Intranuclear Inclusions in the Ameboid Cells of Protostelium zonatum*

SYNOPSIS. Two morphologically distinct types of intranuclear inclusions are found in ameboid cells of the protostelid mycetozoan Protostelium zonatum. One type of inclusion is a coiled tubular structure which in cross section appears as cisternae and oval to elliptical vesicles 40–60 nm in diameter. These tubular and vesicular structures are formed by a unit membrane that is connected directly with the inner nuclear membrane. The other type of inclusion is a membrane-bound structure that contains amorphous and/or fibrous material. These inclusions usually are present at several locations in a nucleus. No similar structures occur in the cytoplasm.     

北京鸭产卵期输卵管管状腺细胞超微结构研究

用电子显徽镜对北京鸭输卵管管状腺细胞进行观察。鸭输卵管由五部分组成:漏斗、蛋白分泌部、峡部、壳腺和阴道。蛋白分泌部的管状腺细胞有四种类型。A型细胞有电子密度深色颗粒;B型细胞充满了无定型低电子密度物质;C型细胞具有非常明显的粗面内质网和高尔基复合体;D型细胞是由致密的颗粒和低电子密度的颗粒所组成,腔内充满分泌颗粒。我们在这篇文章中分析了蛋白分泌周期的四个不同阶段。     

Ultrastructure of crystalline inclusions in the thylakoids of dodder<Emphasis Type="Italic">(cuscuta japonica)</Emphasis> plastids

The plastids from seedlings of the parasitic angiospermCuscuta japonica were ultrastructurally investigated. In shoot subapical cells from 3-d-old seedlings grown in the dark, the etioplasts contained prolamellar bodies and amorphous and dense inclusions. In the shoot subapical cells obtained from 6-d-old seedlings grown under light conditions for the last 3 d, the underdeveloped chloroplasts contained phytoferritin within the stroma as well as amorphous and dense inclusions that were limited by the thylakoid membranes. In the developing chloroplasts, electron-dense materials were detected within the transversely sectioned thylakoid lumens. This dense material presented two different images, depending upon the sectional plane. When transversely prepared, the materials appeared as somewhat thick, linear structures, whereas longitudinally sectioned thylakoids revealed very large crystalline inclusions. In the developed chloroplasts, the amounts of electron-dense material or crystalline inclusions were remarkably reduced in the thylakoid lumens, which were electron-translucent. Far fewer crystalline inclusions were observed in the developed chloroplasts of seedlings than in the developing chloroplasts. These results suggest that the crystalline inclusions may be temporarily reserved within the thylakoid lumens of chloroplasts in the Gjaponica seedlings.     

Deletion of the fiber gene induces the storage of hexon and penton base proteins in PML/Sp100-containing inclusions during adenovirus infection

The present study has documented changes in the in situ distribution of viral DNA and capsid proteins in 293 cells infected with fiber gene-deleted adenoviruses. It shows that infection results in the intense production of progeny viruses which appear morphologically intact although they are devoid of fiber-coding sequence in their genome and hence of fiber protein in their capsid. The data confirm, therefore, that fiber protein is not essential for the assembly of progeny viruses. The main contribution of our observations concerns specific intranuclear structures induced by infection with either wild-type or fiber gene-deleted viruses. These clear amorphous inclusions contain two cellular proteins, PML and Sp100, which in non-infected cells co-localize to a special type of nuclear bodies. PML and Sp100 nuclear bodies appear to directly modulate or to be altered in a wide variety of situations including viral infections, cell death and transformation. In cells infected with fiber gene-deleted viruses, the clear amorphous inclusions now accumulate non-used hexon and penton base proteins, whereas the absence of fiber protein prevents the assembly of capsid proteins in crystallin arrays. Taken together, the data suggest that the clear amorphous inclusions may correspond to storage sites of structural and regulatory proteins. Consequently, these virus-induced structures may promote the productive cycle of adenoviruses by regulating the amount of over-produced viral proteins and the shutoff of the host cell metabolism.     

Analytical electron microscopic study of mitochondrial inclusions in canine myocardial infarcts.

