Qualitative modification of muscle metabolic organization with thermal acclimation of rainbow trout,Oncorhynchus mykiss

Rainbow trout (Oncorhynchus mykiss) were acclimated to 4 and 18°C and fed at rations levels which led to an equal change in mass at these temperatures during the six week acclimation. Thermal acclimation markedly modified the metabolic organization of red and white muscle. Cold-acclimated fish had activities of -hydroxyacyl CoA dehydrogenase in both red and white muscle that were twice those of warm-acclimated fish. By contrast, the activities of cytochrome oxidase were unchanged by thermal acclimation. Thus, the capacity for -oxidation of lipids is specifically enhanced in the muscle of cold-acclimated trout. In white muscle, citrate synthase and phosphofructokinase activities were also enhanced by cold acclimation (increases of 125% and 35% respectively), while cytochrome oxidase levels were unchanged. The non-parallel changes in the activities of mitochondrial enzymes strongly suggest that trout muscle mitochondria undergo qualitative reorganization during cold acclimation. The relative activities of mitochondrial enzymes suggest that mitochondria from red muscle have a threefold greater capacity to oxidize lipids than those from white muscle.     

Body growth, mitochondrial enzymatic capacities and aspects of the antioxidant system and redox balance under calorie restriction in young turbot (Scophthalmus maximus, L.)

Calorie restriction (CR) without undernutrition has been found to enhance stress resistance and life span in endotherms and ectotherms. We investigated the effect of 30% reduction in food offering on growth, aerobic capacities and oxidative stress parameters in young turbot (Scophthalmus maximus, L.). No differences in body weight, length and hepatosomatic index between the ad libitum (AL)-fed and the CR group occurred after 55 days of diet application. Of the mitochondrial marker enzymes, only citrate synthase (CS) activity in the liver was reduced under CR, whereas muscle CS activity and cytochrome oxidase (CCO) activity in both tissues remained the same in both feeding groups. The concentration of reduced glutathione increased significantly during feeding in muscle of CR fish, resulting in a more reduced glutathione redox ratio (GSH/GSSG) compared with AL fish muscle. Thiobarbituric acid-reactive lipid hydroperoxides (lipid peroxidation) but not protein carbonyl content (protein oxidation) was significantly reduced in CR fish muscle. Liver oxidative stress parameters did not vary significantly between experimental feeding groups. We conclude that 30% CR over 8 weeks has no adverse effect on young turbot. On the contrary, CR supports a reduced tissue oxidation state and reduces accumulation of lipid peroxidation products in muscle at sustained muscular aerobic capacity.     

Changes in mitochondrial fatty acid composition following temperature acclimation of carp and their possible effects on FoF1-ATPase activity

Carp undergo temperature acclimation of respiratory function by altering mitochondrial ATP synthase (F_oF₁-ATPase) both quantitatively and qualitatively (Itoi et al. 2003). To address such acclimation temperature-dependent changes of F_oF₁-ATPase activity, we investigated in this study the correlation between the fatty acid composition and F_oF₁-ATPase activity in fast muscle of thermally acclimated carp. The quantities of saturated fatty acids of mitochondria from carp acclimated to 10 °C were significantly lower than those of carp acclimated to 30 °C. While mono- and poly-unsaturated fatty acids tended to increase with cold acclimation of carp, the molar concentration of 16:0 aldehyde in mitochondria from the 10 °C-acclimated carp were less than those from the 30 °C-acclimated fish. The specific activities of F_oF₁-ATPase in the 10 °C- and 30 °C-acclimated fish mitochondria were calculated to be 167±22 and 56±10 nmol/min ⋅ mg mitochondrial protein, respectively, the difference being significant at P<0.005. Taken together, the increase in F_oF₁-ATPase activity in fast muscle mitochondria of carp after cold temperature acclimation may be closely related to the increase of unsaturated fatty acids in mitochondria. Abbreviations: BSA - bovine serum albumin; DHA - docosahexaenoic acid; EGTA - ethyleneglycol bis(2-aminoethylether)tetraacetic acid; EPA - eicosapentaenoic acid; F_oF₁-ATPase - mitochondrial ATP synthase; α-F₁-ATPase - F_oF₁-ATPase α-subunit; β-F₁-ATPase - F_oF₁-ATPase β-subunit; HEPES - 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid; SDS - sodium dodecyl sulfate; SDS-PAGE - SDS-polyacrylamide gel electrophoresis. This revised version was published online in July 2006 with corrections to the Cover Date.     

