Autonomy of ascidian fork head/HNF-3 gene expression

Mech Dev. 1997 Dec;69(1-2):143-54. doi: 10.1016/s0925-4773(97)00162-7.


We have characterized the expression pattern of a class I fork head/HNF-3 gene (HrHNF3-1) of the ascidian Halocynthia roretzi. Zygotic HrHNF3-1 expression was detectable as early as the 16-cell stage, and the transcript was evident in blastomeres of the endoderm, notochord and mesenchyme lineages of the early embryos. After the late gastrula stage, HrHNF3-1 was also expressed in the presumptive spinal cord cells and some brain cells. The spinal cord of the ascidian tadpole consists of four layers of cells; the dorsal layer, two lateral layers and the ventral layer, the latter of which simply lies on the notochord. Cross-sections of in situ hybridized specimens showed that HrHNF3-1 was expressed in cells of the ventral layer, reminiscent of the floor plate of vertebrate embryos. In addition, we found autonomy in the initiation of early HrHNF3-1 expression, because the gene was expressed in blastomeres continuously dissociated from the first cleavage until the 16-cell stage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Blastomeres / physiology
  • Blotting, Northern
  • Cloning, Molecular
  • DNA-Binding Proteins / genetics
  • Embryo, Nonmammalian
  • Endoderm / physiology
  • Forkhead Transcription Factors
  • Gene Expression Regulation, Developmental*
  • Hepatocyte Nuclear Factor 3-beta
  • Mesoderm / physiology
  • Molecular Sequence Data
  • Notochord / physiology
  • Nuclear Proteins / genetics
  • Phylogeny
  • Sequence Homology, Amino Acid
  • Spinal Cord / embryology
  • Trans-Activators / genetics*
  • Transcription Factors / genetics*
  • Urochordata / embryology*
  • Urochordata / genetics*


  • DNA-Binding Proteins
  • FOXI1 protein, human
  • FOXJ1 protein, human
  • Forkhead Transcription Factors
  • Nuclear Proteins
  • Trans-Activators
  • Transcription Factors
  • Hepatocyte Nuclear Factor 3-beta

Associated data

  • GENBANK/AB007406