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Utilization of polyadenylate mRNA during growth and starvation in Physarum polycephalum
Abstract:
The effect of growth on the efficiency of utilization of poly(A)-containing mRNA for translation has been investigated in microplasmodia of Physarum polycephalum. Measurement of the relative proportions of poly(A)-rich mRNA in polysomal and post-polysomal fractions isolated by sucrose density gradient centrifugation reveals that newly synthesized poly(A)-rich mRNA is present in increasing proportions in the polysomal region during exponential growth. However, the proportion of long-lived poly(A)-rich mRNA observed in actively-translating polysomes declines as starvation approaches. The ribonuclease content and morphology of the microplasmodia were monitored during growth and starvation in an effort to related this phenomenon to the onset of spherulation.
Insights
During growth, newly synthesized poly(A)-rich mRNA is increasingly translated in Physarum polycephalum. However, this translation efficiency declines as starvation approaches, preceding spherulation.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Polyadenylated mRNA (poly(A)-rich mRNA) plays a crucial role in gene expression and protein synthesis.
- Understanding mRNA utilization efficiency during different growth phases is vital for cell biology research.
- Physarum polycephalum serves as a model organism for studying cellular growth and differentiation.
Purpose of the Study:
- To investigate the impact of growth on the translation efficiency of poly(A)-rich mRNA in Physarum polycephalum microplasmodia.
- To correlate changes in mRNA translation with cellular growth and starvation-induced spherulation.
Main Methods:
- Sucrose density gradient centrifugation was used to isolate polysomal and post-polysomal fractions.
- Relative proportions of poly(A)-rich mRNA in these fractions were measured.
- Ribonuclease content and microplasmodia morphology were monitored during growth and starvation.
Main Results:
- Newly synthesized poly(A)-rich mRNA showed increasing proportions in polysomes during exponential growth.
- The proportion of long-lived poly(A)-rich mRNA in actively translating polysomes decreased as starvation commenced.
- Changes in mRNA translation efficiency were observed in relation to the onset of spherulation.
Conclusions:
- Cellular growth influences the efficiency of poly(A)-rich mRNA utilization for translation.
- A decline in the translation of long-lived mRNA precedes starvation-induced spherulation in Physarum polycephalum.
- These findings provide insights into the regulation of gene expression during developmental transitions.