Biochemical and autoradiographic analysis of regeneration in two hydroids

Abstract

AbstractPodocoryne carnea and Hydractinia echinata are organisms at a similar taxonomic level with different regenerative abilities. This investigation compared biochemical events following wounding of these organisms, and additionally examined autoradiographically the incorporation of macromolecular precursors into cells in the cut, proximal area of their gastrozooids.Although the non‐regenerating gastrozooids of both organisms incorporated little 3H‐thymidine into cells near the proximal tip, amputation provided a stimulus for cells in this area of both organisms to incorporate greater levels of this precursor. However, the level of stimulation of total incorporation into gastrozooids was substantially greater in Podocoryne. During regeneration, Podocoryne gastrozooids were stimulated to incorporate peak levels of 3H‐uridine into RNA at 6, 15 and 24 hours, whereas Hydractinia gastrozooids exhibited no peak levels of incorporation throughout the 27‐hour post‐wounding period. In the initial nine hours following wounding, Podocoryne gastrozooids were stimulated to much greater levels of incorporation of 3H‐leucine into protein over non‐regenerating gastrozooids than were Hydractinia polyps.Therefore, the results of this biochemical and autoradiographical investigation demonstrated that Podocoryne gastrozooids, which regenerate proximally, had substantially higher levels of stimulation of precursor incorporation into macromolecules during 27 hours following wounding than Hydractinia gastrozooids, which do not regenerate proximally. Additionally, when this level of incorporation was depressed by the use of inhibitors in Podocoryne polyps, they were unable to complete regeneration in the normal manner.