An analytical electron microscopic study, utilizing scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy, was made of two types of mitochondrial inclusions identified in canine myocardial infarcts. The data were obtained from thin sections of tissues that were fixed in aldehyde, osmicated and embedded in epoxy resin. Calcium peaks of variable intensity were detected in inclusions which contained very electron-dense spicular material and which were localized to muscle cells at the peripheries of the infarcts. These findings indicate that the spicular inclusions represent early stages in the process of mitochondrial calcification in myocardial infarcts. In contrast, calcium or other trace elements were not detected in moderately electron-dense amorphous inclusions which were present in mitochondria of muscle cells throughout the infarcts. With the tissue preparative techniques employed, the possibility cannot be excluded that the amorphous inclusions contained calcium, either in small amounts or in a readily diffusable state, in vivo. The data, however, are in accord with the previously advanced hypothesis that the amorphous inclusions represent precipitates of denatured mitochondrial protein formed during the evolution of irreversible cellular injury. This study provides further evidence that analytical electron microscopy can yield important information regarding the nature of various inclusions occurring in normal and diseased tissues.     

Immunogold labelling indicates high catalase concentrations in amorphous and crystalline inclusions of sunflower (Helianthus annuus L.) peroxisomes

Summary Immunogold labelling and electron microscopy were used to investigate whether catalase was present in peroxisomal inclusions, the composition of which has not yet been determined in plant cells. In the mesophyll cells of sunflower (Helianthus annuus L.) cotyledons, the catalase gold label was confined to peroxisomes. At day 2 of postgerminative growth in darkness, peroxisomes were free of inclusions, and the matrix was homogeneously labelled with gold particles. Thereafter, amorphous inclusions appeared, but by day 5 of growth, conspicuous crystalline inclusions (cores) were the predominant type. This developmental change, first observed in cotyledons grown in continuous light between day 2.5 and 5, also took place in cotyledons kept in permanent darkness. Both amorphous and crystalline inclusions showed a much higher immunogold label than did the peroxisomal matrix, indicating that catalase was a component of both types of peroxisomal inclusions. In contrast to catalase, the immunogold label of glycolate oxidase was almost completely absent from cores and was confined to the peroxisomal matrix. Together with reports on the absence of other enzymes from peroxisomal inclusions in sunflower and other species (Vaughn, 1989) our results suggest that catalase is a major constituent of amorphous and crystalline peroxisomal inclusions in plants.     

Structure of the cell of the amoeboid flagellate <Emphasis Type="Italic">Thaumatomonas coloniensis</Emphasis> Wylezich et al., 2007 (Thaumatomonadida (Shirkina) Karpov, 1990)

The ultrathin structure of the amoeboid flagellate Thaumatomonas coloniensis Wylezich et al. has been studied. The cell is surrounded by somatic scales forming on the surface of the mitochondria. The heterodynamic flagella emerge from the small flagellar pocket. Both flagella are covered by pineal scales and thin twisted mastigonemes. The kinetosomes lie parallel to each other. The transitional zone of the flagella carries the thin-walled cylinder. The transversal plate of the flagella is above the cell surface. The flagellar root system consists of three microtubular bands and a fibrillar rhizoplast. The vesicular nucleus and Golgi apparatus are of the usual structure. The mitochondria contain tubular cristae. The extrusive organelles (kinetocysts) contain amorphous material and a capsule; they are located in cytoplasm. The capsule consists of a muff and cylinder. Osmiophilic bodies of various shapes contain crystalloid inclusions. The pseudopodia capturing the bacteria emerge from the ventral groove. The groove is armored by the two longitudinal groups of the close situated microtubules. Microbodies and symbiotic bacteria have not been discovered. The resemblance of Th. coloniensis with other thaumatomonads is discussed.     

