Genomic insights of body plan transitions from bilateral to pentameral symmetry in Echinoderms
Yongxin Li, Akihito Omori, Rachel L. Flores, Sheri Satterfield, Christine Nguyen, Tatsuya Ota, Toko Tsurugaya, Tetsuro Ikuta, Kazuho Ikeo, Mani Kikuchi, Jason Cheok Kuan Leong, Adrian Reich, Meng Hao, Wenting Wan, Yang Dong, Yaondong Ren, Si Zhang, Tao Zeng, Masahiro Uesaka, Yui Uchida, Xueyan Li, Tomoko Shibata, Takahiro Bino, Kota Ogawa, Shuji Shigenobu, Mariko Kondo, Fayou Wang, Luonan Chen, Gary M. Wessel, Hidetoshi Saiga, R. Andrew Cameron, Brian T. Livingston, Cynthia A. Bradham, Wen Wang, Naoki Irie
Abstract
Echinoderms are an exceptional group of bilaterians that develop pentameral adult symmetry from a bilaterally symmetric larva. However, the genetic basis in evolution and development of this unique transformation remains to be clarified. Here we report newly sequenced genomes, developmental transcriptomes, and proteomes of diverse echinoderms including the green sea urchin (L. variegatus), a sea cucumber (A. japonicus), and with particular emphasis on a sister group of the earliest-diverged echinoderms, the feather star (A. japonica). We learned that the last common ancestor of echinoderms retained a well-organized Hox cluster reminiscent of the hemichordate, and had gene sets involved in endoskeleton development. Further, unlike in other animal groups, the most conserved developmental stages were not at the body plan establishing phase, and genes normally involved in bilaterality appear to function in pentameric axis development. These results enhance our understanding of the divergence of protostomes and deuterostomes almost 500 Mya.