Nonsegmental organization of positional information in regenerating Ambystoma limbs
| Autor: | David L. Stocum, Maurice J. Pescitelli |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
Appendage
Missing limb Regeneration (biology) Extremities Cell Biology Anatomy Biology Ambystoma Transplantation Autologous Single segment body regions Sequence hypothesis Species Specificity Larva Homologous chromosome Animals Regeneration Molecular Biology Developmental Biology Sequence (medicine) |
| Zdroj: | Developmental biology. 82(1) |
| ISSN: | 0012-1606 |
| Popis: | Positional information in cockroach appendages has previously been shown to be organized in homologous, segmentally repeating sequences ( H. Bohn, 1970, Wilhelm Roux' Arch. Entwicklungsmech. Organismen 165, 303–341; 1970, Develop. Biol. 23, 355–379 ). We have conducted experiments to determine whether similar sequences exist in Ambystoma limbs. The same or different segment levels of these limbs were combined by grafting together mature limb regions and by grafting regeneration blastemas to mature limb regions. The repeating segmental sequence hypothesis predicts that no intercalary regeneration should occur when the same segment levels are apposed, and that only the positional values necessary to restore a single segment sequence should be intercalated when different segment levels are apposed. When regeneration blastemas are grafted to mature limb regions, all of the missing limb regions are restored by intercalary regeneration, regardless of the segment levels that are combined. When mature limb regions are grafted together, only the host stump segment is intercalated, and this intercalation also takes place without regard to which segment levels are combined. These results are not compatible with the segmental sequence hypothesis, and suggest instead that positional information is organized in a single limb sequence. Histological data indicate that the reason more complete intercalation does not take place after grafting mature limb regions is that dedifferentiated cells are unable to display positional information and divide long enough to restore more than the host segment. |
| Databáze: | OpenAIRE |
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