Correct option is B
In Caenorhabditis elegans, the ABp and ABa cells (daughters of the AB cell) have different fates despite being genetically identical. This difference in fate arises because of the interaction between the AB cell and the P2 cell.
P2 cell and ABp fate: When the AB cell divides to form the ABa (anterior) and ABp (posterior) cells, the differentiation of ABp is influenced by its interaction with the P2 cell. This interaction causes the ABp cell to adopt a distinct fate compared to ABa. This is a classic example of conditional specification, where cell fate is influenced by neighboring cells through signals.
ABp versus ABa: While both ABp and ABa are derived from the same AB blastomere, the positional information provided by P2 differentiates ABp from ABa.
- Option (a): Incorrect. If the AB and P1 cells are separated, the AB cell will not generate all of the cells it normally would. The P1 cell is crucial for the posterior fate specification, and without it, the AB cell would only form anterior structures.
- Option (c): Incorrect. The specification of the AB cell is not solely determined by cytoplasmic determinants. It is influenced by interactions with surrounding cells, notably the P1 and P2 cells.
- Option (d): Incorrect. While P2 produces signals that influence ABp fate, it is the interaction of P2 with AB that determines the identity of ABp (not a direct morphogen gradient).
Information Booster:
- ABa and ABp: These are the two daughter cells resulting from the division of the AB blastomere. Their fates are different because of the P2 cell's influence on ABp.
- Conditional specification: This refers to the process where the fate of a cell is determined by its environment, in this case, the interaction with neighboring cells like P2.
- Cell-cell signaling: The interaction between AB and P2 is a key example of how cell fate can be determined by signaling rather than intrinsic genetic programming alone.
