Purpose:Telomerase was discovered recently as an important tumor marker, and the necessary gene sequence which is closely related with telomerase activity is one of the methods to study the telomerase regulation mechanism. Methods:RT PCR, Northern blot were used to test the relationship between the expression of hEST2 reverse transcriptase motif fragment and telomerase activity, classic telomerase measurement method was set up as contol. Results:Indicate that the expression of 7 RT motifs fragment which include telomerase specific T motif have a close relationship with telomerase activity. Conclusions:It will be helpful to further research of telomerase regulation mechanism, diagnosis and inhibition.

Objectives. In order to identify the relationship between telomerase and the biological effect of radiation injury,and investigate the role of human telomerase catalytic subunit gene (hEST2) reverse transcriptase(RT) segment in the expression of telomerase activity. Methods. Tumor HeLa cells, KB cells and A431 cells were employed to measure the change in telomerase activity after 60Co ray irradiation at RNA level and protein level. Quantitative PCR and Northern blotting were used to determine the expression of hEST2 RT segment that encodes seven motifs of the human telomeres, a PCR based telomeric repeat amplification protocol (TRAP)was used to assay telomerase activity after exposure to radiation. Results. Both of telomerase activity and the expression hEST2 RT segment were decreased with increasing dosage of radiation. In addition, testing the expression of motifs domain is similar to the measurement of telomerase activity. Conclusion. The detection of the hEST2 RT segment by Northern blotting and quantitative PCR are new methods for testing telomerase activity. Furthermore, radiation can cause a dose dependent decrease in telomerase activity. The effect of radiation on telomerase is one possible reason for the death of cancer cells after irradiation.