Nonphosphorylating Oxidation in Mitochondria and Related Processes

The mechanism of oxidative phosphorylation and its regulation remain one of the main problems of bioenergetics. Efficiency of the mitochondrial energization is determined by the relationship between the rate of generation of electrochemical potential of hydrogen ions and the rate of its expenditure on the synthesis of ATP and the use of ATP in endergonic reactions. Uncoupling (partial or complete), which occurs in the process of uncontrolled and controlled leakage of ions through the inner mitochondrial membrane, on the one hand leads to the decrease in the relative synthesis of ATP, and on the other, being consistent with the law of conservation of energy, leads to the formation of heat, generation of which is an essential function of the organism. In addition to increased thermogenesis, the increase of non-phosphorylating oxidation of various substrates is accompanied by the decrease in transmembrane potential, production of reactive oxygen species, and activation of oxygen consumption, water and carbon dioxide production, increase in the level of intracellular ADP and acidification of the cytosol. In this analysis, each of these factors will be considered separately for its role in regulating metabolism.

Ultrastructure of Hepatocytes from Laboratory Mice Fed a Standard Dry Laboratory Animal Diet

The significant destructive changes in ultrastructure of hepatocytes from laboratory mice kept in different vivariums in Moscow and fed with dry laboratory animal diets acquired from different domestic manufacturers that were not standardized for initial products were demonstrated using electron microscopy. Furthermore, disruption in the ultrastructure of liver parenchymal cells occurred regardless of the animal status (SPF or conventional), conditions of various vivariums, as well as the feed manufacturer. At the same time, studies on ultrastructure of liver hepatocytes from mice kept in the Charles River Laboratory facilities in Germany and fed with the Altromin Spezialfutter laboratory animal diet (GmbH & Co., Germany) that was produced using quality control of ingredients did not reveal destructive changes in the internal ultrastructure of hepatocytes. However, if these mice were later fed with the food produced in local manufactures, changes in the structure of liver cells developed after 2 months. Thus, feeding with dry diet from the domestic producers of an unspecified composition causes significant changes in the ultrastructure of hepatocytes in control animals, reflecting the development of some pathological processes in the body.

Mitochondria in Obliquely Striated Muscles of the Horsehair Worm Gordionus alpestris (Nematomorpha, Gordioidea) with Structural Organization Typical of Cells with Energy-Intensive Processes

The ultrastructure of mitochondria in the flattened circomyarian fibers of the horsehair worm Gordionus alpestris (Nemathelminthes) was examined. In contrast to the previously published data, we showed these mitochondria to be giant elongated organelles that densely fill the central cytoplasmic space of the ribbon-like muscle fibers. No fundamental differences were found in the ultrastructure of the muscle tissue mitochondria in actively moving free-living and parasitic G. alpestris worms. The functional significance of the observed ultrastructural organization of mitochondria is discussed in connection with the necessity for an extended mitochondrial membrane system for a uniform supply of active muscle tissue with energy.

Study of Age-Dependent Structural and Functional Changes of Mitochondria in Skeletal Muscles and Heart of Naked Mole Rats (Heterocephalus glaber)

Morphometric analysis of mitochondria in skeletal muscles and heart of 6- and 60-month-old naked mole rats (Heterocephalus glaber) revealed a significant age-dependent increase in the total area of mitochondrial cross-sections in studied muscle fibers. For 6- and 60-month-old animals, these values were 4.8 ± 0.4 and 12.7 ± 1.8%, respectively. This effect is mainly based on an increase in the number of mitochondria. In 6-month-old naked mole rats, there were 0.23 ± 0.02 mitochondrial cross-sections per µm² of muscle fiber, while in 60-month-old animals this value was 0.47 ± 0.03. The average area of a single mitochondrial cross-section also increased with age in skeletal muscles - from 0.21 ± 0.01 to 0.29 ± 0.03 µm². Thus, naked mole rats show a drastic enlargement of the mitochondrial apparatus in skeletal muscles with age due to an increase in the number of mitochondria and their size. They possess a neotenic type of chondriome accompanied by specific features of mitochondrial functioning in the state of oxidative phosphorylation and a significant decrease in the level of matrix adenine nucleotides.

Age-Related Changes in Ultrastructure of Mitochondria. Effect of SkQ1

For many years, investigators have attempted to identify unique ultrastructural conditions of mitochondria related to aging. However, this did not result in definitive results. At present, this issue has again become of topical interest due to development of the mitochondrial theory of aging and of engineering of a novel antioxidant class known as mitochondria-targeted antioxidants. The review briefly discusses experimental results that, from our perspective, allow the most objective understanding regarding age-related changes in mitochondrial ultrastructure.

[Structural and functional basis for accelerated thymic involution in OXYS rats]

Thymus involution is one of the most pronounced manifestations of aging immune system, associated with increase susceptibility to infections, autoimmune diseases and cancer. Its nature in normal aging is actively under investigation. Much less attention is paid to the study of mechanisms of accelerated thymic involution. Previously, we showed the connection of accelerated senescence in OXYS rats with accelerated thymic involution, the mechanisms of which remain unclear. The aim of the present work was to study multifunctional condition of thymic epithelial cells in aging OXYS rats. Immunohistochemical analysis showed the reduction of thymic epithelial cell net in OXYS rats, significant decrease in volume and surface area of epithelial cells in cortical substance as compared to control Wistar rats. Electron microscopic study revealed the marked changes of epithelial cell ultrastructure, namely the reduction of cytoplasm volume, sharp decrease in size and quantity of secretory vacuoles, the presence of multiple autophagosomes and phagolysomes. The results indicate that one of the possible mechanisms of epithelial cell net reduction in thymus of senescence-accelerated OXYS rats can be the aggravation of autophagy, probably associated with mitochondrial dysfunction typical for OXYS rats. Despite the known fact of slowing autophagy with aging in some tissues, the example of OXYS rats allows to suggest that chronic deviation of intensity of this process from physiological level, either to decrease or activation, can lead to degenerative changes in organs and finally form the progeric phenotype of the whole organism.

