The respiratory changes wvhich take place in slices of tubers and tuberous roots have long been of interest to plant physiologists. As early as 1887, the wound respiration of white potato tubers was described (3), and since then many of the factors affecting this phenomenon have been analyzed (17). In recent years, the fact that the developed respiration is resistant to cyanide andl carbon monoxide has attracte(d special attention (18,25 The potato tuber slices, in which there is a striking change within one day, seemii ideally suited for further investigations on the problem of inhibitorresistant respiration. The plan of the present study has been to compare the respiratory mechanisms in freshly-cut and day-old slices, and to ascertain the conditions necessary for the development of the wound respiration. The w\ork has been carried on at two levels: with tissue slices and with isolated cell fractions. Oxygen uptake h1as been used as a measure of respiratory activity, and its coupling to phosphorylation estimated by following phosphate uptake. The respiratory components involved in hydrogen and electron transport have been exanmined by both enzymatic and spectrophotometric techniques. The evidence indicates that during the aerobic incubation of potato slices there is a metabolism-dependent moidification of the mitochondrial respiratory chain, prob-1

The occurrence and properties of enzymes of carbohydrate metabolism were studied during dikaryotic fruiting of the mushroom Coprinus lagopus. Enzymes of hexose monophosphate catabolism, sugar alcohol (polyol) dehydrogenases (DH), and trehalase occurred throughout development. The ratio of xylitol DH to sorbitol DH was greater than unity in both monokaryotic mycelium and dikaryotic fruit body caps, whereas this ratio decreased in the stipe (stalk) tissue. Xylitol DH and sorbitol DH were both dependent upon nicotinamide adenine dinucleotide (NAD) and showed maximal activity at pH 9. Two separate enzymes were suspected on the basis of preferential utilization of the NAD analogue, thionicotinamide-NAD, by xylitol DH, and this feature was consistent throughout development. An appraisal of the carbohydrate pool revealed trehalose and glucose, with the former predominant in the stipe and the latter in excess in the cap of dikaryotic fruit bodies. Trehalase activity in dialyzed enzyme extracts showed pH optima at acid and alkaline pH levels in monokaryotic mycelium, dikaryotic stipes, and cap tissues.Developmental studies of the fruiting basidiomycetous fungus Coprinus have provided basic information relative to general problems of microbial morphogenesis (9). Vegetative monokaryotic hyphae ordinarily produce asexual propagules called oidia. These uninucleate cells may either germinate to produce monokaryotic hyphae or serve as fertilizing elements for compatible vegetative hyphae (6-8). Mating occurs by hyphal anastomosis and nuclear exchange between monokaryons bearing dissimilar A and B incompatibility factors to produce a dikaryon containing clamp connections. Profound morphological changes in filamentous dikaryotic hyphae produce a gilled fruitbody consisting of a prominent stipe (stalk) and cap. Diploidization and meiosis in the basidium are followed by basidiospore production. The mature fruit body cap then undergoes autolysis and basidiospore dissemination.Much past research dealing with sporogenesis in Coprinus has been descriptive. The origin of lamellae was outlined in fruit bodies of Coprinus micaceus (19), and growth kinetics were defined during fruiting of C. lagopus (4). Later work by Madelin (23) showed that reserves were drawn from vegetative mycelium, presumably to sustain fruit body development in C. lagopus, and that these stores may originate in swollen hyphae containing glycogen and protein (25). The effects of light and temperature (5,16,24) and the role of the nutritional milieu have also been clarified (2, 10, 30). Further insight was gained from electron microscopy studies of the hymenium of sporulating fruit bodies of C. lagopus; the occurrence and morphological details of synaptinemal complexes (21, 22) were correlated with genetic evidence for meiosis (cf. 15).In contrast to this sort of information, little is known about the physiological changes accompanying morphogenesis of C. lagopus. Accordingly, biochemical studies were initiated concerning the intermediary metabolism of carbohydrates d...

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