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. Author manuscript; available in PMC: 2021 Jul 28.
Published in final edited form as: Cell Rep. 2021 Jun 22;35(12):109274. doi: 10.1016/j.celrep.2021.109274

Figure 5. Mitotic interchromosomal recombination efficiency and sister chromatid segregation patterns for all MADM reporters in cortical projection neurons.

Figure 5.

(A) Representative images of MADM-labeling pattern (green, GFP; red, tdT; yellow, GFP/tdT) in cerebral cortex in three exemplary MADM lines in combination with the Emx1-Cre driver at P21. (Top) MADM-9GT/TG;Emx1Cre/+; (middle) MADM-17GT/TG;Emx1Cre/+; (bottom) MADM-19GT/TG;Emx1Cre/+. Scale bar: 100 μm.

(B) Classification of MADM lines. (Top) Sparse (< 25 cells/mm3). (Middle) Intermediate (25–100 cells/mm3). (Bottom) Dense (>100 cells/mm3). Bars represent mean ± SEM. Data show M7, M11, and M19 (n = 5); M2, M3, M5, M8–M10, and M12–M18 (n = 6); M4 and M6 (n = 8), and M1 (n = 12 mice).

(C) MADM principle illustrating G2-X and G2-Z segregation patterns. Upon Cre-mediated interchromosomal recombination at the loxP site in the MADM cassettes in G2 phase of the cell cycle, recombinant chromosomes can either segregate together to the same daughter cell (G2-Z segregation; yellow, GFP/tdT and unlabeled cell) or each recombinant chromosome may segregate to distinct daughter cells (G2-X segregation; green, GFP+ and red tdT+ cell, respectively) upon mitosis.

(D) Definition of yellow-green-red-index index (YGRI). The YGRI is calculated from the number of yellow cells divided by the average of green and red cells to compensate for G2-Z events that leads to labeling of only one daughter cell (yellow) and an (invisible) unlabeled cell. Note that yellow cells emerging from G1/G0 events contribute to the total number of yellow cells.

(E) YGR index in neuronal lineages. (Top) YGRI for cortical projection neurons in P21 neocortex of all 19 MADM reporter lines in combination with the Emx1-Cre driver. Note that (1) YGRI varies from 1 to 10 but is never below 1 and (2) YGRIs do not correlate with the sizes of the respective MADM chromosomes. Bars represent mean ± SEM. Data show M2, M3, M5, and M7–M19 (n = 6); M4 and M6 (n = 8); and M1 (n = 12). (Bottom) YGRI ranking in correlation (red line) to recombination frequency index (RFI). Note that MADM chromosomes with a high recombination frequency do not necessarily present high YGRI and vice versa.

See also Figures S1 and S9.