SkQ1 slows development of age-dependent destructive processes in retina and vascular layer of eyes of wistar and OXYS rats

We show the development of clearly pronounced age-related pathological changes in eye tissues of Wistar and OXYS rats. Photoreceptor cells were virtually absent in all OXYS rats in the age of 24 months. Massive accumulations of lipofuscin granules were detected in the pigmented epithelium cells. Flattening, overgrowing, and degradation of endothelial cells of choriocapillaries were also observed. Along with these changes, vessels without signs of degradation were detected in the pigmented epithelium. In 24-month-old Wistar rats these changes were local and were seen in only some of the animals. The mitochondria-targeted antioxidant SkQ1 (the rats were given SkQ1 daily with food at the dose of 250 nmol/kg for 5 months, starting from the age of 19 months) prevented the development of these pathological changes in both Wistar and OXYS rats. The data were subjected to mathematical processing and statistical analysis.

Lipofuscin granule dynamics during development of age-related macular degeneration

The pigment epithelium cell structure and therapeutic effect of antioxidant SkQ1, selectively penetrating into mitochondria from eye drops, were studied upon development in OXYS rats of age-related retinopathy as a model of macular degeneration. The characteristic dynamics and ultrastructural peculiarities of the layer of electron-dense cytoplasmic structures of the pigment epithelium apex part and incorporated lipofuscin granules were revealed. The therapy of OXYS animals for 68 days using 250 nM SkQ1 drops decreased the extent of development of age-related macular degeneration. Electron-microscopic investigation showed that SkQ1 prevented development of ultrastructural changes in the pigment epithelium characteristic of macular degeneration, the condition of which after therapy with SkQ1 drops corresponded to ultrastructure of pigment epithelium in Wistar rats of the same age having no symptoms of retinal damage. It is supposed that ultrastructural changes in the electron-dense layer upon development of age-related macular degeneration are indicative of disturbances in the optical cycle functioning, especially of disturbances in functioning of photoreceptor membranes.

Mitochondrial matrix fragmentation as a protection mechanism of yeast Saccharomyces cerevisiae

It was shown that separate fragments of the inner mitochondrial compartment (mitoplasts) can exist under a single non-fragmented outer membrane. Here we asked whether fragmentation of the inner mitochondria could prevent rupturing of the outer membrane and release of pro-apoptotic molecules from the mitochondrial intermembrane space into the cytoplasm during mitochondrial swelling. First, we showed that in Saccharomyces cerevisiae yeast addition of amiodarone causes formation of electrically separate compartments within mitochondrial filaments. Moreover, amiodarone treatment of Deltaysp2 mutant produced a higher proportion of cells with electrically discontinuous mitochondria than in the wild type, which correlated with the survival of cells. We confirmed the existence of separated mitoplasts under a single outer membrane using electron microscopy. Mitochondria with fragmented matrixes were also detected in cells of the stationary phase. Our data suggest that such fragmentation acts as a cellular protective mechanism against stress.

Mitochondria-targeted plastoquinone derivatives as tools to interrupt execution of the aging program. 1. Cationic plastoquinone derivatives: synthesis and in vitro studies

Synthesis of cationic plastoquinone derivatives (SkQs) containing positively charged phosphonium or rhodamine moieties connected to plastoquinone by decane or pentane linkers is described. It is shown that SkQs (i) easily penetrate through planar, mitochondrial, and outer cell membranes, (ii) at low (nanomolar) concentrations, posses strong antioxidant activity in aqueous solution, BLM, lipid micelles, liposomes, isolated mitochondria, and cells, (iii) at higher (micromolar) concentrations, show pronounced prooxidant activity, the "window" between anti- and prooxidant concentrations being very much larger than for MitoQ, a cationic ubiquinone derivative showing very much lower antioxidant activity and higher prooxidant activity, (iv) are reduced by the respiratory chain to SkQH2, the rate of oxidation of SkQH2 being lower than the rate of SkQ reduction, and (v) prevent oxidation of mitochondrial cardiolipin by OH*. In HeLa cells and human fibroblasts, SkQs operate as powerful inhibitors of the ROS-induced apoptosis and necrosis. For the two most active SkQs, namely SkQ1 and SkQR1, C(1/2) values for inhibition of the H2O2-induced apoptosis in fibroblasts appear to be as low as 1x10(-11) and 8x10(-13) M, respectively. SkQR1, a fluorescent representative of the SkQ family, specifically stains a single type of organelles in the living cell, i.e. energized mitochondria. Such specificity is explained by the fact that it is the mitochondrial matrix that is the only negatively-charged compartment inside the cell. Assuming that the Deltapsi values on the outer cell and inner mitochondrial membranes are about 60 and 180 mV, respectively, and taking into account distribution coefficient of SkQ1 between lipid and water (about 13,000 : 1), the SkQ1 concentration in the inner leaflet of the inner mitochondrial membrane should be 1.3x10(8) times higher than in the extracellular space. This explains the very high efficiency of such compounds in experiments on cell cultures. It is concluded that SkQs are rechargeable, mitochondria-targeted antioxidants of very high efficiency and specificity. Therefore, they might be used to effectively prevent ROS-induced oxidation of lipids and proteins in the inner mitochondrial membrane in vivo.

