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。     

ELECTRON MICROSCOPIC RADIOAUTOGRAPHIC DETECTION OF SITES OF PROTEIN SYNTHESIS AND MIGRATION IN LIVER

The sites of synthesis of proteins and their subsequent migration in rat liver have been studied during a 75 min period after labeling of liver-slice proteins by exposure to leucine-H³ for 2 min. Incorporation of the label into protein began after 1 min and was maximal by 4 min. Electron microscopic radioautography showed that synthesis of proteins in hepatocytes occurs mainly on ribosomes, particularly those in rough endoplasmic reticulum and, to some extent, in nuclei and mitochondria. Most of the newly formed proteins leave the endoplasmic reticulum in the course of 40 min, and concurrently labeled proteins appear in Golgi bodies, smooth membranes, microbodies, and lysosomes. A likely pathway for the secretion of some or all plasma proteins is from typical rough endoplasmic reticulum to a zone of reticulum which is partially coated with ribosomes, to the Golgi apparatus, and thence to the cell periphery. The formation of protein by reticuloendothelial cells was measured and found to be about 5% of the total protein formed by the liver.     

Temperature regulation during centrifugal elutriation and its effect on cell separation

Centrifugal elutriation appears to be a promising method for cell separation. The quality of the separation may be limited by the control of temperature within the separation chamber, which affects the fluid viscosity and rotor speed. The factors affecting the temperature regulations have been re-examined. At flow rates between 10 and 40 mL/min the temperature within the chamber was primarily dependent on the temperature of the fluid flowing into the rotor. Increases in the temperature of the fluid while it flowed through the rotor were observed and were greater at higher rotor speeds and lower flow rates. This heating, caused by friction at the rotating seal, could raise the fluid temperature within the chamber by as much as 6 degrees C. Fluctuations in the temperature of the centrifuge produced temperature variations of only 0.3 degrees C in the fluid in the elutriation chamber. Small increases in the rate of elutriation of cells, concomitant with centrifuge cooling and speed fluctuations, were detected by optical density measurements. However, neither the modal volume nor coefficient of variation of the collected cells were affected.     

THE DEVELOPMENT OF MICROBODIES AND PEROXISOMAL ENZYMES IN GREENING BEAN LEAVES

The ontogeny of leaf microbodies (peroxisomes) has been followed by (a) fixing primary bean leaves at various stages of greening and examining them ultrastructurally, and (b) homogenizing leaves at the same stages and assaying them for three peroxisomal enzymes. A study employing light-grown seedlings showed that when the leaves are still below ground and achlorophyllous, microbodies are present as small organelles (e.g., 0.3 µm in diameter) associated with endoplasmic reticulum, and that after the leaves have turned green and expanded fully, the microbodies occur as much larger organelles (e.g., 1.5 µm in diameter) associated with chloroplasts. Specific activities of the peroxisomal enzymes increase 3- to 10-fold during this period. A second study showed that when etiolated seedlings are transferred to light, the microbodies do not appear to undergo any immediate morphological change, but that by 72 h they have attained approximately the size and enzymatic activity possessed by microbodies in the mature primary leaves of light-grown plants. It is concluded from the ultrastructural observations that leaf microbodies form as small particles and gradually develop into larger ones through contributions from smooth portions of endoplasmic reticulum. In certain aspects, the development of peroxisomes appears analogous to that of chloroplasts. The possibility is examined that microbodies in green leaves may be relatively long-lived organelles.     

Actin-endoplasmic reticulum complexes inDrosera

In epidermal cells ofDrosera tentacles that have been preserved for ultrastructural analysis through high pressure freeze fixation and freeze substitution we describe the frequent occurrence of microfilament (MF)-endoplasmic reticulum (ER) complexes. These are found throughout the cytoplasm where they are observed in close association with the plasmalemma (PL), the tonoplast, nuclei, mitochondria, chloroplasts, and microbodies. The MF component of the complexes is identified as actin based on immunogold labelling with actin antibodies. The actin-ER complexes are prominent in the cortical cytoplasm. In this region a network of predominantly tubular ER occupies an intermediary position in which it associates closely with both the PL and the actin MFs. We suggest that the ER, especially those elements adjacent to the PL in the cortical cytoplasm, stabilizes the actin MFs and provides the necessary anchor against which the forces for cytoplasmic streaming are generated.Abbreviations CF chemical fixation - ER endoplasmic reticulum - FS freeze substitution - HPF high pressure freezing - MF microfilaments - MT microtubules - PL plasmalemma     

CORRELATED MORPHOMETRIC AND BIOCHEMICAL STUDIES ON THE LIVER CELL : II. Effects of Phenobarbital on Rat Hepatocytes

