Symmorphosis and livestock bioenergetics: production animal muscle has low mitochondrial volume fractions

A comparative analysis of skeletal muscle structure reveals that production species (nine species, representing three mammalian families and an avian family) have mitochondrial volume fractions (MVF) 37% lower than the non‐production species at equivalent size (17 species, with representatives from 10 mammalian families) ( Fig. 1 ; F_1,25 = 4.79; p = 0.039). As MVF provides evidence of oxidative capacity, this comparative analysis indicates that production animals share an exceptionally low oxidative capacity muscle phenotype. A possible bioenergetic reason for this observation, relating to a reduction in the cost of maintaining trans‐membrane ion gradients is briefly discussed. This discussion is framed within a biological economic design theory called symmorphosis and makes predictions about avenues for improvements in livestock bioenergetics.

Figure 1 Open in figure viewer PowerPoint The scaling of log skeletal muscle mitochondrial volume density (MVF) with log endotherm size. Production species (PS) (red circles, red line) have a 37% lower MVF than non‐production species (NPS) (blue circles, blue line). NPS log MVF = ?0.11 log M_b + 0.88 (r² = 0.48, n = 17). PS log MVF = ?0.11 log M_b + 0.74 (r² = 0.69, n = 9).     

线粒体融合、分裂及其相关疾病的研究进展

近年来,有关线粒体融合和分裂机制的相关研究越来越多。线粒体是所有真核生物都不可或缺的双层膜细胞器,大多数细胞中线粒体是高度动态的,且通过不断地融合、分裂来维持动态平衡。线粒体外膜与内膜的融合分别由Mfn1、Mfn2与多种形式的OPA1调控;DRP1介导外膜分裂,内膜的分裂可能是由S-OPA1和MTP18介导。多种客观因素通过影响融合或分裂的程度,进而影响线粒体的融合与分裂,提高线粒体融合程度或降低线粒体分裂程度都将导致在细胞内形成个体大、数量少的线粒体;反之,将出现个体小、数量多的线粒体。可以据此特性间接检测某项影响线粒体形态学变化的因素,了解线粒体动态变化所涉及的蛋白,以及影响线粒体形态学的重要外部因素、线粒体相关疾病的发病原因。因此,作者在总结前人研究成果的基础上,针对线粒体融合与分裂、参与线粒体融合与分裂的相关蛋白及线粒体融合、分裂与疾病的发生进行了综述。     

Liver mitochondrial oxygen consumption and proton leak kinetics in broilers supplemented with dietary copper or zinc following coccidiosis challenge

Mitochondrial respiration was assessed in sixteen 7‐day‐old broilers as a subset of a larger study assessing the effects of Cu and Zn supplementation above requirements with a coccidiosis challenge on gain/feed ratio. The birds were selected from four treatments (four birds/treatment): a control diet (Cu 15 mg/kg and Zn 60 mg/kg) + coccidiosis challenge (CC), a Cu diet with 245 mg/kg Cu from tribasic copper chloride (TBCC) + CC, a negative control diet (Cu 15 mg/kg and Zn 60 mg/kg) ‐ CC and a Zn diet with 2000 mg/kg Zn from ZnO. The diets were composed of 49% corn, 40% soybean meal, 6.2% vegetable oil (diet dry matter = 90.62%, crude protein = 21.37%, fat = 7.7%, metabolizable energy = 12.1 MJ/day) and were fed for 14 days. Birds were dissected, and approximately one gram of liver tissue was used for mitochondrial oxygen consumption and proton leak kinetics assays. Respiratory control ratio and mitochondrial proton leak assessed by calculating rates of oxygen consumption at 175mV membrane potential were greater for the negative control group, but there were no differences in average gain/feed among treatments. In summary, broilers that did not undergo coccidiosis challenge had lower proton leak and higher respiratory control ratio. However, the impact of supplementation of Cu and Zn above requirements did not appear to prevent changes in respiratory control ratio and proton leak kinetics with coccidiosis challenge.     

