National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan
Relatively conserved exon sequences among distant aquatic animal taxa (Copepoda, Echinodermata, and Teleostei) were determined for 12 ribosomal protein genes, and 19 primer pairs were designed for an exon-primed intron-crossing polymerase chain reaction strategy. The universal utility of these primers was evaluated in distant animal species (sea urchin, squid, crab, shark, and tuna). Fragment amplification was confirmed for at least three species for all primer pairs, and single fragment amplification was observed for at least one species in 16 primer pairs. Primer sets presented here may serve as an initial step for isolating single-copy nuclear DNA sequences in a wide variety of marine animals.