Vertebrate Cartilage Evolution 74. Ettensohn CA, Illies MR, Oliveri P, De Jong DL (2003) Alx1, a member of the Cart1/Alx3/Alx4 subfamily of Paired-class homeodomain proteins, is an essential component of the gene network controlling skeletogenic fate specification in the sea urchin embryo. Development 130: 2917–2928. 75. Mori-Akiyama Y, Akiyama H, Rowitch DH, de Crombrugghe B (2003) Sox9 is required for determination of the chondrogenic cell lineage in the cranial neural crest. Proceedings of the National Academy of Sciences of the United States of America 100: 9360–9365. 76. Jeffery WR, Strickler AG, Yamamoto Y (2004) Migratory neural crest-like cells form body pigmentation in a urochordate embryo. Nature 431: 696–699. 77. Kee Y, Hwang BJ, Sternberg PW, Bronner-Fraser M (2007) Evolutionary conservation of cell migration genes: from nematode neurons to vertebrate neural crest. Genes & Development 21(000-000): 6. 78. Manni L, Lane NJ, Sorrentino M, Zaniolo G, Burighel P (1999) Mechanism of neurogenesis during the embryonic development of a tunicate. Journal of Comparative Neurology 412: 527–541. 79. Haldin CE, LaBonne C (2010) SoxE factors as multifunctional neural crest regulatory factors. Int J Biochem Cell Biol 42: 441–444. 80. Meulemans D, Bronner-Fraser M (2007) Insights from amphioxus into the evolution of vertebrate cartilage. PLoS ONE 2: e787. 81. Rychel AL, Swalla BJ (2007) Development and evolution of chordate cartilage. J Exp Zoolog B Mol Dev Evol 308: 325–335. 82. Walshe J, Mason I (2003) Fgf signalling is required for formation of cartilage in the head. Developmental Biology 264: 522–536. 83. Schwend T, Ahlgren SC (2009) Zebrafish con/disp1 reveals multiple spatiotemporal requirements for Hedgehog-signaling in craniofacial develop- ment. BMC Dev Biol 9: 59. 84. Shimeld SM (1999) The evolution of the hedgehog gene family in chordates: insights from amphioxus hedgehog. Development Genes and Evolution 209: 40–47. 85. Takio Y, Kuraku S, Murakami Y, Pasqualetti M, Rijli FM, et al. (2007) Hox gene expression patterns in Lethenteron japonicum embryos--insights into the evolution of the vertebrate Hox code. Developmental Biology (Orlando) 308: 606–620. 86. Kimmel CB, Miller CT, Kruze G, Ullmann B, BreMiller RA, et al. (1998) The shaping of pharyngeal cartilages during early development of the zebrafish. Developmental Biology 203: 245–263. 87. Perriere G, Gouy M (1996) WWW-query: An on-line retrieval system for biological sequence banks. Biochimie 78: 364–369. 88. Nikitina N, Bronner-Fraser M, Sauka-Spengler T (2009) Microinjection of RNA and morpholino oligos into lamprey embryos. CSH Protoc 2009: pdb prot5123. 89. Henrique D, Adam J, Myat A, Chitnis A, Lewis J, et al. (1995) Expression of a delta-homolog in prospective neurons in the chick. Nature 375: 787–790. PLoS ONE | www.plosone.org 13 July 2011 | Volume 6 | Issue 7 | e22474