The changes occurring in rat hepatocytes during a 5 day period of treatment with phenobarbital were determined by morphometric and biochemical methods, particular attention being paid to the endoplasmic reticulum. The hepatocytic cytoplasm played an overwhelming part in the liver hypertrophy, while the hepatocytic nuclei contributed to only a moderate extent. The endoplasmic reticulum accounted for more than half of the increase in cytoplasmic volume. The increase in the volume and number of hepatocytic nuclei in the course of phenobarbital treatment was associated with changes in the ploidy pattern. Until the 2nd day of treatment both the rough-surfaced endoplasmic reticulum (RER) and the smooth-surfaced endoplasmic reticulum (SER) participated in the increase in volume and surface of the whole endoplasmic reticulum (ER). Subsequently, the values for RER fell again to control levels, whereas those for SER continued to increase, with the result that by the 5th day of treatment the SER constituted the dominant cytoplasmic element. The specific volume of mitochondria and microbodies (peroxisomes) remained constant throughout the duration of the experiment, while that of the dense bodies increased. The specific number of mitochondria and microbodies displayed a significant increase, associated with a decrease in their mean volume. The phenobarbital-induced increase in the phospholipid and cytochrome P-450 content of the microsomes, as well as in the activities of microsomal reduced nicotinamide-adenine dinucleotide phosphate-cytochrome c reductase and N-demethylase, was correlated with the morphometric data on the endoplasmic reticulum.     

The mandibular organ of the lobster,Homarus americanus

The lobster mandibular organ is well vascularized and its polygonal cells are arranged loosely around blood vessels and blood sinuses. Numerous mitochondria and microbodies (peroxisomes) give the acidophilic cytoplasm a finely granular appearance, but there is no evidence of secretory granules. The abundant endoplasmic reticulum is almost entirely agranular and occurs in two morphologically distinct forms: tubular and cisternal. The tubular reticulum is randomly distributed and may represent the site of synthesis and transport of the mandibular organ product. The cisternal reticulum is frequently associated with microbodies. Both forms of endoplasmic reticulum proliferate during mid to late premolt. Mandibular organ ultrastructure closely resembles that of cells known to synthesize steroids or lipids, which suggests that this organ may have a similar function. There is no functional evidence of involvement in molt control in Homarus, but ultrastructural and other evidence suggests an analogy with insect corpus allatum.     

Temperature regulation during centrifugal elutriation and its effect on cell separation

Centrifugal elutriation appears to be a promising method for cell separation. The quality of the separation may be limited by the control of temperature within the separation chamber, which affects the fluid viscosity and rotor speed. The factors affecting the temperature regulation have been re-examined. At flow rates between 10 and 40 mL/min the temperature within the chamber was primarily dependent on the temperature of the fluid flowing into the rotor. Increases in the temperature of the fluid while it flowed through the rotor were observed and were greater at higher rotor speeds and lower flow rates. This heating, caused by friction at the rotating seal, could raise the fluid temperature within the chamber by as much as 6°C. Fluctuations in the temperature of the centrifuge produced temperature variations of only 0.3°C in the fluid in the elutriation chamber. Small increases in the rate of elutriation of cells, concomitant with centrifuge cooling and speed fluctuations, were detected by optical density measurements. However, neither the modal volume nor coefficient of variation of the collected cells were affected.     

PHYSIOLOGICAL IMPLICATIONS OF VICIA FABA AND NICOTIANA TABACUM GUARD-CELL ULTRASTRUCTURE

The guard cells of Vicia faba and Nicotiana tabacum contain numerous mitochondria, elements of endoplasmic reticulum, spherosomes, and peroxisome-like microbodies. A full ribosomal complement appears in young but not in fully mature guard cells. Numerous small lipid droplets external to the plasmalemma were noted in mature Vicia guard cells. Chloroplasts were found in both epidermal and guard cells of both species. Full photosynthetic capacity was indicated by the grana fretwork of guard-cell chloroplasts. A specialized peripheral reticulum was observed in the guard-cell chloroplasts of Vicia. Plasmodesmata were observed in both walls between sister guard cells and between guard and epidermal cells. In the latter case plasmodesmata were found primarily in pit fields of transverse walls. It is postulated that the small volume of guard cells allows them an osmotic advantage over larger neighboring cells in generating turgor.     

Proteinaceous crystals in cells of virus infected plants

Crystal-containing organelles in cells of virus infected plants lying at chloroplasts and mitochondria are identical with single membrane-bound microbodies containing crystals of catalase described in healthy plants. Massive complex inclusions caused by turnip mosaic virus very frequently contain the same microbodies with crystal inclusions; that phenomenon may be related to some pathophysiological changes of virus infected plants. Comparable proteinaceous crystals, but not lying within microbodies limited by a membrane, may also be found in cytoplasm of infected cells. These crystals are sometimes surrounded by a substance resembling the microbody matrix. Disintegrated cytoplasm of virus infected cells may also contain the same crystals lying free in “empty spaces”. Cytopathological effects responsible for this phenomenon and possible artifacts as well are discussed.     