[Yeast cell ultrastructure after amiodarone treatment]

[Amiodarone is used as a pharmaceutical substance for treating a number of diseases. However it is known that structural and functional disturbances are caused by amiodarone in patient's tissues. Here particular features of amiodarone effect are studied in yeast Saccharomyces cerevisiae, where amiodarone was shown to cause apoptosis. Electron-microscopic study of yeast cells after amiodarone treatment reveals a significant increase in lipid particle number which can lead to formation of a structural complex by interacting with membranous organelles of a cell. Amiodarone causes the appearance of small and separated slightly swollen mitochondria. Chro-matin displacement to the periphery of nucleus, nuclear sectioning and nuclear envelope disturbances are observed in the cells under these conditions. The detected cell ultrastructure alterations in the S. cerevisiae are considered to be specific response to the phospholipidosis and apoptosis caused by amiodarone.

[The cytochrome c oxidase activity in mitochondria of cardiomyocytes of isolated cardiac tissue under long-term hypoxic incubation]

Using method of electron microscopic histochemistry based upon the oxidative polymerization of 3,3'-diaminobenzidine (DAB) to reveal cytochrome c oxidase activity we identified that long hypoxic incubation of isolated small pieces of cardiac tissue during 72 h caused changes in mitochondrial ultrastructure followed by a breach of functional activities of mitochondria, and, in particular, complex IV of the respiratory chain. But for all that, small electron-dense mitochondria appearing inside electron-light mitochondria ("mitochondria inside mitochondria") stained positively for cytochrome c oxidase activity along the full length of cristaes. The results obtained are discussed in connection with conception of changes in the mitochondrial reticulum ultrastructure during mitoptosis.

Programmed cell death in plants: effect of protein synthesis inhibitors and structural changes in pea guard cells

Pea leaf epidermis incubated with cyanide displayed ultrastructural changes in guard cells that are typical of apoptosis. Cycloheximide, an inhibitor of cytoplasmic protein synthesis, and lincomycin, an inhibitor of protein synthesis in chloroplasts and mitochondria, produced different effects on the dynamics of programmed death of guard cells. According to light microscopy data, cycloheximide reinforced and lincomycin suppressed the CN(-)-induced destruction of cell nuclei. Lincomycin lowered the effect of cycloheximide in the light and prevented it in the dark. According to electron microscopy data, the most pronounced effects of cycloheximide in the presence of cyanide were autophagy and a lack of apoptotic condensation of nuclear chromatin, the prevention of chloroplast envelope rupturing and its invagination inside the stroma, and the appearance of particular compartments with granular inclusions in mitochondria. Lincomycin inhibited the CN(-)-induced ultrastructural changes in guard cell nuclei. The data show that programmed death of guard cells may have a combined scenario involving both apoptosis and autophagy and may depend on the action of both cytoplasm synthesized and chloroplast and mitochondrion synthesized proteins.

[Dynamics of mitochondrial ultrastructure in small pieces of cardiac tissue under long-term anoxic incubation]

Anoxic incubation of isolated small pieces of cardiac tissue for 72 h caused emergence of an unusual population of mitochondria, referred to as "mitochondrion inside mitochondrion". We studied dynamics of the origin of this event. In the most part of a mitochondrial population after a 6 h anoxic incubation of myocardial tissue, a local increase in some region of the intermembrane space was observed. Some regions of matrix with adjoined inner membrane move into these regions of intermembrane space, to be constricted eventually. After 12 h of incubation densely neighbouring layers of membrane are observed in these structures. By 24 h of incubation, inside new-formed structures well-distinguished concentric layers of membrane appear. Between these layers some electron-dense material ultrastructurally identical to mitochondrial matrix is seen. By 72 h of anoxic incubation, in cardiomyocytes of the experimental tissue structures with well-marked morphological features of mitochondria appear, which we called "mitochondrion inside mitochondrion". Results of our study are discussed in terms of a conception of changes that occur in the structure of mitochondrial reticulum during apoptosis.

Effect of "external" superoxide anion on apoptosis in coleoptiles of wheat seedlings

A derivative of phthalic acid, dibutylphthalate (DBP), which has gametocidal effect at the concentration of approximately 10(-4) M, increased apoptosis in coleoptiles of wheat seedlings. This was associated with activation of chromatin margination and generation of mitochondria-containing vesicles. At the same concentration, DBP activated the release by the coleoptiles of superoxide anion into the environment. Lower (10(-5) M) and higher (10(-3) M) concentrations of DBP virtually had no effect on either process. A probable mechanism of effect of the "external" superoxide anion on apoptosis within the plant cell is discussed.

Programmed cell death in plants: ultrastructural changes in pea guard cells

Treatment with cyanide of epidermal peels isolated from pea leaves resulted in destruction of nuclei in the guard cells of stomata, which is visible with a light microscope. The process was accelerated by illumination. Electron microscopy revealed significant CN--induced changes in the ultrastructure of guard cells, which increased with time. Margination of chromatin, which is one of the first signs of apoptosis, was observed in the guard cells even after 1 h incubation of the isolated epidermis with CN-. Subsequent chromatin condensation, swelling of the endoplasmic reticulum with formation of large tanks covered with ribosomes, changes in the structure of dictyosomes, and a slight swelling of mitochondria were observed after 3 h of the epidermis incubation with CN-. After 6 h of incubation with CN-, the bulk volume of the guard cells was filled with vacuoles, the cytoplasm occupied the thin marginal layer, the nucleus was in the center similarly to the control experiment, but it was polylobal, extended in narrow cytoplasmic bands, and, despite the loss of the nuclear envelope integrity, appeared to be a self-dependent structure. In the envelope-free open regions of the nucleus, mitochondria and chloroplasts directly contacted with chromatin. Much like the cell nucleus, chloroplasts lost the integrity of the membrane, but did not swell and retained the stroma and integrity of the thylakoid system. An antioxidant di-tert-butyl-4-hydroxytoluene prevented ultrastructural changes in the cells observed after 6 h of incubation with CN-. Thus, the CN--induced death of the guard cells of stomata occurs through the mechanism of apoptosis.