植物线粒体结构基因组研究进展

植物线粒体基因组具有复杂的结构特征:基因组200~2 400 kb不等,变化大、重组频繁,存在水平基因迁移现象等。基因组中既含有非常保守的功能基因,也存在高度变异的基因间区序列。大量研究表明,线粒体基因组是植物细胞质雄性不育因子的载体。综述了近年来植物线粒基因组结构特征、基因组成和热点研究的进展,为进一步深入研究植物细胞质雄性不育的分子机理,并为胞质雄性不育三系杂交种选育、作物杂种优势利用提供理论指导。     

甘草不同时期愈伤组织细胞形态与线粒体变化的研究

此实验为甘草愈伤组织继代培养和进一步研究提供方法依据。以乌拉尔甘草不同来源愈伤组织为材料,采用石蜡切片法观察了不同时期甘草愈伤组织细胞大小变化;采用悬滴法观察了不同时期甘草愈伤组织线粒体形态、大小变化。试验结果表明：愈伤组织细胞大小受外植体来源影响显著（P<0.05）,芽来源愈伤组织细胞大小（均值31.40 μm）大于叶来源愈伤组织细胞大小（均值29.41 μm）且大于根来源愈伤组织细胞大小（均值25.67 μm）;愈伤组织细胞大小受培养时期影响极显著（P<0.01）,培养到30天时细胞达最大,均值为37.45 μm,之后到40天时,细胞平均减小到29.55 μm。芽和叶来源愈伤组织细胞内的哑铃状线粒体数目高于根来源愈伤组织细胞内的哑铃状线粒体数目。愈伤组织细胞线粒体大小与外植体来源及培养时期有显著交互作用（P<0.05）,根来源愈伤组织在培养30天时线粒体长度均值最大,达2.60 μm。芽来源愈伤组织在培养40天时线粒体长度均值最大,达2.07 μm。叶来源愈伤组织在细胞培养40天时线粒体长度均值最大,达2.01 μm;培养时期对愈伤组织细胞线粒体大小影响极显著（P<0.01）,培养到30天时细胞最大,均值为2.06 μm。此研究结果,为甘草愈伤组织继代培养奠定了基础,同时为甘草脱分化及再分化调控提供细胞学方面的依据。     

Low expression of mitofusin 1 is associated with mitochondrial dysfunction and apoptosis in porcine somatic cell nuclear transfer embryos

Mitochondria are necessary for the transition from oocyte to embryo and for early embryonic development. Mitofusin 1 is the main mediator of mitochondrial fusion and homeostasis. We investigated Mitofusin 1 expression levels in porcine somatic cell nuclear transfer (SCNT) embryos. The rate of blastocyst formation in SCNT embryos was reduced significantly compared with that of parthenogenetic activation embryos. SCNT embryos showed significantly decreased Mitofusin 1 expression and mitochondrial membrane potential, while exhibiting increased reactive oxygen species and apoptosis. Mitochondrial functional changes were observed in the SCNT embryos and may be correlated with low levels of Mitofusin 1 to negatively affect development.     

环境化学污染物对线粒体呼吸链系统作用机制的研究进展

环境化学污染物严重威胁人类健康，目前对其毒性作用机制研究已逐步深入到细胞器和分子水平。线粒体作为细胞“动力站”，其呼吸链系统是许多外源性物质的优先作用靶标。初步探讨了环境化学污染物对线粒体呼吸链系统的几种作用机制及其相互之间的联系，并在总结国内外研究的基础上，提出了今后相关研究的内容和方向。     

Cracking the Cytotoxicity Code: Apoptotic Induction of 10-Acetylirciformonin B is Mediated through ROS Generation and Mitochondrial Dysfunction

