Fig. 6
Pathophysiological characterization of RFC5 and NOA1 mutants in Normande and Montbeliarde cattle, respectively. a WebLogo representation of multiple protein alignments showing perfect conservation of the glutamic acid residue at position 369 amino acids in bovine among 633 eukaryotic RFC5 orthologs (Additional file 1: Table S28). b Detail of the shoulder and base of the neck of a homozygous mutant heifer showing a thin and wavy hair coat. c, d Images of the same animal showing alopecia of the ears, the top of the snout, extremities of the limbs, and tail. Skin sections of shoulder skin samples from wild-type (e) and RFC5 homozygous mutant (f) 1.5-year-old heifers stained with a Roan solution. Scale bars = 200 µM. g Analysis of shoulder skin sections from 4 cases and 4 control heifers for hair density in a randomly selected square of 1 mm2, and median size of 50 adjacent pilary canals (Additional file 1: Table S29). h Analysis of birth weight for the three genotypes at the RFC5 deletion (Additional file 1: Table S30). i Schematic representation of the bovine NOA1 protein (Ensembl ID: ENSBTAP00000025792, 731 aa). If expressed, the p.D400RfsX9 frameshifted bovine protein would lack half of the P-loop containing nucleoside triphosphate hydrolase domain (P-loop) and a conserved C-terminal region, the deletion of which causes impaired mitochondrial import of NOA1 in cultured mouse myoblasts [69]. j Percentage of natural deaths by trimester for 145 thousand females genotyped for the NOA1 frameshift variant. Note that only the first 2 years of a 6-year study are shown (Additional file 1: Table S35). k Wild-type (left) and NOA1 homozygous mutant (right) 4.5-month-old heifers. l Relative changes in mitochondrial-to-nuclear (Mt/Nu) DNA ratio in heart samples determined by qPCR (Additional file 1: Tables S37 and S38). Transmission electron microscopy images of myocardial samples from wild-type (m) and NOA1 homozygous mutant (n) 4-month-old heifers. Scale bars = 1 µM. S, sarcomere, the basic unit of myofibrils; M, mitochondria; LM, lysed mitochondria. Note the presence of empty spaces between myofibrils due to increased mitochondrial cell death in (n). ** and ***: Student t-test p value ≤ 0.01 and ≤ 0.001, respectively. 0, 1, and 2: wild-type, heterozygous, and homozygous genotypes for the RFC5 inframe deletion or NOA1 frameshift insertion, respectively