Figure 4.

Fractionated irradiation reduces proliferation and causes an overall reduction in basal progenitor cell number. (A) In AT, Mki67 expression was downregulated during (striped bars) (IR Day 2 and 3) and shortly after (gray bars) (2 dpi) fractionated IR, then substantially overshot controls (white bar) before a second drop in expression at 21 dpi. (B) In the CVP, Mki67 expression was significantly downregulated at IR Day 3, overshot controls at 2–3 dpi, and returned to control levels at 10 dpi. (C) In the CVP, fractionated irradiation caused a significant reduction in the Proliferation Index (#Ki67⁺ basal cells/#DAPI⁺ basal cells) and led to significantly fewer total DAPI⁺ progenitor cells along the basement membrane (yellow dotted line) (D). The size of basal nuclei in control CVP was significantly different in irradiated CVP at 2 dpi (Mann & Whitney test, Supplementary Fig. S3A), and thus required Abercrombie correction (see Methods, uncorrected data in Supplementary Fig. S3B). (E–G) Representative images are compressed z-stacks of CVP sections immunostained for Ki67 (magenta), Krt8 (taste buds; green), and DAPI counterstained (white). Scale bar 50 µm for (E–G). (A,B) Data are represented as median (bars) with 95% confidence interval (error bars), and individual points (scatter plot). Horizontal grey bars represent control 95% confidence interval. Mann & Whitney test (* p < 0.05, **p < 0.01, ***p < 0.001). N AT (Controls vs IR mice) Day 1, 6 vs 7; Day 2, 5 vs 5, Day 3, 8 vs 6; 2 dpi, 5 vs 4; 3 dpi, 9 vs 8; 10 dpi, 6 vs 5; 21 dpi, 4 vs 4. N CVP (Controls vs IR mice) IR Day 1, 5 vs 6; IR Day 2, 4 vs 4; IR Day 3, 3 vs 5; 2 dpi, 5 vs 4; 3 dpi, 9 vs 8; 10 dpi, 6 vs 5; 21 dpi, 4 vs 4. (C,D) Data are represented as violin plots with median (blue line) and 1^st and 3^rd quartile (red line). Mann & Whitney test (*p < 0.05, **p < 0.01, ***p < 0.001). Controls vs IR (N = mice, n = trench profiles) IR Day 3 N = 6 vs 5, n = 73 vs 33; 2 dpi N = 4 vs 5, n = 50 vs 70.