โ Scribed by Spindler-Barth, Margarethe ;Schmidt, Heinrich ;Drews, Ulrich ;Spindler, Klaus -Dieter
No coin nor oath required. For personal study only.
An epithelial cell line from Chironomus tentans exhibits acetylcholinesterase activity (specific activity 0.05-0.2 nkat/mg protein), which rises 30-to 40-fold after addition of 10 -6 M 20-OH-ecdysone. The first visible increase occurs after 4 days of incubation with hormone. The enzyme has an apparent K,, of 2.3_+0.2 x 10 4M for acetylthiocholine iodide as substrate and is inhibited by eserine and BW284 C51 (50% inhibition at 5 x 10-7 M for both inhibitiors) as well as by high concentrations of substrate, but not by tetraisopropylpyrophosphamide. The sensitivity against inhibitors is the same in extracts from hormonetreated cells and from controls. The cholinesterase activity correlates with morphological changes (shape and cell arrangement) and is indepenent of neuronal differentiation. We therefore propose a function for this activity during morphogenesis.
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