Differential radio-sensitivities of human chromosomes 1 and 2 in one donor in interphase- and metaphase-spreads after 60Co γ-irradiation

Upon blood collection, dosimetry and irradiation were performed. Lymphocytes were isolated after whole-blood irradiation with 60Co γ-rays in the dose range of 0–5 Gy for both interphase, and metaphase aberration studies. Induction of premature chromosome condensation in interphase cells was accomplished using a phosphatase inhibitor, calyculin-A. Metaphase spreads were harvested from short-term peripheral blood lymphocyte cultures following colcemid arrest and using an automated metaphase harvester and spreader. Aberration analysis in both interphase and metaphase spreads were done using FISH.In interphase, aberrant cell and aberration frequency involving chromosome 1 and/or 2 increased linearly with radiation dose. In metaphase, aberrations increased in a linear-quadratic manner with dose. Our studies ascertain that chromosome-2 is more radio-sensitive than chromosome-1 in both interphase and metaphase stages, albeit the DNA content of chromosome-2 is lesser than chromosome-1 by almost 10 million base pairs.Differences in radio-sensitivities of chromosomes have implications in genetic damage, chromosome organization, and chromosome function. Designing research experiments based on our vital findings may bring benefit to radiation-induced risk assessment, therapeutics and development of chromosome specific biomarkers.Radiation-induced chromosome aberrations lead to a plethora of detrimental consequences at cellular level. Inter-chromosomal differences in radio-sensitivity may indicate various underlying differences such as organization of chromatin material or genetic damage etc,. Careful and systematic analysis of chromosomal radio-sensitivity reveals differential susceptibility of chromosome(s) for aberration induction. Further it has been recently reported that a specific set of periodic DNA motif in genomic DN A, influence human chromosome function via chromatin organization [1].Chromosome size, in general, is proportional to DNA content. Pandita et al. [2] and