猫肾离体保存中亚细胞水平上Ca^2＋浓度的X—射线微区分析

应用定量Ｘ－射线微区分析技术结合细胞化学技术,分析测定用单纯冷冻法保存离体猫肾脏过程中肾脏细胞的胞浆、线粒体、内质网、细胞核等细胞器内的Ｃａ２＋浓度变化,并探索钙通道阻滞剂对这种变化的影响。保存３６小时及７２小时后,线粒体与胞浆中Ｃａ２＋的峰背比极显著地提高,内质网、细胞核中钙颗粒减少。添加Ｖｅｒａｐａｍｉｌ后,保存过程中细胞器内Ｃａ２＋无显著变化。线粒体中的Ｃａ２＋峰背比与胞浆中的呈强的正相关,ｒ＝０９９０。实验结果显示：保存过程中,Ｃａ２＋由钙库（内质网等）进入胞浆中,线粒体在胞浆Ｃａ２＋浓度高时摄取Ｃａ２＋,而钙通道阻滞剂可抑制该过程。     

NEW OBSERVATIONS ON MICROBODIES : A Cytochemical Study on CPIB-Treated Rat Liver

The liver of male rats has been studied after CPIB stimulation by using the peroxidase reaction for localizing catalase in hepatic cells. CPIB administration leads to an increase in the number of microbodies, and it is suggested that one mechanism by which microbody proliferation occurs is a process of fragmentation or budding from preexisting microbodies. Reaction product was observed not only within the microbody matrix, but outside the limiting membrane of the microbody and in association with ribosomes of adjacent rough endoplasmic reticulum. This localization of reaction product is interpreted as evidence that catalase after synthesis on rough endoplasmic reticulum may accumulate near microbodies and may be transferred directly into these organelles without traversing the cisternae of the endoplasmic reticulum or Golgi apparatus.     

Synthesis of prenyl lipids in cells of spinach leaf. Compartmentation of enzymes for formation of isopentenyl diphosphate

Purified spinach chloroplasts incorporate [1-14C]isopentenyl diphosphate into prenyl lipids in high yields. The immediate biosynthetic precursors of isopentenyl diphosphate (hydroxymethylglutaryl-CoA, mevalonate, mevalonate-5-phosphate, mevalonate-5-diphosphate), on the other hand, are not accepted as substrates and the corresponding enzymes hydroxymethylglutaryl-CoA reductase, mevalonate kinase, phosphomevalonate kinase, and diphosphomevalonate decarboxylase are not present in the organelles. These enzymes can only be detected in a membrane-bound form at the endoplasmic reticulum (hydroxymethylglutaryl-CoA reductase) and as soluble activities in the cytoplasm. The concept is developed that isopentenyl diphosphate is formed in the cytoplasm as a 'central intermediate' and is distributed then to other cellular compartments (endoplasmic reticulum, plastids, mitochondria) for further biosynthetic utilization.     

Functional anatomy of the mechanoreceptor cells in tendrils of Bryonia dioica Jacq.

The ultrastructure of epidermal cells of tendrils of Bryonia dioica Jacq. (Cucurbitaceae) was determined using microscopic, histochemical and immunochemical techniques with focus on the tactile blep, the mechano-receptor of these cells. Tactile bleps resemble bordered pits in structure and probably in formation. They contain cytoplasm rich in endoplasmic reticulum, dictyosomes, mitochondria and microbodies. The cytoplasm is highly vesiculated and usually contains lipid-body-like structures. Cytoskeletal elements (microtubules, actin filaments) are uniquely arranged in the tactile blep, and chlorotetracycline-fluorescence analysis shows large amounts of membrane-associated calcium within the tactile blep. We propose a physically interconnected cytoskeleton-membrane device as the immediate force sensor and transducer which creates a primary intracellular signal, for which calcium is a likely candidate.Abbreviations CTC chlorotetracycline - ER endoplasmic reticulum - MT microtubule This work was funded by grants of the Deutsche Forschungsgemeinschaft to E.W.W. and G.W. (SFB 1462) and by the Fonds der Chemischen Industrie (literature provision).     

