Comparative studies on the histology of the ovotestis in Hypselodoris tricolor and Godiva banyulensis (Gastropoda,Opisthobranchia), with special reference to yolk formation

The histology of the ovotestis was studied by light and electron microscopy in two nudibranch gastropod species. While in Hypselodoris tricolor the ovotestis is intimately associated with the digestive gland tissue, the large gonadal mass of Godiva banyulensis is placed freely in the haemocoele. This fact results in great histological differences between both species. As is common among Mollusca, the immature yolk granule in Hypselodoris and Godiva presumably originates from membrane-rich cytoplasmic inclusions, which we have termed dense multivesicular bodies. Such inclusions consist of an outer membrane enclosing membrane remnants and a granular, electron-dense material. These elements are accumulated and mixed in the center of the dense multivesicular body and could be actually transformed into the paracrystalline core of the immature yolk granule, the cortex of which is made up of part of the central accumulation materials that have not spread into the crystal. During vitellogenesis, some mitochondria are subjected to a process of transformation affecting mainly their inner membrane (including mitochondrial cristae) and matrix. However, the conversion of modified mitochondria into yolk precursors, as reported for other gastropod species, could not be determined with absolute certainty on the basis of our observations on static material. The mature yolk granule consists of a central paracrystalline core, similar in structure to that of the immature yolk granule, and a peripheral membranous cortex, which seems to spread centripetally, thus permitting the crystal to grow. The cortical material consumed in synthesizing the central core appears to be restored by addition of degenerative mitochondria to the yolk granule surface.     

Intramitochondrial inclusions in various cells of a snake (Elaphae quadrivirgata)

Summary A variety of inclusion bodies occur in the mitochondria of several cell types of the snake, Elaphae quadrivirgata. These lie in the mitochondrial matrix or within the space of the cristae. The inclusions in the matrix are as follows: dense homogeneous and fine granular materials, structures with finger-print appearance and with filamentous and/or crystalloid pattern and fine ring-shaped and/or microtubular structures. The inclusions within mitochondrial cristae are glycogen particles, globular materials, and strand-like structures.These inclusions occur not only during the hibernation period of the snake, but also in the arousal period. Furthermore, some inclusions are encountered in fetal tissues. The functional significance of these inclusions is unknown; however, the present study suggests that they are related to the metabolic activity of the cells.     

Electron microscopic study of monoaminergic fibers in the posterior lobe of the rat hypophysis]

Monoaminergic fibers and their swellings containing dense core vesicles, 700-1000 A in diameter, were found by electron microscopic studies in the posterior pituitary of rat. Most of them are situated far from capillaries and are surrounded by neurosecretory fibers and pituicytes. There are usually no specialized structures at the sites of contact between them. Single monoaminergic fibers come in contact with the capillaries and even penetrate the pericapillary space. Large swelling of these fibers which sometimes occur contain different polymorphous inclusions, degenerating mitochondria and numerous small tubules along with the dense core vesicles.     

Ultrastructural and Cytochemical Identification of Peroxisomes in the Ciliate Ichthyophthirius multifiliis

ABSTRACT. The peroxisomes of the parasitic ciliate Ichthyophthirius multifiliis were studied, using ultrastructural and cytochemical techniques. In this ciliate most peroxisomes possess a circular or oval section less than 0.6 μm in diameter. However, some dumbbell-shaped and elongated peroxisomes could also be observed. These organelles were frequently associated with the mitochondria and were more abundant in the cell cortex than in the center of the ciliate. Small vesicles and dense nucleoids were usually present in the ultrathin sections of these peroxisomes. Peroxisomal vesicles and tubular structures were selectively impregnated with osmium tetroxide. Catalase was detected by cytochemical techniques in I. multifiliis peroxisomes.     

Fine Structure of Mitochondria of Spirostomum ambiguum as Seen in Sectioned and Negatively-Stained Preparations*

SYNOPSIS. Comparisons are made between sectioned and negatively-stained mitochondria of the ciliate Spirostomum ambiguum. Particulate elements 70–80 A in diameter are associated with the surface of tubular cristae of negatively-stained and disrupted mitochondria; such particles are not seen in sectioned mitochondria fixed in various ways. As measured in sectioned material, the inner mitochondrial membrane forming the tubular cristae is about 100 A thick, while the outer mitochondrial membrane is about 50 A thick and is the more labile of the 2.     

