BACKGROUND: In the simple ascidian chordate Ciona, the signaling pathways and gene regulatory networks giving rise to initial notochord induction are largely understood and the mechanisms of notochord morphogenesis are being systematically elucidated. The notochord has generally been thought of as a non-compartmentalized or regionalized organ that is not finely patterned at the level of gene expression. Quantitative imaging methods have recently shown, however, that notochord cell size, shape, and behavior vary consistently along the anterior-posterior (AP) axis. RESULTS: Here we screen candidate genes by whole mount in situ hybridization for potential AP asymmetry. We identify 4 genes that show non-uniform expression in the notochord. Ezrin/radixin/moesin (ERM) is expressed more strongly in the secondary notochord lineage than the primary. CTGF is expressed stochastically in a subset of notochord cells. A novel calmodulin-like gene (BCamL) is expressed more strongly at both the anterior and posterior tips of the notochord. A TGF-β ortholog is expressed in a gradient from posterior to anterior. The asymmetries in ERM, BCamL, and TGF-β expression are evident even before the notochord cells have intercalated into a single-file column. CONCLUSIONS: We conclude that the Ciona notochord is not a homogeneous tissue but instead shows distinct patterns of regionalized gene expression.
BACKGROUND: In the simple ascidian chordate Ciona, the signaling pathways and gene regulatory networks giving rise to initial notochord induction are largely understood and the mechanisms of notochord morphogenesis are being systematically elucidated. The notochord has generally been thought of as a non-compartmentalized or regionalized organ that is not finely patterned at the level of gene expression. Quantitative imaging methods have recently shown, however, that notochord cell size, shape, and behavior vary consistently along the anterior-posterior (AP) axis. RESULTS: Here we screen candidate genes by whole mount in situ hybridization for potential AP asymmetry. We identify 4 genes that show non-uniform expression in the notochord. Ezrin/radixin/moesin (ERM) is expressed more strongly in the secondary notochord lineage than the primary. CTGF is expressed stochastically in a subset of notochord cells. A novel calmodulin-like gene (BCamL) is expressed more strongly at both the anterior and posterior tips of the notochord. A TGF-β ortholog is expressed in a gradient from posterior to anterior. The asymmetries in ERM, BCamL, and TGF-β expression are evident even before the notochord cells have intercalated into a single-file column. CONCLUSIONS: We conclude that the Ciona notochord is not a homogeneous tissue but instead shows distinct patterns of regionalized gene expression.
Authors: Y Satou; N Takatori; L Yamada; Y Mochizuki; M Hamaguchi; H Ishikawa; S Chiba; K Imai; S Kano; S D Murakami; A Nakayama; A Nishino; Y Sasakura; G Satoh; T Shimotori; T Shin-I; E Shoguchi; M M Suzuki; N Takada; N Utsumi; N Yoshida; H Saiga; Y Kohara; N Satoh Journal: Development Date: 2001-08 Impact factor: 6.868
Authors: Ivonne M Sehring; Pierre Recho; Elsa Denker; Matthew Kourakis; Birthe Mathiesen; Edouard Hannezo; Bo Dong; Di Jiang Journal: Elife Date: 2015-10-21 Impact factor: 8.140
Authors: Matthew J Kourakis; Wendy Reeves; Erin Newman-Smith; Benoit Maury; Sarah Abdul-Wajid; William C Smith Journal: Dev Biol Date: 2014-08-28 Impact factor: 3.582