Wheat root cells functioning under inhibition of I and II complexes of mitochondrial respiratory chain

A joint effect of rotenone and malonate on the intensity of respiration, output of K+ and ultrastructure of wheat root cells treated for 6 h was studied. The addition of malonate to rotenone containing solution, in which wheat roots had been incubated for an hour, caused further decrease in respiration intensity and K+ output into external medium. Many mitochondria acquired torus shape in 2h after malonate addition. The increase in respiratory intensity and re-entry of K+ from the incubation medium into the cells were observed during following hours of incubation. We assume that reparation and adaptation processes took place in this case. The observed contacts of endoplasmic reticulum lumens with mitochondria are indicative of possible synthesis of an enzyme able to metabolize malonate to acetyl-CoA and CO2. We propose that torus shape of mitochondria is due to the increase in their outer surfaces, that, in turn, is a result of activation of external NAD(P)H-dehydrogenase. These findings may be evidence of possible adaptation of the root cells to the joint effect of the inhibitors.     

Ultrastructural characteristics of mitochondria during cell adaptation to rotenone

A study was made of respiration, heat production, K+ output and ultrastructure of wheat root cells treated for 6 h with rotenone (10 microM), an inhibitor of HADH-ubiquinone oxidoreductase (Complex I). Besides, the involvement of alternative pathways for adaptation to this inhibitor was studied. After 20 min of treatment, a brightened mitochondrial matrix and mitochondria with torus shapes were observed. We propose that the outer area of mitochondria increases due to their torus shapes, and this can point to the activating of extremal NAD(P)H-dehydrogenase, which uses enternal NAD(P)H. Further on the normal ultrastructure of mitochondria was observed, which may result from activation of succinate dehydrogenase and rotenone resistant NAD(P)H-dehydrogenase. After 1 h of treatment, a decrease in respiration, heat production, K+ output and pH increase of incubation medium were observed. Starting from 2 h of incubation and up to the end of the experiment, an increase of respiration and heat production was observed, pointing to the activation of oxidative phosphorilation. Besides, re-entry of K+ and pH decrease in the incubation medium were observed. We conclude that these findings may indicate to a possible adaptation of root cells to this inhibitor. We propose that the torus shape of mitochondria may be associated with function of external NAD(P)H-dehydrogenase.     

Peculiarities of functioning of wheat cut-off root cells at inhibition of complexes I and II of mitochondrial respiratory chain

Combined action of rotenone and malonate, inhibitors of complexes I and II of the mitochondrial electron transport chain (ETC), on wheat cut-off root seedlings was studied after 6 h of incubation. Intensity of oxygen consumption and release of potassium ions into incubation medium were determined simultaneously with the study of changes in cell ultrastructure. Malonic acid was added 1 h after the root incubation in the rotenone solution and produced inhibition of respiration, as well as a greater release of K⁺ into the incubation solution as compared with effect of rotenone alone. After 2 h of the combined action of these inhibitors, many mitochondria acquired a toroidal shape, thereby increasing the outer surface. For the ensuing hours, stimulation of oxygen consumption by the roots and a decrease of K⁺ content in the incubation medium were observed. Mitochondria once again acquired a round or oval shape and compensation-reparation processes took place. Contacts of endoplasmic reticulum channels with mitochondria were observed, which seems to be due to the synthesis of the enzyme splitting malonate to acetyl-CoA, which in turn can be included both into the Krebs cycle and into lipogenesis. It is suggested that the toroidal form of mitochondria is associated with the activation of the external NAD(P)H-dehydrogenase of the inner mitochondrial membrane, as under these conditions, at the inhibition of the ETC complexes I and II, the activity of other dehydrogenises is blocked. Thus, the use of the external NAD(P)H allows the activity of the ETC mitochondria to be restored, which facilitates the course of the reparation processes and allows cells to be adapted to this action.     

