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. 2024 Feb 9;27(3):109157. doi: 10.1016/j.isci.2024.109157

Figure 1.

Figure 1

Myocyte and mitochondrial morphology and biogenesis during cardiac development

(A) Graphical representation of work flow with silhouettes of hearts at various ages. Birth is marked in red on the timeline.

(B) Representative electron micrographs of E9.5, P1, and Adult (A) WT cardiac myocytes.

(C–J) Morphometry was performed using low- and high-powered electron micrographs, a tablet to outline cellular structures, and Fiji/ImageJ. Shape descriptors were copied into Excel spreadsheets and data was compiled for statistical analysis. Myocyte morphometry from electron micrographs shows changes in cell size (C), contractile apparatus area (D) and mitochondrial area (E) as a percentage of cell area, and mitochondrial number per cell (F) at each age and genotype (WT, CypD KO). Morphometry of individual mitochondria shows changes in mitochondrial area (G) and form factor (H) during development. Plot of mitochondria subgroups (% of total mitochondrial number/cell (D)) in WT (I) and CypD KO (J) mitochondria (C-cytoplasmic, IM-intermyofibrillar, PN-perinuclear, SS-subsarcolemmal).

(K) Mitochondrial to nuclear (mt/nuc) DNA ratio of WT and CypD KO hearts at different ages using primers to mt-CO1 and 18s rRNA for qPCR.

(L) Expression of the voltage-dependent anion channel (VDAC) in homogenates from hearts at each age and genotype analyzed by densitometry of denaturing immunoblots normalized to protein loading (A.U., arbitrary units). Data presented as Mean ± SEM and analyzed by one-way ANOVA with Sidak’s multiple comparison test (C-F, I-L) or Median +/− interquartile (IQ) range and Kruskal-Wallis with Dunn’s multiple comparison test (G, H) to compare data between WT and CypD KO cells at each age (red stars, C-H, K, L) and for differences between successive ages of the same genotype (black stars/bar, K). Only significant differences noted, ∗p <0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001; N: C-F, I, J = 9 cells or 18 cells for E11.5 and E13.5, G-H presented in G above the X axis, K = 3–6, L = 3. See also Figures S1–S6.