Close juxtaposition between inducing chordamesoderm and reacting neuroectoderm is a prerequisite for neural induction in Xenopus laevis

Tacke, Lothar; Grunz, Horst

doi:10.1016/0045-6039(88)90084-x

Cited by 8 publications

(1 citation statement)

References 24 publications

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“…Since reduction of the cytochalasin B concentration enhanced the cell-cell interaction between a4-2 and A4-1 blastomeres, induction must require close physical contact between the membranes of two blastomeres. In the amphibian it was reported that the close contact between ectoderm and mesoderm plays an important role in neural induction (Suzuki, Nakatake & Hidaka, 1984;Tacke & Grunz, 1988). However, since cytochalasin B is reported to inhibit exocytosis in some cells (Davies & Allison, 1978), we cannot exclude the possibility that induction is performed by secreted substances which diffuse over extremely short distances.…”

Section: Effects Of Changing Cytochalasin B Concentrationmentioning

confidence: 88%

Induced neural‐type differentiation in the cleavage‐arrested blastomere isolated from early ascidian embryos.

Okado

Takahashi

1990

The Journal of Physiology

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SUMMARY1. Isolated blastomeres and pairs of blastomeres from 8-cell embryos of Halocynthia roretzi and Halocynthia aurantium were cleavage-arrested with cytochalasin B and cultured. Their differentiation was examined in terms of membrane excitability, immunoreactivity to an epidermis-specific monoclonal antibody (2C5), and the presence of acetylcholinesterase.2. The blastomeres that showed epidermal-type differentiation had Ca2+-dependent action potentials and membrane currents, and immunoreactivity to 2C5. The blastomeres that showed neural-type differentiation had Na+-, Ca2+-and TEAsensitive delayed K+ channels, and lacked immunoreactivity to 2C5.3. Cleavage-arrested anterior-animal blastomeres, a42, when cultured in isolation from an 8-cell embryo, differentiated exclusively into epidermal-type cells. However, when cultured in contact with anterior-vegetal blastomeres, A41, they mostly showed neural-type differentiation (seventeen out of twenty-four cells in H. roretzi).4. Reduction of the cytochalasin B concentration enhanced neural-type development of a4-2 blastomeres in contact with A4 1 blastomeres in H. aurantium, possibly by tightening the physical contact between the blastomeres.5. When a cleavage-arrested and isolated a4-2 blastomere was treated with 2%pronase at 10°C for 15 min at the time when sister control embryos reached the 32-cell stage, the blastomere underwent neural-type differentiation in a manner identical to that of a4 2 blastomeres contacted by A4 1 cells. 6. The period during which neural-type differentiation of a4 2blastomeres could be induced by treatment with pronase was from the 8-cell to the 110-cell stage. At the late gastrula stage neural-type differentiation of a4 2 blastomeres was not induced by pronase. The effective period for neural-type differentiation of a4 2 blastomeres in contact with A4 1 cells was between the 64-cell stage and late gastrula stage.Competence of the a4 2 blastomere to undergo neural-type differentiation decreased during gastrula stages, while the inducing ability of the A4-1 blastomere lasted longer.7. In a few cases the posterior-animal blastomere, b4-2, could also be induced to undergo neural-type differentiation after contact with A4-1 cells or after pronase treatment.8. The appearance of Na+ spikes in a42 blastomeres in contact with A4-1 cells was MS 7761 H. OKADO AND K. TAKAHASHI considered a manifestation of neural induction, similar in principle to the induction of ectoderm by the chorda-mesoderm in higher vertebrates.

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Section: Effects Of Changing Cytochalasin B Concentrationmentioning

confidence: 88%

Induced neural‐type differentiation in the cleavage‐arrested blastomere isolated from early ascidian embryos.

Okado

Takahashi

1990

The Journal of Physiology

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Partial characterization of neural-inducing factors from Xenopus gastrulae Evidence for a larger protein complex containing the factor

Janeczek

Born

Hoppe

et al. 1992

Roux's Arch Dev Biol

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High (Mr ≈ 90-110 kDa) and low (Mr ≈ 15-30 kDa) molecular weight forms of neural-inducing factors have been found in the supernatant of Xenopus gastrula homogenate. The factors, which are protein in nature, have been partially purified by size exclusion high-performance liquid chromatography (HPLC) and sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis. The factor of smaller size, which could be derived from a precursor, is associated with other proteins in a larger complex. The neural-inducing factors are not irreversibly inactivated after chemical deglycosylation with trifluoromethansulfonic acid. The neural-inducing protein which is found in ribonucleoprotein (RNP)-particles was partially purified by hydrophobic chromatography. Possible relationships of the factors in different subcellular fractions and their physiological significance are discussed.

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Changes in the interior surface of newly mesodermalized ectoderm and its contact activity with competent ectoderm in the newtCynops (Amphibia)

Suzuki

Miyagawa

Kuwana

1991

Roux's Arch Dev Biol

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The presumptive ectoderm (pE) ofCynops gastrulae was artificially mesodermalized by contact with teleost swimbladder. The newly mesodermalized ectoderm (mE) acquired the capacity for neural induction (Suzuki et al. 1986a). SEM observations revealed that the mE cells altered their cellular profiles immediately after mesodermalization. The characteristics of the cell surface and the cell architecture became similar to those of invaginated mesoderm cells. There were distinct differences in the cellular contact between mE-pE and pE-pE combinations. The mE-pE combinations kept close contact at their interior surfaces, while the pE-pE combinations did not keep contact. Both TEM and SEM observations also indicated that there were tight contacts between mE and pE cells. These findings suggest that neural-inducing activity of the newly mesodermalized ectoderm cells is coupled with acquisition of cellular affinity toward the interior surface of competent ectoderm cells, and probably requires close cell contacts.

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Close juxtaposition between inducing chordamesoderm and reacting neuroectoderm is a prerequisite for neural induction in Xenopus laevis

Cited by 8 publications

References 24 publications

Induced neural‐type differentiation in the cleavage‐arrested blastomere isolated from early ascidian embryos.

Induced neural‐type differentiation in the cleavage‐arrested blastomere isolated from early ascidian embryos.

Partial characterization of neural-inducing factors from Xenopus gastrulae Evidence for a larger protein complex containing the factor

Changes in the interior surface of newly mesodermalized ectoderm and its contact activity with competent ectoderm in the newtCynops (Amphibia)

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