Destructive and restorative processes of the liver in rats under intensive physical loading

The ultrastructure of rat liver cells after running exercise was investigated. When rats were trained for a month and sacrificed immediately after the last exercise it was revealed that the number of liver cells mitochondria increased, but many of them had alterations: mitochondria became swollen, had lucid matrix. There were some variations in degree of alterations between different mitochondria: a) in the same hepatocyte, b) in different hepatocytes of the same animal, that was connected with individual sensitivity of organelles on the levels of the cell and of the organ. Rough endoplasmic reticulum bore few ribosomes. Glycogen was absent. There were abundant vesicles of smooth endoplasmic reticulum, autophagic vacuoles and peroxisomes in the liver cell cytoplasm. Adaptation of rat liver to the exercise programme becomes evident by 1.5 month of exercise. Mitochondria and rough endoplasmic reticulum were numerous and of normal structure. There were many peroxisomes and glycogen granules in the cytoplasm of hepatocyte. The presence of large autophagic vacuoles in the cytoplasm of some hepatocytes were obviously connected with more rapid destruction of some organelles, than in control.     

Dynamics of structural and functional changes in wheat root cells under the action of protonophore

Structural and functional changes in wheat root cells during long-term action of a protonophore--carbonyl cyanide 3-chlorophenylhydrazone (CCCP)--were studied. It was demonstrated that CCCP affected the electrical potential and inward resistance of cells, increased K+ ions release to the incubation medium, inhibits oxygen uptake for 1-4 h, which was followed by oxygen uptake stimulation for 6 h of treatment. These changes of physiological processes were accompanied with a variety of ultrastructural changes in cell organization, namely in the structure of mitochondria, endoplasmic reticulum canals, and the nucleus. The role of protons is discussed, in particular, in the regulation of metabolic state of mitochondria, and in general regulation of structural and functional conditions of cells.     

Intracellular Transport and Elimination of Resin from Epithelial Duct-cells of Pinus halepensis

The ultrastructure of the resin secreting cells of root ductsof young Pinus halepensis seedlings was studied. It is suggestedthat the endoplasmic reticulum (ER) in addition to taking partin resin synthesis also plays a role in transporting the resinfrom the plastids, mitochondria and nuclear envelope to theplasmalemma. By fusing with the plasmalemma the ER releasesthe resin to the outside of the protoplast. The resin producedin the ground cytoplasm and by the Golgi apparatus seems tobe eliminated by plasmalemma invaginations. Pinus halepensis, resin secretion, root ducts, endoplasmic reticulum     

Comparative study of the ultrastructure of immune and normal phytohemagglutinin-treated lymphocytes]

Immune lymphocytes sorbed on the surface of the target cells were characterized during the period of the first three hours of combined incubation by the presence of the electron-dense matrix, abundance of mitochondria and lipids; small lymphocytes had disseminated ribosome organized into polysomes in the medium lymphocytes forming individual cysterns of the granular endoplasmic reticulum in the large lymphocytes, this indicating active protein synthesis by these cells. There were also revealed cells of plasmatic type. Cells incubated with the PHA for one hour represented a homogenous population of small lymphocytes of the same size as the clear cytoplasm containing free ribosomes and individual mitochondria. The proportion of the medium lymphocytes and the blasts increased with increase of the incubation period. These are cells with the clear cytoplasm freely disseminated polyribosomes in which no developed granular endoplasmic reticulum was sometimes revealed. The presence of two types of cells whose ultrastructure reflected their functional characteristics is discussed.     

细叶黄芪叶肉原生质体发育早期几种细胞器的变化

在细叶黄芪叶肉原生质体发育早期,细胞器的变化较大。离体培养4h后,线粒体的嵴和基质物质开始增加。培养3—5天后,线粒体的数量增加5倍以上,此时可见大部分线粒体围绕细胞核分布。在培养24h后,高尔基体开始发育,它们主要分布在细胞质周边区域。多糖细胞化学染色表明,高尔基体内沉积着大量嗜银物质。培养1天后,粗面内质网开始发育。培养3天时,部分叶绿体边缘出现一些空隙结构。随着叶绿体内膜结构的消失,淀粉粒增大,叶绿体逐渐转变为造粉质体。     

GL生根剂对扶桑插条不定根皮层细胞超微结构的影响

研究了GL生根剂对扶桑插条不定根皮层细胞超微结构的影响。GL生根剂使皮层细胞中线粒体和内质网增加,液胞、线粒体和内质网膜有局部损害．经GL生根剂处理的皮层细胞含有的淀粉粒和脂质体数目较对照皮层细胞多．该实验结果为了解GL生根剂促进不定根形成的原因提供了细胞学基础．     

Effects of glucose starvation on mitochondrial subpopulations in the meristematic and submeristematic regions of maize root

