Stimulation of head-specific nerve cell formation in Hydra by pulses of diacylglycerol.
In Hydra magnipapillata, repeated pulses of diacylglycerol (DG) induce a lengthening of the body column and the formation of ectopic head structures (Müller, 1989). In the present study, seven pulses given on 7 successive days led, in the gastric region, to a 1.87-fold increase in the number of epithelial cells from 16,200 to 30,400; a 4.6-fold increase in the total number of nerve cells from 2900 to 13,400; and an 18-fold increase of RF-amide immunopositive nerve cells from 100 to 1800. This subset of neurons, which is normally distributed in the form of a density gradient having its high point around the mouth and ending below the tentacle whorl in the upper gastric column, displays an altered pattern in DG-treated animals. While the density peak in the original head persisted, a second peak developed in the lower gastric region at the site of imminent ectopic tentacle formation, reflecting the local increase in positional value. Thus, the temporal sequence in which DG-induced ectopic apical body structures arise is a function of the rise in positional value and reflects the normal spatial sequence of these structures along the body column: first RF-amide neurons appear, then tentacles, and finally hypostomes.
Zoologisches Institut der Universität, Heidelberg, Germany.
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Müller
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D004075:Diglycerides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000187:drug effects; D006829:Hydra / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D009479:Neuropeptides / Q000096:biosynthesis
C011439:1,2-diacylglycerol; D004075:Diglycerides; D009479:Neuropeptides; C058047:arginylphenylalaninamide