Fig. 5. Mitochondrial clustering in tau transfected CHO cells in which tau is not phosphorylated at the Tau-1 site. (a-f) CHO cells transfected with tau were triple stained with Mito Tracker Red® (mitochondria) and antibodies R134d to total tau (green) and Tau-1 to unphosphorylated tau (blue). Arrows indicate the cells with mitochondrial clustering, arrowheads indicate the cells with normal mitochondrial distribution. Both arrows and arrowheads show the position of the cell membrane seen by phase microscopy (not shown). In cells with unphosphorylated tau (blue) clustering of mitochondria was observed (a,d; arrows). In contrast, the distribution of mitochondria was almost normal in cells containing phosphorylated tau (a,d; arrowheads). Asterisks indicate non-tau-expressing cells (e,f) with normal distribution of mitochondria (d). Tau-transfected CHO cell (g,h; left) with mitochondria clustered around the nucleus, double stained (g) for tau (R134d, green) and mitochondria (Mito Tracker Red®). The cell on the right in g, h is not transfected. Orange in g indicates overlapping areas of tau and mitochondrial stains. (h) Phase micrograph of g showing that the periphery of the transfected cell (g,h; left) is practically free of organelles. Scale bars: 10 µm.