Isolation and characterization of five rice telomere-associated sequences

According to the telomere repeated sequences of rice, two primers: (TTTAGGG) 3 and (CCCTAAA) 3CCC were used to amplify rice telomere associated sequences (TASs). For PCR template preparation, total DNA was digested with restrictive endonuclease and then ligated.Using the ligates or total DNA as template, eight fragments were obtained with the single primer by the PCR reaction.To confirm that the sequences are derived from telomeric DNA, we conducted Bal31 digestion analysis. Of the eight fragments, seven were susceptible to Bal31 treatment, suggesting that they were TASs. These DNA fragments were further demonstrated to be rice sub telomeric sequences by RFLP mapping. Five sequences have been mapped to the distal ends on rice chromosome 5,6,7 and 9, and two other sequences have been mapped at interstitial sites, suggesting that (TTTAGGG) n also exist in the middle of rice chromosomes. All eight fragments were sequenced and characterized.