Fig. 1.

(a) Paraffin sections from 4, 6, and 8 month JNPL3 mouse brain (entorhinal cortex) were labeled with 9G3 and viewed by epifluorescence. Scale bar: 20μm. Insets at lower magnification show that 8 month old sample displayed increased number of phospho-Tyr18 tau positive cells relative to 6 month old. Phospho-Tyr18 tau immunoreactivity was lacking in 8-month-old non-transgenic mouse (upper left, scale bar: 30μm). (b) Phospho-Tyr18 tau appears at four months in three of the four brain regions and steadily increases with age in JNPL3 mice. Percentage of cells positive for 9G3 (number of positive cells divided by total number of cells examined in each brain region, as determined by Hoechst staining) was calculated from each animal (n=3). Values are expressed in mean percentage ±SEM. Comparisons were made between different brain regions within the same age group and for the same brain regions across different age groups. Differences that were statistically significant by unpaired t-test are indicated (*p<0.05; **p<0.01; ***p<0.005). BS-Brain Stem; SC-SubCortical structures; HI-Hippocampus; EC-Entorhinal Cortex (c) Correlation plot showing that the percentage of cells (mean+SEM) labeled for phospho-Tyr18 tau (squares) or AT8 (circles) increased with age in different brain regions of JNPL3 mice. AT8 or 9G3 positive cells were counted following single labeling. Individual markers (square or circle) within each age group represent the percentage of positive cells in brain stem (BS), subcortical structures (SC), hippocampus (HI) and entorhinal cortex (EC). Total number of cells examined per region (100%) was based on Hoechst staining. (d) Linear regression analysis between percentage of AT8 and 9G3 positive cells showed a significant correlation between 9G3 and AT8 immunoreactive cells in the different brain regions of each age group studied.