Kayser Ernst-Bernhard, Hoppel Charles L, Morgan Phil G, Sedensky Margaret M
Department of Anesthesiology, University Hospitals, Cleveland, Ohio 44106, USA.
Alcohol Clin Exp Res. 2003 Apr;27(4):584-92. doi: 10.1097/01.ALC.0000060524.62805.D2.
The gene gas-1 encodes the 49-kDa subunit of complex I of the mitochondrial electron transport chain in Caenorhabditis elegans. A mutation in gas-1 profoundly increases sensitivity to ethanol and decreases complex I-dependent metabolism in mitochondria.
Mitochondria were isolated from wild-type and gas-1 strains of C. elegans. The effects of ethanol on complex I-, II-, and III-dependent oxidative phosphorylation were measured for mitochondria from each strain. Reversibility of the effects of ethanol was determined by measuring oxidative phosphorylation after removal of mitochondria from 1.5 M ethanol. The effects of ethanol on mitochondrial structure were visualized with electron microscopy.
We found that ethanol inhibited complex I-, II-, and III-dependent oxidative phosphorylation in isolated wild-type mitochondria at concentrations that immobilize intact worms. It is important to note that the inhibitory effects of ethanol on mitochondria from either C. elegans or rat skeletal muscle were reversible even at molar concentrations. Complex I activity was lower in mitochondria from gas-1 animals than in mitochondria from wild-type animals at equal ethanol concentrations. Complex II activity was higher in gas-1 than in wild-type mitochondria at all concentrations of ethanol. No difference was seen between the strains in the sensitivity of complex III to ethanol.
The difference in ethanol sensitivities between gas-1 and wild-type nematodes results solely from altered complex I function. At the respective concentrations of ethanol that immobilize whole animals, mitochondria from each strain of worms displayed identical rates of complex I-dependent state 3 respiration. We conclude that a threshold value of complex I activity controls the transition from mobility to immobility of C. elegans.
基因gas-1编码秀丽隐杆线虫线粒体电子传递链复合体I的49 kDa亚基。gas-1中的突变会显著增加对乙醇的敏感性，并降低线粒体中复合体I依赖的代谢。
从秀丽隐杆线虫的野生型和gas-1菌株中分离出线粒体。测量乙醇对每种菌株线粒体中复合体I、II和III依赖的氧化磷酸化的影响。通过测量从1.5 M乙醇中取出线粒体后的氧化磷酸化来确定乙醇作用的可逆性。用电子显微镜观察乙醇对线粒体结构的影响。
我们发现，在使完整线虫固定的浓度下，乙醇抑制分离的野生型线粒体中复合体I、II和III依赖的氧化磷酸化。重要的是要注意，即使在摩尔浓度下，乙醇对秀丽隐杆线虫或大鼠骨骼肌线粒体的抑制作用也是可逆的。在相同乙醇浓度下，gas-1动物的线粒体中复合体I的活性低于野生型动物的线粒体。在所有乙醇浓度下，gas-1中线粒体复合体II的活性均高于野生型。在复合体III对乙醇的敏感性方面，两种菌株之间没有差异。
gas-1和野生型线虫对乙醇敏感性的差异完全是由复合体I功能改变所致。在使整个动物固定的各自乙醇浓度下，每种线虫菌株的线粒体显示出相同的复合体I依赖的状态3呼吸速率。我们得出结论，复合体I活性的阈值控制着秀丽隐杆线虫从活动到静止的转变。
