Cell Division after Laser Microirradiation of Mitotic Chromosomes

DNA damage induced during mitosis undergoes DNA repair synthesis

“…These methods of DNA damage induction result in genome-wide alterations that may lead to different DDRs. However, the laser has demonstrated to be very useful for DNA damage response studies because of its ability to target a submicron region within a specified chromosome region [23][24][25][26][27][28][29]. Interestingly, a laser micro-irradiation study conducted over forty years ago, showed that when the nucleolar organizer was specifically damaged in mitotic cells, a few of the irradiated cells were able to undergo a subsequent mitosis.…”

Inhibition of Nucleolar Formation in Pt-Kl Rat-Kangaroo Cells by Laser Microbeam Irradiation

“…It has been observed, repeatedly (Berns et al 1971;Ohnuki et al 1972), that the cell cycle can be followed after random microbeam irradiation of chromosomes (not in the NO region).…”

“…Microbeam irradiation of the secondary constrictions in anaphase chromosomes caused a reduction in nucleolar number in reconstructed daughter nuclei. This indicated that the argon laser microbeam system is an efficient tool to analyze genetic function of specific sites of large urodele chromosomes, and Berns et al (1971) have demonstrated that it can be applied to produce non-specific lesions in small mammalian chromosomes.…”

DNA damage induced during mitosis undergoes DNA repair synthesis

“…We investigated the ability of cells damaged in mitosis to enter a second mitosis. This is an important question raised by early studies using a different laser (argon ion laser emitting 488 or 514 nm light) where mitotic cells with focal damage to a single chromosome were still able to undergo a subsequent mitosis and produce apparently normal cells [26]. This is significant because entry into second mitosis is indicative of checkpoint recovery and thus DNA repair to the point that it is no longer halting cell cycle progression.…”