Studien über die Determination der Bilateralsymmetrie des jungen Seeigelkeimes

Hörstadius, Sven; Wolsky, Alexander

doi:10.1007/bf02569029

Cited by 65 publications

(21 citation statements)

References 30 publications

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“…The experiments performed by Hörstadius (1936), Hörstadius and Wolsky (1936), and Hardin and Armstrong (1997) on the differentiation of bilaterally symmetrical structures in isolated fragments of embryos revealed that the embryos gradually lose the ability to reset the oral-aboral pattern. The plasticity is completely gone by the early gastrula stage.…”

Section: Discussionmentioning

confidence: 99%

Hbox1 and Hbox7 are involved in pattern formation in sea urchin embryos

et al. 1999

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In spite of their potential importance in evolution, there is little information about Hox genes in animal groups that are related to ancestors of deuterostome. It has been reported that only two Hox genes (Hbox1 and Hbox7) are expressed significantly in sea urchin embryos. Expression of Hbox1 protein is restricted to the aboral ectoderm, and Hbox7 expression is restricted to oral ectoderm, endoderm and secondary mesenchyme cells in sea urchin embryos after the gastrula stage. With the aim of gaining insight into the role of Hbox1 and Hbox7 in sea urchin development, Hbox1 and Hbox7 overexpression experiments were performed. Overexpression of Hbox1 repressed the development of oral ectoderm, endoderm and mesenchyme cells. On the contrary, overexpression of Hbox7 repressed the development of aboral ectoderm and primary mesenchyme cells. The data suggest that Hbox1 and Hbox7 are expressed in distinct non‐overlapping territories, and overexpression of either one inhibits territory‐specific gene expression in the domain of the other. It is proposed that an important function of both Hbox1 and Hbox7 genes is to maintain specific territorial gene expression by each one, in its domain of expression, while repressing the expression of the other in this same domain.

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Section: Discussionmentioning

confidence: 99%

Hbox1 and Hbox7 are involved in pattern formation in sea urchin embryos

et al. 1999

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“…The extreme regulative capacity of sea urchin embryos was first revealed by experiments carried out by Driesch in which four-cell stage embryos were dissociated into individual blastomeres, and each blastomere developed into a small normal larva (reviewed in Horstadius and Wolsky, 1936). More recent experiments have demonstrated that sea urchin embryos maintain their regulative capacity throughout early development.…”

Section: Introductionmentioning

confidence: 99%

Sphedgehog is expressed by pigment cell precursors during early gastrulation in Strongylocentrotus purpuratus

Egaña

Ernst

2004

Developmental Dynamics

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We have sequenced the Sphedgehog (Sphh) gene from the sea urchin Strongylocentrotus purpuratus. Sphh transcripts are detected first at the mesenchyme blastula stage, and they accumulate throughout early embryogenesis. The Sphh protein is produced by precursor pigment cells during early and midgastrulation. NiCl 2 inhibits pigment cell differentiation in sea urchins. Here, we show that, in S. purpuratus, nickel affects a process(es) between 17 and 24 hr of development, corresponding to the time period when Sphh mRNA is first detected. However, nickel treatment does not alter the early expression of Sphh.

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“…Since, as noted above, even in early blastula-stage embryos the progenitors of the aboral ectoderm express a set of genes not transcribed in the progenitors of the oral ectoderm, initial specification of the oral-aboral axis must occur during if not before cleavage. There is no convincing, or direct, evidence that the oral-aboral axis is preformed in the egg, as is the animal-vegetal axis (though this has been argued by H6rstadius and Wolsky 1936), and reversal of the animal pole blastomere cap shows that this axis can be respecified far into cleavage (for review, see H6rstadius 1973). However, Czihak (1963) demonstrated that those animal and vegetal blastomeres of eight-cell-stage Paracentrotus embryos destined to give rise to ectoderm on the future oral side stain differentially for cytochrome oxidase.…”

mentioning

confidence: 99%

Lineage and fate of each blastomere of the eight-cell sea urchin embryo.

Cameron¹,

Hough-Evans²,

Britten³

et al. 1987

Genes Dev.

202

112

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A fluoresceinated lineage tracer was injected into individual blastomeres of eight-cell sea urchin(Strongylocentrotus purpuratus) embryos, and the location of the progeny of each blastomere was determined in the fully developed pluteus. Each blastomere gives rise to a unique portion of the advanced embryo. We confirm many of the classical assignments of cell fate along the animal-vegetal axis of the cleavage-stage embryo, and demonstrate that one blastomere of the animal quartet at the eight-cell stage lies nearest the future oral pole and the opposite one nearest the future aboral pole of the embryo. Clones of cells deriving from ectodermal founder cells always remain contiguous, while clones of cells descendant from the vegetal plate {i.e., gut, secondary mesenchyme) do not. The locations of ectodermal clones contributed by specific blastomeres require that the larval plane of bilateral symmetry lie approximately equidistant {i.e., at a 45 ° angle) from each of the first two cleavage planes. These results underscore the conclusion that many of the early spatial pattems of differential gene expression observed at the molecular level are specified in a clonal manner early in embryonic sea urchin development, and are each confined to cell lineages established during cleavage.

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Studien über die Determination der Bilateralsymmetrie des jungen Seeigelkeimes

Cited by 65 publications

References 30 publications

Hbox1 and Hbox7 are involved in pattern formation in sea urchin embryos

Hbox1 and Hbox7 are involved in pattern formation in sea urchin embryos

Sphedgehog is expressed by pigment cell precursors during early gastrulation in Strongylocentrotus purpuratus

Lineage and fate of each blastomere of the eight-cell sea urchin embryo.

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