Evolutionary conservation of vertebrate notochord genes in the ascidian Ciona intestinalis.
To reconstruct a minimum complement of notochord genes evolutionarily conserved across chordates, we scanned the Ciona intestinalis genome using the sequences of 182 genes reported to be expressed in the notochord of different vertebrates and identified 139 candidate notochord genes. For 66 of these Ciona genes expression data were already available, hence we analyzed the expression of the remaining 73 genes and found notochord expression for 20. The predicted products of the newly identified notochord genes range from the transcription factors Ci-XBPa and Ci-miER1 to extracellular matrix proteins. We examined the expression of the newly identified notochord genes in embryos ectopically expressing Ciona Brachyury (Ci-Bra) and in embryos expressing a repressor form of this transcription factor in the notochord, and we found that while a subset of the genes examined are clearly responsive to Ci-Bra, other genes are not affected by alterations in its levels. We provide a first description of notochord genes that are not evidently influenced by the ectopic expression of Ci-Bra and we propose alternative regulatory mechanisms that might control their transcription.
Kugler
Jamie E
JE
Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, New York 10065, USA.
Passamaneck
Yale J
YJ
Feldman
Taya G
TG
Beh
Jeni
J
Regnier
Todd W
TW
Di Gregorio
Anna
A
D000818:Animals; D002938:Ciona intestinalis / Q000235:genetics*; D019143:Evolution, Molecular; D005326:Fetal Proteins / Q000235:genetics; D015870:Gene Expression; D009672:Notochord / Q000737:chemistry* / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000235:genetics; D014158:Transcription, Genetic; D000098908:Brachyury Protein
D005326:Fetal Proteins; D020825:T-Box Domain Proteins; D000098908:Brachyury Protein