Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet: (A) Representative double plotted actograms of wheel running activity from one WT and one PS19 mouse in a 12:12 h light:dark (LD) condition at 3 months- and 8 months-of-age. Darkened regions of the actograms denote periods when the lights were off. (B) Mean (± SEM) daily activity profiles of WT (grey) and PS19 (blue) mice in LD. Quantification of the mean (± SEM) average daily activity (counts/day), phase angle of entrainment of activity onset relative to the start of the dark phase, and percent of total activity in the dark phase for 3-month-old (C) and 8-month-old (D) mice. Data in B-D were analyzed from 8-14 mice for each genotype. Circadian entrainment and locomotor activity were comparable between PS19 mice and WT littermates at both ages tested (no statistically significant changes were identified for the noted parameters at each age; Student’s t-test). Closed shapes indicate male mice (both 3- and 8-month-old) and open shapes indicate female mice (8 month-old).

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Activity Assay

Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet: Representative double plotted actograms of wheel running activity from one WT mouse and three PS19 mice in constant darkness (A) at 4-5 months- and 9-10 months-of-age and constant light (D) at 5-6 months-of-age. (B & C) Quantification of the mean (± SEM) circadian period, acrophase, alpha, and average daily activity in DD at 4- 5 months- (B) and 9-10 months-of-age (C). (E) Quantification of the mean (± SEM) circadian period, average daily activity in LL, and the percentage of activity in LL (relative to activity levels under LD: please see the Methods section for a description of the analysis approach). Of note, relative to WT mice, the PS19 mice exhibited a significant reduction in LL-induced activity damping. The percentage activity levels for LL were calculated based on levels of activity in the LD period preceding the transition to the LL condition; The percentage activity is also shown for the LD cycle that followed LL. (E). Data in B & C and E were calculated from 7-13 mice for each genotype; * = p < 0.05, significantly different from WT control; Student’s t-test. Percent of LD pre activity was calculated using 2-way repeated measures ANOVA; * = p < 0.05, ** = p < 0.01, **** = p < 0.0001. Closed shapes indicate male mice (both 3- and 8-month-old) and open shapes indicate female mice (8-month-old).

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Activity Assay, Control

Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet: Representative coronal brain sections from 2-, 4-, and 11-month-old PS19 (A-C’) and an 11-month-old WT littermate (D) labeled with the AT8 antibody recognizing p-tau and developed for immunohistochemistry using a DAB-based method. Dark labeling represents AT8 antibody labeling (Boxed regions in A: SCN: suprachiasmatic nuclei, RSC: retrosplenial cortex, ST: striatum, PC: piriform cortex). Higher magnification images of the SCN reveal marked p-tau labeling at 2-months of age (A’) with small inclusions beginning to form in the SCN by 4 months (B’), and by 11 months (C’) inclusions are broadly observed within the SCN and the surrounding hypothalamic tissue (arrows in magnified image denote cells with inclusions). E-G: Age-matched WT littermate brain tissue was immunolabeled using the AT8 antibody for comparison, and very low DAB reactivity was detectable, as expected. H: Quantification of the AT8 signal in the SCN of PS19 mice at 2-, 4-, and 11-months with labeling at 11 months significantly lower than 2- and 4-month-old SCN, * = p < 0.05, ** = p < 0.01, ANOVA; 5-8 animals per group. Scale bars in panels A and A’ are 1000 and 100 microns, respectively.

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Labeling, Immunohistochemistry, Antibody Labeling, Immunolabeling, Comparison

Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet: Immunohistochemical labeling for p-tau (from ; AT8 antibody) in the piriform cortex (A-C), striatum (D-F), and retrosplenial cortex (G-I) in 2-, 4-, and 11-month-old PS19 mice. P-tau is observed in the piriform cortex at 2 months-of-age (A) with a marked increase in labeling at 4 months-of-age (B), and inclusions are detected at the 11-month time point (C). The striatum and retrosplenial cortex have clear p-tau labeling at 11 months-of-age, but not at 2- or 4-months-of-age (D-I). Scale bar in panel A is 200 microns.

