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#C. elegans development

2 public questions tagged with this topic.

C-Elegans Development-l

What is the role of PAR proteins in early C. elegans development?

PAR family establishes early embryonic polarity without zygotic transcription relying solely on maternal proteins and sperm cue. PAR-2 RING finger protein recruited posteriorly after sperm centrosome signal suppresses anterior actomyosin contractility via RhoGAP regulation, preventing PAR-3/PAR-6/PKC-3 complex binding posteriorly. PAR-3 scaffolds anterior complex regulating cortical contractility and spindle positioning via GPR-1/2 and LIN-5. Mutual antagonism creates bistable cortical domains translated into cytoplasmic gradients MEX-5 anterior high and PIE-1 posterior high via differential phosphorylation. Conservation from worms to mammals underscores fundamental cortical polarity principle defining axes before gastrulation.

Ref: Kemphues, Annual Review Cell Dev Biology: PAR proteins localize to cortex establishing anterior-posterior polarity.

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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 induction via cell contacts.

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

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