真核生物的基因组存在着大量DNA重复序列，这些序列广泛分布于染色体上，可用来标记以区分染色体。据此，本申请项目针对海带染色体因个体小且数目多以致难以分辨、核型分析不清这个问题，首先采用基因克隆、细菌人工染色体（BAC）文库筛选与测序、着丝粒特异蛋白CENH3抗体制备等手段获得海带核糖体RNA基因、端粒与着丝粒等DNA重复序列并分析其组成与结构特征；然后将这些DNA重复序列及已筛选到的海带微卫星序列标记成荧光探针，利用本课题组已掌握的荧光原位杂交（FISH）技术将它们共定位于染色体上，以进行分带鉴定、染色体个体分辨与核型分析。本项目研究任务的顺利完成，不仅为海带遗传学、杂交育种、海洋地理环境对海带染色体畸变的影响等研究提供准确的染色体数目及核型，同时也为未来海带基因组物理图谱框架的组装与完善，并根据核型分析的结果推测海带是否存在性染色体等研究奠定良好的基础。

Repetitive DNA sequence is a major component of eukaryotic genomes, and these sequences are distributed abroad on the chromosomes and verified to mark the chromosomes for their recognition. Based on this fact and aiming at the problem that Laminaria japonica chromosome individuals are difficultly recognized and this kelp karyotype has not yet been discernible due to the small sizes and a large number of chromosomes, this proposal is first planning to clone and characterize the repetitive DNA sequences of ribosomal RNA genes, telomeres and centromeres by use of gene cloning, screening and sequencing of bacterial artificial chromosomes (BAC) and antibody preparation of the centromere-specific protein CENH3; second to label these cloned sequences with fluorescent probes and co-localize the labelled probes on the chromosomes using fluorescent in situ hybridization (FISH) in order to put colorful bands on the chromosomes, recognize the chromosome individuals and analyze the karyotype of L. japonica. The fulfillment of this project will not only provide the genetics study, cross breeding and effect investigation of marine environment on chromosome aberration with accurate chromosome number and karyotype of L. japonica, but also lay a foundation for the physical mapping assembly of this kelp genome in the future and deduce the existence possibility of sex chromosome in L. japonica.