雷蒙德氏棉一段单拷贝序列的FISH分析

FISH Analysis of a Single-Copy Sequence from Gossypium raimondii

雷蒙德氏棉基因组草图的完成为棉花的基础研究奠定基础,然而该基因组草图仍需要后续的补充和完善。利用雷蒙德氏棉基因组草图信息,分别在6条较长染色体的端部选取了4 kb的序列。通过生物信息学分析这些序列在基因组中的拷贝情况,发现2号染色体一端的序列Chr2D属于单拷贝序列,且其内部没有重复序列。随后以该段序列为探针,对雷蒙德氏棉有丝分裂中期染色体进行荧光原位杂交,结果显示在1号染色体和4号染色体的一端有明显的杂交信号,信号大小远远大于4 kb序列所能产生信号的大小,而信号的强度则比正常的杂交信号暗弱。试验结果说明该4 kb序列Chr2D可能在1号染色体和4号染色体的1个端部有较高的拷贝数,而信号强度的暗弱则说明该序列在染色体上的分布方式可能为散漫分布。杂交信号在1号染色体和4号染色体上的相似性说明,这2对染色体可能有一定的亲缘关系。该结果将对雷蒙德氏棉基因组草图的补充完善有帮助。

While the draft genome of Gossypium raimondii provides a firm foundation for cotton fundamental research, it requires further work to make it complete and robust. Four-kilobyte-long sequences were selected from terminal sections of six of the longer chromosomes using the G. raimondii draft genome. After analysis of the selected sequences by bioinformatics, Chr2 D was found to be a single-copy sequence without repetitive sequences. Obvious hybridization signals were detected in one terminal region of chromosomes 1 and 4 when sequence Chr2 D was used as a probe and mitotic metaphase chromosomes of G. raimondii were used as target DNA. The size of the signal is significantly larger than a 4-kb sequence would account for while the signal brightness is fainter than that of normal hybridization signals. This indicates that Chr2 D may not actually be a single-copy sequence and that the copy number of the sequence in one terminal region of chromosomes 1 and 4 may be huge. The brightness of the signal suggests that the distribution of repetitive sequence may be loose. The similarity of hybridization signals on chromosome 1 and 4 show that the pair of chromosomes may be homologous. These results will help complement the draft genome of G. raimondii.