A labile period in the determination of the anterior-posterior axis during early neural development in Xenopus

Saha, Margaret S.; Grainger, Robert M.

doi:10.1016/0896-6273(92)90123-u

Cited by 98 publications

(33 citation statements)

References 45 publications

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“…Saha and Grainger (1992) and Nieuwkoop and Albers (1990) recently presented strong evidence that positional information in the axis is not well established until stage 14, by which time gastrulation has been completed. Our observations indicate that NAC can produce radical anteriorisation as late as stage 11/12, which is fully consistent with their conclusions.…”

Section: Discussionmentioning

confidence: 96%

N-acetyl-cysteine causes a late re-specification of the anteroposterior axis in theXenopus embryo

Gatherer

Woodland

1996

Dev. Dyn.

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Section: Discussionmentioning

confidence: 96%

N-acetyl-cysteine causes a late re-specification of the anteroposterior axis in theXenopus embryo

Gatherer

Woodland

1996

Dev. Dyn.

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“…Vodicka and Gerhart (49) report that certain genes expressed in dorsal mesoderm of early gastrulae already show presumptive A-P regionalization (including a more anterior pattern for gsc and a more posterior one for Xbra), suggesting that some A-P patterning has occurred at these stages. However, their work, and a number of other studies (2,4,50,51) argue that A-P patterning in dorsal mesodermal cells is not fixed until neurula stages. Conclusions that emerge are that, while D-V and A-P axes are intimately related (see ref.…”

Section: Discussionmentioning

confidence: 97%

Anteroposterior neural tissue specification by activin-induced mesoderm

Green

Cook

Smith

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

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The transforming growth factor ␤ superfamily member, activin, is able to induce mesodermal tissues in animal cap explants from Xenopus laevis blastula stage embryos. Activin can act like a morphogen of the dorsoventral axis in that lower doses induce more ventral, and higher doses more dorsal, tissue types. Activin has also previously been reported to induce neural tissues in animal caps. From cell mixing experiments it was inferred that this might be an indirect effect of induced mesoderm signaling to uninduced ectoderm. Here we demonstrate directly that neural tissues do indeed arise by the action of induced mesoderm on uninduced ectoderm. Dorsal mesoderm is itself subdivided into posterior and anterior domains in vivo, but this had not been demonstrated for induced mesoderm. We therefore tested whether different concentrations of activin recreate these different anteroposterior properties as well. We show that the anteroposterior positional value of induced mesoderm, including its neuroinductive properties, depends on the dose of activin applied to the mesoderm, with lower doses inducing more posterior and higher doses giving more anterior markers. We discuss the implications of these results for patterning signals and the relationship between anteroposterior and dorsoventral axes.

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“…In a similar type of study, Saha and Grainger ( 1992) found that in the midgastrula, three regions of dorsal mesoderm along the A,-P axis could induce the anterior gene, opsin (which is retina-specific) as well as the posterior gene, X1Hbox6, while mesoderm from the early neurula was more spatially restricted. They also found that the specification state of ectoderm overlying the regions of the mesoderm reflected the inducing ability of the dorsal mesoderm, both during the madgastrula and the early neurula.…”

Section: Studies Of Vertical Induction Using Molecular Markers For A-mentioning

confidence: 90%

Planar and vertical induction of anteroposterior pattern during the development of the amphibian central nervous system

Doniach

1993

J. Neurobiol.

113

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In amphibians and other vertebrates, neural development is induced in the ectoderm by signals coming from the dorsal mesoderm during gastrulation. Classical embryological results indicated that these signals follow a "vertical" path, from the involuted dorsal mesoderm to the overlying ectoderm. Recent work with the frog Xenopus laevis, however, has revealed the existence of "planar" neural-inducing signals, which pass within the continuous sheet or plane of tissue formed by the dorsal mesoderm and presumptive neurectoderm. Much of this work has made use of Keller explants, in which dorsal mesoderm and ectoderm are cultured in a planar configuration with contact along only a single edge, and vertical contact is prevented. Planar signals can induce the full anteroposterior (A-P) extent of neural pattern, as evidenced in Keller explants by the expression of genes that mark specific positions along the A-P axis. In this review, classical and modern molecular work on vertical and planar induction will be discussed. This will be followed by a discussion of various models for vertical induction and planar induction. It has been proposed that the A-P pattern in the nervous system is derived from a parallel pattern of inducers in the dorsal mesoderm which is "imprinted" vertically onto the overlying ectoderm. Since it is now known that planar signals can also induce A-P neural pattern, this kind of model must be reassessed. The study of planar induction of A-P pattern in Xenopus embryos provides a simple, manipulable, two-dimensional system in which to investigate pattern formation.

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A labile period in the determination of the anterior-posterior axis during early neural development in Xenopus

Cited by 98 publications

References 45 publications

N-acetyl-cysteine causes a late re-specification of the anteroposterior axis in theXenopus embryo

N-acetyl-cysteine causes a late re-specification of the anteroposterior axis in theXenopus embryo

Anteroposterior neural tissue specification by activin-induced mesoderm

Planar and vertical induction of anteroposterior pattern during the development of the amphibian central nervous system

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