E1’s ion-binding sites are exposed to the cytoplasm, and it has high affinity for Na+ but low affinity for K+

TLS Online TPP Program

#Id: 4749

#Unit 5. Developmental Biology

At the same time, the sperm microtubules induce the contraction of the actin-myosin cytoskeleton toward the anterior, thereby clearing PAR-3, PAR-6, and PKC-3 from the posterior of the 1-cell embryo.

TLS Online TPP Program

#Id: 4750

#Unit 5. Developmental Biology

During first cleavage, the metaphase plate is closer to the posterior, & fertilized egg is divided into two cells:

one having the anterior PARs (PAR-6 and PAR-3)

one having the posterior PARs (PAR-2 and PAR-1)

TLS Online TPP Program

#Id: 4751

#Unit 5. Developmental Biology

C. elegans demonstrates both the conditional and autonomous modes of cell specification. 

TLS Online TPP Program

#Id: 4752

#Unit 5. Developmental Biology

The P1 cell develops autonomously without the presence of AB, generating all the cells it would normally make, and the result is the posterior half of an embryo.

TLS Online TPP Program

#Id: 4753

#Unit 5. Developmental Biology

AB cell in isolation makes only a small fraction of the cell types it would normally make.

TLS Online TPP Program

#Id: 4754

#Unit 5. Developmental Biology

The determination of the P1-derived somatic founder cells (MS, E, C, and D)are autonomous, with cell fates determined by internal cytoplasmic factors SKN-1, PAL-1, and PIE-1