CYTOCHEMICAL STUDIES OF MITOCHONDRIA : I. THE SEPARATION AND IDENTIFICATION OF A MEMBRANE FRACTION FROM ISOLATED MITOCHONDRIA

Mitochondria isolated from rat liver and suspended in 0.44 M sucrose were disrupted by treatment with 0.3 per cent Na deoxycholate. The treated suspension was fractionated by differential centrifugation into a number of fractions and the respective pellets were examined in sections in the electron microscope. One of these fractions was found to consist of apparently membrane-bound (vesicular) elements. The difference between interfaces and membranes was discussed and the material of this fraction was found to meet stated requirements identifying it as membranous. A detailed study of the disruption process undergone by mitochondria in the presence of Na deoxycholate showed that the elements of this fraction were derived from structural elements assumed to be mitochondrial membranes. The findings thus demonstrate that mitochondria do possess membranes as defined and that these membranes can be isolated in a relatively pure form.     

粘虫痘病毒酶的初步研究

在粘虫痘病毒包涵体中检测到一种碱性蛋白酶。最适ｐＨ为８．８,最适温度为２０℃,是热不稳定的,可被２－硫基乙醇激活,其活性不需二价阳离子。在粘虫痘病毒颗粒中检测到两种脱氧核糖核酸酶,均能降解变性的大肠杆菌ＤＮＡ,最适ｐＨ分别为５．０和８．０     

BIOCHEMICAL AND ULTRASTRUCTURAL PROPERTIES OF A MITOCHONDRIAL INNER MEMBRANE FRACTION DEFICIENT IN OUTER MEMBRANE AND MATRIX ACTIVITIES

Treatment of the inner membrane matrix fraction of rat liver mitochondria with the nonionic detergent Lubrol WX solubilized about 70% of the total protein and 90% or more of the following matrix activities: malate dehydrogenase, glutamate dehydrogenase, and isocitrate dehydrogenase (NADP). The Lubrol-insoluble fraction was enriched in cytochromes, phospholipids, and a Mg⁺⁺-stimulated ATPase activity. Less than 2% of the total mitochondrial activity of monoamine oxidase, an outer membrane marker, or adenylate kinase, an intracristal space marker could be detected in this inner membrane fraction. Electron micrographs of negatively stained preparations showed vesicles (≤0.4 µ diameter) literally saturated on the periphery with the 90 A ATPase particles. These inner membrane vesicles, which appeared for the most part to be inverted with respect to the normal inner membrane configuration in intact mitochondria, retained the succinicoxidase portion of the electron-transport chain, an intact phosphorylation site II with a high affinity for ADP, and the capacity to accumulate Ca⁺⁺. A number of biochemical properties characteristic of intact mitochondria and the inner membrane matrix fraction, however, were either absent or markedly deficient in the inner membrane vesicles. These included stimulation of respiration by either ADP or 2,4-dinitrophenol, oligomycin-sensitive ADP-ATP exchange activity, atractyloside sensitivity of adenine nucleotide requiring reactions, and a stimulation of the Mg⁺⁺-ATPase by 2,4-dinitrophenol.     

STUDIES ON THE CONTENT AND ORGANIZATION OF THE RESPIRATORY ENZYMES OF MITOCHONDRIA

(1) The mathematical calculations relating spectrophotometric data with the data of Allard et al. (4, 5) on mitochondrial counts, is presented. Such a calculation indicates that an "average mitochondrion" from rat liver would contain about 17,000 molecules of each cytochrome pigment. (2) Hematocrit determinations relating respiratory pigment content for mitochondria isolated from a variety of tissues have been presented, showing a fivefold variability depending upon the source of the mitochondria. (3) Speculations on the organization of the respiratory enzymes associated with the membrane structure of the mitochondria are discussed.     