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Immunohistochemical staining, Labeling

Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet: Immunofluorescence labeling for p-tau (AT8 antibody; magenta) and arginine vasopressin (AVP; a marker of SCN shell neurons; A-F’; green) or vasoactive intestinal peptide (VIP; a marker of SCN core neurons; G-L’; green) from 9-month-old WT littermate and PS19 transgenic mice. Confocal images were generated from 40-μm- thick sections of the central SCN. Boxed regions in D’-F’ and J’-L’ are magnified and shown in the panels to the right. The magnified images were generated from maximum-projected z-stacks of the 40-μm thick section and are provided to highlight the colocalization of phosphorylated tau in AVP- and VIP-positive neurons. SCN: suprachiasmatic nucleus; SON: supraoptic nucleus; PVN: paraventricular nucleus. Scale bar in panel F’ is 200 microns; and 10 microns in the magnified panel to the right.

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Immunofluorescence, Labeling, Marker, Transgenic Assay, Generated

Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet:

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Activity Assay

Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet: (A) Representative double plotted actograms of wheel running activity from one WT mouse and three PS19 mice at 3-4 months- and 8-9 months-of-age. Mice were entrained to a 12:12 L:D cycle and then were exposed to a 6-h phase advance. After stable re-entrainment following phase advance, mice were subjected to a 6-h phase delay. Darkened regions of the actograms denote periods when the lights were off. Relative to WT animals, PS19 mice did not exhibit significant differences in the rate of re-entrainment to either the light advancing (B) or delaying (C) paradigm. Quantification of the total days for mice to re-entrain and the average re-entrainment profiles in mice at 3-4 months- and 8-9 months-of-age. Data in B-C were collected from 8-13 mice for each genotype. No statistically significant changes were identified between the genotypes for the noted parameters at each age; Student’s t-test. Closed shapes indicate male mice (both 3-4- and 8-9-month-old) and open shapes indicate female mice (8-9-month-old).

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Activity Assay

Journal: bioRxiv

Article Title: Circadian timing and entrainment properties of the SCN pacemaker in the PS19 mouse model of tau pathology

doi: 10.1101/2025.06.06.655835

Figure Lengend Snippet: SCN explants were prepared from WT:: Per1 -Venus (WT) and PS19:: Per1 -Venus 1-day old pups and maintained in culture for several weeks on the incubator stage of a confocal microscope with Venus fluorescence acquisition occurring every hour. Baseline (Week 0) measurements were made on untreated cultures before the addition of either 1.7 µg/ml (A-C) or 7.0 µg/ml (D-F, O-P) tau PFF to the culture media. The circadian period was quantified in weekly intervals (from traces as depicted in O-P) and are plotted for individual SCN explants in A-B and D-E (open symbols indicate explants that have missing values either at the beginning or end of the acquisition). Scatterplots (C, F) of the baseline and final week period values for each tau PFF concentration depict a lack of statistically significant effect of treatment on circadian period (one-way ANOVA). Tau pathology in the PS19 explants treated with tau PFF (7.0 µg/ml) was confirmed by immunolabeling with AT8 (magenta pseudocolor) and MC1 (cyan pseudocolor) antibodies (G-H, K-L). Compared to WT, there was strong labeling with both pathologic tau antibodies, and individual cells with high levels of p-tau can be visualized. Venus immunolabeling and DRAQ5 (nuclear stain) labeling are included (I-J and M-N) for each genotype to demonstrate comparable levels of Venus expression and general explant morphology.

Article Snippet: For wheel-running and immunohistochemistry/immunofluorescence experiments, PS19 breeder pairs (B6;C3-Tg(Prnp-MAPT*P301S) PS19Vle/J Strain #008169; ) were obtained from The Jackson Laboratory (Bar Harbor, ME).

Techniques: Microscopy, Fluorescence, Concentration Assay, Immunolabeling, Labeling, Staining, Expressing