番茄端粒的宏观结构。
Macrostructure of the tomato telomeres.
作者信息
Ganal M W, Lapitan N L, Tanksley S D
机构信息
Department of Plant Breeding and Biometry, Cornell University, Ithaca, New York 14853.
出版信息
Plant Cell. 1991 Jan;3(1):87-94. doi: 10.1105/tpc.3.1.87.
The macrostructure of the tomato telomeres has been investigated by in situ hybridization, genomic sequencing, and pulsed-field gel electrophoresis. In situ hybridizations with a cloned telomeric sequence from Arabidopsis thaliana indicated that the telomeric repeat of tomato cross-hybridizes with that of Arabidopsis and is located at all telomeres. Bal31 digestion kinetics confirmed that the tomato telomeric repeat represents the outermost DNA sequence of each tomato chromosome. Genomic sequencing of enriched tomato telomeric sequences, using primers derived from the Arabidopsis sequence, revealed that the consensus sequence of the tomato telomeric repeat is TT(T/A)AGGG compared with the Arabidopsis consensus sequence of TTTAGGG. Furthermore, as shown by pulsed-field gel electrophoresis, the telomeric repeat of tomato is separated by not more than a few hundred kilobases from a previously described 162-base pair satellite DNA repeat of tomato (TGR I) at 20 of the 24 telomeres. Together, these sequences are found in the heterochromatic terminal knob observed in pachytene chromosomes. Therefore, these two repeats determine the structure of 20 of the 24 tomato chromosome ends over approximately 2% of the total chromosome length.
通过原位杂交、基因组测序和脉冲场凝胶电泳对番茄端粒的宏观结构进行了研究。用来自拟南芥的克隆端粒序列进行原位杂交表明，番茄的端粒重复序列与拟南芥的端粒重复序列交叉杂交，且位于所有端粒处。Bal31消化动力学证实，番茄端粒重复序列代表每个番茄染色体的最外层DNA序列。利用源自拟南芥序列的引物对富集的番茄端粒序列进行基因组测序，结果显示，与拟南芥的TTTAGGG共有序列相比，番茄端粒重复序列的共有序列为TT(T/A)AGGG。此外，如脉冲场凝胶电泳所示，在24个端粒中的20个端粒处，番茄的端粒重复序列与先前描述的番茄162碱基对卫星DNA重复序列（TGR I）相隔不超过几百千碱基。这些序列共同存在于粗线期染色体中观察到的异染色质末端结中。因此，这两个重复序列在约占染色体总长度2%的范围内决定了24个番茄染色体末端中20个末端的结构。
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