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.
Interference microscopy of onion epidermal nuclei in response to three fungal pathogens
Abstract Onion bulbs were injured on four sides with a sterile cork borer (5 mm diameter) and three such injuries were used as inoculation sites for Botrytis allii, Aspergillus niger and an unidentified neckrot fungus. Nuclei of cells in control tissue increased in size and dry mass as a result of wounding. Each of the fungi caused a decreased size and dry mass of host nuclei, with Botrytis allii being the most effective in this regard.
The physiology of host–parasite relations. XIX. Further observations on nucleoprotein changes in wheat leaf nuclei during rust infection
Cytophotometric measurements of DNA (Feulgen) and protein-bound lysine and arginine (fluorodinitrobenzene-Sakaguchi) were made on nuclei in mesophyll cells of infected and uninfected leaves of Little Club wheat at intervals of 2 to 4 days up to 13 days after inoculation with uredospores of race 15B of the stem rust fungus (Puccinia graminis tritici Erikss. and Henn.). No change in host DNA was found within 6 days after inoculation, but there were marked decreases in protein-bound lysine and arginine as early as 2 days after inoculation. The DNA/lysine and DNA/arginine ratios were higher in rust-affected host nuclei, but infection did not alter the ratio of protein-bound lysine to arginine. In another series of measurements it was shown that rust infection caused striking increases in the volume and the RNA and protein contents of host nucleoli. These changes persisted even in advanced infections.All the results are consistent with our earlier observations and indicate that profound changes in nuclear meta...