Fig. 1

Total tau amounts are elevated throughout AD progression, whereas increased tau phosphorylation is only detectable at end-stage disease. a Representative immunoblots of cortical homogenates from postmortem brain. Blots were probed with antibodies to detect total (phosphorylated and non-phosphorylated) amounts of tau (DAKO) at 50 to 70 kDa, and tau phosphorylated at Ser396/404 (PHF-1) at 50 to 70 kDa. Blots were also probed with an antibody against neuron-specific enolase (NSE, 45 kDa) which acted as a loading control. Bar graphs show the amounts of DAKO and PHF-1 once standardized to NSE content in each sample. b Representative immunoblots of samples from sarkosyl extraction protocols showing low speed supernatants, sarkosyl-soluble and sarkosyl-insoluble tau probed with antibodies against total tau (DAKO). Bar charts show sarkosyl-soluble and sarkosyl-insoluble tau as a proportion of tau in low speed supernatants as a measure of total tau. c Postmortem brain sections immunostained with an anti-tau (AT8) antibody show Braak staging of AD brain. NFTs are absent from age-matched control brain. CTRL: control (n = 5), Braak II AD (n = 4), Braak III AD (n = 3), Braak IV AD (n = 4), Braak V AD (n = 3), Braak VI AD (n = 5). Data is mean ± SEM. *p < 0.05, **p < 0.01