Development of woronin bodies from microbodies inFusarium oxysporum f. sp.lycopersici

Summary Woronin bodies are cytoplasmic organelles which commonly lie near the septa in ascomycetous fungi. Although these organelles were observed nearly 100 years ago, little is known about their origin and development. The present ultrastructural investigation describes the ontogeny of Woronin bodies inFusarium oxysporum f. sp.lycopersici [Sacc.] Snyd. and Hans. In this fungus, Woronin bodies are produced by microbodies. Development of the Woronin body begins with the appearance of electron dense material within the microbody. This material aggregates adjacent to the membrane of the microbody and condenses into a single paracrystalline inclusion. Following its formation, the inclusion is gradually extruded and is eventually separated from the parent organelle by an exocytotic mechanism. After the separation, the paracrystalline inclusion is found at the septal pore. Although many recent electron microscopic studies have used various terms to designate these membrane bound organelles, inFusarium these inclusions are believed to correspond to the Woronin bodies initially described by light microscopists.     

Paracrystalline arrays in mitochondria following ageing of mitochondriain situ

Paracrystalline arrays of helical configuration were observed in the mitochondrial intracrystal spaces following prolonged ageing of mitochondriain situ. The occurrence of these mitochondria with the paracrystalline arrays, average diameter of about 70 Å, appeared to increase following an increase in the time of ageingin situ.The exact function of the mitochondria containing the paracrystalline arrays is unknown. These mitochondria could not possibly be responsible for the overall decline in the State 3 respiration, respiratory control index and the ADP/O ratio observed with intact mitochondria isolated after prolonged ageingin situ [21].     

Diversité des formes d'accumulation de la phytoferritine dans les cellules constituant l'épithème des hydathodes de Taraxacum officinale Weber et Saxifraga aizoon Jacq.

Summary In Taraxacum officinale and Saxifraga aizoon particular aggregations found in plastids of epithem are considered to be phytoferritin. The diversity of plant ferritin arrangement within the plastids is studied. High magnification study of these inclusions indicates that they can be classified morphologically into three distinct groups: dense and amorphous aggregate (F₁), crystalline inclusion (F₂) and diffuse paracrystalline arrangement (F₃). The crystalline (F₂) and amorphous (F₁) structures are both present in the plastids of Saxifraga aizoon; similarly, paracrystalline (F₃) and amorphous inclusions (F₁) are both present in the plastids of Taraxacum officinale. Because of their location and the nature of their organization, we think that the phytoferritin complexes under discussion may be important in phytoferritin synthesis or phytoferritin utilization within the living plant.     

Characterization of paracrystalline inclusions in chinese hamster oocytes and early embryos

Paracrystalline inclusions, readily visible with light microscopy, were found to be present in ovarian oocytes (beginning with unilaminar follicles), ovulated ova, and preimplantation embryos of the Chinese hamster. These inclusions appeared to be aggregates of finer filamentous structures visible only with electron microscopy. The use of various histochemical techniques suggested that the paracrystals were composed of protein with little or no lipid associated with them. Autoradiographic studies using ³H-uridine and enzymatic studies did not support the hypothesis that the paracrystalline inclusions were composed of RNA masked by a crystalline protein lattice.     

Adult rat cardiomyocytes cultured in creatine-deficient medium display large mitochondria with paracrystalline inclusions, enriched for creatine kinase

In adult regenerating cardiomyocytes in culture, in contrast to fetal cells, mitochondrial creatine kinase (Mi-CK) was expressed. In the same cell, two populations of mitochondria, differing in shape, in distribution within the cell and in content of Mi-CK, could be distinguished. Immunofluorescence studies using antibodies against Mi-CK revealed a characteristic staining pattern for the two types of mitochondria: giant, mostly cylindrically shaped, and, as shown by confocal laser light microscopy, randomly distributed mitochondria exhibited a strong signal for Mi-CK, whereas small, "normal" mitochondria, localized in rows between myofibrils, gave a much weaker signal. Transmission EM of the giant mitochondria demonstrated paracrystalline inclusions located between cristae membranes. Immunogold labeling with anti-Mi-CK antibodies revealed a specific decoration of these inclusions for Mi-CK. Addition of 20 mM creatine, the substrate of Mi-CK, to the essentially creatine-free culture medium caused the disappearance of the giant cylindrically shaped mitochondria as well as of the paracrystalline inclusions, accompanied by an increase of the intracellular level of total creatine. Replacement of creatine in the medium by the creatine analogue and competitor beta-guanidinopropionic acid caused the reappearance of the enlarged mitochondria. It is believed that the accumulation of Mi-CK within the paracrystalline inclusions, similar to those observed in certain myopathies, represents a compensatory effect of the cardiomyocytes to cope with a metabolic stress situation caused by low intracellular total creatine levels.     

