A novel satellite/microsatellite combination in the genome of the marine shrimp, Penaeus vannamei

In our studies of repeated sequences in the genome of the marine shrimp, Penaeus vannamei ( Pv), we have discovered a novel combination of sequence elements. We inserted restriction fragments of genomic DNA into a plasmid vector and screened for recombinant plasmids containing repeated sequences. Ten of the resulting isolates contained representatives of the same repeated element, a satellite sequence present in one or more blocks of tandemly repeated units. The cloned repeat units range in size from 139 to 188 bp. Embedded within each cloned repeat unit are 6–15 copies of a tandemly repeated pentanucleotide microsatellite. The genome of Pv contains approx. 1 000 000 copies of this satellite/microsatellite unit. Sequences that cross-hybridize strongly with this structure were found in the genomes of lobster and crayfish, but not in other species of the genus Penaeus.