Selective elimination of mitochondria from living cells induced by inhibitors of bioenergetic functions

The inhibitors of oxidative phosphorylation induced fragmentation of mitochondria without any signs of apoptosis in CV-1 and HeLa cells. Prolonged treatment with the uncouplers (alone or in combination with the inhibitors of respiration) caused perinuclear clusterization of mitochondria, followed by their selective elimination. The fraction of mitochondria-depleted cells remained viable.

Apoptosis in wheat seedlings grown under normal daylight

Apoptosis was observed in the coleoptile and initial leaf in 5-8-day-old wheat seedlings grown under normal daylight. Apoptosis is an obligatory event in early wheat plant ontogenesis, and it is characterized by cytoplasmic structural reorganization and fragmentation, in particular, with the appearance in vacuoles of specific vesicles containing intact organelles, chromatin condensation and margination in the nucleus, and internucleosomal fragmentation of nuclear DNA. The earliest signs of programmed cell death (PCD) were observed in the cytoplasm, but the elements of apoptotic degradation in the nucleus appeared later. Nuclear DNA fragmentation was detected after chromatin condensation and the appearance in vacuoles of specific vesicles containing mitochondria. Two PCD varieties were observed in the initial leaf of 5-day-old seedlings grown under normal daylight: a proper apoptosis and vacuolar collapse. On the contrary, PCD in coleoptiles under various growing (light) conditions and in the initial leaf of etiolated seedlings is only a classical plant apoptosis. Therefore, various tissue-specific and light-dependent PCD forms do exist in plants. Amounts of O2*- and H2O2 evolved by seedlings grown under normal daylight are less than that evolved by etiolated seedlings. The amount of H2O2 formed in the presence of sodium salicylate or azide by seedlings grown under normal daylight was increased. Contrary to etiolated seedlings, the antioxidant BHT (ionol) did not inhibit O2*- formation and apoptosis and it had no influence on ontogenesis in the seedlings grown under normal daylight. Thus, in plants grown under the normal light regime the powerful system controlling the balance between formation and inactivation of reactive oxygen species (ROS) does exist and it effectively functions. This system is responsible for maintenance of cell homeostasis, and it regulates the crucial ROS level controlling plant growth and development. In etiolated plants, this system seems to be absent, or it is much less effective.

Apoptosis in plants: specific features of plant apoptotic cells and effect of various factors and agents

Apoptosis is an integral part of plant ontogenesis; it is controlled by cellular oxidative status, phytohormones, and DNA methylation. In wheat plants apoptosis appears at early stages of development in coleoptile and initial leaf of 5- to 6-day-old seedlings. Distinct ultrastructural features of apoptosis observed are (1). compaction and vacuolization of cytoplasm in the apoptotic cell, (2). specific fragmentation of cytoplasm and appearance in the vacuole of unique single-membrane vesicles containing active organelles, (3). cessation of nuclear DNA synthesis, (4). condensation and margination of chromatin in the nucleus, (5). internucleosomal fragmentation of nuclear DNA, and (6). intensive synthesis of mitochondrial DNA in vacuolar vesicles. Peroxides, abscisic acid, ethylene releaser ethrel, and DNA methylation inhibitor 5-azacytidine induce and stimulate apoptosis. Modulation of the reactive oxygen species (ROS) level in seedling by antioxidants and peroxides results in tissue-specific changes in the target date for the appearance and the intensity of apoptosis. Antioxidant butylated hydroxytoluene (BHT) reduces the amount of ROS and prevents apoptosis in etiolated seedlings, prolongs coleoptile life span, and prevents the appearance of all apoptotic features mentioned. Besides, BHT induces large structural changes in the organization of all cellular organelles and the formation of new unusual membrane structures in the cytoplasm. BHT distorts mitosis and this results in the appearance of multiblade polyploid nuclei and multinuclear cells. In roots of etiolated wheat seedlings, BHT induces differentiation of plastids with the formation of chloro(chromo)plasts. Therefore, ROS controlled by BHT seems to regulate mitosis, trigger apoptosis, and control plastid differentiation and the organization of various cellular structures formed by endocytoplasmic reticulum.

Functional activity and ultrastructure of mitochondria isolated from myocardial apoptotic tissue

Apoptosis in myocardial tissue slices was induced by extended incubation under anoxic conditions. Mitochondria were isolated from the studied tissue. A new method of isolation of mitochondria in special conditions by differential centrifugation at 1700, 10,000, and 17,000 g resulted in three fractions of mitochondria. According to the data of electron microscopy the heavy mitochondrial fraction (1700 g) consisted of mitochondrial clusters only, the middle mitochondrial fraction (10,000 g) consisted of mitochondria with typical for isolated mitochondria ultrastructure, and the light fraction consisted of small mitochondria (2 or 3 cristae) of various preservation. The heavy fraction contained unusual structural elements that we detected earlier in apoptotic myocardial tissue--small electron-dense mitochondria incorporated in bigger mitochondria. The structure of small mitochondria from the light fraction corresponded to that of the small mitochondria from these unusual elements--"mitochondrion in mitochondrion". The most important functions of isolated mitochondria are strongly inhibited when apoptosis is induced in our model. The detailed study of the activities of the two fractions of the apoptotic mitochondria showed that the system of malate oxidation is completely altered, the activity of cytochrome c as electron carrier is partly inhibited, while succinate oxidase activity is completely preserved (complexes II, III, and IV of the respiration chain). Succinate oxidase activity was accompanied by high permeability of the internal membrane for protons: the addition of uncoupler did not stimulate respiration. ATP synthesis in mitochondria was inhibited. We demonstrated that in our model of apoptosis cytochrome c remains in the intermembrane space, and, consequently, is not involved in the cascade of activation of effector caspases. The possible mechanisms of induction of apoptosis during anoxia are discussed.

