Figure 4.

The Stem Cells with the Highest Telomere Intensity Are nanos⁺

(A) Schematic and tissue section indicate the distribution of four cell populations in a 7dS planarian. Double arrow indicates plane of sagittal sectioning.

(B) Representative tissue section with four telomere intensity maps that represent the four cell populations displayed in (A). The intensity maps show the nuclei colored according to their telomere fluorescence intensity. The stacked bar graphs represent the proportion of nuclei within a given category of intensity. smedwi-1⁺/nanos⁻ is chosen as the reference population. Most of the stem cells with the longest telomere intensity are nanos⁺/smedwi-1⁺. Magenta box indicates the area shown. Anterior is to the left and dorsal is up.

(C) The column scatterplot shows all the pooled nuclei broken down into four cell populations. Any of the three subclasses of stem cells display longer telomeres than non-stem cells smedwi-1⁻/nanos⁻ (two-tailed Mann-Whitney U test; p < 0.0001 for each of the three combinations). The median telomere intensity is higher in the smedwi-1⁺/Smed-nanos⁺ when compared with the smedwi-1⁺/nanos⁻ (two-tailed Mann-Whitney U test; p < 0.0001). n, number of planarians analyzed.

Scale bars, 200 μm (main images) and 30 μm (high-magnification images). See also Figure S3.