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Hanson AD, Jacobsen JV: Control of Lactate Dehydrogenase, Lactate Glycolysis, and alpha-Amylase by O (2) Deficit in Barley Aleurone Layers. Plant Physiol. 1984 Jul;75(3):566-572.
After 4 days in an atmosphere of N (2), aleurone layers of barley (Hordeum vulgare L. cv Himalaya) remained viable as judged by their ability to produce near normal amounts of alpha-amylases when incubated with gibberellic acid (GA (3)) in air. However, layers did not produce alpha-amylase when GA (3) was supplied under N (2), apparently because alpha-amylase mRNA failed to accumulate.When an 8-hour pulse of [U-(14) C] glucose was supplied under N (2) to freshly prepared aleurone layers, both [(14) C] lactate and [(14) C] ethanol accumulated; the [(14) C] lactate/[(14) C] ethanol ratio was about 0.3. Prior incubation of layers for 1 day under N (2) changed this ratio to about 0.8, indicating an increase in the relative importance of the lactate branch of glycolysis.l (+) Lactate dehydrogenase (LDH) activity was low in freshly prepared aleurone layers and increased 10-fold during 2 days under N (2), whereas alcohol dehydrogenase activity (ADH) was high initially and rose by 60%. The responses of LDH and ADH activities to O (2) tension were dissimilar; when layers were incubated in various O (2)/N (2) mixtures, LDH activity peaked at 2 to 5% O (2) whereas ADH activity was highest at 0% O (2). The LDH activity was resolved into several enzymically active bands by native polyacrylamide gel electrophoresis.We conclude that barley aleurone layers are highly adapted to O (2) deficiency, that they possess an inducible LDH system as well as an ADH system, and we infer that the LDH and ADH systems are independently regulated. |
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