Differential sensitivity of polytene chromosomes to Nd:YAG laser
A fundamental understanding of the interaction of Nd:YAG lasers with biological tissues have remained a challenging field demanding further investigation, especially exploring the threshold level of chromatin damage. The present study aims at addressing these questions using an insect derived model tissues, namely salivary glands (SG) and malpighian tubules (MT) of a midge Chironomus ramosus. Both SG & MT have polytenized chromosomes in their nuclei with a variable number of chromatids. Upon Nd:YAG (λ = 1064 nm) laser irradiation, using a fixed dose with variable time of exposure, SG & MT showed different levels of sensitivity. The onset and rate of induction of pyknotic nuclei and the threshold level of laser-induced pyknosis of chromatin material were dependent on exposure time. Parameters used for laser irradiation were non-ablative in order to avoid thermal injury. The temperature of the samples was kept controlled within ± 1 °C and did not vary during laser exposure. Our findings suggest that non-ablative laser-induced cell death is dependent on chromatin organization.
International Journal of Biological & Chemical Sciences Vol. 1 (1) 2007: pp. 1-6