[Ultrastructure of mitochondria apparatus of cardiomyocytes in apoptosis induced by long-term anoxia in rats]

Apoptosis in cardiomyocytes was induced by incubation of pieces of cardiac tissues under condition of anoxia. Electronmicroscopic investigation detected previously unknown changes in mitochondrial ultrastructure. The mitochondrial population was characterized by morphological heterogeneity. In addition to a mitochondrial population characterized with irrigated cleared matrix, anoxia induced the appearance of an atypical and previously unknown population of small electron-dense cardiomyocyte mitochondria. They were characterized by unusual localization inside electron-light mitochondria ("mitochondria inside mitochondria"). The most part of mitochondria with the irrigated matrix are commonly characterized by unusual types of rearrangements of the inner mitochondrial membrane. Under anoxic conditions, the inner mitochondrial membrane formed electron-dense ordered structures. This is a spongy structure with cells of equal size. Results of our study are discussed in terms of conception of changes in mitochondrial reticulum ultrastructure during apoptosis.

Apoptosis in the initial leaf of etiolated wheat seedlings: influence of the antioxidant ionol (BHT) and peroxides

Apoptosis was observed in the initial leaf of 5-8-day-old etiolated wheat seedlings. A condensation of cytoplasm in apoptotic cells, formation of myelin-like structures, specific fragmentation of cytoplasm, appearance in vacuoles of specific vesicles containing subcellular organelles, condensation and margination of chromatin in the nucleus, and internucleosomal fragmentation of nuclear DNA are ultrastructural features of apoptosis in the initial wheat leaf. Single-membrane vesicles detected in vacuoles of the leaf cells resemble in appearance the vacuolar vesicles in the coleoptile apoptotic cells described earlier (Bakeeva, L. E., et al. (1999) FEBS Lett., 457, 122-125); they contain preferentially plastids but not mitochondria as was observed in coleoptile. The vacuolar vesicles are specific for the apoptotic plant cells. Thus, apoptosis in various tissues is an obligatory element of plant (wheat) growth and development even in the early stages of ontogenesis. Contrary to strong geroprotecting action in coleoptile, the known antioxidant BHT (ionol, 2.27 x 10(-4) M) does not prevent in the leaf cells the apoptotic internucleosomal DNA fragmentation and appearance of specific vacuolar vesicles containing subcellular organelles. Therefore, the antioxidant action on apoptosis in plants is tissue specific. Peroxides (H2O2, cumene hydroperoxide) stimulated apoptosis (internucleosomal DNA fragmentation) in coleoptile and induced it in an initial leaf when apoptosis in a control seedling leaf was not yet detected. Thus, apoptosis that is programmed in plant ontogenesis and controlled by reactive oxygen species (ROS) can be modulated by anti- and prooxidants.

Induction of apoptosis in rat myocardium under anoxic conditions

The effect of anoxic incubation of small slices of isolated rat hearts on respiration, internucleosomal DNA fragmentation, and mitochondrial ultrastructure was investigated. Anoxic incubation for 72 h induced apoptosis accompanied by internucleosomal DNA fragmentation and changes in respiration and mitochondrial ultrastructure. The mitochondrial population was characterized by morphological heterogeneity. In a significant part of the mitochondrial population there were signs of mitochondrial swelling and appearance of electron-dense mitochondria. Anoxia also induced the appearance of an atypical (and previously unknown) population of small electron-dense mitochondria. They were characterized by unusual localization inside electron-light mitochondria. Under anoxic conditions the inner mitochondrial membrane formed electron-dense ordered structures. All changes described here reflect two opposing processes occurring in mitochondria: apoptotic destruction and compensatory processes responsible for maintenance of mitochondria.

Mitochondria enter the nucleus (one further problem in chronic alcoholism)

Electron microscopy of cardiomyocytes of patients with hypertrophic and alcoholic cardiomyopathies revealed the presence of nuclei with mitochondria accumulated in their core. This was associated with chromatin displacement towards the core of the nucleus. No large-scale intermixing of the nuclear content with the cytosol was found, although in some sections there were disruptions in the nuclear envelop continuity. The entrance of mitochondria into the nucleus was modeled in rats that were given ethanol and the catalase inhibitor aminotriazole for 12 weeks. It is suggested that the entrance of mitochondria into the nucleus promotes both the attack of mitochondria by nuclear proteins and the attack of nuclear DNA and proteins by proteins of the mitochondrial intermembrane space.

