The nuclear genome harbours hundreds to several thousand copies of ribosomal DNA. Despite their essential role in cellular ribogenesis few studies have addressed intrapopulation, interpopulation and interspecific levels of rDNA variability in wild plants. Some studies have assessed the extent of rDNA variation at the sequence and copy-number level with large sampling in several species. However...

The fraction and distribution of DNA complementary to ribosomal RNA and preribosomal RNA was investigated by the technique of molecular hybridization with the DNA of isolated nucleoli and nuclei of rat liver. Nuclear DNA complementary to ribosomal 18 S RNA and 28 S RNA was 0.014% and 0.032%, respectively. Nucleolar DNA complementary to ribosomal 18 S RNA and 28 S RNA was 0.10% and 0.22%, respec...

The kinetics of synthesis of ribosomal, nonribosomal, and total protein, and of ribosomal ribonucleic acid (RNA), were measured in Escherichia coli during a shift-up involving a doubling of specific growth rate. The increase in ribosomal protein synthesis was not accompanied by a corresponding decrease in non-ribosomal protein synthesis. Thus, the average rate of protein synthesis per ribosome ...

Amino acid deprivation of a "relaxed" auxotroph of Escherichia coli results in the accumulation of protein-deficient, immature ribosomes ("relaxed particles"). The ribonucleic acid (RNA) of these particles was shown to differ from mature ribosomal RNA in both sedimentation characteristics and in elution from columns of methylated albumin-keiselguhr. When relaxed particles were allowed to become...

Methionine limitation during growth and sporulation of a methionine-requiring diploid of Saccharomyces cerevisiae causes two significant changes in the normal synthesis of ribonucleic acid (RNA). First, whereas 18S ribosomal RNA is produced, there is no significant accumulation of either 26S ribosomal RNA or 5.8S RNA. The effect of methionine on the accumulation of these RNA species occurs afte...

Streptomycin produces multiple effects in growing cultures of bacteria, including stimulation of ribonucleic acid (RNA) and inhibition of protein synthesis (Erdos and Ullman, Nature 183:618, 1959), interference with ribosomal function (Speyer et al., Proc. Nat. Acad. Sci. U.S. 48:684, 1962), deranged deoxyribonucleic acid (DNA) and RNA metabolism, and changes in membrane integrity (Dubin et al....

A form of dwarfism known as Meier-Gorlin syndrome (MGS) is caused by recessive mutations in one of six different genes (ORC1, ORC4, ORC6, CDC6, CDT1, and MCM5). These genes encode components of the pre-replication complex, which assembles at origins of replication prior to S phase. Also, variants in two additional replication initiation genes have joined the list of causative mutations for MGS ...

The heating of Salmonella typhimurium 7136 at 48 C for 30 min produces a population of cells that are incompetent at division on Levine Eosin Methylene Blue Agar containing 2.0% NaCl (EMB-NaCl). When these injured cells were placed in fresh citrate salts medium they recovered, and regained their tolerance to the EMB-NaCl medium and grew out. The addition of the selective inhibitors rifamycin, 5...