Corn Mitochondrial Swelling and Contraction-an Alternate Interpretation

Mitochondria isolated from 3-day-old etiolated corn shoots (Zea mays L.) can be categorized into three separate groups, each group characteristic of the cell type from which the mitochondria were isolated. Phloem sieve tubes and some adjacent parenchyma cells contain mitochondria that have few cristae and little amorphous matrix. Mitochondria from meristematic and undifferentiated cells have more cristae and matrix. Vaculate and differentiated cells have mitochondria with well-developed cristae and abundant matrix. Each mitochondrial type exhibits typical in vitro spontaneous swelling and substrate-induced contraction responses. characterized by change or lack of change in cristae size and in density of amorphous material. For the second and third types of mitochondria, swelling and contraction are characterized by a change in degree of cristae size and in matrix density. The first type undergoes few changes upon swelling or contraction. Radical changes of the inner membrane, withdrawal and infolding, are associated with cell differentiation and not with swelling and contraction of isolated corn shoot mitochondria.     

Ultrastructure of myocardial widened Z bands and endocardial cells in two teleostean species

Summary Widened myocardial Z bands and endocardial cells are described in two teleostean species Cichlasoma meeki and Corydoras aeneus. Widened Z bands containing mainly amorphous and electron-dense material were seen in a number of myocardial cells. Further, similar material may occur in large amounts beneath the sarcolemma and at intercellular junctions. Occasionally, we observed continuity between the latter material and that in expanded Z bands.In C. meeki the ventricular endocardial layer consists of two structurally different cell types, whereas in C. aeneus only one cell type was seen. The functional aspects of widened Z bands are discussed.     

Tubule bundle-inclusions in vacuoles of Tamarix aphylla L. mesophyll cells

Summary Vacuoles of differentiating mesophyll cells of Tamarix aphylla contain an amorphous electron-dense material in which stacks of parallel aligned striations are embedded. Cross-sections of the striations disclosed that they represent profiles of longitudinally sectioned bundles of tubules (tubule outer diameter 9.0 nm, tubule wall thickness 1.8 nm). In advanced mesophyll cell development, the amorphous vacuolar material disappears, whereas the bundles of tubules turn into bundles of double helices (double helix diameter 14.5 nm). Cytochemical treatment of mesophyll cells with the enzymes pepsin and trypsin has revealed that both the bundles of tubules/double helices and the embedding material are constituted of protein. The possible functional role of the vacuolar inclusions is discussed.     

Influence of starvation and feeding on the hepatopancreas of larvalHyas araneus (Decapoda,Majidae)

Zoea-1 larvae ofHyas araneus were kept under different nutritional conditions. Their midgut glands were investigated with a transmission electron microscope. The glandular epithelium consists of the cell types known from adult decapods. It is mainly the R-cell type that undergoes ultrastructural alterations which reflect nutritional conditions. R-cells of fed larvae are characterized by large lipid inclusions; after a certain period of food deprivation (point-of-no-return) the original ultrastructure cannot be reestablished. Refeeding results in large glycogen deposits in these cells.     

Light and electron microscopy of virus inclusions inAmaranthus lividus cells

Summary Amaranthus plants infected with a virus of rod-shaped particles showed under the light microscope intracytoplasmic amorphous and crystalline inclusions.The submicroscopic organization of mesophyll cells from infectedAmaranthus leaves by electron microscopy is described. Besides big crystalline inclusions, long dark inclusions correspondent to needle-like inclusions observed by light microscopy are definable in the cytoplasm. The amorphous inclusion bodies were formed by an overgrown protrusion of vacuolate cytoplasm containing virus particles, long very dark stained inclusions forming dense bands and rings, normal elements of the cytoplasm such as mitochondria, endoplasmic reticulum and ribosomes, and some spherosomes. Inclusions and virus particles were not found in chloroplasts, mitochondria or nuclei of infected cells.     

