FIGURE 6

Clustering, and mapping of 4w_Mg clusters on 5d_Mg clusters. (A) Mapping of 4w_Mg clusters onto 5d_Mg clusters. Left panel shows the original UMAP of 4wpf_Mg clusters. Middle panel shows the “predicted.id” UMAP of 4w_Mg clusters, in which each 4w_Mg cell is assigned to either 5d_Mg cluster, whose transcriptomic profile shows the highest similarity to that of the targeted 4w_Mg cell. Right panel shows the breakdown of percentage of 4w_Mg cells assigned to each 5d_Mg cluster. (B) Plotting of individual 4w_Mg1/2/3/4 cells on the triangular diagram of the three 5d_Mg clusters, using transcriptomic similarity percentages of individual 4w_Mg1/2/3/4 cells to each 5d_Mg cluster, calculated with the cluster mapping analysis shown in (A). The left panel shows merged plotting of all 4w_Mg cells. Right panels show plotting of each 4w_Mg cluster, in which plotting density is also shown. 4w_Mg1 cells (red circles) are mapped around the edge that connects vertices of 5d_Mg3 and 5d_Mg2. 4w_Mg2 cells (green circles) are mapped around the edge that connects vertices of 5d_Mg1 and 5d_Mg3. 4w_Mg3 cells (blue circles) are mapped around the edge that connects vertices of 5d_Mg1 and 5d_Mg2. Almost all 4w_Mg4 cells (purple circles) are mapped to the vertex of 5d_Mg1. These spatial plotting data are consistent with cluster mapping data shown in (A); however, importantly, each 4w_Mg cell population shows heterogeneity on inheritance rate of characteristics of each 5d_Mg cluster. (C) Visualization of il1b expression levels in each 4w_Mg cell mapped onto a triangular diagram of 5d_Mg1/2/3 clusters. Expression level is indicated with red (high)‐green (low) color code. 4w_Mg cells highly expressing il1b are located around the vertex showing the highest transcriptomic similarity to stress‐response microglia 5d_Mg2. Thus, il1b expression level is determined by transcriptomic similarity to stress‐response microglia even in 4w_Mg cells. (D) Summary of the transcriptomic similarity between 5d_Mg clusters and 4w_Mg clusters. 4w_Mg1 inherits characteristics of homeostatic 5d_Mg3 and stress‐response 5d_Mg2. 4w_Mg2 inherits characteristics of degeneration‐response 5d_Mg1 and homeostatic 5d_Mg3. 4w_Mg3 inherits characteristics of degeneration‐response 5d_Mg1 and stress‐response 5d_Mg2. 4w_Mg4 purely inherits characteristics of degeneration‐response 5d_Mg1.