安徽3株柔嫩艾美耳球虫cox1基因部分序列的比对分析

为研究柔嫩艾美耳球虫不同地理株的线粒体细胞色素c氧化酶第1亚基(cox1)基因与球虫种群之间的遗传关系,以安徽3个地区的3株柔嫩艾美耳球虫为研究对象,通过卵囊的分离与纯化获得纯种虫株,然后应用PCR技术对柔嫩艾美球虫3个地理株的cox1序列进行扩增,并与GenBank上登录的鸡柔嫩艾美耳球虫、巨型艾美耳球虫、布氏艾美耳球虫和堆形艾美耳球虫虫株的相应序列进行比对分析。结果显示,每个虫株都成功扩增出800 bp左右的cox1部分有效序列(pcox1),与柔嫩艾美耳球虫pcox1序列种内无差异,pcox1相应序列种间的差异程度为9.9%～14.9%。表明柔嫩艾美耳球虫的cox1序列可作为艾美耳球虫种间遗传变异研究的标记,为进一步研究艾美耳球虫的群体遗传学特性和耐药性奠定了基础。     

零下低温对小麦线粒体呼吸功能的影响

用氧电极法测定了两个品种小麦线粒体有关呼吸功能的3项指标,研究其冻害问题。结果表明,-15℃低温促进了线粒体呼吸状态4耗氧量的增大,对呼吸控制率(呼吸状态3与呼吸状态4的比值)和磷氧比却有降低作用,NaCl更加剧了零下低温(-15℃)对线粒体的伤害。零上低温(2℃)锻炼有削弱或减缓线粒体冻害的作用。小麦品种之间对-15℃低温或NaCl的反应有差异。说明线粒体膜是冻害的位点之一,膜结构和功能是一致的,线粒体能量代谢失调可能是冻害的部分原因。     

怒江裂腹鱼鳃的显微和超微结构

通过光镜、扫描电镜及透射电镜技术,研究了怒江裂腹鱼(Schizothorax nukiangensis)鳃的组织结构和超微结构。结果表明,怒江裂腹鱼鳃基本结构与其他硬骨鱼相似,均由鳃耙、鳃弓、鳃丝以及鳃小片构成,且各部分具有不同的组织结构和细胞类型。扁平上皮细胞覆盖于整个鳃表面,其表面的纹路主要有3种类型,在鳃上不同的部位具有不同的结构和功能。线粒体密集细胞主要分布于鳃小片基部,仅有一种细胞类型,顶端膜内凹呈浅滩型,细胞内具有大量圆形的线粒体。怒江裂腹鱼鳃内扁平上皮细胞和线粒体密集细胞的形态结构与其在急流中游泳和摄食活动等生活习性相适应。本研究结果丰富了怒江裂腹鱼的基础生物学资料,并为阐明鱼类鳃的结构特征与其生活习性之间的关系提供参考。     

飞行前后意大利蝗飞行肌及 能源消耗比较

意大利蝗(Calliptamus italicus)具有长距离迁飞行为,并常给迁入区造成严重损失。若要提高对其监测预警和防控水平,就需要掌握其飞行肌结构特征,分析其体内能源物质积累与飞行消耗的动态,因此本研究比较了意大利蝗吊飞前后飞行肌肌节长度、肌原纤维直径和线粒体含量差异及飞行不同距离虫体内糖原和甘油酯含量变化。结果表明,吊飞组与未吊飞对照组雌虫之间、雄虫之间线粒体含量均差异显著(P0.05)。意大利蝗雌成虫飞行超过2.8km后糖原消耗最多,为11.15mg·g~(-1),雄虫飞行2.1~2.8km时消耗最多,为16.10mg·g~(-1)。雌、雄成虫均在飞行距离大于2.8km后甘油酯消耗最多,分别为61.69和69.75mg·g~(-1)。意大利蝗飞行同时消耗糖类和脂肪两类能源物质,且雌雄成虫分别飞行超过2.8km和2.1~2.8km时糖原利用效率最大,飞行超过2.8km后甘油酯利用效率最大。本研究得出吊飞组个体能改变自身的飞行肌结构来适应飞行活动;且飞行过程中意大利蝗能同时利用糖类与脂类,糖类能快速产生能量以供起飞与短距离飞行,随后主要消耗甘油酯供长距离飞行。     