蚕豆萎焉病毒2感染豌豆叶细胞后引起的线粒体增生和聚集

应用超薄切片和免疫金标记电镜技术,结合体视学分析研究了受蚕豆萎焉病毒2(BBWV 2) 中国分离物B935侵染的豌豆(Pisum sativum)叶细胞中线粒体的异常变化。结果表明,感病细胞线粒体增生并聚集于细胞质的膜增生区周围,体积增大,形状畸变,一些线粒体内含有类结晶包涵体。病叶细胞与健康对照之间线粒体的体积密度(VV)、表面积密度(SV)、数密度(NV)等参数存在显著差异(P<0.01),而形状因子(PE)、周长指数(CI)、比表面积(RSV)等参数随不同病变阶段而有变化。在线粒体周围及线粒体之间的网格结构可被BBWV 2金标记抗体特异性标记．推断为正在组装的病毒粒子。子代病毒形成结晶体和管状体,有高密度的免疫金颗粒标记。上述研究结果提示BBWV 2 引起的细胞线粒体异常变化与病毒复制组装有关,聚集线粒体的外膜粘连面可能是病毒粒子组装部位,一些线粒体内的类结晶包涵体可能代表了某种蛋白质异常积累。     

蚕豆萎焉病毒2感染豌豆叶细胞后引起的线粒体增生和聚集

应用超薄切片和免疫金标记电镜技术,结合体视学分析研究了受蚕豆萎焉病毒2（BBWV2）中国分离物B935侵染的豌豆（Pisumsativum）叶细胞中线粒体的异常变化。结果表明,感病细胞线粒体增生并聚集于细胞质的膜增生区周围。体积增大,形状畸变,一些线粒体内含有类结晶包涵体。病叶细胞与健康对照之间线粒体的体积密度（Vv）、表面积密度（Sv）、数密度（Nv）等参数存在显著差异（P〈0．01）,而形状因子（PE）、周长指数（CI）、比表面积（Rsv）等参数随不同病变阶段而有变化。在线粒体周围及线粒体之间的网格结构可被BBWV2金标记抗体特异性标记。推断为正在组装的病毒粒子。子代病毒形成结晶体和管状体,有高密度的免疫金颗粒标记。上述研究结果提示BBWV2引起的细胞线粒体异常变化与病毒复制组装有关。聚集线粒体的外膜粘连面可能是病毒粒子组装部位。一些线粒体内的类结晶包涵体可能代表了某种蛋白质异常积累。     

Electron microscopic studies on the macronuclear development in the ciliate Chilodonella uncinata.

The development of macronuclear anlage in the ciliate Chilodonella uncinata has been studied through electron microscopy. The ultrastructure of macro- and micronuclei is described for comparison. During the first stage of development, when the DNA content of the macronuclear anage increases from 2 C to 32 C, chromosomes are visible as distinct osmiophilic bodies inside the anlage. At the end of the initial polyploidization phase, the chromosomes despiralize, giving rise to long filamentous structures 25 to 50 nm in diameter. The latter show a singular banding pattern, with dense bands 12 to 25 nm thick alternating regularly with less dense interbands. Such an organization has not yet been observed in any other type of nucleus. These filamentous structures have been interpreted as highly despiralized oligotenic chromosomes. During the final stage of macronuclear development, these structures condense into thin chromatin strands and small dense granules; the number of granules increases progressively as the chromatin strands disappear. These small granules very likely fuse amongst themselves to form the chromatin granules of the vegetative macronucleus. No evidence has yet been found for a fragmentation of chromatin in this ciliate, but this problem needs further study. The old macronucleus maintains a normal ultrastructure until a late stage of development of the macronuclear anlage, becoming pycnotic only towards the very end of the latter process.     

