Regenerative abnormalities in Notophthalmus viridescens induced by repeated amputations

Abstract

The fidelity of the regenerative response in the adult newt, Notophthalmus viridescens, was examined following repeated amputations at the level of the distal one-third of humerus. Three to four months following amputation, all regenerates were scored for gross morphology, reamputated, and stained with methylene blue for skeletal elements. The occurrence of abnormal regeneration with respect both to gross morphology and to skeletal structure was found to increase directly with the number of times the limb stumps were required to initiate dedifferentiation and repair. The initial amputation-regeneration process produced structurally normal replacement limbs in 91% of the cases examined. Reamputations of 4-digit regenerates (3--4 months after the previous transection) resulted in structurally abnormal regenerates in 28% of the cases following two amputations; 50% of the cases following three amputations; 65% of the cases following four amputations; and 81% of the cases following five amputations. The relationships between repeated dedifferentiation, proliferation, and redifferentiation and normal limb development are discussed.

Tetrapod limb and sarcopterygian fin regeneration share a core genetic programme

“…Here we showed that Lepidosiren collected from natural sources display a high percentage of pathological fins, similar to regeneration pathologies found in natural salamander populations2829. Furthermore, the morphological steps leading to blastema formation in the lungfish and salamanders are strikingly similar and involve extensive histolysis, AEC formation and a blastema that lacks a basement membrane.…”

Retrotransposon long interspersed nucleotide element‐1 (LINE‐1) is activated during salamander limb regeneration

“…In the future, it would be of interest to test whether a higher frequency of aberrant limb regeneration would be observed in animals that receive additional limb amputation surgeries due to the higher frequency of potentially deleterious LINE-1 integration events that occur during the process of axolotl limb regeneration. Indeed, a previous study by Dearlove & Dresden (1976) did show increasing incidence of limb abnormalities with progressive amputations. One could speculate that a higher level of L1 retrotransposition activities and the resultant increase in L1 genomic content as a consequence of progressive limb amputation might contribute to the increased occurrence of hazardous genomic integration of newly synthesized L1s, and provide a potential mechanism for the frequent occurrence of abnormal limb regeneration observed by Dearlove and Dresden.…”

Amphioxus makes the cut—Again

“…In Notophthalmus viridescens , limb regeneration is near perfect after the first amputation. However, after the second, almost 30% of animals show abnormalities, the most severe concerning patterning of the distal digit tips, defects that exceeded 80% after 5 amputations 23 . Since the amphioxus tail is considerably less complex than a vertebrate limb, our gross observations may fail to detect cryptic patterning defects.…”