针刺大椎、人中、百会穴对脑缺血再灌注损伤大鼠脑线粒体超微结构的影响

目的 观察针刺大椎、人中、百会穴对脑缺血再灌注后大鼠脑线粒体超微结构的影响,探讨针刺对脑缺血再灌注损伤的部分作用机制。方法 40只大鼠随机挑选10只为假手术组,其余30只大鼠造模后随机分为模型组、针刺对照点组、针刺穴位组3组,每组10只。大鼠造模成功后,模型组、假手术组只捆绑不针刺,针刺穴位组针刺大椎、人中、百会三穴,针刺对照点组针刺针刺穴位左侧旁开0.3 cm处,每12小时针刺1次,6次治疗后处死大鼠,取缺血海马组织电镜下观察线粒体超微结构。结果 治疗后,除假手术组外其余各组大鼠神经功能缺损评分均下降（P<0.05）;与模型组比较,针刺穴位组和针刺对照点组均下降更明显（P<0.05）。电镜观察结果显示,假手术组线粒体结构正常;模型组线粒体肿胀明显,嵴断裂,空泡结构明显;针刺对照点组线粒体肿胀,可见嵴断裂,少量空泡结构;针刺穴位组线粒体稍肿胀,嵴断裂及空泡化不明显。结论 针刺能减轻脑缺血再灌注损伤,其机制可能与改变缺血再灌注局灶的线粒体超微结构损伤有关。     

动物产品中猪源性和牛源性成分双重荧光PCR检测方法的建立

[目的]建立双重荧光PCR法,检测动物产品中猪、牛源性成分。[方法]分别针对猪、牛线粒体DNA（mitochondrial DNA,mtDNA）种间保守基因,设计特异性引物与探针,通过对反应体系和反应条件的优化筛选,建立了双重荧光PCR方法,在同一个荧光PCR反应中完成2种动物源性成分的检测。并对该方法的特异性、敏感性进行评估。[结果]对16种不同的动物DNA进行检测．仅猪、牛源性成分收集到相应的典型的S型扩增曲线,对猪、牛二联模板的检测,可同时收集到相应模板的扩增曲线．其余14种动物源性成分未发现扩增曲线。双重荧光PCR对猪肉、牛肉模板的最低检出限均为10^-5,与相应的单重荧光PCR方法的检出限一致。[结论]该方法特异性强,敏感性高,适用于肉制品、奶制品、饲料等动物源性产品的检测。     

Three-dimensional structural analysis of mitochondria composing each subtype of fast-twitch muscle fibers in chicken

In a previous study, the three-dimensional structures of mitochondria in type I and type IIb muscle fibers of chicken were analyzed. The study reported differences in the shape of the mitochondria and the distribution of lipid droplets. In this study, we three-dimensionally analyzed mitochondria and lipid droplets of type II muscle fiber subtypes IIa, IIb, and IIc of chicken lateral iliotibial muscle in the same field of view using correlative light electron microscopy (CLEM) and array tomography methods. The reconstructed images showed that the mitochondria of type IIa muscle fiber were thick and aligned along the myofibrils, and many lipid droplets were embedded in the mitochondria. The mitochondria of type IIb muscle fibers were intermittent, aligned along the myofibrils, and showed contact between adjacent horizontal mitochondria. No lipid droplets were observed in type IIb muscle fiber. In type IIc muscle fiber, we observed irregularly shaped mitochondria with small diameters aligned along the myofibrils. Lipid droplets not only were embedded in the mitochondria but also existed independently in some cases. The combination of array tomography and CLEM methods enabled three-dimensional electron microscopic observation of mitochondria in different subtypes of type II muscle fibers. The subtypes of type II muscle fibers differed in mitochondrial occupancy and morphology and in lipid droplet distribution, and characteristics that had been demonstrated biochemically were also demonstrated ultrastructurally.