Correct option is B
We are asked to identify the correct combination of statements about the interaction between two adjacent cells, Z1.ppp and Z4.aaa, in C. elegans hermaphrodites, where one becomes the anchor cell and the other becomes the precursor to uterine tissue.
Breakdown of Statements:
Statement A: "The cell secreting LAG-2 becomes the anchor cell."
Correct: In C. elegans, LAG-2 is a Notch ligand that is secreted by one of the adjacent cells. The cell that secretes LAG-2 activates Notch signaling in the neighboring cell, and this cell becomes the anchor cell. This statement is accurate and explains the basic mechanism of anchor cell determination.
Statement B: "The cell secreting LIN-12 remains as the precursor of the uterine tissue."
Correct: LIN-12 is a receptor for LAG-2, and the cell receiving LAG-2 signaling through LIN-12 becomes the uterine precursor. The cell that does not secrete LAG-2 but expresses LIN-12 will remain the precursor of the uterine tissue. This is consistent with how the differentiation of uterine tissue occurs in C. elegans.
Statement C: "The LIN-12 secreting cell takes the fate of the anchor cell while the LAG-2 secreting cell takes the fate of uterine precursor cell."
Incorrect: This statement is incorrect because it reverses the roles of LIN-12 and LAG-2. LAG-2 is the key factor that determines the anchor cell fate, and LIN-12 is involved in the signaling of the adjacent cell that becomes the uterine precursor.
Statement D: "The Hippo signaling pathway brings lateral inhibition so that one cell is inhibited and the other cell is promoted to become the anchor cell."
Incorrect: While lateral inhibition plays a role in ensuring one cell adopts the anchor cell fate and the other adopts the uterine precursor fate, Hippo signaling is not the primary pathway mediating this in this particular context. The Notch signaling pathway, through LAG-2 and LIN-12, is the more accurate signaling mechanism at play here.
Correct Combination:
Option (2) A and B is correct because both Statement A and Statement B accurately describe the processes of anchor cell formation and uterine precursor specification:
Statement A explains that the LAG-2 secreting cell becomes the anchor cell.
Statement B explains that the cell secreting LIN-12 remains the precursor of uterine tissue.
Information Booster:
LAG-2 and LIN-12 Signaling: In C. elegans, LAG-2 is the ligand that activates Notch signaling in the neighboring cell, and this signaling leads to the differentiation of the anchor cell. The cell receiving LAG-2 signaling via LIN-12 will remain as the uterine precursor.
Lateral Inhibition and Notch Signaling: The interaction between LAG-2 and LIN-12 ensures that one cell adopts the anchor cell fate while the other adopts the uterine precursor fate. This lateral inhibition mechanism is crucial for proper cell fate determination during development.
Additional Information:
Option (1) A and D: Statement D is incorrect because the Hippo signaling pathway is not the primary mechanism for lateral inhibition in this case; Notch signaling (via LAG-2 and LIN-12) is the key factor here. Hence, this option is incorrect.
Option (3) D only: Statement D alone does not provide a complete and accurate description of the process, as it incorrectly attributes the lateral inhibition to the Hippo signaling pathway.
Option (4) C only: Statement C is incorrect because it reverses the roles of LAG-2 and LIN-12 in the cell fates. Thus, this option is incorrect.
