Initial analysis of tandemly repetitive sequences in the genome of Zhikong scallop (Chlamys farreri Jones et Preston).

Tandemly repetitive sequences are widespread in all eukaryotic genomes, but data on tandem repeats are limited in Zhikong scallop (Chlamys farreri). In the present study, paired-end sequencing of 2016 individual fosmid clones resulted in 3646 sequences. A total of 2,286,986 bp of genomic sequences were generated, representing approximately 1.84 per thousand of the Zhikong scallop genome. Using tandem repeats finder (TRF) software, a total of 2500 tandem repeats were found, including 313 satellites, 1816 minisatellites and 371 microsatellites. The cumulative length of tandem repeats was 552,558 bp, accounting for 24.16% of total length. Specifically, the length of microsatellites, minisatellites and satellites was 9425, 336,001 and 207,132 bp, accounting for 1.71, 60.81 and 37.49% of the length of tandem repeats, and 0.41, 14.69 and 9.06% of total length, respectively. The detailed information on the characteristic of all repeat units was also represented, which will provide a useful resource for physical mapping and better utilization of the existing genomic information in Zhikong scallop.