Western blot analysis of FMRP protein expression in homozygous B-Fmr1 KO mice. Various tissue lysates were collected from wild-type C57BL/6 mice (+/+) and homozygous B-Fmr1 KO mice (-/Y), and then analyzed by western blot with anti-FMRP antibody. 40 μg total proteins were loaded for western blotting analysis. FMRP was not detectable in homozygous B-Fmr1 KO mice.

B-Fmr1 KO mice exhibit social deficits in the three-chamber social test. A, Time spent interacting with stranger mouse is significantly reduced in B-Fmr1 KO mice, indicating impaired sociability. B, Social preference index is markedly decreased in B-Fmr1 KO mice compared to wild-type controls. Data were represented as mean ± SEM. Statistical analysis was performed using two-way ANOVA (A) or unpaired t-test (B). * P < 0.05, ** P< 0.01.

B-Fmr1 KO mice exhibit anxiety and repetitive behavior in the Marble-burying test. The number of marbles buried is significantly increased in B-Fmr1 KO mice compared to wild-type controls mice, indicating anxiety and repetitive behavior. Data were represented as mean ± SEM. Statistical analysis was performed using unpaired t-test. ** P< 0.01.

B-Fmr1 KO mice show significant hyperactivity in the open field test. B-Fmr1 KO mice travelled a significantly longer distance than C57BL/6 mice (A) and spent more time in the center of the open field (C), where they entered more rapidly (B). Data presented as mean ± SEM. Statistical analysis was performed using unpaired t-test. ***P < 0.001.