Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583-0908, USA.
J Anim Sci. 2013 May;91(5):2077-82. doi: 10.2527/jas.2012-5975. Epub 2013 Mar 5.
Selection was practiced for high (MH) and low (ML) heat loss using direct calorimetry to create lines of mice differing in feed intake per unit average BW (FI/BW). A total of 25 generations of selection was practiced during maintenance of an unselected control (MC). As a percentage of MC, mice of MH and ML lines differed in heat loss and FI/BW by 56 and 34%, respectively, when selection ceased. The purpose of this study was to determine hepatic mitochondrial efficiency in mice at maintenance across the genetic lines. After measurement of feed intakeand BW over a 2-wk period, mice were euthanized, and their livers were extracted. Livers were homogenized and mitochondria were isolated in buffer for measurement of oxygen consumption and, hence, mitochondrial activity using a Clark-type oxygen electrode. Mitochondria of ML mice expressed greater (P < 0.03) respiratory control ratio by 22% than that for MH mice, revealing greater degree of uncoupling during electron transport in MH mice. Difference in FI/BW (P < 0.001) was large with MH mice consuming 34% more than ML mice. The respiratory control ratio differed between mice of MH and ML lines as expected; however, regression analysis revealed that it explained essentially no variation in feed intake per BW.
选择是通过直接量热法进行的，以高（MH）和低（ML）热量损失为目标，从而创建了不同饲料摄入量与平均体重（FI/BW）的小鼠品系。在未选择的对照（MC）的维持过程中，进行了总共 25 代的选择。当选择停止时，MH 和 ML 品系的小鼠在热量损失和 FI/BW 方面分别与 MC 相比差异了 56%和 34%。本研究的目的是确定在遗传品系中维持时小鼠肝脏线粒体的效率。在 2 周的时间内测量饲料摄入量和体重后，将小鼠安乐死，并提取其肝脏。将肝脏匀浆并在缓冲液中分离线粒体，以使用克拉克型氧电极测量耗氧量，从而测量线粒体活性。ML 小鼠的线粒体表现出更高的呼吸控制比（P < 0.03），高出 22%，表明 MH 小鼠在电子传递过程中解偶联程度更高。FI/BW 差异（P < 0.001）很大，MH 小鼠比 ML 小鼠多消耗 34%。正如预期的那样，MH 和 ML 品系的小鼠之间的呼吸控制比存在差异；然而，回归分析表明，它基本上不能解释 BW 每单位饲料摄入量的变化。
