Open AccessMetabolic Stability of the Extrachromosomal Ribosomal RNA Genes in the Slime Mould Physarum polycephalum
Author(s) -
HALL Len,
GUBLER Ueli,
BRAUN Richard
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12282.x
Subject(s) - physarum polycephalum , extrachromosomal dna , ribosomal rna , dna , biology , slime mold , ribosomal dna , 28s ribosomal rna , gene , physarum , ribosome , biochemistry , microbiology and biotechnology , rna , phylogenetic tree , plasmid
The rRNA genes of the slime mould Physarum polycephalum are located on free, linear DNA molecules of a discrete size, M r = 38 × 10 6 . Using an isotope dilution technique we have examined the metabolic stability of these extrachromosomal genes during active, balanced growth. Microplasmodia, prelabelled with [ 3 H]thymidine, were used to prepare synchronous surface plasmodial cultures which were subsequently grown on unlabelled medium. The gross synthesis of ribosomal DNA was then determined over three consecutive mitotic divisions from the ratio of 3 H to 14 C in a hybrid formed between the extracted ribosomal [ 3 H]DNA and a [ 14 C]rRNA probe. It was found that ribosomal DNA, like chromosomal DNA, is completely stable during active growth.