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#blastomere specification

2 public questions tagged with this topic.

Elegans -ll

Which of the following is responsible for EMS blastomere specification in C. elegans?

EMS blastomere, daughter of P1, generates MS mesoderm and E endoderm. Its polarity depends on POP-1, C. elegans TCF transcription factor downstream of Wnt/MAPK signaling from P2. In anterior daughter MS, high nuclear POP-1 represses endoderm genes; in posterior E maintained in contact with P2, Wnt signal phosphorylates POP-1 lowering nuclear levels and converting it to activator cooperating with SKN-1 and MED factors to induce END-1/3. Loss of POP-1 causes both daughters to become E-like, showing POP-1 essential for EMS asymmetry and proper endomesoderm specification throughout intestine and p

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 4: EMS specification and POP-1 TCF role in C. elegans.

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Elegans -ll

Which of the following best describes the specification of P1 and AB blastomeres in C. elegans?

In early C. elegans embryo, P1 inherits posterior determinants including P-granules, SKN-1, PIE-1 from asymmetric division driven by PAR proteins, giving autonomous specification independent of neighbors. Isolated P1 continues producing EMS and P2 lineages in culture. Conversely AB blastomere requires glp-1/Notch signaling contact between ABp and P2, involving LAG-2/APX-1 ligands to distinguish ABa from ABp fates. Isolated ABa both produce identical ABa-like lineages lacking pharyngeal differences. Thus P1 fate is maternally determined autonomously, while AB division relies on conditional indu

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 4: C. elegans early cleavage - autonomous versus conditional specification of P1 and AB.

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