College of Livestock Husbandry and Veterinary Engineering, Henan Agricultural University, No. 15 Longzi Lake University Campus, Zhengzhou, 450046, P.R. China.
Sci Rep. 2020 Feb 24;10(1):3240. doi: 10.1038/s41598-020-60123-1.
Mitochondrial DNA (mtDNA) copy number reflects the abundance of mitochondria in cells and is dependent on the energy requirements of tissues. We hypothesized that the mtDNA copy number in poultry may change with age and tissue, and feed restriction may affect the growth and health of poultry by changing mtDNA content in a tissue-specific pattern. TaqMan real-time PCR was used to quantify mtDNA copy number using three different segments of the mitochondrial genome (D-loop, ATP6, and ND6) relative to the nuclear single-copy preproglucagon gene (GCG). The effect of sex, age, and dietary restriction (quantitative, energy, and protein restriction) on mtDNA copy number variation in the tissues of broilers was investigated. We found that mtDNA copy number varied among tissues (P < 0.01) and presented a distinct change in spatiotemporal pattern. After hatching, the number of mtDNA copies significantly decreased with age in the liver and increased in muscle tissues, including heart, pectoralis, and leg muscles. Newborn broilers (unfed) and embryos (E 11 and E 17) had similar mtDNA contents in muscle tissues. Among 42 d broilers, females had a higher mtDNA copy number than males in the tissues examined. Feed restriction (8-21 d) significantly reduced the body weight but did not significantly change the mtDNA copy number of 21 d broilers. After three weeks of compensatory growth (22-42 d), only the body weight of broilers with a quantitatively restricted diet remained significantly lower than that of broilers in the control group (P < 0.05), while any type of early feed restriction significantly reduced the mtDNA copy number in muscle tissues of 42 d broilers. In summary, the mtDNA copy number of broilers was regulated in a tissue- and age-specific manner. A similar pattern of spatiotemporal change in response to early feed restriction was found in the mtDNA content of muscle tissues, including cardiac and skeletal muscle, whereas liver mtDNA content changed differently with age and dietary restriction. It seems that early restrictions in feed could effectively lower the mtDNA content in muscle cells to reduce the tissue overload in broilers at 42 d to some degree.
线粒体 DNA（mtDNA）拷贝数反映了细胞中线粒体的丰度，并且依赖于组织的能量需求。我们假设家禽的 mtDNA 拷贝数可能会随着年龄和组织的变化而变化，并且通过以组织特异性的方式改变 mtDNA 含量，饲料限制可能会影响家禽的生长和健康。使用三个不同的线粒体基因组片段（D 环、ATP6 和 ND6）相对于核单拷贝前胰高血糖素基因（GCG），TaqMan 实时 PCR 用于定量 mtDNA 拷贝数。研究了性别、年龄和饮食限制（定量、能量和蛋白质限制）对肉鸡组织中 mtDNA 拷贝数变化的影响。我们发现 mtDNA 拷贝数在组织间存在差异（P<0.01），并且呈现出明显的时空变化模式。孵化后，肝脏中的 mtDNA 拷贝数随着年龄的增长而显著减少，而肌肉组织中的心脏、胸肌和腿部肌肉中的 mtDNA 拷贝数增加。新生肉鸡（未喂食）和胚胎（E11 和 E17）在肌肉组织中具有相似的 mtDNA 含量。在 42 日龄肉鸡中，雌性组织中的 mtDNA 拷贝数高于雄性。饲料限制（8-21 日龄）显著降低了体重，但对 21 日龄肉鸡的 mtDNA 拷贝数没有显著影响。经过三周的补偿性生长（22-42 日龄），只有定量饮食限制的肉鸡体重仍然明显低于对照组（P<0.05），而早期任何类型的饲料限制都显著降低了 42 日龄肉鸡肌肉组织中的 mtDNA 拷贝数。总之，肉鸡的 mtDNA 拷贝数以组织和年龄特异性的方式受到调节。在肌肉组织（包括心脏和骨骼肌）的 mtDNA 含量中发现了一种对早期饲料限制的时空变化的类似模式，而肝脏 mtDNA 含量随年龄和饮食限制而变化不同。似乎早期限制饲料可以有效地降低肌肉细胞中的 mtDNA 含量，从而在一定程度上降低 42 日龄肉鸡的组织过载。