Mitochondria isolated from 3-mm long maize (Zea mays L. var Dea) root tips were found to be heterogeneous on Percoll density gradients. The ultrastructure of these isolated mitochondria correlated well with that of mitochondria observed in situ and was consistent with the existence of mitochondria at different stages of maturation during cell development. The mitochondria of higher density presented an ultrastructure with many cristae and a dense matrix. These mitochondria showed classic respiratory properties, although with low ADP/O ratios. In contrast, the mitochondria of lower density showed few cristae and a clear matrix and did not seem to be fully functional because their rate of respiration was low and showed weak respiratory control. Lower- and higher- density mitochondria were shown to be differentially affected during the first stages of glucose starvation. The higher-density mitochondria from glucose-starved maize root tips retained the ultrastructure and most of the respiratory properties of nonstarved mitochondria, whereas lower- and intermediate-density mitochondria were absent in the mitochondrial preparations from glucose-starved maize root tips and were not observed in situ. Quantitatively, there was a decrease of the total mitochondrial pool when expressed as the amount of mitochondrial protein per root tip. However, this decrease affected low- and intermediate-density mitochondria, but not higher-density mitochondria. Thus, it was shown that a significant pool of functional mitochondria is maintained in maize root tips during the first stages of glucose starvation. The reasons for these apparently selective effects of glucose starvation on mitochondria are discussed in relation to effects on mitotic and differentiation processes.     

Increase in the number of contacts of endoplasmic reticulum with mitochondria and plasma membrane in yeast cells stimulated to division with He-Ne laser light

We studied the ultrastructure of Torulopsis sphaerica yeast cells irradiated with He-Ne laser (lambda = 632.8 nm, dose--460 J/m2) and then cultured for 6 h in the nutrient with 1% glucose by aeration. The length of membranes of endoplasmic reticulum (ER) and the number of its associations with mitochondria (M) and plasma membrane (PM) were measured on ultrathin sections. A distance of less than 50 nm between heterogeneous membranes was considered as an "association". The cells from irradiated cultures are characterized by the following features: 1) the length of cortical ER membranes in relation to cellular perimeter, and the length of perinuclear ER membranes in relation to nuclear perimeter increase, resp., by 21 and 79%; 2) the number of ER-PM associations per cellular section, and that per unit of PM length increase, resp., by 26 and 41%; 3) the number of ER-M association in relation to the total mitochondrial perimeter, and to perimitochondrial ER increase by 80 and 87%, resp. The latter may be associated with Ca2+ uptake by mitochondria associated with ER, which results in activation of respiration and ATP production.     

Ultrastructure of the steroidogenic cells in the ovary of the Russian sturgeon before and after maturation under exposure to luliberin

Cells with the ultrastructure typical of steroid cells of vertebrates were found in the theca and stroma of the Russian sturgeon ovary. Mitochondria with the tubulo-vesicular internal structure, smooth and rough endoplasmic reticulum, lipid droplets or liposomes were observed in the cytoplasm of these cells. After the ovulation of fishes, the volumetric density and mean diameter of cell mitochondria and of the reticulum are found to increase; besides, mitochondria are seen vacuolized. The ultrastructural changes may indicate that the production of steroid sex hormones is more intensive in fish during ovulation. These suggestions are in accordance with biochemical data available in the literature.     

Embryogenesis and germination in rye (Secale cereale L.)

Summary When rye embryos imbibe water they rapidly return to a condition of biochemical and structural complexity. Three stages of imbibition can be recognised: Phase I a short period (10 min) of physical wetting; Phase II a longer period (1 h) when little further imbibition occurs, followed by Phase III a continuous phase of active water uptake. The latter coincides with an increase in respiration rate and an increase both in the number of mitochondria and of cristae within them. Changes in fine structure become evident in all organelles in Phase III, after 2 h of imbibition. In the unimbibed embryo endoplasmic reticulum is present only as short crescents associated with electron lucent bodies, but in Phase III the endoplasmic reticulum proliferates to form many surrounding cirlets. After 6 h these circlets become fewer and instead the endoplasmic reticulum is seen in close association with the nuclear membrane. Concurrently incorporation of radioactive uridine and thymidine is first detectible. This suggests that the large increase in protein synthesis occurs on new ribosomes present on the reticulum associated with the nuclear membrane. For the first 6 h protein synthesis must occur either on polysomes within the dense packing of ribosomes or on these circlets of endoplasmic reticulum associated with electron lucent bodies.     