Effect of the antioxidant ionol (BHT) on growth and development of etiolated wheat seedlings: control of apoptosis, cell division, organelle ultrastructure, and plastid differentiation

Ionol (BHT), a compound having antioxidant activity, at concentrations in the range 1-50 mg/liter (0.45 x 10(-5)-2.27 x 10(-4) M), inhibits growth of etiolated wheat seedlings, changes the morphology of their organs, prolongs the coleoptile life span, and prevents the appearance of specific features of aging and apoptosis in plants. In particular, BHT prevents the age-dependent decrease in total DNA content, apoptotic internucleosomal fragmentation of nuclear DNA, appearance in the cell vacuole of specific vesicles with active mitochondria intensively producing mtDNA, and formation of heavy mitochondrial DNA rho = 1.718 g/cm3) in coleoptiles of etiolated wheat seedlings. BHT induces large structural changes in the organization of all cellular organelles (nucleus, mitochondria, plastids, Golgi apparatus, endocytoplasmic reticulum) and the formation of new unusual membrane structures in the cytoplasm. BHT distorts the division of nuclei and cells, and this results in the appearance of multi-bladed polyploid nuclei and multinuclear cells. In roots of etiolated wheat seedlings, BHT induces intensive synthesis of pigments, presumably carotenoids, and the differentiation of plastids with formation of chloro- or chromoplasts. The observed multiple effects of BHT are due to its antioxidative properties (the structural BHT analog 3,5-di-tert-butyltoluene is physiologically inert; it has no effect similar to that of BHT). Therefore, the reactive oxygen species (ROS) controlled by BHT seem to trigger apoptosis and the structural reorganization of the cytoplasm in the apoptotic cell with formation of specific vacuolar vesicles that contain active mitochondria intensively producing mtDNA. Thus, the inactivation of ROS by BHT may be responsible for the observed changes in the structure of all the mentioned cellular organelles. This corresponds to the idea that ROS control apoptosis and mitosis including formation of cell wall, and they are powerful secondary messengers that regulate differentiation of plastids and the Golgi apparatus in plants.

Subcellular reorganization of mitochondria producing heavy DNA in aging wheat coleoptiles

Unusual closed membrane vesicles containing one or more mitochondria were isolated from homogenates of aging wheat coleoptiles. Very similar (or the same) bodies were shown to exist in situ in vacuoles of undividing cells in the apical part of intact senescent coleoptiles. Vesicles isolated from coleoptile homogenate free of nuclei by 10 min centrifugation at 1700 x g and traditional mitochondria (sedimented at between 4300 x g and 17,400 x g) are similar in respiration rate, composition and content of cytochromes and sensitivity to respiration inhibitors. However, vesicles contain about 2-fold more Ca2+ ions than free mitochondria do. The specific feature of vesicles containing mitochondria in aging coleoptiles is an intensive synthesis of heavy (rho = 1.718 g/cm3) mitochondrial DNA (H-mtDNA). Thus, aging in plants is accompanied by an increased selective H-mtDNA production and change in subcellular organization of mitochondria.

[Energy-dependent changes in the ultrastructure of human cardiomyocyte mitochondria in alcoholic heart disease]

It is shown for the first time that energy dependent alterations of mitochondrial ultrastructure, well studied in vitro, can be demonstrated in vivo in human cardiomyocytes on the material of endomyocardial biopsies of the left ventricles taken from patients with alcoholic heart disease. Mitochondria in cardiomyocytes of these patients were in four energy dependent ultrastructural states: orthodoxal, energized, energized-twisted, deenergized. These alterations are interpreted as resulting from mitochondrial energetic disturbance in alcoholic heart disease.

Contraction transitions of F1-F0 ATPase during catalytic turnover

Strong acoustic pressure was applied to submitochondrial particles (SMP) from bovine heart in order to drive ATP synthesis by F1-F0 complex for the account of sound waves. We observed a net ATP production at two narrow frequency ranges, about 170 Hz and about 340 Hz, that corresponds to the resonance oscillations of experimental cuvette when the acoustic pressure had a magnitude of 100 kPa. The results can be explained quantitatively by contractive conformational changes of F1-F0 complex during catalytic turnover. Negative staining electron microscopy of SMP preparations was used to visualize the ADP(Mg2+)-induced conformational changes of F1-F0 complex. In the particles with high ATPase activity in the presence of phosphate the factors F1 and F0 formed a congregated domain plunged into the membrane without any observable stalk in between. The presence of ADP(Mg2+) caused a structural rearrangement of F1-F0 to the essentially different conformation: the domains F1 and F0 were dislodged distinctly from each other and connected by a long thin stalk. The latter conformation resembled well the usual bipartite profile of ATPase. The data indicate that besides rotation, the catalytic turnover of ATP synthase is also accompanied by stretch transitions of F1-F0 complex.

[Destructive changes in the mitochondria of human cardiomyocytes in alcoholic heart lesion]

Destructive changes in cardiomyocyte mitochondria of patients with diagnosis of alcoholic heart lesion were observed by the ultrastructural analysis of the endocardial biopsies serial sections. The appearance of mitochondria with the third additional compartment and mitochondria having two zones of different electron density not separated into the special compartments are described for the first time. The development of megamitochondria having different morphology is demonstrated. Mitochondrial origin of lipophuscin granules is suggested on the basis of the ultrastructural changes. Unusual structure of atypical mitochondria may provide new properties of these organelles this being considered by the authors as an adaptive cell and mitochondria response to the new metabolic conditions.

Ultrastructure of mitochondrial reticulum of human cardiomyocytes in alcohol cardiomyopathy

Endomyocardial left ventricular biopsy material from patients with chronic alcoholism exhibits structural alterations of the mitochondrial reticulum in alcohol cardiomyopathy. The progress of gradually developing structural changes depends on the stage of the disease. The early stage of the disease is characterized by spatial reorganization of the mitochondrial reticulum: intermitochondrial junctions disappear and mitochondria form separate clusters uniformly distributed within a muscle cell. Subsequently, in the second and third stages of chronic disease, destructive irreversible changes in the ultrastructural organization of mitochondria develop. Megamitochondria and septate mitochondria appear. A third additional compartment containing granules forms in mitochondria. Many lipofuscin granules appear due to the accumulation of lipids in mitochondria. Structural changes of the mitochondrial reticulum are considered as a compensatory adaptive reaction of the cardiomyocyte mitochondrial system in response to altered myocardial function in alcohol cardiomyopathy, including abnormalities in the cardiac rhythm and ventricular conductance.

