The pattern of cell division in the early development of the sea urchin, Paracentrotus lividus

Parisi, Elio; Filosa, Stefania; Petrocellis, B. De; Monroy, Alberto

doi:10.1016/0012-1606(78)90177-x

Cited by 63 publications

(31 citation statements)

References 20 publications

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“…The quantity of P3A2 cleus is taken as the amount synthesized from the generated curve nd end of each cleavage stage, as shown by the hatched bars. Two are in detail inaccurate are made for simplicity: (i) that all the cells which they are not (with interesting consequences; see text) and (ii) s are wholly synchronous, while in fact after the first few cleavages lineages are retarded relative to the others, and the animal cap brecede the vegetal lineages (25,26). Cell number at the sixth cleavage ier than 64 over the time interval shown, in accord with observation.…”

supporting

confidence: 52%

Rare maternal mRNAs code for regulatory proteins that control lineage-specific gene expression in the sea urchin embryo.

Cutting

Höög

Calzone

et al. 1990

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

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The prevalence of mRNAs coding for the sea urchin embryo regulatory factors P3A1 and P3A2 was measured by single-strand probe excess solution hybridization. P3A1 and P3A2 are not homologous proteins, though they both bind specifically to a particular cis-regulatory sequence. Interaction at this target site is known to be required for lineagespecific expression of an aboral ectoderm-specific gene and probably for several other genes as well. Genome blot hybridizations show that both factors are encoded by single-copy genes. Maternal mRNAs for both factors are present at less than 103 molecules per egg, which places them in the rare mRNA class. During development to the mesenchyme blastula stage, the amount of P3A1 mRNA (per embryo) increases severalfold while that of P3A2 remains approximately constant. Specification of the aboral ectoderm founder cells and of their initial patterns of gene expression must occur during early to mid-cleavage stage. Therefore, the regulatory proteins needed for this process must be produced by this stage. We show that the quantities of the P3A proteins that can be synthesized from the numbers of mRNA molecules present in the large blastomeres of the early embryo are sufficient to be functional, because these proteins will be accumulated in the nuclei. Thus maternal P3A1 or P3A2 proteins are not required, nor were these detected in earlier studies. Furthermore, differential spatial (as well as temporal) distribution of both of these newly synthesized factor species could result from the unequal cleavage pattern utilized in the sea urchin egg.

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supporting

confidence: 52%

Rare maternal mRNAs code for regulatory proteins that control lineage-specific gene expression in the sea urchin embryo.

Cutting

Höög

Calzone

et al. 1990

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

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“…Macromere and mesomere lineages always undergo shorter cell cycles and continue cycling longer than micromere lineage (Masuda and Sato, 1984). At the blastula stage prior to hatching, the division proceeds in an asynchronous way (Parisi et al, 1978) and this embryonic stage corresponds to a normal cell-cycle length with the presence of gap phases. Therefore, the progressive reappearance and accumulation of these two eIF4E-binding proteins could play an important role in the control and organization of cell-cycle length during early embryonic development.…”

Section: Discussionmentioning

confidence: 99%

Embryonic-stage-dependent changes in the level of eIF4E-binding proteins during early development of sea urchin embryos

Salaün

Boulben

Mulner‐Lorillon

et al. 2005

Journal of Cell Science

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The eukaryotic initiation factor 4E (eIF4E)-binding proteins (4E-BPs) inhibit translation initiation by binding eIF4E and preventing recruitment of the translation machinery to mRNA. We have previously shown that fertilization of sea urchin eggs triggers eIF4E–4E-BP complex dissociation and 4E-BP degradation. Here, we show that microinjection of eIF4E-binding motif peptide into unfertilized eggs delays the onset of the first mitosis triggered by fertilization, demonstrating that dissociation of the eIF4E–4E-BP complex is functionally important for the first mitotic division in sea urchin embryos. We also show by gel filtration analyses that eIF4E is present in unfertilized eggs as an 80 kDa molecular mass complex containing 4E-BP and a new 4E-BP of 40 kDa. Fertilization triggers the dissociation of eIF4E from these two 4E-BPs and triggers the rapid recruitment of eIF4E into a high-molecular-mass complex. Release of eIF4E from the two 4E-BPs is correlated with a decrease in the total level of both 4E-BPs following fertilization. Abundance of the two 4E-BPs has been monitored during embryonic development. The level of the two proteins remains very low during the rapid cleavage stage of early development and increases 8 hours after fertilization. These results demonstrate that these two 4E-BPs are down- and upregulated during the embryonic development of sea urchins. Consequently, these data suggest that eIF4E availability to other partners represents an important determinant of the early development of sea urchin embryos.

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“…2), we can see that differently sized cells have different interdivision times, the cell-cycle length being inversely proportional to cell size. Due to this organization, the inverse correlation between size and cycle timing results in a spatially organized distribution of mitotic times (mitotic gradient), observable from the fifth or sixth, depending on the species, until the ninth cleavage of macromeres and mesomeres (Agrell, 1956(Agrell, , 1964Parisi et al, 1978).…”

Section: Physiology Of Early Development Of Sea Urchin Embryosmentioning

confidence: 98%

“…However, a clear endpoint can be identified at ciliogenesis, because ciliated cells have much longer interdivision times (Masuda, 1979;Masuda and Sato, 1984). Indeed, shortly thereafter, during hatching, the mitotic index of Paracentrotus lividus embryos drops from 60% to 11%, and to 4% in the swimming blastula (Parisi et al, 1978), when we assume all cells are in LE. Masuda (1979) reports that, in T. toreumaticus, small micromeres acquire cilia after the fifth division, large micromeres after the seventh, 70% of mesomeres acquire cilia after the eighth division and the remaining 30% after the ninth, and macromeres become ciliated after the ninth division.…”

Section: Physiology Of Early Development Of Sea Urchin Embryosmentioning

confidence: 99%

Mathematical Model for Early Development of the Sea Urchin Embryo

Ciliberto

Tyson

2000

Bulletin of Mathematical Biology

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In Xenopus and Drosophila, the nucleocytoplasmic ratio controls many aspects of cell-cycle remodeling during the transitory period that leads from fast and synchronous cell divisions of early development to the slow, carefully regulated growth and divisions of somatic cells. After the fifth cleavage in sea urchin embryos, there are four populations of differently sized blastomeres, whose interdivision times are inversely related to size. The inverse relation suggests nucleocytoplasmic control of cell division during sea urchin development as well. To investigate this possibility, we developed a mathematical model based on molecular interactions underlying early embryonic cell-cycle control. Introducing the nucleocytoplasmic ratio explicitly into the molecular mechanism, we are able to reproduce many physiological features of sea urchin development.

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The pattern of cell division in the early development of the sea urchin, Paracentrotus lividus

Cited by 63 publications

References 20 publications

Rare maternal mRNAs code for regulatory proteins that control lineage-specific gene expression in the sea urchin embryo.

Rare maternal mRNAs code for regulatory proteins that control lineage-specific gene expression in the sea urchin embryo.

Embryonic-stage-dependent changes in the level of eIF4E-binding proteins during early development of sea urchin embryos

Mathematical Model for Early Development of the Sea Urchin Embryo

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