PUBLICATION

Initial anteroposterior pattern of the zebrafish central nervous system is determined by differential competence of the epiblast

Authors

Koshida, S., Shinya, M., Mizuno, T., Kuroiwa, A., and Takeda, H.

ID

ZDB-PUB-980601-11

Date

1998

Source

Development (Cambridge, England) 125: 1957-1966 (Journal)

Registered Authors

Koshida, Sumito, Mizuno, Toshiro, Shinya, Minori, Takeda, Hiroyuki

Keywords

neural induction; otx2; hoxa-1; Spemann's organizer; embryonic shield; mesoderm inductin; induction; zebrafish

MeSH Terms

Homeodomain Proteins/analysis
Mesoderm/physiology
Mutation
Body Patterning/physiology*
Nerve Tissue Proteins/analysis
Cell Transplantation
Biomarkers
Embryonic Induction/physiology
COS Cells
Otx Transcription Factors
Receptors, Fibroblast Growth Factor/physiology
Egg Yolk
Zebrafish
Ectoderm/cytology
Ectoderm/physiology*
RNA, Messenger/analysis
Gene Expression Regulation, Developmental/physiology
Animals
Transcription Factors/analysis
Trans-Activators/analysis
Central Nervous System/embryology*
Gastrula/transplantation
Zebrafish Proteins

(all 23)

PubMed

9550728 Full text @ Development

Abstract

Analyses using amphibian embryos proposed that induction and anteroposterior patterning of the central nervous system is initiated by signals that are produced by the organizer and organizer-derived axial mesoderm. However, we show here that the initial anteroposterior pattern of the zebrafish central nervous system depends on the differential competence of the epiblast and is not imposed by organizer-derived signals. This anteroposterior information is present throughout the epiblast in ectodermal cells that normally give rise both to neural and non-neural derivatives. Because of this information, organizer tissues transplanted to the ventral side of the embryo induce neural tissue but the anteroposterior identity of the induced neural tissue is dependent upon the position of the induced tissue within the epiblast. Thus, otx2, an anterior neural marker, was only ever induced in anterior regions of the embryo, irrespective of the position of the grafts. Similarly, hoxa-1, a posterior neural marker was induced only in the posterior regions. Furthermore, the boundary of each ectopic expression domain on the ventral side was always at an equivalent latitude to that of the endogenous expression of the dorsal side of the embryo. The anteroposterior specification of the epiblast is independent of the dorsoventral specification of the embryo because neural tissues induced in the ventralized embryos also showed anteroposterior polarity. Cell transplantation and RNA injection experiments showed that non-axial marginal mesoderm and FGF signalling is required for anteroposterior specification of the epiblast. However, the requirement for FGF signalling is indirect in that cells with compromised ability to respond to FGF can still respond to anteroposterior positional information.

Genes / Markers

Figures