NADH and NADPH Dependent Malate Dehydrogenases of Phaseolus vulgaris

French bean (Phaseolus vulgaris L. cv. Contender) leaf extracts catalyse the reduction of oxaloacetate to malate in the presence of NADH and NADPH. Under the experimental conditions used, the optimum pH values are 8 and 6 respectively. After chromatography on diethylaminoethyl cellulose, two principal forms of NADH-MDH (L-malate: NAD⁺ oxidoreductase, E.C. 1.1.1.37) upon which NADPH activities are superposed, can be characterized. This result is confirmed by electrophoresis on polyacrylamide gel. On the other hand, after filtration on Ultrogel 34, NADH-MDH is eluted as a single peak; once again, NADPH activity is associated with it. When PtCl^2?₄, a powerful inhibitor of MDH, is added to the reaction medium, the degree of inhibition is the same irrespective of the cofactor employed. When root extracts are submitted to chromatography on diethylaminoethyl cellulose, activity profiles are identical to those obtained with leaves. These results suggest that the NAD dependent enzymes can also utilize NADP to reduce oxaloacetate. After addition of dithiothreitol, another NADPH-MDH activity manifests itself in the leaf extracts; it differs from the foregoing ones in its optimum pH, its chromatographic properties and its response to PtCl^2?₄ action. Root extracts do not exhibit this activity thus showing a specific localization of this enzyme in the green part of the plant.     

Body size and elevation: do Bergmann's and Rensch's rule apply in the polytypic bushcricket Poecilimon veluchianus?

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Summary

Histological and cytological localization of glycogen was studied in the brain of Pieris brassicae larvae and pupae by histochemistry and electron microscopy. The major glycogen deposits were observed in glial cells located between the cortex and the neuropile and also in perineurial cells. The concentrations of brain glycogen were measured in the larvae and the pupae during non-diapausing and diapausing development. In addition, we demonstrated that starvation reduces the density of the brain glycogen deposits as well as the concentrations of glycogen.