Fig. 1: The Xm chromosome impairs spatial memory in young female mice.
From: The maternal X chromosome affects cognition and brain ageing in female mice
a, Random X-chromosome inactivation in wild-type, non-transgenic mice (Xm+Xp) leads to cells with either an active Xp or active Xm chromosome. In transgenic mice with Xm skew, all cells show only an active Xm. Diagram of the mouse in a is adapted from Nadzeya Shanchuk/Shutterstock (https://www.shutterstock.com/). b, Experimental timeline of experiments conducted over the lifespan. c, Diagram of mice being tested for cognition at young, middle-aged and old life stages. Diagram of the mouse and brain in c are adapted from Nadzeya Shanchuk/Shutterstock and KwangSoo Kim/Shutterstock (https://www.shutterstock.com/), respectively. d, Schematic of the Morris water maze experiment; mice were 4–8 months old. e, Spatial learning in the hidden trials, measured by the distance travelled to find the platform, did not differ between the groups (two-way mixed-model analysis of variance (ANOVA)). (Xm+Xp mice: n = 9; Xm mice: n = 15). f, Probe trials show that Xm skew impaired memory 24 h and 48 h after hidden training. Two-way ANOVA: genotype, *P = 0.0108. Bonferroni-corrected unpaired two-tailed t-test 24 h: P = 0.1092; 48 h: P = 0.1609 (Xm+Xp mice: n = 9; Xm mice: n = 15). g, Schematic of the EPM experiment, which is used for testing anxiety-like behaviour in young mice (age: 4–8 months). h, Anxiety-like behaviour, measured as the percentage of time spent in the open arm, did not differ between groups at either 5 or 10 min (Xm+Xp mice: n = 11; Xm mice: n = 18). i, Total distance travelled in the EPM did not differ between groups at either 5 or 10 min (Xm+Xp mice: n = 11; Xm mice: n = 18). Each open symbol (f,h,i) represents an individual mouse. Data represent mean ± s.e.m.