Synergistic effect of insulin and follicle-stimulating hormone on biochemical and morphological differentiation of porcine granulosa cells in vitro

Insulin and follicle-stimulating hormone (FSH) have been shown to facilitate granulosa cell differentiation in vitro. To gain insight into this process, we evaluated the effects of these hormones, alone and in combination, upon the biochemical parameters of luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor induction and progesterone secretion concomitantly with morphometric analysis of granulosa cell ultrastructure and LH/hCG receptor distribution by quantitative autoradiography under light microscopy. Granulosa cells isolated from small antral follicles (controls) cultured in the absence of exogenous hormones exhibited few microvilli and gap junctions; the mitochondria, endoplasmic reticulum, and Golgi complex were all poorly developed. Progesterone secretion was negligible and the cells bound little [125I]iodo-hCG. Insulin treatment increased gap junction formation, and the extent of smooth and rough endoplasmic reticulum and Golgi complex development (all p less than 0.05) but did not affect mitochondrial ultrastructure or volume. Insulin treatment modestly but significantly increased [125I]iodo-hCG binding and progesterone secretion relative to controls (p less than 0.001). FSH treatment had a similar effect to insulin on cell ultrastructure and additionally enhanced development of the mitochondria and smooth endoplasmic reticulum as well as formation of the microvilli (p less than 0.05). FSH significantly increased [125I]iodo-hCG binding and progesterone secretion relative to insulin-treated samples (p less than 0.001). Combined treatment with insulin and FSH markedly increased gap junction and microvilli formation and enhanced the development of the smooth endoplasmic reticulum and the Golgi complex relative to treatment with either hormone alone (p less than 0.05). Additionally, the combined treatment produced larger mitochondria with tubular christae. Consistent with the morphological development, the combined treatment of insulin and FSH significantly increased progesterone secretion and [125I]iodo-hCG binding (p less than 0.001). Autoradiographic analysis showed that aggregated cells in general exhibited higher LH/hCG receptor density than nonaggregated cells, and a significantly higher overall receptor density compared to nonaggregated cells or to cells treated either with insulin or FSH alone. Our results indicate that insulin and FSH facilitate morphological differentiation of the granulosa cell in a synergistic manner, stimulating gap junctions and microvilli formation and enhancing development of the mitochondria, endoplasmic reticulum, and Golgi complex.(ABSTRACT TRUNCATED AT 400 WORDS)     

铜对鲫鱼脾细胞超微结构的影响

应用透射电镜的方法,研究了三种铜离子浓度对鲫鱼脾细胞超微结构的影响。结果表明：脾细胞超微结构变化明显,主要表现在线粒体和内质网,线粒体双层膜解体,形成空白区,嵴断裂,膨大和扭曲,内质网亦变化明显。     

Steroidogenic characteristics of the adrenal cortex of the mare studied by electron microscopy

The three concentric zones of the horse adrenal cortex (zonae glomerulosa, fasciculata and reticularis) showed marked interpenetration and exhibited a different relative development according to their position in the gland. Whereas the three cortical zones each had a specific histological structure, the ultrastructure of their cells showed a certain qualitative homogeneity. The differences corresponded essentially to the relative abundance of the constituents which are generally considered typical of steroidogeneous cells: mitochondria with vesicular cristae, smooth endoplasmic reticulum and lipid droplets. Their importance increased progressively from the zona glomerulosa to the zona reticularis. In this zone, the presence of gap and septate-like cell junctions, and mitochondria with vesicular cristae in close proximity to a smooth endoplasmic reticulum with numerous dilated tubules, suggested that steroidogenesis may be the most active. Ultrastructural findings were indicative of only quantitative differences between the steroidogenic capacities of the three zones of the mare adrenal cortex.     

The contribution of adenine nucleotide loss to ischemia-induced impairment of rat kidney cortex mitochondria.

