Synteny analysis was performed with SyRI software to illustrate the shared regions of chromosomes with the largest percentage increase in size in the present assembly compared with mRatBN7.2. Chr 3, Chr 11, and Chr 12 are acrosomal chromosomes in which rDNA arrays are located in the acrosomal arms. The current assembly has greatly extended the chromosome in the region of these arms. Chr 19 shows a large insertion spanning >15 Mb that was not included in mRatBN7.2. Chr Y shows good synteny with mRatBN7.2 across the Y-specific coding regions of the chromosome. However, the more distal regions were not assembled in mRatBN7.2, undoubtedly reflecting the repetitive heterochromatic region of this chromosome.
