ABSTRACT
We describe two laser microirradiation optical platforms to study:
(i) DNA damage responses following selective damage to a single
mitotic chromosome arm and (ii) inhibition of cytokinesis resulting
from damage to single and/or multiple chromosome tips (pre-
sumptive telomeres) of cells in the anaphase stage of mitosis. For
studies on DNA damage a 200 femtosecond near-IR laser and a 12
nanosecond 532 nm second harmonic Nd:YVO4 laser were used, and
for microirradiation of chromosome tips a 532 nm 12 picosecond
second harmonic Nd:YAG laser was used. The DNA damage studies
showed that the structure of the alteration was the same for both
lasers, and very specific chemical sensing and repair pathways were
activated in mitosis. This was evidenced by the accumulation of
these proteins at the irradiation sites. Irradiation of the chromosome
tips resulted in an inhibition or delay in cytokinesis in a significant
percentage of cells. This result suggests that the chromosome tip, the
location of telomere, may have a regulatory role in the final stage of
cell division.
