利用荧光原位杂交技术在海带伸展的DNA纤维上刻画45S rRNA基因的高分辨率可视图谱OA北大核心CSCDCSTPCD

The DNA fiber-fluorescence in situ hybridization(FISH)technique offers high spatial resolution.However,so far,it has not been reported in algal cytogenetics research.To address this gap,the present study optimized the nuclear lysis time and conditions for the DNA fiber extension method to obtain high-quality genomic DNA from isolated nuclei of Saccharina japonica gametophytes.Fiber-FISH was subsequently conducted on the extended DNA fibers using fluor-ophore-labeled 18S rDNA as a probe.The resulting FISH signals exhibited a linear,beads-on-a-string arrangement along the genomic DNA fibers.This pattern was consistent with that obtained using a bacterial artificial chromosome clone containing the kelp 45S rDNA sequence.Based on these extended genomic DNA fibers,a high-resolution physical map of 45S rDNA genes was constructed,achieving a resolution of≤2.09 kb,comparable to that reported in higher plants.This map provides crucial cytological evidence for accurate kelp genome assembly.In addition,it may also serve as a reference approach for assembling tandem repeat sequences and multi-copy genes in other algal genomes.