A marine furanoterpenoid derivative, 10-acetylirciformonin B (10AB), was found to inhibit the proliferation of leukemia, hepatoma, and colon cancer cell lines, with selective and significant potency against leukemia cells. It induced DNA damage and apoptosis in leukemia HL 60 cells. To fully understand the mechanism behind the 10AB apoptotic induction against HL 60 cells, we extended our previous findings and further explored the precise molecular targets of 10AB. We found that the use of 10AB increased apoptosis by 8.9%–87.6% and caused disruption of mitochondrial membrane potential (MMP) by 15.2%–95.2% in a dose-dependent manner, as demonstrated by annexin-V/PI and JC-1 staining assays, respectively. Moreover, our findings indicated that the pretreatment of HL 60 cells with N-acetyl-l-cysteine (NAC), a reactive oxygen species (ROS) scavenger, diminished MMP disruption and apoptosis induced by 10AB, suggesting that ROS overproduction plays a crucial rule in the cytotoxic activity of 10AB. The results of a cell-free system assay indicated that 10AB could act as a topoisomerase catalytic inhibitor through the inhibition of topoisomerase IIα. On the protein level, the expression of the anti-apoptotic proteins Bcl-xL and Bcl-2, caspase inhibitors XIAP and survivin, as well as hexokinase II were inhibited by the use of 10AB. On the other hand, the expression of the pro-apoptotic protein Bax was increased after 10AB treatment. Taken together, our results suggest that 10AB-induced apoptosis is mediated through the overproduction of ROS and the disruption of mitochondrial metabolism.     

干旱胁迫对银沙槐幼苗叶绿体和线粒体超微结构及膜脂过氧化的影响

以沙生植物银沙槐(Ammodendron argenteum)幼苗为实验材料,利用透射电镜技术,结合丙二醛(MDA)和细胞膜透性的测定,观察干旱胁迫对银沙槐子叶期幼苗的叶肉细胞及下胚轴细胞超微结构的变化,分析干旱胁迫对银沙槐幼苗细胞超微结构和膜脂过氧化的影响。结果显示:随着干旱胁迫的加剧,叶绿体变形、外被膜波浪状、断裂不完整。同时,基粒和基质类囊体膜结构模糊,基粒弯曲、膨胀、排列混乱;线粒体膜完整性低、内部嵴消失、空泡化。细胞膜透性和膜脂过氧化产物MDA含量均升高,显著高于对照(P0.05),细胞膜结构受到破坏,细胞膜脂过氧化作用增强。子叶的细胞膜透性和MDA含量显著高于下胚轴(P0.05),细胞器形态变化早于下胚轴,表明下胚轴耐旱性相对于子叶较强。子叶中线粒体受损晚于叶绿体,线粒体的耐旱性要比叶绿体强。不同组织间及同一组织不同细胞器之间对干旱胁迫反应的差异,可能是植物组织细胞应对外界不利环境的一种防御反应。干旱胁迫下超微结构的变化反映了细胞内膜系统的紊乱和伤害,而膜系统的伤害可能是脂质过氧化作用增强的结果。     

福建省烟粉虱生物型鉴定

采用m tDNA分子标记技术以及西葫芦银叶测定方法,对从福建省8个具有代表性地理区域采集的烟粉虱样品进行生物型鉴定.结果表明:8个烟粉虱种群在m tDNA COⅠ基因720 bp片段序列上的所有位点都相同,它们与Texas-B、Israel-B、Ind ia-B、Morocco-B、France-B1、France-B2、Be ijing-B、Argentina-B、Reun ion-B1、Reun ion-B2、Reun ion-B3等11个B型烟粉虱种群在m tDNA COⅠ基因720 bp序列上的差异很小(序列相似性为99.6%-100%),总体上属于同一进化枝;与Morocco-Q、Colomb ia-A1、Colomb ia-A2烟粉虱种群在m tDNA COⅠ基因720 bp序列上差异较大,分别属于不同的进化枝;8个烟粉虱种群均可引起典型的西葫芦银叶症状.说明福建省8个烟粉虱种群均属于B生物型.