[Ultrastructure of intermitochondrial contacts of human cardiomyocytes in alcoholic cardiomyopathy and ischemic heart disease]

Intermitochondrial contacts in human cardiomyocytes are revealed. In alcoholic cardiomyopathy they have the same morphological features as those previously described in the cardiomyocytes of vertebrates. The ultrastructure of these contacts in patients with circulation deficiency in ischemic heart disease is altered. This alteration of the ultrastructure may represent a direct reaction of the cardiomyocyte mitochondrial system to the change in the level of energetic metabolism.

Relationship between structure and function of liver mitochondria from hibernating and active ground squirrels, Citellus undulatus

1. Electron microscopy of liver tissue preparations, obtained from hibernating ground squirrels, reveals mitochondria in a condensed state. 2. When kept on ice, mitochondria isolated from the livers of hibernating and active ground squirrels are in a shrunken state. 3. Incubation of mitochondria isolated from the livers of active ground squirrels in the presence of succinate, at 27 degrees C, results in mitochondrial swelling, while mitochondria from hibernating ground squirrels under the same conditions remain relatively shrunken. 4. The swollen mitochondria from active ground squirrels show high oxidative activity, while the shrunken mitochondria from hibernating animals show low oxidative activity. 5. Swelling of mitochondria from hibernating ground squirrels in a hypo-osmolar medium is accompanied by a significant increase in oxidative activity. 6. It is inferred that the shrinkage of hibernating ground squirrel mitochondria is one of the main causes of the inhibition of oxidative activity and other mitochondrial functions during hibernation.

[Formation of gigantic mitochondria in human blood lymphocytes under the effect of an He-Ne laser]

A phenomenon of formation of giant mitochondria in lymphocytes after He-Ne-laser irradiation (56 J/m2, 5.6 W/m2) was discovered. Reconstruction of mitochondria from ultrathin sections through the whole lymphocyte showed that 1 h after the irradiation the number of mitochondria was reduced to 9-12 compared to 40-45 in the control cells. In the irradiated lymphocytes 2-4 branching giant mitochondria were revealed instead of small discrete mitochondria in the control cells. Other 6-7 mitochondria were found to retain their shape and volume. It is suggested that the giant mitochondria are formed by fusion of small mitochondria. Formation of giant mitochondria may reflect the increase in the energy exchange level.

[Two qualitatively different structuro-functional states of mitochondria]

Low (120 mosM) tonicity of incubation media of mitochondria was found to be associated with anomalous phase transition at 19--26 degrees C. A rise in temperature caused a decrease in the pyrene excitation in border lipids of the mitochondrial membrane. Within this temperature range the quenching of intrinsic protein fluorescence by pyrene was sharply decreased. It may be inferred from these data that at 100mosM tonicity and temperatures below 19 degrees C, mitochondrial membrane proteins are in an aggregated state. At temperatures above phase transition protein deaggregation takes place. It was shown that a decrease in tonicity from 300 to 120 mosM at 15 degrees C or a rise in temperature from 15 degrees to 37 degrees C at 300 mosM tonicity increased the phosphorylation of the 52 kDa mitochondrial protein. It was assumed that swelling of mitochondria in hypotonic media simulates one of the steps of the hormone-induced signal transfer in mitochondria in vivo.

[Existence of an additional structural component in the basal bodies of Escherichia coli and Vibrio alginolyticus flagellae]

The structure of Escherichia coli and Vibrio alginolyticus flagella was studied using electron microscopy. An additional protein structure was shown to exist in the basal bodies of intact flagella in these organisms. It is possible that this structure involves three proteins important for the assembly of flagella, energy transduction, and a change-over in the direction of flagellar rotation.

Coupling membranes as energy-transmitting cables. I. Filamentous mitochondria in fibroblasts and mitochondrial clusters in cardiomyocytes

An hypothesis considering mitochondria as intracellular power-transmitting protonic cables was tested in human fibroblasts where mitochondria are thin and long and in rat cardiomyocytes where they show cluster organization. Mitochondria in the cell were specifically stained with fluorescent-penetrating cation ethylrhodamine, which electrophoretically accumulates in the mitochondrial matrix. A 40-micron-long mitochondrial filament of fibroblast was illuminated by a very narrow (less than or equal to 0.5 micron) laser beam to induce local damage of the mitochondrial membranes. Such a treatment was found to induce quenching of the ethylrhodamine fluorescence in the entire filament. According to the electron microscope examination, the laser-treated filament retained its continuity after the laser illumination. Other mitochondrial filaments (some of which were localized at a distance less than 10 micron from the laser-treated one) remained fluorescent. In a cell where mitochondrial filaments seemed to be united in a network, laser illumination of one filament resulted in fluorescence quenching in the whole network, whereas fluorescence of small mitochondria not connected with the network was unaffected. The illumination of cardiomyocyte was found to result in the fluorescence quenching not only in a laser-illuminated mitochondrion but also in a large cluster of organelles composed of many mitochondria. Electron microscopy showed that all the mitochondria in the cluster change from the orthodox to the condensed state. It was also found that mitochondria in the cluster are connected to one another with specific junctions. If a mitochondrion did not form junctions with a quenched cluster, its fluorescence was not decreased even when this mitochondrion was localized close to an illuminated one. The size of the mitochondrial cluster may be as long as 50 micron. The cluster is formed by branched chains of contacting mitochondria, which may be defined as Streptio mitochondriale. In the cardiomyocyte there are several mitochondrial clusters or, alternatively, the quenched cluster is a result of decomposition of a supercluster uniting all the mitochondria of the cell. Cluster organization of mitochondria could also be revealed when a single mitochondrion was punctured in situ with a microcapillary. The obtained data are in agreement with the idea that mitochondrial junctions are H+ permeable so that, within the cluster, delta psi may be transmitted from one mitochondrion to another. The above results are consistent with the assumption that mitochondrial filaments or networks represent a united electrical system.(ABSTRACT TRUNCATED AT 400 WORDS)

