Accessibility of ribosomal genes to trimethyl psoralen in nuclei of Physarum polycephalum

Journal Article · Mon Mar 01 00:00:00 EST 1982 · Mol. Cell. Biol.; (United States)

DOI:https://doi.org/10.1128/MCB.2.3.211· OSTI ID:5649907

Judelson, H S; Vogt, V M

The authors have probed the accessibility of the genes for rRNA in Physarum polycephalum by using the photoreactive DNA cross-linking agent 4,5',8-trimethyl psoralen. Nuclei isolated from actively growing Physarum were treated with trimethyl psoralen and irradiated with 360-nm light in order to form cross-links. The palindromic, extrachromosomal rDNA then was isolated, and the positions of cross-links were determined by electron microscopy of the DNA under totally denaturing conditions. The results indicate that the frequency of cross-linking, after correction for base sequence bias of the reaction, is up to sixfold higher in the transcribed regions than in the central or the terminal spacer regions. There is no detectable heterogeneity among the different rDNA molecules or between the halves of a single molecule. Cross-linked molecules invariably occur in a linear as opposed to a cruciform structure. The preferential cross-linking of the transcribed region is nearly eliminated in spherules, a dormant transcriptionally inactive form in the Physarum life cycle.

• Research Organization: Lab. of Biophysics, Univ. of Wisconsin, Madison, WI 53706
• OSTI ID: 5649907
• Journal Information: Mol. Cell. Biol.; (United States), Vol. 2:3
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
DNA
CROSS-LINKING
ELECTRON MICROSCOPY
NUCLEIC ACID DENATURATION
DNA ADDUCTS
PHYSARUM
GENETIC RADIATION EFFECTS
PSORALEN
MUTAGENESIS
PHOTOREACTIVATION
CELL CULTURES
FREQUENCY MEASUREMENT
GENES
LIFE CYCLE
METHYL RADICALS
MUTATIONS
RIBOSOMAL RNA
TRANSCRIPTION
ULTRAVIOLET RADIATION
ADDUCTS
ALKYL RADICALS
ANTICOAGULANTS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CHEMICAL REACTIONS
COUMARINS
DRUGS
ELECTROMAGNETIC RADIATION
FUNGI
GENETIC EFFECTS
HEMATOLOGIC AGENTS
HETEROCYCLIC COMPOUNDS
MICROSCOPY
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PLANTS
POLYMERIZATION
RADIATION EFFECTS
RADIATIONS
RADICALS
RECOVERY
REPAIR
RNA
560152* - Radiation Effects on Animals- Animals
550400 - Genetics
560300 - Chemicals Metabolism & Toxicology