Supplemental Figure S1 -
Fig. S1. Constituents of two-cell clones are likely to be immediate neighbors in the sequence of cell genesis. (A) We collected a total of 52 two-cell clones. The red cells in the table indicate those composed of homogeneous sisters. Most commonly, two-cell clones are sequential neighbors in the sequence of genesis. As the sequential distance, or 'gap', increases, the frequency of two-cell clones decreases and none span the full sequence (i.e. RGC-MG). (B) To quantify this relationship we devised the 'cell gap score', which is defined as the distance between cells in the sequence of genesis. For example, two cells of the same phenotype have a cell gap score of 0, whereas an RGC-Ho two-cell clone would have a score of 1, and an RGC-CPr would be 2. (C) Comparison of the distribution of cell gap scores for two-cell clones from our data with that expected if the pairings were random and unidirectional. The greatest frequency of random pairing is homogeneous. The median cell gap score is 2 for the random sample, whereas the median for our two-cell clones is 1. There is a significant difference in the frequency of gap scores of 0 and 1 between the random and experimental data sets. The majority of sisters in the two-cell clones are not self-pairs but are close neighbors in the sequence of cell genesis (gap score of 1). The data show a close temporal/ordinal relationship between phenotypes in two-cell clones according to the sequence of cell genesis.
