Mitotic Activity and Cell Proliferation in Primary Induction of Newt Embryo

Suzuki, Akio; Kuwabara, Kazushi

doi:10.1111/j.1440-169x.1974.00029.x

Cited by 13 publications

(1 citation statement)

References 14 publications

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“…The average nuclear volumes of the ectomesodermal parts of blastulae and gastrulae have been given in Table 1. The n could be assumed as 12 to give 4,096 cells for a blastula and as 14 to give 16,400 cells for a gastrula (BERRILL, 1935;SUZUKI and KUWABARA, 1974). Putting these values into the equation, the Vo was calculated to be about 26 X lo6 pm3, a value near the volume of the fully grown germinal vesicle (Table 1).…”

Section: Discussionmentioning

confidence: 99%

Possible Significance of Nuclear Volume Change During Early Development of Newt Embryos

Imoh

Sameshima

1976

Dev Growth Differ

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The nuclear volumes at several stages of development were measured on Triturus pyrrhoguster embryos and changes in the fine structure and reactivity towards alkaline fast green of the nuclei were also examined. It was shown that the blastula nuclei were reduced about 80% to reach a constant volume of about 1,400 pm3 by the tail bud stage in ectomesodermal parts of the embryos. In the endoderm, the decrease in the nuclear volume was slightly delayed.Application of the decreasing rate of nuclear volume, from blastula to gastrula, to a simple model suggested that an amount of material, equivalent to that of a fullsized germinal vesicle, is stored in the egg to support the rapid nuclear divisions during the early phase of development.Studies on the fine structure of nuclei in developing newt embryos have shown that the large, irregularly shaped nuclei in early embryos before gastrulation have dispersed euchromatic fibrils and numerous nuclear pores. These features change during development through the neurula to the tail bud stage, in which the nuclei have condensed euchromatic fibrils among dense heterochromatic regions, much smaller volume with a spherical shape, and decreased numbers of nuclear pores (KARASAKI, 1957, 1959 and 1961). The decrease in nuclear volume during development has been emphasized in the nuclear transplantation experiments of amphibia (GRAHAM, ARMS and GURDON, 1966; GURDON and WOODLAND, 1968), where the transplanted nuclei from older embryos swell considerably in the cytoplasm of earlier embryos or eggs.On the other hand, changes in the nuclei have also been reported from histochemical studies. ALFERT and GESCHWIND (1953) reported a selective staining method for the basic proteins of cell nuclei with an acid dye, fast green FCF, at slightly alkaline pH. Applying this method to eggs and embryos of R a m pipiens and Ambystoma opacum, HORN (1962) observed that the nuclei of ovarian oocytes and those of pregastrular embryos gave a negative reaction to the dye whereas, at the onset of gastrulation, all of the embryonic nuclei began to show the intense reaction typical to the nuclei of adult cells. Although these observations were discussed in 45

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Section: Discussionmentioning

confidence: 99%

Possible Significance of Nuclear Volume Change During Early Development of Newt Embryos

Imoh

Sameshima

1976

Dev Growth Differ

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Morphogenetic gradients in multiple‐graft Hydra viridis. I. The effects of colcemid and colchicine

Shostak

Adams

1975

J. Exp. Zool.

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The morphogenesis of so-called secondary (2 degree) heads, budding regions and feet, and separations at graft borders, is studied in multiple-graft animals containing three gastric regions (3g animals) treated with Colcemid or colchicine. Control animals consist of three non-treated pieces. Animals consisting of two non-treated and one treated piece are also employed. The main effects of Colcemid are the promotion of graft healing at the distal graft border, and of 2 degree head formation on the proximal gastric region (g-1). Colchicine also promotes graft healing at the distal graft border, but in contrast to the effect of Colcemid, promotes the formation of ectopic feet (tertiary feet) and inhibits head regeneration at the distal end of the middle gastric region (g-2). Colchicine also accelerates an inversion of polarity in 2 degree budding regions on the g-2 pieces of animals with 2 degree heads on their g-1 pieces. Treatment of a distal graft piece with Colcemid promotes 2 degree head formation on the nearest proximal piece which is not treated, but the inhibition of 2 degree head formation by colchicine occurs only on colchicine treated pieces. The morphogenetic effects of the drugs are interpreted as consequences of their actions on nerve differentiation and cell division. The paper argues that homeostatic control of a hydra's cell population depends on dividing cells influencing cell loss, and that similar mechanisms are involved in the rejection of a graft and the separation of a bud.

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Protein kinases in amphibian ectoderm induced for neural differentiation

Davids

1988

Roux's Arch Dev Biol

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Ectoderm explants from early gastrula stages of Xenopus laevis were induced with a neutralizing factor. The factor was isolated from Xenopus gastrulae and partially purified by chromatography on DEAE cellulose. The ectoderm was cultured for different periods of time and then homogenized. Protein kinase activity was determined in the homogenates from induced and control explants with histone H 1 or C-terminal peptide derived from histone H 1 as substrates. The C-terminal peptide is a more specific substrate for protein kinase C, whereas histoneH 1 is a substrate for cAMP/cGMP-dependent protein kinases as well protein kinase C. With both substrates the enzyme activity increases after induction. With the C-terminal peptide as the substrate the protein kinase activity is lower, but its relative increase after induction higher. This suggests that besides cAMP/cGMP dependent protein kinases protein kinase C or related enzymes are involved in the neural induction and differentiation processes. This corresponds to previous experiments which have shown that treatment of ectoderm with phorbol myristate acetate, an activator of protein kinase C and protein kinase C related enzymes, initiates neural differentiation. Endogeneous substrates, which are more intensively phosphorylated after induction are proteins with apparent molecular weights 21 kDa and 31 kDa. Addition of protein kinase C to the induced and control homogenates abolishes the difference in the phosphorylation rate of these proteins.

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Mitotic Activity and Cell Proliferation in Primary Induction of Newt Embryo

Cited by 13 publications

References 14 publications

Possible Significance of Nuclear Volume Change During Early Development of Newt Embryos

Possible Significance of Nuclear Volume Change During Early Development of Newt Embryos

Morphogenetic gradients in multiple‐graft Hydra viridis. I. The effects of colcemid and colchicine

Protein kinases in amphibian ectoderm induced for neural differentiation

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