Mutations in the sigma subunit of E. coli RNA polymerase which affect positive control of transcription

Summary An electrophoretic mobility variant of phenoloxidase in a lz stock of Drosophila melanogaster was identified as the A₃ component of the phenoloxidase complex by using two different activators to study enzyme activity — natural activator isolated from pupae and 50% 2-propanol. The structural gene for the A₃ proenzyme, Dox-3, was not associated with lz on the X chromosome; it mapped to the right of rdo (53.1) and left of M(2)m in the second linkage group.The lz locus affects the differentiation of the crystal cell, the type of hemocyte that carries prophenoloxidase(s) in paracrystalline form. Alleles of lz lacking paracrystalline inclusions in their hemocytes do not have phenoloxidase activity whereas alleles with paracrystalline inclusions have enzyme activity. The presence of proenzyme in the paracrystalline inclusions was demonstrated by in situ activation with natural activator or propanol followed by incubation in buffered dopa.     

The Feeding Ecology of Actinophrys sol (Sarcodina: Heliozoa) in Chesapeake Bay

The occurrence of Actinophrys sol, a planktonic heliozoan, in Chesapeake Bay was monitored over a four-year period (1988–1991). Actinophrys sol was widely-distributed throughout Chesapeake Bay and could exceed densities of 5,000 cells liter ^?1. It was most abundant during the warmer months. Feeding experiments were conducted with field populations of heliozoa using 1-μm fluorescent microspheres to label ciliate prey. Two ciliates, a small Strobilidium sp. (30 μ in diameter) and a Pleuronema sp. (45 μ length), were the primary ciliate-prey items in the water column when the experiments were conducted, although a wide range of ciliate taxa was ingested. Two other ciliates not present in situ, a Cyclidium sp. (20 μ length) and a Uronema sp. (40 μ length), were also labeled and added at various concentrations to field populations of plankton containing A. sol. Heliozoan ingestion rates on in situ prey at concentrations of 30 Strohilidium and one Pleuronema ml^?1 were 0.2 to 0.3 prey heliozoan^?1 hour^?1. Ingestion rates increased to a maximum of 1.2 prey heliozoan ^?1 hour^?1 with additions of 100 Uronema ml^?1. A mean clearance rate of 0.15 ml heliozoan^?1 day^?1 did not change with increasing prey abundance. The abundance and distribution of A. sol suggests that these sarcodines may exert strong grazing pressure on the planktonic ciliate populations of Chesapeake Bay at certain times of the year, and may be important in shaping the ciliate community composition and distribution.     

Histochemical studies on the yolk-nucleus in fish oogenesis

Summary A histochemical study of the oogenesis of two species of fresh water fishes, Channa maruleus and Heteropneustes fossilis, was undertaken to reveal the origin, structure, histochemical nature, and function of the so-called yolk-nucleus. The basophilic substance of the yolk-nucleus, which is situated in the juxta-nuclear cytoplasm, gradually accumulates adjacent to the nuclear membrane. It is a homogeneous, spherical mass. In Channa, some basophilic, dense bodies develop in the yolk-nucleus. Histochemical tests show that the yolk-nucleus and dense bodies are rich in RNA and proteins. Mitochondria of lipoprotein composition and lipid inclusions, composed of unsaturated phospholipids, appear in association with the yolk-nucleus. Throughout previtellogenesis, the yolk-nucleus continues to proliferate its basophilic, RNA-containing substance and other inclusions. Finally it disintegrates while lying in the peripheral cytoplasm of the larger oocytes which show the synthesis of yolk bodies. During yolk formation, lipid inclusions and mitochondria start disappearing from view but the RNA-containing substance, originated from the yolk-nucleus of previtellogenesis, continues to persist among the growing yolk bodies. The latter arise de novo from the ground cytoplasm, under the influence of the RNA-containing substance, mitochondria and lipid inclusions of previtellogenesis.This work was carried out in the Department of Zoology, University of Gorakhpur, Gorakhpur, India.Population Council Post-Doctoral Fellow.     

