University:
Swansea University
Course:
PM-133 | Evolutionary and Molecular Genetics
Academic year:

2023
Views:

156

Pages:

3
Author:

Amal J.

Axis Specification: Anterior-Posterior Axis: PAR proteins are key for anterior-posterior axis specification (e.g., partitioning defective). After fertilization: PAR-3, 6 & PKC are located in the peripheral cytoplasm (cortical region) and are attached to the cytoskeletal network. PAR-1 & 2 are located in the clear cytoplasm and are involved in posterior specification. Mechanism: PAR-3, 6, and PKC tend to enter the cortical cytoplasm. PKC phosphorylates incoming PAR proteins causing them to move back. Dorsal-Ventral Axis: Rho GEF activates Rho GTP, leading to actin polymerization and maintaining cytoskeletal tension. Rho inactivation: Rho GTP leads to actin depolymerization, releasing cytoskeletal tension. At the point of sperm entry, PAR-3, 6 & PKC are depleted, ensuring proper dorsal-ventral axis specification. Post 2nd Cleavage: In the 4-cell stage, the abnormal AB cell is positioned above EMS, leading to dorsal specification, while normal positioning leads to ventral specification. Right-Left Axis: 12-cell stage: MS cells are in contact with granddaughter cells of ABa. The right side specification leads to the determination of the right side, and the opposite side is designated as the left side. Autonomous and Conditional Specifications: SKN-1: Autonomously specifies the EMS cell. PAL-1: Specifies the somatic descendants of the P2 cell to follow the C fate. PIE-1: Specifies the germline (P fate).