Wounding Stimulates Cyanide-sensitive Respiration in the Highly Cyanide-resistant Leaves of Bryophyllum tubiflorum Harv.

The rate of respiration in sectioned leaves of Bryophyllum tubiflorum Harv. increases with decreasing section thickness. The rates of uninhibited respiration in 2- and 8-millimeter-thick sections are 74 and 46 microliters of O(2) per gram fresh weight of unruptured tissue per hour at 20 C, whereas the rate in the presence of cyanide is 31 microliters of O(2) in each case.

Restoration of Organic Acid Accumulation in Sectioned Leaves of Bryophyllum tubiflorum Harv.

When leaves of Bryophyllum tubiflorum were cut into transverse sections, and held at 20 C in the dark, the capacity to accumulate organic acid decreased with decreasing section thickness. In addition, the rate of respiration increased with decreasing section thickness and was unaffected by changes in O(2) concentration above 5% or by the presence (1%) of CO(2). It was concluded that O(2) ventilation is not a controlling factor in respiration.

Glutamate dehydrogenase from apodachlya (oomycetes).

A glutamate dehydrogenase specific for nicotinamide-adenine-dinucleotide has been purified 50-fold from Apodachlya brachynema (Leptomitales). Certain physical, chemical, and kinetic properties of this enzyme have been studied, particularly specificity for coenzymes and substrates. With glucose as the sole carbon source, the synthesis of glutamate dehydrogenase was repressed, whereas glutamate, proline, alanine, or ornithine plus aspartate as sole carbon sources induced synthesis of the enzyme.