The Site of the Target Region for Radiation-Induced Mitotic Delay in Cultured Mammalian Cells

X-ray-induced Delay in the Chinese Hamster Cell-cycle: Dependence on Phase Irradiated under Different Culturing Conditions, BUdR Incorporation, and Hypertonic Treatment

“…No explanation can be offered for their uniform response during the cell-cycle, since we have found the differential response under a variety of culturing conditions, including one in which we attempted to duplicate their culturing medium and conditions . Furthermore, this differential effect has been shown by others in Chinese hamster cells (Froese 1966, Yu and Sinclair 1967, 1970 as well as in other cell-lines (Froese 1966, Terasima and Tolmach 1963, Tolmach, Terasima and Phillips 1965, Whitmore, Till and Gulyas 1967 .…”

“…First, the lesions, at least those associated with the delay during G 2 (G2 block), are located either in or immeditely adjacent to the nucleus (Munro 1970) but differ from those responsible for chromosomal aberrations and cell killing . In addition there are probably two separate types of lesions in the cell responsible for division delay, i .e ., those responsible for delay in entering and traversing the S phase and those responsible for the G 2 block (Leeper et al .…”

Targeted cytoplasmic irradiation with alpha particles induces mutations in mammalian cells

“…Earlier studies using polonium-tipped microneedles to deliver ␣-particles largely to either the nucleus or cytoplasm of CHO cells showed that the nucleus was the determining site for cellular survival (26), as well as induction of mitotic delay (27). Although these earlier studies were not very precise and used the distance between the needle tip and cell surface to estimate the particle fluency and, derivatively, the dose, nevertheless, they demonstrated that irradiation of cytoplasm was largely innocuous (26) and strongly indicated that DNA was the target for the radiobiological effects of ionizing radiation (28).…”

Sensitivity to X-rays in Terms of Mitotic Delay (Sd) and Killing (Sk): Correlation betweenSdandSkfor Sub-lines of Murine Leukaemic Cells

“…Today, extensive evidence suggests that nuclear DNA is a major target for radiation-induced reproductive death (RIRD), although the specific types of damage to DNA leading to death have not been identified (Okada 1970) . Little is known about the damage resulting in radiation-induced mitotic delay (RIMD) ; there are contradictory reports concerned with the possible involvement of DNA (Schneider and Johns 1966, Humphrey and Dewey 1965, Bootsma and Lohman 1968, but good evidence obtained with Chinese hamster cells indicates that the target(s) for division delay is within the nucleus or near the nuclear membrane (Munro 1970) . Since a major part of RIMD in mammalian cells often involves prolongation of the G 2 stage of the cell-cycle, regardless of the age of the cell at the time of exposure (Harrington 1960), RIMD is sometimes referred to as radiation-induced G 2-block .…”