Adenine nucleotides and respiration were assayed with rat kidney mitochondria depleted of adenine nucleotides by pyrophosphate treatment and by normothermic ischemia, respectively, with the aim of identifying net uptake of ATP as well as elucidating the contribution of adenine nucleotide loss to the ischemic impairment of oxidative phosphorylation. Treatment of rat kidney mitochondria with pyrophosphate caused a loss of adenine nucleotides as well as a decrease of state 3 respiration. After incubation of pyrophosphate-treated mitochondria with ATP, Mg2+ and phosphate, the content of adenine nucleotides increased. We propose that kidney mitochondria possess a mechanism for net uptake of ATP. Restoration of a normal content of matrix adenine nucleotides was related to full recovery of the rate of state 3 respiration. A hyperbolic relationship between the matrix content of adenine nucleotides and the rate of state 3 respiration was observed. Mitochondria isolated from kidneys exposed to normothermic ischemia were characterized by a decrease in the content of adenine nucleotides as well as in state 3 respiration. Incubation of ischemic mitochondria with ATP, Mg2+ and phosphate restored the content of adenine nucleotides to values measured in freshly-isolated mitochondria. State 3 respiration of ischemic mitochondria reloaded with ATP recovered only partially. The rate of state 3 respiration increased by ATP-reloading approached that of uncoupler-stimulated respiration measured with ischemic mitochondria. These findings suggest that the decrease of matrix adenine nucleotides contributes to the impairment of ischemic mitochondria as well as underlining the occurrence of additional molecular changes of respiratory chain limiting the oxidative phosphorylation.     

The parathyroid gland of the woodchuck (Marmota monax): a study of seasonal variations in the chief cells

The ultrastructure of the parathyroid chief cell in the woodchuck, Marmota monax, was studied during the four seasons of the year. Spring chief cells have stacks of granular endoplasmic reticulum, prominent multiple Golgi zones and many clumped mitochondria. Summer cells resemble those seen in the spring but the mitochondria are associated with stacks of granular endoplasmic reticulum. Multiple areas of stacked granular endoplasmic reticulum characterize the fall chief cells. Their Golgi zones are large and are associated with many dense core secretory granules. Lipoid vacuoles are frequently noted. Winter chief cells have secretory granules and phagolysosomes (dense bodies). Some of these cells contain stacked arrays of granular endoplasmic reticulum associated with mitochondria, others have only short segments. The above morphological findings are discussed in relation to those in other hibernators, the parafollicular (C) cell, and to the cyclic seasonal activities of the woodchuck.     

The influence of protonophore high concentration on the structure and functions of wheat root cells

Protonophore induced structural and functional changes in cells of excised roots of wheat seedlings have been investigated. The vector transfer of H+ inside the cells was accompanied by a decrease in energy supply of these cells (suppression of oxygen consumption and heat release), an output of K+ ions to the incubation medium, and by an increase in its pH value. The initial increase in heat release by roots (1 h) apparently reflects the process of dissipation of deltamicro H+ in plasma membrane. Within the first 5-10 min of exposure of 50 microM CCCP, changes in cell ultrastructure were observed that involved activation of Golgi apparatus, secretion of vesicle contents to the vacuole, and swelling of endoplasmic reticulum canals. Following a 2 h treatment with CCCP, structural and functional changes acquired a destructive character, and after 5-6 h of treatment with protonophore a complete desintegration of cell structure occurred demonstrating formations of myelin-like bodies, fragmentation of plasma membrane, and destruction of the nucleus. Thus, the protonophore induced proton excessive transport inside cells is fast and may cause an irreversible cell de-energization followed by serious disruption of ultrastructural organization of cells leading eventually to their death.     

麻疯树小孢子发育的研究

用透射电镜观察了麻疯树(Jatropha curcas L.)小孢子发育的超微结构。小孢子母细胞时期内质网和质体较多;减数分裂和四分体时期,细胞处于明显的代谢活跃状态,细胞器丰富,主要有内质网、线粒体、质体、高尔基体和球状体;在小孢子发育早期和晚期,线粒体和内质网仍较丰富;小孢子经过高度的不对称分裂后,形成较大的营养细胞和较小的生殖细胞,营养细胞中细胞器数量明显减少,含大量的淀粉和脂类物质,生殖细胞中脂类物质丰富;表皮、药室内壁和中层细胞在小孢子母细胞和四分体时期淀粉粒丰富,小孢子时期明显减少,绒毡层从小孢子母细胞至小孢子发育晚期的细胞器都很丰富,主要为内质网、质体和线粒体,为二胞花粉发育奠定基础。