Autophagy of metabolically inert substances injected into fibroblasts in culture

We have examined the morphologic characteristics of fibroblasts cultured from the beige mouse, a genetic variant phenotypically similar to human Chediak-Higashi syndrome (CHS). These cultured fibroblasts are characterized by large, amorphous dense body inclusions in their cytoplasm, often as large as the cell nucleus. Using time-lapse video phase-contrast microscopy, we have observed the formation of these large dense bodies through fusion of relatively normal-appearing lysosomes in the beige mouse fibroblast. After formation of these large inclusions, cells occasionally extruded the contents of these structures through apparent fusion with the plasma membrane and rapid exocytosis. Fibroblasts cultured from normal black mice showed no evidence of fusion between lysosomes or exocytosis of lysosomes. However, the uptake of extracellular medium through macropinocytosis, subsequent actions of lysosomes on these macropinosomes through saltatory motion, cellular migration and ruffling activity appeared normal in beige mouse fibroblasts. Immunocytochemical localization of α₂-macroglobulin, a normal serum protein commonly incorporated into lysosomes in cultured fibroblasts by receptor-mediated endocytosis, showed that the large dense bodies contained α₂-macroglobulin, in keeping with their lysosomal origin. This suggested further that receptor-mediated endocytosis in these cells was relatively normal. In addition, light and electron microscopic cytochemistry showed these large inclusions to be acid-phosphatase positive, further characterizing them as lysosomal. The electron microscopic appearance of these dense inclusions was consistent with their origin through repeated fusion of lysosomes. It is suggested that a primary defect in this disease may be the ability of mature lysosomal membranes to fuse, unlike normal lysosomal membranes, indicating perhaps an alteration in some specific component of the lysosomal membranes in CHS.     

A survey on the intraclear inclusions in the Schrophulariaceae and their systematic significance

A survey of nuclear inclusions in chlorenchyma cells is given for 290 taxa of the Scrophulariaceae, covering 72 genera; 172 are new data and the remainder are from previous reports by the author. In addition to the 5 types of nuclear inclusions already determined by their different ultrastructural morphology — amorphous (A), lamellar (L), fibrillar (F), tubular (T), and crystalline (C) — and to subtypes C2, three new subtypes — A2, L2, T2 - specific to certain genera or small groups of genera are reported. These new subtypes are described in detail and their distribution in the family discussed. Although the proteinic nature was unquestionably demonstrated, the origin and function of plant nuclear inclusions is far from being understood. In the Scrophulariaceae they have been recognized in 242 out of 290 taxa studied (83.4%), in a total of 60 out of 72 genera (83.3%). On the basis of the occurrence and qualitative distribution of the nuclear inclusions, the family can be subdivided into four main group: 1) with lamellar inclusions, 2) with amorphous inclusions, 3) with inclusions other than those in the two former groups, and 4) with no nuclear inclusions. The relationship between the distribution on the nuclear inclusions throughout the family and the current systematic arrangement into subfamilies are analyzed and the transfer of some genera to different tribes or to a tribe of their own is proposed, e.g., in the case of Mimulus, Leucocarpus, Halleria, Russelia, Angelonia, Rehmannia , and Campylanthus . Finally, a possible evolutionary trend of the different types of nuclear inclusions based on their structural complexity and on the occurrence in allied families is offered.     

Ultrastructure of fat body cells of the velvetbean caterpillar infected with a nuclear polyhedrosis virus

During a study of the ultrastructure of a nuclear polyhedrosis virus of the velvetbean caterpillar, Anticarsia gemmatalis, various types of nuclear and cytoplasmic inclusions were found in fat body tissue heavily infected with the virus. Virogenic stroma was present in the nuclei of most infected cells. Bundles of fibrous material were observed in the nuclei and cytoplasm of cells containing polyhedral bodies. Other nuclear inclusions included concentric multilayered material, vacuoles, and membrane structures.     

Formation and structure of the surface coat in the midgut of a waterstrider,Gerris najas deg. (Heteroptera : Gerridae)

The midgut epithelium of Gerris najas (Heteroptera : Gerridae) consists of a single cell type in different differentiating and functioning states. Cells elongate from nests of regenerative cells, forming together with their differentiating neighbours an interepithelial cavity, which contains coat material of membrane-like structure, and aggregations of cubic crystals visible only at this stage. Having reached a fold, the contents of the cavity are discharged into the lumen, and the young cells join the columnar cells. Exocytosis of coat material continues, while the cells gradually change to typical digestive columnar cells. The membrane-like material spreads from the folds into the lumen in whorls without forming a continuous cover of the luminal surface. Therefore, a peritrophic membrane does not exist in Gerris.     

