| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2016: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Outline of Final Research Achievements |
Hemichordates and echinoderms are sister taxa of the Ambulacraria clade, and share tripartite larvae. Hemichordates inherit the body plan (proboscis-collar-trunk) from larvae. In contrast, echinoderms form a pentaradial body plan in the adult rudiment and metamorphose into juveniles. The evolution of this unique body plan of echinoderms still remains a mystery in zoology.
We isolated sand dollar orthologs of anteroposterior (AP) map genes that control ectodermal patterning along the AP axis in hemichordates, and examined their expression in the sand dollar. Solely orthologs of collar AP map genes were expressed in ectoderm of the adult rudiment, and their expression was restricted to the future ambulacral ectoderm. I propose that the evolution of echinoderms was accompanied by loss of the proboscis and trunk from a common ancestor, concomitant with radial outgrowth from the collar. Co-linear expression of Hox complex suggests adult mouth-anus axis may represent AP axis of echinoderms.
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