用识别四个GC对的限制酶研究高等担子菌线粒体DNA

本文报道了用识别四个GC对的限制性内切酶HaeⅢ、CofI、MsPI酶切高等担子菌伞菌目（Agaricales）、非褶菌目（Aphyllophorales）12个菌株的总DNA,在琼脂糖凝胶上显现线粒体DNA带谱的结果。通过对带型、累加分子量、酶切片段数和同源性的分析表明,不同种类高等担子菌的线粒体DNA变化较大．研究还显示,以多种识别四个GC对的限制酶分析高等担子菌的线粒体DNA及其它们的RFLP,比只用HaeⅢ更灵敏有效。     

ADENINE NUCLEOTIDE-INDUCED CONTRACTION OF THE INNER MITOCHONDRIAL MEMBRANE : II. Effect of Bongkrekic Acid

In bovine heart mitochondria bongkrekic acid at concentrations as low as about 4 nmol/mg protein (a) completely inhibits phosphorylation of exogenous adenosine diphosphate (ADP) and dephosphorylation of exogenous adenosine triphosphate (ATP), (b) completely reverses atractyloside inhibition of inner membrane contraction induced by exogenous adenine nucleotides, and (c) decreases the amount of adenine nucleotide required to elicit maximal exogenous adenine nucleotide-induced inner membrane contraction to a level which appears to correspond closely with the concentration of contractile, exogenous adenine nucleotide binding sites Bongkrekic acid at concentrations greater than 4 nmol/mg protein induces inner membrane contraction which seems to depend on the presence of endogenous ADP and/or ATP. The findings appear to be consistent with the interpretations (a) that the inner mitochondrial membrane contains two types of contractile, adenine nucleotide binding sites, (b) that the two sites differ markedly with regard to adenine nucleotide affinity, (c) that the high affinity site is identical with the adenine nucleotide exchange carrier, (d) that the low affinity site is accessible exclusively to endogenous adenine nucleotides and is largely unoccupied in the absence of bongkrekic acid, and (e) that bongkrekic acid increases the affinity of both sites in proportion to the amount of the antibiotic bound to the inner membrane.     

FRACTIONATION OF OLFACTORY TISSUE HOMOGENATES. ISOLATION OF A CONCENTRATED PLASMA MEMBRANE FRACTION

Abstract— Differential and sucrose-density-gradient centrifugation techniques were used for studies on the separation of subcellular particles from rabbit brain and olfactory tissue. Comparisons were made among various fractions from the two types of tissue. These comparisons included protein concentration and enzyme activities of the individual fractions as well as their distribution in subfractions from density gradient separations. In tissue whole homogenates, the percentage of total ATPase activity as ouabain sensitive Na⁺-K⁺ ATPase activity was about 4 times greater in brain cortex (63 per cent) than in olfactory tissue (17 per cent). Cytochrome oxidase and Na⁺-K⁺ ATPase activities were used to indicate the presence and the concentration of mitochondria and of the plasma membranes. A fraction with properties similar to the mitochondria plus nerve ending fraction from brain homogenates (fraction B) was obtained from olfactory tissue. Nerve ending concentration subfractions (B₂) were prepared from the B primary fractions. Plasma membrane subfractions were obtained by osmotic shock treatment of B₂, In the fraction of plasma membrane from olfactory tissue (E₂), 56 per cent of the total ATPase activity was Na⁺-K⁺ ATPase activity. In E₂ from brain 71 per cent was Na⁺-K⁺ ATPase activity. Deoxycholate (DOC)-treated fractions containing nerve endings from brain preparations showed much greater increase in cytochrome oxidase activity than did similar fractions from olfactory tissue. DOC treatment increased the NADH cytochrome c reductase activity of all fractions and subfractions from brain, while it decreased activity in all but one fraction from olfactory tissue. DOC treatment decreased both the Mg²⁺ and Na⁺-K⁺ ATPase activities in both types of tissue. Electron photomicrographs of olfactory B₂, B₃, E₂ and E₃ show clear morphological differences among these subfractions. The presence of possible cilia and basal bodies on vesicles in B₂ gives morphological evidence for the presence of terminal swellings in this subtraction in agreement with enzyme marker activity results.     

