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Identification of mRNA in the slime mold Physarum polycephalum
Abstract:
Using a differential extraction procedure which had previously been shown to yield one nucleic acid fraction enriched in cytoplasmic RNA and another enriched in nuclear RNA, we have been able to isolate two polyadenylated RNA populations from microplasmodia of Physarum polycephalum. The poly(A)-containing RNA from the cytoplasmic-enriched fraction accounts for approximately 1.2% of the cytoplasmic nucleic acid, has a number-average nucleotide size of 1339+/- 39 nucleotides, and has been shown, in a protein-synthesizing system in vitro, to be capable of directing the synthesis of peptides which have also been shown to be synthesized in vivo by microplasmodia. The poly(A)-containing RNA from the nuclear-enriched fraction has a number-average nucleotide size of 1533 +/- 104 nucleotides and represents a mixture of cytoplasmic and nuclear adenylated RNA molecules. Based upon these observations, we have identified the polyadenylated RNA isolated from the fraction enriched in cytoplasmic nuclei acid as Physarum poly(A)-containing messenger RNA.
Insights
Researchers identified Physarum poly(A)-containing messenger RNA in cytoplasmic fractions. This polyadenylated RNA directs protein synthesis in vitro, confirming its messenger role in microplasmodia.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Polyadenylated RNA plays a crucial role in gene expression and mRNA stability.
- Understanding RNA populations in different cellular compartments is key to deciphering gene regulation.
Purpose of the Study:
- To isolate and characterize polyadenylated RNA populations from Physarum polycephalum microplasmodia.
- To identify the specific fraction of polyadenylated RNA that functions as messenger RNA.
Main Methods:
- Differential extraction to isolate cytoplasmic and nuclear RNA fractions.
- Analysis of poly(A)-containing RNA size and distribution.
- In vitro protein synthesis assays to assess RNA functionality.
Main Results:
- Two distinct polyadenylated RNA populations were isolated from Physarum polycephalum microplasmodia.
- Cytoplasmic poly(A)-containing RNA (1.2% of cytoplasmic nucleic acid) averaged 1339 nucleotides and directed in vitro peptide synthesis.
- Nuclear-enriched fraction contained a mix of cytoplasmic and nuclear adenylated RNA molecules.
Conclusions:
- The polyadenylated RNA isolated from the cytoplasmic-enriched fraction is identified as Physarum messenger RNA.
- This finding supports the role of polyadenylated RNA in directing protein synthesis in Physarum.
- The study provides insights into the compartmentalization and function of mRNA in this organism.