[Similarity of Vibrio alginolyticus, V. cholerae and other Vibrio species with respect to the structure of their flagellar apparatus and ribosomal 5S-RNA]

Electron microscopic analysis of basal bodies of the flagella Vibrio alginolyticus revealed a structure composed of four discs. The diameters of two discs localized in the cytoplasmic membrane appeared to be twice as little as those of the other two discs. In this respect the basal body of V. alginolyticus resembles that of V. cholerae. The 5S sequence of ribosomal RNA from V. alginolyticus appeared to be similar to those of V. cholerae, V. harveyi and some other vibrios. Comparison of 5S-RNA sequence culminated in a dendrogram of evolutionary relationships of various bacterial species, suggesting that V. alginolyticus is a typical representative of the Vibrionacea family. The data obtained are discussed in terms of the role of Na+ energy metabolism in living cells.

The sodium cycle. III. Vibrio alginolyticus resembles Vibrio cholerae and some other vibriones by flagellar motor and ribosomal 5S-RNA structures

An electron microscopic study of the basal bodies of the Vibrio albinolyticus flagellum revealed a four-disc structure. The diameters of the two discs localized closer to the cytoplasmic membrane proved to be about 2-fold shorter than those of the two others. In this respect the basal body of V. alginolyticus resembles very much that of V. cholerae described by Ferris and co-workers. The sequence of the V. alginolyticus ribosomal 5S-RNA showed that it is similar to those of V. cholerae, V. harveyi and some other vibriones. On the basis of the 5S-RNA sequences, a dendrogram of prokaryotes is presented. It confirmed the suggestion that V. alginolyticus is a typical representative of Vibrionaceae rather than a 'monster' greatly differing from other vibriones. Possible evolutionary relation of various bacterial species possessing the primary Na+ pumps is discussed.

[Effect of palmitate on energy coupling in lymphocyte mitochondria]

In the presence of 0.1 micrograms/ml of oligomycin, DNP (40-60 microM) increases lymphocyte respiration 10-fold and more. Palmitate taken at the same concentration stimulates the respiration of isolated mitochondria (1-2 mg prot/ml) in the presence of 1 mg/ml of BSA and the respiration of lymphocytes (10(8) cells/ml). When BSA and EGTA are absent in mitochondria isolation media, the mitochondrial respiration does not increase after DNP or ADP addition. Lymphocyte preparations are mostly distinguished by mitochondrial morphology in the presence of the uncoupler; they differ less by changes in dis-C3-(5) fluorescence after addition of 5-10 microM DNP and only insignificantly by the stimulation of respiration by DNP and palmitate. These results may be explained by the increase in the uncoupler-induced permeability of mitochondria for K+ and by partial transformation of delta psi m into delta pH in some cells, which may increase the cell resistance to damaging influences.

[Mitochondrial nature of newly synthesized DNA in aging coleoptiles of etiolated wheat shoots]

In mature ageing coleoptiles as well as in cut-off etiolated wheat shoots exhausted by incubation in H2O nuclear DNA (nDNA) synthesis does not occur. However, the synthesis of another DNA is continued under these conditions. The parameters of this DNA (e. g. buoyant density, rho = 1.716 g/cm3, and composition - 56 mol.% GC) differs from those of nDNA (rho = 1.700 g/cm3, 44 mol.% GC). The newly synthesized DNA is non-methylated and metabolically stable. It is not sensitive to cycloheximide (20 micrograms/ml) but is markedly inhibited by ethidium bromide (2-10 micrograms/ml). The synthesis of this DNA is localized in the mitochondria, thus indicating that in ageing coleoptiles and exhausted wheat shoots all the newly synthesized DNA is of mitochondrial origin.

[Interaction of diS-C3-(5) and ethylrhodamine with lymphocyte mitochondria]

The interaction of thymocyte mitochondria with two types of dyes - potential indicators commonly used in lymphocyte studies, has been investigated. Ethylrhodamine at concentrations up to 16 microM does not influence the systems of oxidation and energy coupling in lymphocyte mitochondria. Carbocyanines-diS-C3-(5) and diO-C3-(5) inhibit oxygen uptake by the lymphocytes in the presence of glucose and pyruvate at the same low concentrations as does rotenone (40% inhibition occurs at 10 nM). DNP reduces the inhibition of respiration by carbocyanines but not by rotenone. The increase in the fluorescence of diS-C3-(5) and in the rate of oxygen uptake in the absence of diS-C3-(5) occurs at close concentrations of the uncoupler. This indicates that the changes in the fluorescence caused by FCCP reflect the membrane potential of lymphocyte mitochondria. The maintenance of the membrane potential in lymphocyte mitochondria in the presence of diS-C3-(5) provides evidence for the absence of the corresponding changes in mitochondrial ultrastructure after addition of 0.6 microM diS-C3-(5) which completely inhibits oxygen uptake.