THE ISOLATION OF A CELL MEMBRANE FRACTION FROM RAT LIVER

A procedure is described for isolating cell membranes from rat liver homogenates. 20 gm. of rat liver was homogenized in a Dounce homogenizer in ice cold water buffered to pH 7.5 with NaHCO₃, rupturing all of the cells and most nuclei. The diluted homogenate was filtered through cheesecloth to remove precipitated nucleoprotein and centrifuged at 1500 g, 10 minutes, to sediment a crude membrane fraction. The membrane containing sediment was recentrifuged 3 times in conical tubes (1220 g, 10 minutes), the top layer of the 2-layered sediment being retained. Flotation in a sucrose solution d = 1.22 freed the preparation from contaminating cell fragments and nuclear membranes not previously disintegrated. The floating material ~0.4 ml. was quite homogeneous and consisted of thin amorphous membranes. Electron micrographs revealed numerous double profiles similar in shape and dimensions to apposed liver cell membranes in intact tissue.     

p-NITROPHENYL PHOSPHATASES OF A MEMBRANE FRACTION FROM BOVINE CEREBRAL CORTEX

Abstract— Three different types of p -nitrophenyl phosphatases (NPPases) were solubilized by deoxycholate treatment from a membrane fraction of bovine cerebral cortex, and their characteristics were determined. Of these three NPPases (acid, Mg²⁺-activated, and K⁺, Mg²⁺-activated), only K-Mg NPPase was stimulated about two-fold by phospholipid and was inhibited by unsaturated neutral lipids and fatty acids. Unlike Na⁺-K⁺-Mg^a+-activated ATPase, the enzyme did not absolutely require phospholipid for its activity, but was similarly thermolabile and was protected by phospholipid from thermal inactivation. Acid NPPase was separable from the other two NPPases by ammonium sulphate fractionation, and partly solubilized by dialysis against ATP-mercaptoethanol solution. Hg²⁺ inhibited equally all three NPPases, but Ca²⁺ inhibited only Mg and K-Mg NPPases. Ouabain was effective on K-Mg NPPase alone.     

红莲型水稻与细胞质雄性不育相关mtDNA片段的分离及序列测定

应用AFLP分析技术,比较了红莲型水稻雄性不育系和保持系线粒体DNA,找到一不育系特异条带TA1。以该条带DNA为探针与不育系、保持系以及F1杂种线粒体总RNA杂交,结果显示该片段黄化苗期三者均转录一个RNA分子,但转录产物分子量各不相同,说明三者该片段阅读框架不同。经测序,该片段长202bp,序列内含密码子ATG、ATT、AGA、AGG以及正向重复序列5’TGTAC3’、5’ATTATTTT3’和倒重复序列5’GGGAAACA3’。上述特点表明该片段可能是某一蛋白编码序列,并可能与红莲型水稻雄性不育性状形成有关。     

ADENINE NUCLEOTIDE-INDUCED CONTRACTION OF THE INNER MITOCHONDRIAL MEMBRANE : I. General Characterization

The inner membranes of isolated bovine heart mitochondria undergo pronounced contraction upon being exposed to exogenous adenosine diphosphate (ADP), adenosine triphosphate (ATP), and certain other high-energy phosphate compounds. Contraction results in decrease of inner membrane expanse which in turn results in decrease of intracristal space and increase of mitochondrial optical density (OD). The magnitude of the OD change appears to be proportional to the degree of contraction Half-maximal contraction can be achieved with ADP or ATP at concentrations as low as about 0 3 µM. Atractyloside at concentrations as low as about 1.2 nmol/mg mitochondrial protein completely inhibits the contraction. It is concluded from these and other observations that inner membrane contraction occurs as a result of adenine nucleotide binding to the carrier involved in the exchange of adenine nucleotides across the inner mitochondrial membrane.     

LARGE SCALE PREPARATION OF A CRUDE MEMBRANE FRACTION FROM OX BRAIN

Abstract— Two procedures are described for preparing from ox brain grey matter a subcellular fraction enriched in neuronal membranes. In the first, an angle rotor was used to fractionate the crude mitochondrial and nuclear fraction and yielded 1·3–1·4 g of membrane protein from 200 g of tissue. The second procedure employed essentially the same principle except that a zonal rotor was used to fractionate in the final stage. The two methods gave comparable results for yields of protein, Na-K-Mg AT Pase and succinate dehydrogenase.