Additional data on complex inclusions evoked by wisteria vein mosaic virus in pea leaf cells

Large complex inclusions evoked by wisteria vein mosaic virus contain cylindrical inclusions, mostly pinwheels (and bundles) and rarely also scrolls and laminar inclusions. Bundles are often abutted to cell walls at plasmodesmata and show association with endoplasmic reticulum and cisternae. Virus aggregates are attached to cylindrical inclusions, various membranes and/or plasmalemma. Cytoplasm contains more or less disintegrated chloroplasts and mitochondria, abnormal membranes, many ribosomes, bounded vesicles with fibrillar contents, numerous and large microbodies, and membranous whorls. These phenomena are not specific.     

Addressed protein transport in the cell

The paper summarizes data on the nature of signals (mainly amino acid sequences) determining the intracellular movement of newly formed polypeptide chains: their secretion, incorporation into the cytoplasmic or endoplasmic reticular membranes, into different compartments of mitochondria and chloroplasts. Some information is given about the polypeptide transport into the nucleus and microbodies (glyoxysomes, peroxysomes, glucosomes). The intracellular movement of polypeptides is supposed to be proteolytically controlled.     

Shedding of peripheral cytoplasm - a mechanism of liver cell atrophy in human amyloidosis.

A liver biopsy specimen from a case of primary amyloidosis was investigated by electron microscopy. The cytoplasmic periphery of the hepatocytes showed degenerativechanges which are interpreted as indicating shedding of peripheral parts of the cytoplasm. Two main variants of this process could be discerned: 1) Protrusion and sequestration of hernia-like blebs of cytoplasm, and 2) shedding of vesicles derived from degenerated endoplasmic reticulum. In the latter case transient defects of the plasma membrane seem to be relevance. Endoplasmic reticulum and cytoplasmic ground substance appeared to be shed preferentially, whereas mitochondria are retained within the cell. As a consequence the fractional volume of the mitochondria in the cytoplasm of atrophic cells is markedly increased. Shedding of peripheral cytoplasm, therefore, seems to be an effective mechanism enabeling the cell to adapt the mass and the composition of its cytoplasm to an unfavourable environment.     

高度抗寒植物冬季线粒体的电镜观察

冬季沙冬青叶肉我线粒体相当丰富,常常位于叶绿体出芽和分裂处,在质膜大量内隐形成管状细胞的附近和含有颗粒状物质、膜状物质或特殊内含和的周围也随时可见了线粒体也经常与微体和叶绿体在一起。有时甚至还不同程度地被内多所包围。沙冬青叶肉细胞中的的线粒一般灯承圆形,被膜清晰完整,嵴丰富,基质电子度较高。有时基质中有小泡或电子密度很高的颗粒和内含物,个别线粒体的基质中学有类髓样体结构。文中讨论了沙冬青线粒体的形     

甜菜夜蛾微孢子虫研究:Ⅲ.超微结构与致病机理

从甜菜夜蛾幼虫体内首次分离到一种侵染寄主脂肪体、马氏管和中肠的微孢子虫,该微孢子虫对甜菜夜蛾、菜青虫和棉铃虫幼虫有较强的致病力,并可经卵垂直传播;水平传播主要借助于病虫的粪便及虫尸。用电镜观察了该微孢子虫感染甜菜夜蛾幼虫后的超微结构变化。结果表明：寄主细胞被感染后,细胞核膨大并变形,由正常的圆球形被挤压成长条状,但核膜及核周间隙没有发生变化;线粒体体积变小,嵴增宽,嵴的排列方向发生改变,双层膜部分     

Studies on the leaf of Amaranthus retroflexus (Amaranthaceae): ultrastructure,plasmodesmatal frequency,and solute concentration in relation to phloem loading

Both the mesophyll and bundle-sheath cells associated with the minor veins in the leaf of Amaranthus retroflexus L. contain abundant tubular endoplasmic reticulum, which is continuous between the two cell types via numerous plasmodesmata in their common walls. In bundle-sheath cells, the tubular endoplasmic reticulum forms an extensive network that permeates the cytoplasm, and is closely associated, if not continuous, with the delimiting membranes of the chloroplasts, mitochondria, and microbodies. Both the number and frequency of plasmodesmata between various cell types decrease markedly from the bundle-sheath — vascular-parenchyma cell interface to the sicve-tube member — companion-cell interface. For plants taken directly from lighted growth chambers, a stronger mannitol solution (1.4 M) was required to plasmolyze the companion cells and sieve-tube members than that (0.6 M) necessary to plasmolyze the mesophyll, bundle-sheath, and vascular-parenchyma cells. Placing plants in the dark for 48 h reduced the solute concentration in all cell types. Judging from the frequency of plasmodesmata between the various cell types of the vascular bundles, and from the solute concentrations of the various cell types, it appears that assimilates are actively accumulated by the sieve-tube — companion-cell complex from the apoplast.