Panel A shows box plots of cell volume at the beginning of G1 for daughter and mother cells of various strains, with the x-axis labeled Mothers and Daughters and the y-axis labeled Cell volume at beginning of G1 in femtoliters. Panel B displays box plots of G1 length for the first daughters of S, G2, or M switchers, with the x-axis showing different strains and the y-axis labeled G1 length in minutes. Panel C presents box plots of cell volume at the end of G1 for the first daughters of S, G2, or M switchers, with the x-axis showing different strains and the y-axis labeled Volume at G1 end in femtoliters. Panel D shows box plots of cell volume at the beginning of G1 for daughter and mother cells of various strains with MET promoter CLN3 and MET promoter CLN3-11A, with the x-axis labeled Mothers and Daughters and the y-axis labeled Cell volume at beginning of G1 in femtoliters. Panel E displays box plots of G1 lengths for the first daughters of S, G2, or M switchers with MET promoter CLN3 and MET promoter CLN3-11A, with the x-axis showing different strains and the y-axis labeled G1 length in minutes. Panel F presents box plots of cell volumes at the end of G1 for the first daughters of S, G2, or M switchers with MET promoter CLN3 and MET promoter CLN3-11A, with the x-axis showing different strains and the y-axis labeled Volume at G1 end in femtoliters. Panel G is a schematic illustration of the proposed Bck2 and Cln3 functions during steady-state growth and nutrient shift.
bck2Δ cells have a longer G1 arrest and stronger enlargement than cln3Δ cells after a nutrient switch. (A) Cell volume at the beginning of G1 is plotted for daughter (first-generation) and mother (generation > 1st) cells of various strains. For mothers: nWT = 209, nwhi5Δ = 87, nbck2Δ = 95, nwhi5Δbck2Δ = 95, ncln3Δ = 48, nwhi5Δcln3Δ = 61, nwhi5Δbck2Δcln3Δ = 34. For daughters: nWT = 164, nwhi5Δ = 82, nbck2Δ = 73, nwhi5Δbck2Δ = 77, ncln3Δ = 44, nwhi5Δcln3Δ = 55, nwhi5Δbck2Δcln3Δ = 37. (B and C) G1 lengths (B) and cell volumes at G1 end (C) are plotted for the first daughters of S/G2/M-switchers. The dataset for WT, whi5Δ, bck2Δ, and whi5Δbck2Δ is the same as in Fig. 5. For cln3Δ, whi5Δcln3Δ, and whi5Δbck2Δcln3Δ, cells were pooled from two independent experiments. ncln3Δ = 16, nwhi5Δcln3Δ = 39, nwhi5Δbck2Δcln3Δ = 11. (D) Cell volume at the beginning of G1 is plotted for daughter (first-generation) and mother (generation > 1st) cells of various strains. For METpr-CLN3 mothers: nWT = 44, nbck2Δ = 44, nwhi5Δbck2Δ = 26. For METpr-CLN3 daughters: nWT = 36, nbck2Δ = 32, nwhi5Δbck2Δ = 19. For METpr-CLN3-11A mothers: nWT = 30, nbck2Δ = 22, nwhi5Δbck2Δ = 30. For METpr-CLN3-11A daughters: nWT = 21, nbck2Δ = 20, nwhi5Δbck2Δ = 23. (E and F) G1 lengths (E) and cell volumes at G1 end (F) are plotted for the first daughters of S/G2/M-switchers. Cells were pooled from two independent experiments. For METpr-CLN3: nWT = 18, nbckΔ = 22, nwhi5Δbck2Δ = 15. For METpr-CLN3-11A: nWT = 10, nbckΔ = 16, nwhi5Δbck2Δ = 16. (G) Schematic illustration of the proposed Bck2 and Cln3 function during steady-state growth and nutrient shift. Two-sided Mann–Whitney U tests were used to statistically analyze each strain compared with WT (P < 0.001 not indicated for clarity; **: P < 0.01; *: P < 0.05; ns: not significant, P ≥ 0.05). For boxplots in A–F, box limits show the IQR, whiskers extend to the most extreme data points within 1.5× IQR, the median is shown as a line, and the mean is shown as a cross. WT, wild type; IQR, interquartile range.