Fig. 1

Representation of the concepts used in this study. (A) Schematic representation of a dynamic differentiation process. If one assumes that cells are dots moving in a gene expression space (sphere), then one can represent cells in a 3D (i.e. 3 genes) space. Self-renewing cells (blue cells) display some micro-heterogeneity, as well as differentiating cells (red cells). The differentiation process is accompanied by an increase in cell-to-cell variability (i.e. macro-heterogeneity) that allows the cells to escape locally attractive state and attain a new differentiated state [23,24,25]. (B) Three possible hypotheses on transcriptional memory behavior during a differentiation process (see text for details). (C) The type of genealogical information that was made available by dedicated methods in this paper. (D) Schematic description of a memory gene (upper) and a non-memory gene (lower). In the case of a memory gene, the geometric distance between the sister-cells 1 and 2 is of 2 minus 1, that is 1. The distance between the sister-cells 3 and 4 is of 4 minus 3, that is also 1. The mean distance for the memory gene between all sister-cells is therefore of 1, whereas the mean distance for the non-memory gene between all sister-cells is of 2 in this example