Telomeric localization of the Arabidopsis-type heptamer repeat, (TTTAGGG)n, at the chromosome ends in Saccharina japonica (Phaeophyta)
Telomeric localization of the Arabidopsis-type heptamer repeat, (TTTAGGG)n, at the chromosome ends in Saccharina japonica (Phaeophyta)
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拟南芥型七聚体重复序列 (TTTAGGG)n 在糖精藻（褐藻门）染色体末端的端粒定位
DOI：
10.1111/jpy.12497
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发表时间：
2017
影响因子：
2.9
通讯作者：
Zhou Zhi-Gang
中科院分区：
文献类型：
--
作者：
Yang Qi-Fan;Liu Li;Liu Yu;Zhou Zhi-Gang
端粒通常由小卫星DNA序列的短重复序列组成，并且在染色体鉴定和核型分析中是有用的。迄今为止，端粒还没有在经济上重要的棕色海藻日本，因此，其全面的细胞遗传学研究和遗传育种的潜力还没有实现。在此，日本血吸虫端粒的暂定序列通过PCR扩增鉴定，引物设计基于拟南芥型端粒序列（TTTAGGG）n，其选自通常存在于植物和藻类中的三种可能的端粒重复DNA序列。经PCR优化和克隆后，对扩增产物进行序列分析，结果表明，扩增产物由重复单元（TTTAGGG）n组成，重复单元数为15 ~ 63（n= 46）。以拟南芥端粒序列为探针，通过Southern印迹分析验证了这种重复序列。用核酸外切酶Bal 31消化日本血吸虫基因组DNA表明，与拟南芥型端粒序列相对应的靶序列易受Bal 31消化，这表明重复序列可能位于海带染色体的最外端。与上述探针的荧光原位杂交提供了初步的细胞遗传学证据，杂交信号主要定位于日本血吸虫染色体的两端。本研究通过基因组测序，发现海带染色体的端粒重复序列为（TTTAGGG）n，与先前报道的硅叶海桐染色体的端粒重复序列（TTAGGG）n不同，从而表明褐藻中存在不同的端粒。
Telomeres generally consist of short repeats of minisatellite DNA sequences and are useful in chromosome identification and karyotype analysis. To date, telomeres have not been characterized in the economically important brown seaweedSaccharina japonica, thus its full cytogenetic research and genetic breeding potential has not been realized. Herein, the tentative sequence of telomeres inS. japonicawas identified by PCR amplification with primers designed based on theArabidopsis‐type telomere sequence (TTTAGGG)n, which was chosen out of three possible telomeric repeat DNA sequences typically present in plants and algae. After PCR optimization and cloning, sequence analysis of the amplified products fromS. japonicagenomic DNA showed that they were composed of repeat units, (TTTAGGG)n, in which the repeat number ranged from 15 to 63 (n= 46). This type of repeat sequence was verified by a Southern blot assay with theArabidopsis‐type telomere sequence as a probe. The digestion ofS. japonicagenomic DNA with the exonucleaseBal31 illustrated that the target sequence corresponding to theArabidopsis‐type telomere sequence was susceptible toBal31 digestion, suggesting that the repeat sequence was likely located at the outermost ends of the kelp chromosomes. Fluorescence in situ hybridizations with the aforementioned probe provided the initial cytogenetic evidence that the hybridization signals were principally localized at both ends ofS. japonicachromosomes. This study indicates that the telomeric repeat of the kelp chromosomes is (TTTAGGG)nwhich differs from the previously reported (TTAGGG)nsequence inEctocarpus siliculosusthrough genome sequencing, thereby suggesting distinct telomeres in brown seaweeds.