Hox genes of the direct-type developing sea urchin Peronella japonica

点击翻译按钮获取中文摘要

Peronella japonica is a direct-type developing sea urchin that metamorphoses in 3 days without feeding, providing us a good system to analyze developmental mechanisms especially at later larval stages to metamorphosis. We surveyed the Hox-type sequences of P. japonica by PCR and RT-PCR, and isolated 13 Hox-type sequences. All of them were detected by RT-PCR, indicative of their expressions in larvae. Phylogenetic analysis and database searches resulted in identification of all the P. japonica orthologs of the Hox genes that have been reported in other sea urchins, plus 3 Hox-type genes: the Evx-type, Xlox-type, and an additional posterior Hox gene. The present results revealed a putative Hox gene cluster of P. japonica, which contains genes representing all the paralog (cognate) groups of vertebrate Hox clusters except that there is a single gene of Hox4-5 types. In spite of the pentaradial body plans lacking apparent cepharic structures, P. japonica appears to retain the Hox cluster that is essentially similar to those of the chordates with bilateral body plans.