Sugar and phosphate metabolism and alkaloid production phases in submerged cultures of two Claviceps strains

Summary In submerged cultures of Claviceps sp. CP II, elymoclavine was synthesized only by the growing mycelium (phase P1), whereas cultures of C. purpurea strain 129 produced agroclavine after vegetative growth had also ceased (phase P2). In strain CP II, the peak of activity of malate dehydrogenase, glucose-6-phosphate dehydrogenase and phosphatases was related to the time of maximum growth rate and alkaloid production. Citrate synthase activity paralleled the course of alkaloid synthesis. Strain 129 exhibited a further activity peak of the same magnitude during phase P2. ATP levels in both cultures corresponded to the pattern of change in enzyme activities. Strain CP II contained roughly twice as much orthophosphate and ATP in its cells as strain 129 and exhibited higher average activity of glucose-6-phosphate dehydrogenase. It follows from these results that alkaloid synthesis requires the processes of primary metabolism, even when it occurs after active growth of the culture has ceased. Cultures producing alkaloids oxidized at C-8 exhibit higher glucose-6-phosphate dehydrogenase activity, probably because of a higher NADPH consumption.     

Effects of light,phosphate, and oxygen on ethylene formation and conidiation in surface cultures ofpenicillium cyclopium westling

Penicillium cyclopium growing in a surface culture with 2-ketoglutarate or glutamate as a sole carbon source produced ethylene in two phases. The first peak of ethylene production (EP 1) was associated with aerial mycelium growth whereas the second peak of ethylene production (EP 2) occurred with formation and maturation of conidia. Conidiation was induced by blue light between 120 and 172 h after the culture was started and depended on the presence of a carbon source at the stage of conidiophore initiation. Exogenous phosphate content dropper rapidly before the onset of conidiation. The EP 2 was connected with conidiation via this drop. Addition of phosphate prior to the conidiophore initiation and during conidiation inhibited EP 2 without affecting conidiation, but conidia lacked a green pigment and their germination ability decreased by 905. Exogenous ethylene did not restore normal development. The EP 2 in asporogenic cultures was evoked by incubation in the dark and by phosphate removal. The EP 2 and conidiation were accompanied by an increased oxygen consumption. The EP 1 yield of ethylene depended only on biomass growth and was unaffected by any treatment mentioned above.     

Inhibition of rabbit liver fructose 1,6-biphosphatase by AMP: effect of temperature and physiological concentrations of cations and anions

Turkey gizzard smooth muscle myofibrils, the actin of which is composed of 75% smooth muscle γ-isoactin and 25% nonmuscle β-isoactin, were separated into an actomyosin and a cytoskeletal fraction. Isoelectric focusing analysis of the actomyosin actin showed it was 80% γ-isoactin and 20% β-isoactin. It thus appears that the major actin in the tissue is also the major form involved in force generation. When the cytoskeletal material was extracted with low-ionic-strength solution for 18 h at 4 °C, the actin released was 95% γ and 5% β compared with the 75:25 ratio found in the original cytoskeletal material. The extracted material revealed the presence of F-actin filaments and high-molecular-weight aggregates. Little of the material was in a low-molecular-weight form. On the other hand, extraction of the cytoskeletal material with 0.6 m KI resulted in the two isoactins being extracted in the same proportions in which they were found in the original cytoskeletal material. However, when this KI-extracted material was subsequently chromatographed on Bio-Gel A-5m equilibrated with 0.6 m KCl, the γ-isoactin migrated predominantly as a very high molecular weight form while the β-isomer moved in the lower-molecular-weight range of the elution profile. This aggregation behavior displayed by the γ-isoactin was not observed with the γ-isoactin in the actomyosin fraction. These results show that the two gizzard isoactins in the cytoskeletal residue behave very differently in response to various extraction media, and are consistent with possible differential isoactin utilization in gizzard smooth muscle.     

Catabolite repression of different inducible enzymes inEscherichia coli and the effect of cAMP

Simultaneous induction of two enzymes sensitive to catabolite repression does not lead to an additive decrease of the specific activity of the two. Exogenously added cAMP increases the specific activity of catabolically repressed enzymes, irrespective of whether the enzyme is induced separately or simultaneously with another enzyme. In the presence of 12 different substrates metabolized by inducible enzymes glucose does not bring about catabolite repression. Synthesis of cAMP is identical with that occurring under conditions when glucose brings about catabolite repression.     

Mucidin-nonproducing mutants ofOudemansiella mucida

Mutants ofOudemansiella mucida, blocked in the biosynthesis of the antibiotic mucidin, were obtained at a 0.28 % frequency after the application of N-methyl-N’-nitro-N-nitrosoguanidine (MNG) to basidiospores under conditions leading to 0.5–5.0 % survival rates. Loss of antibiotic activity was in most isolates accompanied by a decrease in mycelium growth rate and a suppression of dikaryotizing and fructification ability. Recombination analysis of two stable mutants revealed that the block in mucidin synthesis is the result of mutation in the same chromosomal gene(muc). In contrast to the action of MNG, UV-irradiation leads neither to the loss of biosynthetic activity nor to any morphological change.     

The cycling of cadmium and mercury between substrate and fruiting bodies of Agrocybe aegerita (a fungal model system)

Summary The cycling of cadmium and mercury between substrate and fruiting bodies in a model system with wood colonizing basidiomycete Agrocybe aegerita was studied. When radiolabeled ¹⁰⁹CdCl₂ and ²⁰³HgCl₂ were applied to the fruiting bodies of the first flush, they were translocated via substrate into successive harvests. Cadmium and mercury displayed different patterns of distribution in the system. On a percent basis, more cadmium went from the fruiting bodies into the substrate and was retained there. Only minor portions of the metal were translocated into consecutive crops. In contrast, more mercury was retained in the treated fruiting bodies. The fraction which had penetrated into the substrate, however, was more easily translocated into fruiting bodies of successive crops. When calculated on a dry weight basis, the amount of both metals decreased in consecutive harvests.At the end of the experiment, in following distribution patterns for cadmium and mercury were observed: Cd²⁺: first crop (treated), 9.5%; substrate, 77%; combined successive crops (untreated), 9.5%; Hg²⁺: first crop (treated), 36.5%; substrate 21.5%; combined successive crops (untreated), 37%. The patterns reveal that mercury is more mobile in the substrate and therefore more easily translocated to successive fruiting body generations. Hence, from a nutritional point of view, mercury would seem to be more hazardous than cadmium.