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Induction of polyploid nuclei in Physarum polycephalum by cycloheximide treatment in prophase
Abstract:
Macroplasmodia of the acellular slime mold Physarum polycephalum were treated with pulses of cycloheximide (10 micrograms/ml medium, for 3 h), initiated 10-20 min before metaphase in the synchronous nuclear division cycle. This treatment interfered with normal division of the nuclei, but permitted DNA synthesis in the next S phase. This interpretation is supported by measurements of the DNA content per nucleus in cycloheximide-treated cultures as compared to control cultures, which show that some nuclei after cycloheximide treatment are polyploid. By this method we can produce polyploid strains of Physarum, but the elevated nuclear DNA content is not stable, and after several months the strains have reverted to the normal diploid DNA content.
Insights
Cycloheximide treatment of Physarum polycephalum slime mold induced polyploidy by enabling DNA synthesis without nuclear division. However, these polyploid strains were unstable, reverting to diploidy over time.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The acellular slime mold Physarum polycephalum exhibits a synchronous nuclear division cycle.
- Understanding mechanisms that control nuclear division and DNA replication is crucial in cell biology.
Purpose of the Study:
- To investigate the effects of cycloheximide on nuclear division and DNA synthesis in Physarum polycephalum.
- To determine if cycloheximide can be used to induce polyploidy in Physarum polycephalum.
Main Methods:
- Macroplasmodia of Physarum polycephalum were treated with cycloheximide prior to metaphase.
- Nuclear division and DNA content were analyzed in treated and control cultures.
- The stability of induced polyploidy was monitored over several months.
Main Results:
- Cycloheximide treatment inhibited normal nuclear division but allowed DNA synthesis.
- Measurements confirmed the presence of polyploid nuclei in treated cultures.
- Induced polyploidy was not stable, with strains reverting to diploid DNA content within months.
Conclusions:
- Cycloheximide can be used to experimentally induce transient polyploidy in Physarum polycephalum.
- This method provides a tool to study the consequences of altered ploidy in this model organism.
- The instability of induced polyploidy highlights regulatory mechanisms maintaining normal ploidy levels.