The Oxidising Activity of Roots in Waterlogged Soils

Root oxidising activity has been studied quantitatively in two species, Menyanthes trifoliata and Molinia coerulea, using a non-specific dye technique, and an oxygen-specific “polarographic” technique in conjunction with artificial roots constructed from silicone rubber tubing. Oxidising activity in these two species has been found to be up to nine times greater than can be accounted for by oxygen diffusing from the roots. Enzymatic oxidation is thought to be the cause of such high oxidising activity. The characteristic patterns of iron oxidation found on and around roots are discussed, and oxidation of iron at the rhizophere ‘boundary’ is illustrated. Earlier work on root oxidising activity is briefly reviewed.     

Enzymes of ammonia detoxication after portacaval shunt in the rat. II. Enzymes of glutamate metabolism.

Besides the synthesis of urea, ammonia detoxication at high concentrations can also be effected through enzyme reactions involved in glutamic acid metabolism. These mechanisms are also operative in extrahepatic tissues. Hyperammonemia is also found in the animal model of the portacaval shunt (PCS) rat. This model was chosen to study the activities of glutamate dehydrogenase, glutamine synthetase and glutaminase I in liver, brain and kidney 10, 20 and 30 days after PCS. In brain and kidney ammonia is detoxified mainly by the glutamate dehydrogenase and glutamine synthetase reactions whereas in the liver these enzyme reactions play a minor role.