A Contact-Dependent Animal-to-Vegetal Signal Biases Neural Lineages duringXenopusCleavage Stages
| Autor: | Sally A. Moody, Daniel W. Best, Alexandra M. Hainski, Daniel V. Bauer |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Central Nervous System
Blastomeres Xenopus education Central nervous system Biology Midblastula 03 medical and health sciences Transcription (biology) health services administration medicine Animals Molecular Biology health care economics and organizations 030304 developmental biology Embryonic Induction Genetics 0303 health sciences Zygote 030302 biochemistry & molecular biology Embryo Cell Biology Blastomere biology.organism_classification Cell biology medicine.anatomical_structure Neural development Developmental Biology |
| Zdroj: | Developmental Biology. 178:217-228 |
| ISSN: | 0012-1606 |
| Popis: | The central nervous system (CNS) of Xenopus is derived from three of four tiers of blastomeres of the 32-cell embryo, and each blastomere in these tiers produces a characteristic number of primary spinal neurons. The C-tier blastomeres constitute the boundary between those that contribute to the CNS (A-, B-, and C-tiers) and those that do not (D-tier). To test whether the neural lineages descended from the C-tier are established by intrinsic information or by cell–cell interactions, single B-tier blastomeres were deleted and the lineage of their C-tier neighbors mapped. The contributions of C-tier blastomeres to subdivisions of the CNS and to specific spinal neurons were significantly reduced. Contributions of these blastomeres to other tissues were mostly normal, indicating that those C-tier progeny that no longer contribute to CNS are distributed in small numbers throughout the rest of the clone. To test whether the changes in neural lineages after B-tier deletions were the result of the C-tier blastomere changing position, contacting new neighbors, or losing contact with inductive B-tier neighbors, intact embryos were transiently dissociated within their vitelline membranes at different time points prior to the midblastula transition. This treatment disrupted cell–cell contact, but not gap junction-mediated dye coupling or the positions of neighboring cells. C-tier CNS lineages were reduced as after deletion of the B-tier neighbor, suggesting that the neural fate of C-tier cells depends upon specific B-tier interactions. To determine whether these interactions occurred specifically between B-tier and C-tier neighbors, barriers were inserted transiently between individual B/C pairs; similar reductions in C-tier CNS lineages were observed. These data demonstrate that an animal-to-vegetal, contact-dependent signal passes from B-tier to C-tier blastomeres and is required for the normal C-tier contribution to the CNS. This cell–cell interaction occurs many hours before the onset of zygotic transcription or neural induction and may bias the field of cells that can respond to neural induction. |
| Databáze: | OpenAIRE |
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