HrNodal, the ascidian nodal-related gene, is expressed in the left side of the epidermis, and lies upstream of HrPitx.
The nodal-related genes are well known for their fundamental roles during vertebrate development, including mesoderm induction, neural induction, and left-right axis formation, as several nodal-related genes show left-sided expression in mesodermal lineages. We have isolated the first non-vertebrate nodal-related gene, HrNodal, from the ascidian Halocynthia roretzi. During the late cleavage and gastrula stages, HrNodal is transiently and bilaterally expressed in several different cell lineages. Expression at the tailbud stage is observed asymmetrically in the left side, but unexpectedly only in the epidermis of the embryo. We also demonstrate the relationship of HrNodal with HrPitx, a Halocynthia homologue of the Pitx2 gene. HrNodal overexpression results in the disturbance of left-sided HrPitx expression. Our results demonstrate that left-right specification during ascidian embryogenesis involves the HrNodal gene, and that the left-sidedness of the expression is evolutionarily conserved throughout the chordate clade.
Morokuma
Junji
J
Department of Biological Sciences, Tokyo Institute of Technology, Nagatsuta, Yokohama 226-8501, Japan.
Ueno
Motoko
M
Kawanishi
Hiroshi
H
Saiga
Hidetoshi
H
Nishida
Hiroki
H
D000818:Animals; D019521:Body Patterning / Q000235:genetics / Q000502:physiology; D004817:Epidermis / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics; D055457:Nodal Protein; D009687:Nuclear Proteins; D009928:Organ Specificity; D014157:Transcription Factors / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D014561:Urochordata / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D000097577:Homeobox Protein PITX2
D018398:Homeodomain Proteins; D055457:Nodal Protein; D009687:Nuclear Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000097577:Homeobox Protein PITX2