Effect of glucose on growth and ultrastructural phenotype of Polytoma papillatum (chlamydophyceae)

Abstract

Summary We used quantitative light microscopy and electron microscopy of serial sections, analysis of population growth characteristics, and experimental alteration of an individual exogeneous factor (± glucose) to investigate phenotype environment interactions of Polytoma papillatum further. Although the addition of 0.2% glucose to the standard liquid nutrient induced acceleration of reproduction under batch culture conditions, neither the final number of cells nor their span of variability in shape and volume were markedly influenced by glucose supplementation. Compared with cells grown in standard medium, cells exposed to a glucose supplemented environment showed changes in the shape, number, and ultrastructure of the mitochondrial inventory (= chondriome) and in ultrastructure of the nucleolus and leucoplast. Whereas a volumetric balance existed between the cell and the chondriome during both culture conditions, the glucose supplementation brought about (1) an increase in the total number of mitochondria, (2) a numerical increase in intramitochondrial matrix grana, and (3) a change in spatial distribution of the chondriome, indicating profound modifications of the chondriome. Glucose also affected the spatial distribution of nucleolar constituents and caused local diversifications of the leucoplast. The adaptive nature of these responses to the glucose-stimulus is discussed with regard to internal regulatory mechanisms causing or permitting phenotypic expression.