Genome survey sequencing of the Caribbean spiny lobster Panulirus argus: Genome size, nuclear rRNA operon, repetitive elements, and microsatellite discovery

Background: Panulirus argus is an ecologically relevant species in shallow water hard-bottom environments and coral reefs and target of the most lucrative fishery in the greater Caribbean region. Methods: This study reports, for the first time, the genome size and nuclear repetitive elements, including the 45S ribosomal DNA operon, 5S unit, and microsatellites, of P. argus. Results: Using a k-mer approach, the average haploid genome size estimated for P. argus was 2.17 Gbp. Repetitive elements comprised 69.02% of the nuclear genome. In turn, 30.98% of the genome represented low- or single-copy sequences. A considerable proportion of repetitive sequences could not be assigned to known repeat element families. Taking into account only annotated repetitive elements, the most frequent belonged to Class I-LINE which were noticeably more abundant than Class I-LTR-Ty- 3/Gypsy, Class I-LTR-Penelope, and Class I-LTR-Ty-3/Bel-Pao elements. Satellite DNA was also abundant. The ribosomal operon in P. argus comprises, in the following order, a 5' ETS (length = 707 bp), ssrDNA (1,875 bp), ITS1 (736 bp), 5.8S rDNA (162 bp), ITS2 (1,314 bp), lsrDNA (5,387 bp), and 3' ETS (287 bp). A total of 1,281 SSRs were identified.