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Biochemical changes during growth and encystment of the cellular slime mold Polysphondylium pallidum
Abstract:
The growth of the cellular slime mold, Polysphondylium pallidum, was studied on a semidefined medium in shaken suspension. When the medium contained large quantities of particulate material, growth was more rapid and the cellular size and protein content were smaller than when growth occurred on a medium containing less particulate material. The cellular levels of DNA, RNA, and protein; of lysosomal enzymes (acid phosphatase, acid proteinase); and of peroxisomal enzymes (catalase) were assayed during growth and the subsequent stationary phase that led eventually to encystment. Only DNA remained at a constant cellular level. Encystment of exponentially growing cells could also be initiated by washing them and introducing them into a soluble peptone medium. The rate of encystment was proportional to the osmolarity of this medium. The encystment process was followed with respect to the cellular levels of DNA, RNA, protein, carbohydrates, acid phosphatase, acid beta-N-Ac-glucosaminidase, and catalase. The most dramatic change occurred in the cellular cellulose content, which increased by at least an order of magnitude by the time encystment was morphologically complete. It was concluded that the encystment of this slime mold in suspension exhibits a number of biochemical similarities to the development of this and other cellular slime molds on a surface.
Insights
Cellular slime mold growth and encystment were studied in suspension. Key biochemical changes, including increased cellulose, occurred during encystment, similar to surface development.
Area of Science:
- Cell Biology
- Microbiology
- Biochemistry
Background:
- Cellular slime molds, like Polysphondylium pallidum, undergo complex developmental processes.
- Understanding encystment is crucial for comprehending their life cycle and ecological roles.
Purpose of the Study:
- To investigate the growth characteristics of Polysphondylium pallidum in shaken suspension.
- To analyze the biochemical changes during growth and encystment in this organism.
Main Methods:
- Culturing Polysphondylium pallidum on a semi-defined medium in shaken suspension.
- Assaying cellular levels of DNA, RNA, protein, enzymes (acid phosphatase, catalase), and carbohydrates.
- Inducing encystment by altering medium osmolarity and composition.
Main Results:
- Growth rate and cellular characteristics varied with particulate material in the medium.
- DNA levels remained constant, while RNA and protein levels fluctuated during growth and stationary phases.
- Encystment was triggered by osmotic stress and characterized by a significant increase in cellular cellulose content.
Conclusions:
- The encystment of Polysphondylium pallidum in suspension shares biochemical similarities with surface-induced development.
- Cellulose accumulation is a critical feature of the encystment process in this slime mold.