- C. elegans embryo uses both autonomous and conditional modes of specification. Conditional specification at the 4-cell stage can be seen in the development of the endoderm cell lineage and also in the establishment of dorsal-ventral axis. Following are few statements regarding this:
(A) If the P2 cell is removed at the early 4-cell stage, the EMS cell will divide into two MS cells and no endoderm will be made.
(B) In pop-1 deficient embryos, both EMS daughter cells become E cells.
(C) When the position of ABa and ABp was reversed, their fates get reversed and no normal embryo forms.
(D) In embryos whose mother have mutant glp-1, Abp is transformed into ABa cell.
Which of the above statements are true?
(1) A, B and D (2) A, B and C
(3) B, C and D (4) A, C and DCaenorhabditis elegans embryos utilize both autonomous and conditional modes of cell fate specification during early development. Conditional specification is especially evident at the 4-cell stage during endoderm lineage development and dorsal-ventral axis establishment.
Several key experimental observations illuminate these mechanisms:
(A) Removal of the P2 cell at the early 4-cell stage leads the EMS blastomere to divide into two MS cells rather than producing an endodermal E cell, resulting in no endoderm formation. This indicates that the P2 cell provides an essential inductive signal to the EMS cell to specify endoderm fate.
(B) In pop-1 deficient embryos, both EMS daughter cells adopt the E cell fate, suggesting pop-1 regulates the specification balance between mesoderm and endoderm in EMS progeny.
(C) Reversal of the ABa and ABp blastomere positions results in fate reversal and abnormal embryogenesis, confirming positional conditional specification in AB lineage.
(D) In embryos from glp-1 mutant mothers, ABp transforms into ABa, demonstrating GLP-1/Notch signaling’s role in distinct sex-specific fate determination within AB descendants.
Experimental findings confirm that statements (A), (B), and (D) are true, while statement (C) does not fully align with established data.
Hence, the correct answer is:
(1) A, B and D
1 Comment
Muskan Yadav
December 7, 2025(1) A, B and D is correct answer.