Fig. 2.
NIRKO mice display mitochondrial dysfunction. Mitochondrial activity was measured using isolated brain mitochondria in a Seahorse Flux Analyzer as described in Materials and Methods. Basal respiration measurements, displayed as area under the curve, of isolated brain mitochondria from (A) 4-mo-old and (B) 24-mo-old control and NIRKO mice using the XF24 Extracellular Flux Analyzer from Seahorse Bioscience. A total of six control and six NIRKO mice were used. (C) Determination of striatal protein levels of electron transport chain complexes. Representative Western blots are shown of nuclear- and mitochondrial-encoded genes (IR beta, CV-ATP5A, CIII-UQCRC2, CIV-MTCQ1, CII-SDHB, and CI-NDUFB8) using striatal samples from 4-mo-old female control (n = 6) and NIRKO mice (n = 6). β-Actin served as a loading control. (D) Transmission electron microscopy of brain striatum showing mitochondria of 4-mo-old female control and NIRKO mice. This is a representative example of 12 fields in four animals of each genotype. Note the decreased mitochondrial diameter. Original magnification 1:10,000. (E) Morphometric analysis of electron microscopy using ImageJ. Average mitochondrial area and total mitochondrial number of control and NIRKO mice (n = 4 mice of each genotype with 100–200 mitochondria analyzed).