Endurance exercise as a countermeasure for aging. Diabetes 2008;57:2933–2942

The original publication of the article listed above did not clearly state that the representative blots in Fig. 6 are composed of four separate images. As such, the reader may mistakenly presume that the representative bands in Fig. 6 were taken from contiguous lanes of a single blot as in Fig. 4. The purpose of this corrigendum is, first, to clarify that the representative bands in the inset of Fig. 6 are taken from four different blots and, second, to provide additional explanation for this approach. SIRT3 expression was determined from a set of immunoblots where muscle lysates from the four subject groups were loaded onto 12-well gels, with each of the four groups on a different gel. To allow direct comparison of expression levels across different blots, lane 12 of each gel included a common quality control (QC) sample, consisting of a mixture of lysates from all samples. The optical density of each sample was normalized to the density of the corresponding QC for each blot. This normalization approach allowed direct comparison of groups across the four different blots by correcting for potential differences in electrophoresis, blotting, antibody incubations, chemiluminescence reagent, and film exposure time. The new Fig. 6 included here provides the SIRT3 bands for the entire dataset with corresponding densitometry values used to generate the plot in Fig. 6. Since the time of the original publication of this article, the journal has adopted clear policies on presentation of representative bands from immunoblots, specifically that " the grouping of images from different parts of the same gel, or from different gels, fields, or exposures must be made explicit by the arrangement of the figure (i.e., using dividing lines) and in the text of the figure legend. " A link to this statement can be found here: FIG. 6. Protein expression of SIRT3. Protein expression of SIRT3 was lower with age in sedentary adults, with no effect of age in trained adults. Data are presented as means 6 SEM. *Pairwise comparisons revealed significant (P , 0.05) effects of age within activity groups; **significant (P , 0.05) main effects of training.