Practice question

GLP-1 encodes C. elegans Notch receptor essential for AB lineage distinction. After first cleavage, P2 Delta signals via APX-1/LAG-2 activate GLP-1 only in ABp because ABa contact with P2 is minimal. This induces ABp-specific gene expression, including repression of LAG-2 in ABa. In glp-1 loss-of-function embryos, Notch signaling absent in ABp, so ABp defaults to ABa program, producing two ABa-like lineages with duplicated anterior pharynx cells and loss of dorsal ventral patterning. EMS division unaffected but overall embryo fails pharyngeal asymmetry. Thus transformation is ABp to ABa, classic Notch lineage conversion evidence.