Correct option is C
Correct Answer: (c)
Explanation: Deletion of yfg from cell-type ‘A’ leads to a significant increase in the number of neighbouring ‘B’ cells, indicating that yfg normally acts to restrain this increase. Such an outcome implies that in wildtype conditions, yfg expressed in ‘A’ cells suppresses or negatively regulates the proliferation of ‘B’ cells. Removal of this inhibitory influence results in unchecked proliferation. Therefore, yfg inhibits ‘B’ proliferation.
Information Booster
· Loss-of-function phenotypes often reveal inhibitory roles of genes.
· An increase in neighbouring cell population suggests non–cell-autonomous regulation.
· In developmental systems, inhibitory signals are crucial for controlling tissue size and patterning.
· Paracrine signaling between adjacent cell types is common in brain development.
· Gene deletion effects must be interpreted relative to the wildtype regulatory state.
Additional Knowledge
If yfg promoted ‘B’ proliferation, its deletion would have reduced, not increased, ‘B’ cell numbers. A five-fold increase strongly indicates relief from repression rather than absence of function. There is also no evidence provided for yfg regulating its own expression in ‘B’ cells. Such logic-based inference from genetic perturbation experiments is fundamental for deciphering gene function in developmental biology.
