Active ion transport and beta-acdysone induced differentiation of Drosophila melanogaster imaginal discs cultured in vitro

Milner, M.J.; Sang, J.H.

Journal of Embryology and Experimental Morphology 37(1): 119-131


ISSN/ISBN: 0022-0752
PMID: 404384
Accession: 004665065

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The theory that .beta.-ecdysone initiated developmental changes during insect metamorphoosis by causing an increase in intranuclear levels of K+, together with a concomitant decrease in Na+ levels, was investigated by 2 methods. First, imaginal discs from late 3rd instar larvae were cultured with 0.2 .mu.g/ml of .beta.-ecdysone together with inhibitors of active ion transport. Ouabain, the only specific inhibitor of the active transport of Na+ and K+ across membranes, had no effect on development even at a concentration of 10-2 M. Second, a medium containing raised levels of K+, and reduced concentrations of Na+, neither initiated disc development in the absence of .beta.-ecdysone, nor stimulated development induced by suboptimal levels of .beta.-ecdysone, either in the presence or absence of ouabain. Probably, .beta.-ecdysone induced morphogenesis is not dependent upon Na+ and K+ concentrations, or on the activity of an ouabain-sensitive ion pump.