CRYSTALLINE INCLUSIONS IN THE NUCLEAR ENVELOPE AND GRANULAR ENDOPLASMIC RETICULUM OF THE FISH SPINAL CORD

Crystalline inclusions were found in the nuclear envelope and granular endoplasmic reticulum of spinal cord oligodendroglia of the common guppy (Poecilia reticulata) and the lungfish (Polypterus enlicheri). A considerably increased incidence of these inclusions was noted in guppies with congenital and hereditary (sex-linked, recessive) lordosis. Identical crystalline inclusions were observed in protoplasmic and fibrous astrocytes, ependymal cells, and capillary endothelial cells of the spinal cord of the lordotic fish. The oligodendroglia in these fish also revealed a prominent alteration of the endoplasmic reticulum and Golgi apparatus, with the accumulation of dense (secretion?) granules and large amounts of electron-opaque material in markedly dilated sacs of the endoplasmic reticulum. The authors postulate that this alteration is caused by a genetic defect in the control mechanism governing the elaboration of this material in the lordotic guppy, with subsequent stasis and crystallization of this material.     

Graniferous tracheary elements in haustoria of root parasitic angiosperms

Graniferous tracheary elements are unusual xylem conducting cells, characterized by having structural material in the lumen. They are known particularly from certain root parasitic angiosperms. The included material is usually granular but may also be amorphous or fibrillar, all having the same origin during differentiation of the tracheary element. Vessels and tracheids with such inclusions were first reported in 1895 by Heinricher inLathraea (Scrophulariaceae). During the early decades of this century graniferous tracheary elements were noted in a few other taxa by different workers but were largely forgotten until the early 1960’s. This paper reviews the early literature and the research carried out during the past twenty-five years on these peculiar cells. Graniferous tracheary elements are found typically in the body of the haustorium of the root parasite, especially in the expanded xylem tissue or “vascular core.” The cells are most widely documented for the hemi-parasitic Santalaceae and were first recorded there in 1910 by Benson. She named the cells “phloeotracheides,” believing they combined the functions of phloem and xylem conducting elements. Heinricher and Benson both considered the granules to be composed of amylodextrin starch and Benson also believed the cells contained an enucleated protoplast. Our work has demonstrated that the granules in the Santalaceae are proteinaceous and that the cells are dead at maturity. In 1978 we therefore renamed them “graniferous tracheary elements.” They occur in all species of the Santalaceae so far investigated and inAtkinsonia ligustrina andNuytsia floribunda of root parasitic Loranthaceae. In these two families graniferous tracheary elements have the same organization. Their occurrence in haustoria of root parasites from other families is also reviewed. Although few observations are yet available in the Olacaceae, the granules inXimenia americana are found to be starch grains, like those inLathraea, whereas those inOlax phyllanthi are protein. Such fundamentally different material in haustorial tracheary elements within the same taxonomic group naturally raises the question of relationships within the family. The function of graniferous tracheary elements has not been experimentally investigated but we have suggested that for some Santalaceae they might serve as a device for regulating the flow of xylem sap through the haustorium.     

Subcellular localization of the coat protein in tobacco cells infected by cucumber mosaic virus isolated from Catharanthus roseus

Electron microscopy and immunolabelling with antiserum specific to cucumber mosaic virus coat protein were used to examine tobacco leaf cells infected by cucumber mosaic virus isolated from Catharanthus roseus (CMV-Cr). Crystalline and amorphous inclusions in the vacuoles were the most obvious cytological modifications seen. Immunogold labelling indicated that the crystalline inclusion was made up of virus particles and amorphous inclusions contained coat protein. Rows of CMV-Cr particles were found between membranes of dictyosomes, but membranous bodies and tonoplast-associated vesicles were not evident. Virus particles and/or free coat protein were easily detected in the cytoplasm by immunolabelling. No gold labelling was found within nuclei, chloroplasts and mitochondria.