Hensen's node, the amniote equivalent of the amphibian """"""""Spemann's organizer"""""""", is the most important region of the very early, gastrulating embryo. Not only does it generate the midline organs of the body (notochord, somites, gut, floor plate of the neural tube), but is also responsible for inducing and patterning the whole of the central nervous system. Classical studies have claimed, based on morphological criteria, that when Hensen's node is ablated, notochord and somites form normally. This project consists of new investigation of this problem, taking advantage of the many molecular markers now available, to reveal the conditions that specify this unique region of the embryo as """"""""the organizer"""""""" and set its cells aside from the rest of the primitive streak. The study will help to define the organizer in both molecular and embryological terms and to identify the conditions that lead to the regulation of expression of several genes in this region. Finally, the results will reveal which properties of the organizer are under independent control at very early stages of embryonic development. Using transplantation experiments combined with in situ hybridization and retroviral vectors to cause misexpression of specific genes, the following specific questions will be addressed: Do the notochord and somites form after node ablation? Does the stump of the primitive streak express node- specific markers (e.g. goosecoid, sonic hedgehog) after node ablation? After ablation of the node, can the stump of the primitive streak acquire neural inducing ability and/or the ability to induce extra digits in a host limb bud? Is the regenerated node left/right asymmetric (like the normal node)? Is the ability to regenerate node properties restricted to a specific portion of the primitive streak? If any of the above properties cannot be acquired by the primitive streak, can it be made to regenerate these properties if made to express appropriate node marker genes?

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Human Embryology and Development Subcommittee 1 (HED)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Columbia University (N.Y.)
Schools of Medicine
New York
United States
Zip Code
Kelkar, Devaki A; Khushoo, Amardeep; Yang, Zhongying et al. (2012) Kinetic analysis of ribosome-bound fluorescent proteins reveals an early, stable, cotranslational folding intermediate. J Biol Chem 287:2568-78
Skromne, Isaac; Stern, Claudio D (2002) A hierarchy of gene expression accompanying induction of the primitive streak by Vg1 in the chick embryo. Mech Dev 114:115-8
Joubin, K; Stern, C D (2001) Formation and maintenance of the organizer among the vertebrates. Int J Dev Biol 45:165-75
Skromne, I; Stern, C D (2001) Interactions between Wnt and Vg1 signalling pathways initiate primitive streak formation in the chick embryo. Development 128:2915-27
Foley, A C; Skromne, I; Stern, C D (2000) Reconciling different models of forebrain induction and patterning: a dual role for the hypoblast. Development 127:3839-54
Vasiliauskas, D; Stern, C D (2000) Expression of mouse HES-6, a new member of the Hairy/Enhancer of split family of bHLH transcription factors. Mech Dev 98:133-7
Sheng, G; Stern, C D (1999) Gata2 and Gata3: novel markers for early embryonic polarity and for non-neural ectoderm in the chick embryo. Mech Dev 87:213-6
Streit, A; Stern, C D (1999) Mesoderm patterning and somite formation during node regression: differential effects of chordin and noggin. Mech Dev 85:85-96
Joubin, K; Stern, C D (1999) Molecular interactions continuously define the organizer during the cell movements of gastrulation. Cell 98:559-71
Zhu, L; Marvin, M J; Gardiner, A et al. (1999) Cerberus regulates left-right asymmetry of the embryonic head and heart. Curr Biol 9:931-8

Showing the most recent 10 out of 14 publications