Chen C M, Wang C T, Wang C J, Ho C H, Kao Y Y, Chen C C
Institute of Botany, Academia Sinica, Taipei, Taiwan, Republic of China.
Chromosome Res. 1997 Dec;5(8):561-8. doi: 10.1023/a:1018449920968.
Two tandemly repeated telomere-associated sequences, NP3R and NP4R, have been isolated from Nicotiana plumbaginifolia. The length of a repeating unit for NP3R and NP4R is 165 and 180 nucleotides respectively. The abundance of NP3R, NP4R and telomeric repeats is, respectively, 8.4 x 10(4), 6 x 10(3) and 1.5 x 10(6) copies per haploid genome of N. plumbaginifolia. Fluorescence in situ hybridization revealed that NP3R is located at the ends and/or in interstitial regions of all 10 chromosomes and NP4R on the terminal regions of three chromosomes in the haploid genome of N. plumbaginifolia. Sequence homology search revealed that not only are NP3R and NP4R homologous to HRS60 and GRS, respectively, two tandem repeats isolated from N. tabacum, but that NP3R and NP4R are also related to each other, suggesting that they originated from a common ancestral sequence. The role of these repeated sequences in chromosome healing is discussed based on the observation that two to three copies of a telomere-similar sequence were present in each repeating unit of NP3R and NP4R.
从蓝烟草中分离出了两个串联重复的端粒相关序列NP3R和NP4R。NP3R和NP4R的重复单元长度分别为165和180个核苷酸。在蓝烟草的单倍体基因组中，NP3R、NP4R和端粒重复序列的丰度分别为每单倍体基因组8.4×10⁴、6×10³和1.5×10⁶个拷贝。荧光原位杂交显示，在蓝烟草单倍体基因组中，NP3R位于所有10条染色体的末端和/或居间区域，NP4R位于三条染色体的末端区域。序列同源性搜索显示，NP3R和NP4R不仅分别与从烟草中分离出的两个串联重复序列HRS60和GRS同源，而且NP3R和NP4R彼此也相关，这表明它们起源于一个共同的祖先序列。基于在NP3R和NP4R的每个重复单元中存在两到三个端粒相似序列的观察结果，讨论了这些重复序列在染色体修复中的作用。
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