema identity expressing HoxA13 and distal proliferation while failing to activate proximal program Meis. Therefore implantation of FGF alone leads to regeneration of distal structures only, such as hand elements, with poor proximal restoration unless exogenous retinoic acid provides proximalizing cue. Combined RA plus FGF signaling is required for complete limb pattern, but FGFs alone distalize, mirroring developmental AER FGF role in maintaining distal progressive zone during outgrowth.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 21: FGFs promoting distal structures in axolotl limb regeneration.

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Regeneration -lll

Axolotl limb regeneration treated with retinoic acid will:

Axolotl limb amputation at distal level normally regenerates only distal parts. Retinoic acid treatment proximalizes blastema positional memory activating proximal markers Meis1/2, HoxA9 and Prod1, converting distal blastema to proximal identity. Consequently distal wrist blastema treated with RA regenerates complete limb from stylopod through digits, representing serial duplication beyond amputation plane. Experiments by Maden and colleagues showed dose-dependent proximalization: low doses duplicate forearm, high doses duplicate entire arm. This property demonstrates RA as reprogramming agent altering positional value and Hox gene expression during epimorphic regeneration.

Ref: Alberts, Molecular Biology of the Cell, Chapter 22: RA proximalization and complete limb regeneration in axolotl.

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