Extension of Chronological Lifespan by Hexokinase Mutation in Kluyveromyces lactis Involves Increased Level of the Mitochondrial Chaperonin Hsp60
Figure 4
Functional analysis of mitochondria in the long-lived mutant. (a) Comparison of mitochondrial morphology of rag5Δ and wt strains after growth in YPD medium. Analysis was performed by taking aliquots at the indicated times and observing cells after DASPMI staining at the fluorescence microscopy. (b) Mitochondrial membrane potential determined by DiOC6 staining and FACS analysis. Values are expressed as mean fluorescent intensity. Means of four biological replicates ± one standard deviation are graphed. ** value from a Student’s t-test, <0.01, *** value from a Student’s t-test, <0.001. (c) Cytochrome spectra. Cell samples were collected at day 1 and cytochrome spectra were evaluated. The peaks at 550, 560, and 602 nm (vertical bars) correspond to cytochromes c, b, and aa3, respectively. The height of each peak relative to the baseline of each spectrum is an index of cytochrome content. Data are representative of three independent experiments, repeated with similar results. (d) Oxygen consumption rates in wt and rag5Δ cells. Cell samples were collected at days 1, 2, and 4 and oxygen consumption was measured at 30°C using a Clark type oxygen electrode. Data are means ± s.d. of three independent experiments. Data were normalized for the number of live cells.
