Figure 2.
Cell Size Scaling of rΔΨm Is Affected by Temperature and Cellular Metabolism, but Not Cell Cycle
(A) Expected effect of temperature on cell size scaling of rΔΨm. Metabolic theory predicts that metabolic rate changes not only with size but also with temperature (Gillooly et al., 2001), as indicated by the equation. b is a general scaling constant, M is mass, T is temperature, k is Boltzmann's constant, and E is the activation energy of metabolism. Thus, increased temperature is expected to cause a shallower decline in rΔΨm.
(B) Jurkat cells were incubated in complete medium at different temperatures for 2 hr to adjust the metabolic rate followed by JC-1 staining-based analysis. Note that rΔΨm scaling does not change further at the highest temperatures as cells approach denaturating temperatures. n > 1 × 105 for each temperature point.
(C) Effect of mitochondrial nutrient source on cell size scaling of rΔΨm. Glucose-grown cells utilize both glycolysis and mitochondria for energy generation. Galactose-grown cells are reliant on mitochondrial metabolism. Jurkat cells were cultured on glucose-containing medium or adapted to grow on galactose followed by rΔΨm measurement. Δy values show the magnitude of rΔΨm decline in the linear range of the curve.
(D) ΔΨm associates with cell size but not cell cycle. Jurkat cells were stained with JC-1 and NuclearRed ID DNA dye to visualize rΔΨm scaling with cell size in each cell-cycle phase (top left) and with DNA content (bottom right).
(E) Quantification of conditional information analysis of ΔΨm association with cell size and cell cycle showing the strength of ΔΨm association with cell size (S) and cell cycle (CC) from Jurkat cells measured as shown in (D). Data shown represent mean ± SD (n = 3) with >7.5 × 105 cells per replicate.
See also Figure S3.