Spores Of Pithomyces Chartarum Research Articles

Spore Surface Depsipeptides in Some Pithomyces Species

SUMMARY: Spicules morphologically similar to those present on the spores of Pithomyces chartarum invest the spores of several other Pithomyces species. Depsipeptides are quantitatively removed from dried mycelial felts by brief chloroform washing, and their amount is proportional to the number of spores present. Three pure spore-coat depsipeptides have no demonstrable antibiotic activity.

The effect of temperature on the toxicity of spores ofPithomyces chartarum(Berk. & Curt.) M. B. Ellis

Ten isolates of Pithomyces chartarum (Berk. & Curt.) M. B. Ellis were grown on surface-sterilised rye grass at three temperatures, and spore production and toxin content of the spores estimated. There was significantly less toxin produced at 24°c compai ed with 20°c, and for all isolates toxin production was lowest at 28°c. At 28°c there was also a marked drop in sporulation. The application of these results to conditions found in the field is discussed.

The microestimation of sporidesmin

Abstract A manometric method is described for the routine estimation of the sporidesmin content of spores of Pithomyces chartarum (Berk. & Curt.) M. H. Ellis. The method gives results in good agreement with estimations, based on radioactivity and the V.V. absorption spectrum of sporidesmin.

Disturbance of pasture herbage and spore dispersal ofPithomyces chartarum(Berk. & Curt.) M. B. Ellis

Abstract Mobile spore trap counts from fixed transects on pasture herbage showed diurnal periodicity of spores of Pithomyces chartarum (Berk. & Curt.) M. B. Ellis; this was related to the diurnal progression of atmospheric humidity in settled bright weather. In micro wind tunnel experiments, with cultures of the fungus on natural substrate, the lowest wind velocity employed (1 m/sec) detached few spores either at low or at high humidities. When the wind speed was increased to 2.7 m/sec and the air humidity reduced, increased numbers of spores were detached. In water-drop tower studies, it was shown that large drops of water impacting on spore-bearing material detached dry spores in large numbers. The observed rate of fall of single spores of the fungus in still air was close to the theoretical rate of fall of 0.845 cm/sec. Spores of P. chartarum already detached from litter would require only slight air turbulence to keep them airborne. It was shown that rain falling on dry, short pasture could detach and...

Free Sugars in Spores of Pithomyces chartarum

VERY few analyses of free sugars have been reported in fungal spores. Owens et al.1 found 9.3 per cent hot-water soluble carbohydrate in conidia of Neurospora sitophila but only 0.06 per cent free sugars, principally glucose. Other authors2,3 have found higher amounts of free sugars in fungi. Sussman and Lingappa4 found 10 per cent trehalose in ascospores of Neurospora tetrasperma, while other fungi5 and yeasts6 also contain trehalose, often as the main carbohydrate reserve. The conidia of Neurospora sitophila, however, apparently contain none1. Irani and Ganapathi2 found free glucose, ribose and a trace of galac-tose in the mycelium of Penicillium chrysogenum. This report gives results of a study of the free sugars in the spores of Pithomyces chartarum (Berk, and Curt.) M. B. Ellis.

A study of fine structure of the spores ofPithomyces chartarum

Summary Electron microscope investigations of Pithomyces chartarum spores fixed in Osmium tetroxide and embedded in methacrylate have shown the association of a cytoplasmic granule with septal pores. Unusual concentrations of mitochondria and rhibosomes have been noted, and a complex system of layers has been seen in the spore coat. The general cell structure is discussed.

THE SPORE SURFACE IN PITHOMYCES CHARTARUM.

SUMMARY: Crystalline spicules of sporidesmolides, together with some lipid, form the surface layer of spores of Pithomyces chartarum. The formation of the spicules is controlled by the amino acids present in the culture medium.

Loss of sporidesmin from spores ofPithomyces chartarum(Berk. & Curt.) M. B. Ellis

Abstract Sporidesmin ean be rapidly eluted by water from spores of Pithomyces chartarum (Berk. & Curt.) M. B. Ellis. When aqueous extraets eontaining the toxin are exposed to bright sunlight sporidesmin is ehanged to other material whieh is not toxie, or is very mueh less toxie for HeLa eells. Loss of toxin from spores ean oeeur quite rapidly under field eonditions.

Some factors which may affect the toxicity of spores ofPithomyces chartarum(Berk. & Curt.) M. B. Ellis collected from pasture

Abstract Variation of the sporidesmin content of samples of spores of Pithomyces chartarum (Berk. & Curt.) M. B. Ellis collected from pasture is reported. The proportion of sporidesmin readily extracted from these spores by water varies widely, although high extraction is possible with large volumes of water. The instability of sporidesmin in aqueous solutions exposed to sunlight is demonstrated. The possible role of exposure to rain and sunlight in reducing the sporidesmin content of pasture spores is discussed.

Movement of Spores of Pithomyces chartarum on Leaves of Rye-grass

Pithomyces chartarum (Berk and Curt.) M. B. Ellis, the fungus associated with the disease known in New Zealand as ‘facial eczema’1, sporulates abundantly under suitable environmental conditions on litter in the pastures. The spores are found in large numbers on green leaves during periods when pastures are toxic to grazing animals. In this situation they may be ingested with the forage.

Characteristic lesions of facial eczema produced in sheep by dosing material containingPithomyces chartarumcollected from pasture

Abstract Material containing a high proportion of spores of Pithomyces chartarum was collected from grassland herbage by a suction cleaner technique. When dosed to sheep this material produced morphological changes in tissues identical to naturally-occurring asymptomatic cases of facial eczema and to similar cases produced by the oral administration of sporidesmin.