Biochemical analyses and nutritional effects on differentiation (encystment) in the myxomycete, Physarum flavicomum

A method of inducing haploid differentiation (encystment) in the myxomycete Physarum flavicomum variety 1 is established. Incubation of mid-log phase myxamoebae-swarm cells from SD medium to basal salts solution at pH 4 gives a high percentage yield of microcysts. The microcysts are viable upon transfer back to growth medium. Intracellular protein and carbohydrate are degraded to a great extent during this process. RNA degradation is observed and condensation of cytoplasmic materials occurs upon encystment. DNA is conserved and less than 10% is degraded after 72 hours incubation. The cell walls of the mature microcysts are isolated and purified. Chemical analyses on the walls reveal the presence of an amino sugar D-galactosamine and neutral sugars D-glucose, D-galactose and D-ribose. Lipid and protein together are found to constitute more than 40% of the dry weight of the walls. Individual amino acids in the wall protein are identified by amino acid analysis. The microcyst walls also contain 5.8% phosphorus. A total of 91.3% of the components of the purified, dry microcyst walls have been identified. [...]