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Biomedical subjects

R Dulbecco

Publications and source records attributed to R Dulbecco.

At least 91 records · Page 5Linked to original sources
PubMed1970

Conditions determining initiation of DNA synthesis in 3T3 cells.

Experiments were designed to discriminate between inhibition of growth due to contacts or exhaustion of serum factors. The cell layer was wounded and the migrating cells were followed by time-lapse cinematography; DNA synthesis in the same cells was recognized by means of (3)H-thymidine labeling and radioautography. In this way, the complete history of individual cells migrating to the wound could be described. The results show that topographical relationships between cells play an important role in controlling initiation of DNA synthesis. It is still unclear whether initiation is promoted by release from contacts or by the increased ability of the cells to utilize serum factors because of their changes in shapes and activities.

Cell Movement↗
PubMed1970

Behavior of tissue culture cells infected with polyoma virus.

Infection of tissue culture cells with the oncogenic polyoma virus, or its temperature-sensitive mutant Ts-a, causes several changes other than the previously known induction of cellular DNA synthesis. Cellular movement, survival, and mitotic rate are enhanced in low-serum medium, and morphology is changed; the cellular growth parameters, wound serum requirement, and topoinhibition are markedly decreased. The changes are similar to those that occur in cell transformation and are produced by viral functions known to be expressed in transformed cells. Clues as to the possible mechanisms of all these changes are analyzed and a possible mechanism is discussed.

Cell Movement↗
PubMed1970

Temperature-dependent properties of cells transformed by a thermosensitive mutant of polyoma virus.

In cells transformed by ts-3, a thermosensitive mutant of polyoma virus, the loss of inhibition of DNA synthesis by topographical factors (topo-inhibition), is rendered temperature-dependent, providing evidence that the viral genome controls this essential aspect of transformation. The expression of two other attributes of transformed cells, growth in agar and serum requirement for initiation of DNA synthesis in a wound in culture, is not made temperature-dependent. In productive infection of BALB-3T3 cells by ts-3, virus-induced stimulation of cellular DNA synthesis and movement is rendered temperature-dependent.

Agar↗
PubMed1969

The replication of the ring-shaped DNA of polyoma virus. I. Identification of the replicative intermediate.

The replication of the ring-shaped polyoma DNA has been investigated. The replicative intermediate has been identified and characterized; it consists of molecules containing both circular and nicked strands, not longer than the strands of the DNA found in viral particles. The findings exclude certain proposed methods of replication of ring-shaped DNA and are compatible with Cairns' model.

Centrifugation, Density Gradient↗