On the Uptake, Metabolism and Retention of [3H] Gibberellin A1 by Barley Aleurone Layers at Low Temperatures 1

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RESUMO

Barley (c.v. Himalaya) aleurone layers were incubated in [3H]gibberellin A1 (GA1) at low temperatures. At 3 and 4 C, 3H-activity was steadily accumulated in aleurone layers, and this accumulation was correlated with significant [3H]GA1 metabolism. At 1 and 1.5 C, metabolism could not be detected, and at these temperatures aleurone layers equilibrated with the [3H]GA1 concentration in the incubation medium. At equilibrium, the total amount of 3H-activity per unit volume in the aleurone layers was higher than in the incubation medium. Aleurone layers incubated at 0.5 C for 72 hours with [3H]GA1 in the presence of saturating levels of carrier GA1 consistently retained lower levels of 3H-activity than when incubated in [3H]GA1 alone. The retention of [3H]GA1 was unaffected by saturating levels of carrier GA8. GA1 retained by barley aleurone layers that were incubated at 0.5 C for 72 hours was able to induce α-amylase synthesis when aleurone layers were subsequently washed and transferred to a gibberellin-free medium at 25 C.

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