Dry mass of Fusarium roseum spores before and after germination
The total dry mass of Fusarium roseum spores and contained lipid bodies were determined before and after spores germinated using quantitative interference microscopy. The mean for spore dry mass before germination was about 57 pg. Lipid bodies accounted for about 61% of that. Areas of lipid bodies in spores before and after germination were about 23 % but the contents of the lipid bodies accounted for only 10% of the spore dry mass after germination. The total dry mass of the spore and germ tube(s) greatly exceeded that of the spore before germination. We infer that nutrients for germ tube growth are derived from within the germinating spore and from the medium which must contain nutrients leached from non-germinating spores.
Correlation of light and scanning electron microscopy a new method for exfoliative cytology.
A method for preparing locator slides for light and scanning electron microscopy has been developed. These slides make possible correlation of light and scanning electron microscopy of individual cells. Some examples of the value of this method are given.
THE PHYSIOLOGY OF HOST-PARASITE RELATIONS: XII. A CYTOPHOTOMETRIC STUDY OF THE DISTRIBUTION OF DNA AND RNA IN RUST-INFECTED LEAVES
Uninfected and rusted leaves of Little Club wheat (reaction type 4) were sectioned at intervals up to 15 days after inoculation with Puccinia graminis tritici Erikss. and Henn., race 15B. Infection caused a decrease in the size of the chloroplasts, an increase in size followed by a collapse of the nuclei in the mesophyll cells and an increase in the size of the nucleoli. These effects also occurred, but more rapidly, in infected leaves of Khapli wheat (rust reaction type 1). They were most pronounced in the tissue beneath uredia. Cytophotometry of nuclei in Little Club by the 'two-wavelength' method after staining with the Feulgen reagent showed that there was no increase in the level of DNA in enlarged nuclei at 6 days after inoculation; collapse of the nuclei at 15 days after inoculation was accompanied by the loss of 60% of the DNA originally present. Cytophotometry of nucleoli in nuclei in mesophyll cells stained with azure B after selective removal of DNA with DNase showed that nucleolar enlargement ...