The tubular endoplasmic reticulum in the amoebocytes of the shell-regenerating snail,Helix pomatia L.

Summary The tubular endoplasmic reticulum has been studied in the amoebocytes which are present in the connective tissue of the hepatopancreas of the snail, Helix pomatia. The reticulum is similar to that previously described within the glandular cells of the hepatopancreas. Two distinct components are recognizable in the reticulum—central main tubules approximately 100 m in diameter and connecting tubules about 20 m in width. The profile of this tubular network in cross-sections appears as a very regular, apparently crystalline array. The tubules are intimately associated with dense granular material, dense bodies and with mitochondria. The possible function of the tubular endoplasmic reticulum is discussed.This investigation was supported by grants from the Swedish Natural Science Research Council, which are gratefully acknowledged. I am indebted to Miss G. Drugge for her technical assistance.     

Studies on the transport of secretory granules in the magnocellular hypothalamic neurons of the rat

Intrathecal administration of 20 mug of vincristine sulphate in the rat induced in vivo the formation of paracrystalline inclusions mainly in axonal processes. This is associated with an impairment in the migration of neurosecretory granules as shown by their accumulation in the perikarya of the magnocellular neurons. The granules are intermixed with numerous dense bodies of various shape, sometimes with a fibrillar content, and probably of lysosomal origin. In addition to the impairment of the flow of neurosecretory granules, there is also a striking accumulation of mitochondria and synaptic vesicles, and an apparent proliferation of the smooth endoplasmic reticulum. In the posterior lobe, the axonal endings contain a large number of neurosecretory granules, intermingled with bodies of varying shapes and electron density. Occasionally, a dense membrane surrounding a group of elementary granules is observed, reacting positively for acid phosphatase. This suggests an attempted crinophagia.     

ULTRASTRUCTURAL CHARACTERIZATION OF THE LYTIC CYCLE OF AN INTRANUCLEAR VIRUS INFECTING THE DIATOM CHAETOCEROS CF. WIGHAMII(BACILLARIOPHYCEAE) FROM CHESAPEAKE BAY,USA1

Numerous microalgal species are infected by viruses that have the potential to control phytoplankton dynamics by reducing host populations, preventing bloom formation, or causing the collapse of blooms. Here we describe a virus infecting the diatom Chaetoceros cf. wighamii Brightw. from the Chesapeake Bay. To characterize the morphology and lytic cycle of this virus, we conducted a time‐course experiment, sampling every 4 h over 72 h following viral inoculation. In vivo fluorescence began to decline 16 h after inoculation and was reduced to <19% of control cultures by the end of experiment. TEM confirmed infection within the first 8 h of inoculation, as indicated by the presence of virus‐like particles (VLP) in the nuclei. VLP were present in two different arrangements: rod‐like structures that appeared in cross‐section as paracrystalline arrays of hexagonal‐shaped profiles measuring 12 ± 2 nm in diameter and uniformly electron‐dense hexagonal‐shaped particles measuring ～ 22–28 nm in diameter. Nuclei containing paracrystalline arrays were most prevalent early in the infection cycle, while cells containing VLP increased and then declined toward the end of the cycle. The proportion of nuclei containing both paracrystalline arrays and VLP remained relatively constant. This pattern suggests that rod‐like paracrystalline arrays fragmented to produce icosahedral VLP. C. cf. wighamii nuclear inclusion virus (CwNIV) is characterized by a high burst size (averaged 26,400 viruses per infected cell) and fast generation time that could have ecological implications on C. cf. wighamii population control.     

犬传染性肝炎病毒在体外细胞质内的发生

通过对犬传染性肝炎病毒（ＩＣＨＶ）在犬肾传代细胞内形态发生及其抗原定位的电镜和免疫胶体金电镜研究,发现ＩＣＨＶ除了在宿主细胞核内发生外,还有一条细胞质内的发生途径。在细胞质内病毒核壳体的装配是以均质致密包涵体和副晶格包涵体为“基地”,这与人们熟知的细胞核内形态发生方式相似。免疫胶体金标记显示,细胞质包涵体中含有大量的ＩＣＨＶ抗原成分,显核壳体在细胞质内装配病毒的结构蛋白来源。此外,在感染的细胞质内还观察到与核内相同的病毒核心样结构。