Electrophoretic and Immunological Differences Between the Cytochrome c3 of Desulfovibrio desulfuricans and that of Desulfovibrio vulgaris

The cytochrome c(3) of Desulfovibrio desulfuricans and that of D. vulgaris were purified to homogeneity as judged by disc gel electrophoresis and by ultracentrifugation. Both cytochromes had an oxidation-reduction potential of -205 +/- 5 mv at pH 7.0 and showed characteristic absorption bands at 525 and 553 nm in the reduced state. The molecular weights of the two cytochromes (calculated from sedimentation and diffusion data) were similar, with values of 13,500 to 14,300 for D. desulfuricans and 13,800 to 14,700 for D. vulgaris. The two cytochromes differed in their electrophoretic properties on Geon and polyacrylamide gel electrophoresis and did not share a common precipitating antigenic determinant as judged by immunodiffusion data.     

THE PATHOLOGY OF HYPODERMELLA LARICIS ON LARCH,LARIX OCCIDENTALS

A study of the larch needle disease caused by Hypodermella laricis provided information on the mode of infection, the manner of spread, and the relationship between the parasite and its host, Larix occidentalis. Infection by spores occurs in early spring as soon as the leaves emerge, but there is no evidence that hyphae invade the dwarf shoots. The fungus disrupts the normal abscission mechanism, and the fructifications and spores of H. laricis develop on the leaves which remain attached to the dwarf shoots. The time of precipitation is a decisive factor in the initiation of the disease, i.e., infection occurs only when precipitation coincides with the emergence of young leaves. However, vulnerability to infection diminishes rapidly as the leaves mature. By observing leaf size and noting the time of rainfall, the severity of infection can be accurately predicted. Several adaptive mechanisms related to successful parasitism in H. laricis are discussed.     

The Role of Calcium Ions in the Acceleration of Resting Muscle Glycolysis by Extracellular Potassium

The activation of the glycolysis of resting muscle by increased extracellular potassium is dependent upon the simultaneous presence of calcium, but not of sodium ions. This regulation of metabolism by a membrane characteristic seems to act upon an early link in the glycolytic enzyme chain.     

Germination and initial growth of microsporon audouinii from infected hairs

Summary and Conclusion 1. The germinating spores ofMicrosporon audouinii on infected hairs appear to require thiamine, riboflavin and nicotinic acid or its amide for initial growth. They show complete independence for inositol and pyridoxine.2. Components of the arginine-urea cycle and uracil stimulated growth more than other nitrogen sources. Organic nitrogen is more readily utilized than inorganic sources.3. The hexoses glucose, mannose and fructose are the better utilized carbohydrates. Trehalose is more stimulatory for growth than other disaccharides.4. Hydrogen ion optimum for growth is within a narrow range around pH 6.8 for buffered solutions. The optimum range is wider for unbuffered solutions under the conditions tested.5. Optimum temperature for growth lies within a narrow range of the normal variance of room temperature. Growth rate decreases rapidly at either extreme of this range.6. Within the limits of the system tested a positive Eh does not alter the growth rate or incubation time of the organism, but a negative initial redox potential decreases rate of growth and increases incubation time.A preliminary report of this work was presented at the 57th meeting of the Society of American Bacteriologists and was used in a graduate thesis by the senior author at the University of Illinois (24).