Hox code in embryos of Chinese soft-shelled turtle Pelodiscus sinensis correlates with the evolutionary innovation in the turtle

✍ Scribed by Yoshie Kawashima Ohya; Shigehiro Kuraku; Shigeru Kuratani

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 549 KB
• Volume: 304B
• Category: Article
• ISSN: 1552-5007
• DOI: 10.1002/jez.b.21027

✦ Synopsis

Turtles have the most unusual body plan of the amniotes, with a dorsal shell consisting of modified ribs. Because this morphological change in the ribs can be described as an axial-level specific alteration, the evolution of the turtle carapace should depend on changes in the Hox code. To identify turtle-specific changes in developmental patterns, we cloned several Hox genes from the Chinese soft-shelled turtle, Pelodiscus sinensis, examined their expression patterns during embryogenesis, and compared them with those of chicken and mouse embryos. We detected possibly turtle-specific derived traits in Hoxc-6 expression, which is restricted to the paraxial part of the embryo; in the expression of Hoxa-5 and Hoxb-5, the transcripts of which were detected only at the cervical level; and in Hoxc-8 and Hoxa-7 expression, which is shifted anteriorly relative to that of the other two amniote groups. From the known functions of the Hox orthologs in model animals, these P. sinensis-specific changes apparently correlate with specializations in the turtle-specific body plan.