Identification of mRNA in the Slime MoldPhysarum polycephalum

Abstract

Using a differential extraction procedure, previously shown to yield 1 nucleic acid fraction enriched in cytoplasmic RNA and another enriched in nuclear RNA, 2 polyadenylated RNA populations were isolated from microplasmodia of P. 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 in a protein-synthesizing system in vitro can direct the synthesis of peptides which were 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. The polyadenylated RNA isolated from the fraction enriched in cytoplasmic nucleic acid was identified as Physarum poly(A)-containing messenger RNA.