ABSTRACT
Objective To establish a dose-effect curve of premature condensation chromosome ring (PCC-R)in lymphocytes of human peripheral blood after exposed to high doses of Y-rays. Methods Peripheral blood samples was drawn from three healthy individuals, and exposed to 60Co γ-rays with doses between 0 and 30 Gy. The frequencies of PCC-R in premature condensation chromosome (PCC) cells obtained by Okadaic acid (OA) induction were calculated, and a dose-effect curve was fitted. Results PCC index tapered with dose. Frequencies of PCC-R per cell increased until 20 Gy, and then saturation was observed. The results were fitted to a lineal model up to 20 Gy: y = - 0.020 + 0.052D ,where y was the frequencies of PCC-R per cell, D was the radiation dose (Gy). Conclusins The highest dose could be estimated is 20 Gy by the dose-effect curve established with PCC-R method. Its utility and validity will be verified in the future application of radiation accident.
ABSTRACT
Objective To clone and identify the differentially expressed genes of rat intestinal epithelial cell line (IEC 6) before and after exposure to high dose radiation so as to provide proof for the investigation of the molecular mechanisms in the repair of radiation damage of intestinal epithelial cells. Methods A subtractive cDNA library for differentially expressed genes was constructed by suppression subtractive hybridization (SSH) and T/A cloning technique after IEC 6 cells were exposed to radiation at the dose of 35 Gy ? ray. The expressed sequence tag (EST) library was screened by reverse Northern hybridization. Positive clones were sequenced and the similarity was searched against the DNA database in GenBank. Limited clones were identified by Northern hybridization. Results More than 2 000 white clones were harvested after the library amplification. Ninety six of them were randomly picked out for PCR amplification, and 15 positive clones which corresponded to 12 individual genes were identified by reverse Northern hybridization. These genes were involved in cell skeleton, cell stress, cell cycle control, and signal transduction, etc. In addition, a novel cDNA sequence was also obtained. Conclusion A subtractive cDNA library for differentially expressed genes in IEC 6 cells exposed to the radiation at the dose of 35 Gy ? ray has been successfully constructed with SSH and T/A clone techniques. Several positive ESTs which correspond to genes involving in cell skeleton, cell stress, cell cycle control, and signal transduction are identified. These genes may play important roles in the process of the damage and repair of the intestinal epithelial cells exposed to radiation.