Reassociation kinetics of sequences replicated early in S phase and expression of a centriolar antigen

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:7189177

Segarini, P R

This thesis addresses two aspects of the initiation of DNA replication in eucaryotic cells. The major part of this thesis is concerned with an attempt to identify and isolate DNA sequences that are replicated at the onset of S-phase. It was presumed that these sequences contain origins of DNA replication. Growth requirements and restrictions of the epithelial-like cell lines TC7 and COS-1, and the fibroblast-like cell lines 3T3, SV3T3, and CHO have been rigorously characterized. A serum deprivation protocol was adapted for the synchronization of the most useful of these, 3T3 cells. By stimulating a quiescent culture with serum in the presence of the DNA polymerase inhibitor, aphidicolin, the cells progress toward S phase but are held at the G1/S boundary. Upon removal of the drug, the cells, synchronously enter S phase. DNA sequences in 3T3 cells that replicate at entrance to S phase were labelled with /sup 3/H-thymidine and used as tracers in reassociation experiments that examined the complexity of these sequences. Approximately one third of the S-entry labelled sequences were driven to reassociate as sequences that are moderately reiterated in the 3T3 genome. In a separate study, the expression of an antigen located at the centrolar region of TC7 cells was investigated. The expression was dependent on both the position in the cell cycle and on the growth conditions. Within the cell cycle, expression of the centriolar antigen was observed just before and during the onset of S phase. The nature and function of the antigen remains unclear.

• Research Organization: California Univ., Los Angeles (USA)
• OSTI ID: 7189177
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMAL TISSUES
AZINES
BIOCHEMISTRY
BIOSYNTHESIS
BODY
CELL CYCLE
CHEMISTRY
CONNECTIVE TISSUE CELLS
DNA REPLICATION
DNA SEQUENCING
EPITHELIUM
FIBROBLASTS
HETEROCYCLIC COMPOUNDS
KINETICS
LABELLED COMPOUNDS
NUCLEIC ACID REPLICATION
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RIBOSIDES
SOMATIC CELLS
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
THYMIDINE
TISSUES
TRITIUM COMPOUNDS