(A) MARCM allows the derivation of homozygous mutant cells devoid of the GAL80 transgene (plum) following site-specific mitotic recombination. Depending on the GAL4 (blue) expression pattern, subsets of GAL80-negative mutant cells can be uniquely labeled by UAS-reporter (green).
(B) A neuronal lineage forms as one neuroblast (NB) repeatedly bud off ganglion mother cells (GMC) that each divide once to produce two post-mitotic neurons which often acquire distinct binary cell fates (A versus B) due to differential Notch signaling. Given this general pattern of neurogenesis, MARCM allows labeling of either a multi-cellular NB clone or a two-cell GMC clone following mitotic recombination in a dividing NB and marking of either A or B neuron as a single-neuron clone if mitotic recombination occurs in a dividing GMC. Note only post-mitotic neurons are marked in the panels given the transient nature of precursors.
(C) Dual-expression-control MARCM allows differential labeling of distinct populations of GAL80-minus cells via use of two independent GAL80-repressible binary transgene induction systems (e.g. GAL4/UAS & LexA::GAD/lexAop). Green: GAL4+ & LexA::GAD−; red: GAL4− & LexA::GAD+; yellow: GAL4+ & LexA::GAD+.