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Fig. 1 Necdin deficiency impaired heart function (A) Representative M-mode images (upper: wild-type mouse; lower: necdin KO mouse). Double-headed arrows mark left ventricle systolic and diastolic internal diameters (LVIDs and LVIDd), respectively. (B?D) Quantification of echocardiograms: ejection fraction (B), fraction shortening (C), and heart rate (D). Data are presented as means ± SEM; WT: n = 14; KO: n = 11; ?p < 0.05, ??p < 0.01, unpaired t test. (E?H) Echocardiographic image acquisition and speckle-tracking analysis. (E) Representative long-axis B-mode images of left ventricle during diastole and systole period in WT or KO mice. The tracking trace was overlaid on the images showing in the right panels. (F) The global longitudinal strain (GLS) and global longitudinal strain rates (GLSR) in 3 pairs of 4 months male mice. (G) Representative short-axis B-mode images of left ventricle during diastole and systole period in WT or KO mice. The tracking trace was overlaid on the images showing in the right panels. (H) The global circumferential strain (GCS) and GCS rates in 3 pairs of 4 months male mice. Data are presented as means ± SEM; ?p < 0.05, unpaired t test. (I) Representative contraction of cardiac myocytes from WT and KO mice at 4 months of age. (J?L) Quantification of cardiac myocyte contraction: amplitude of contraction (J), maximal velocity of re-lengthening (K), and maximal velocity of shortening (L). Data are presented as means ± SEM, WT: n = 24; KO: n = 24; ?p < 0.05, ??p < 0.01 and ???p < 0.001, unpaired t test. (M) Representative gross anatomy from a WT and a KO mouse at 4 months of age. Statistical data are shown as means ± SEM, WT: n = 6; KO: n = 6; ns: no significant difference, unpaired t test. (N) Cardiomyocyte cross-sectional area (using wheat-germ-agglutinin staining) from WT and KO mice at 4 months. Statistical data are shown as means ± SEM, WT: n = 6; KO: n = 6; ns: no significant difference, unpaired t test. Scale bars: 50 ?m.