Morphology and development of rhabdovirus-like particles inCuscuta odorata (Convolvulaceae) simultaneous infected with virus and mycoplasma-like organisms

Summary Electron microscopic examination ofCuscuta odorata, used for transmission trials, revealed mycoplasma-like organisms (MLO) as well as rhabdovirus-like particles, unknown toCuscuta. The virus infection is confined to certain phloem-parenchyma cells and a 1–2 cell thick layer of parenchyma cells with thickened walls surrounding the central cylinder. Virus particles, mostly bacilliform, could be detected mainly in the nucleus but also in the cytoplasm. They reach a length of 350–400 nm and a diameter of approximately 75 nm. Virus assembly takes place exclusively in the nucleus. Virus maturation occurs in membrane bound areas within the nucleus, which have no connection with the perinuclear space. Formation of nucleocapsids is always associated with a nuclear viroplasm. Envelopment of virus particles occurs in these membrane bound areas. Budding into the perinuclear space does not occur. Virus infection leads to degeneration and finally to death of the protoplast.Abbreviations cy cytoplasm - m membrane stacks - mt mitochondria - my mycoplasma-like organisms - nc nucleocapsid - ncp nucleocapsid particles - nf nuclear filaments - np nucleoplasm - nu nucleus - nvp nuclear viroplasm - oc obliterated cells - p plastid - pc passage cells - ph phloem - ps perinuclear space - spc strand of parenchymatous cells - v virus particle - x xylem     

Occurrence of Mycoplasma-like Organisms in Parenchyma Cells of Cuscuta odorata (Ruiz et Pav.)

In shoots of the dodder Cuscuta odorata mycoplasma-like organisms (MLO) were observed to occur in nearly all mature sieve elements. Their frequency within the sieve elements varied from a few organisms to high concentrations. In addition, MLO, were found in other cell types. By identifying these cells and investigating the location in the vascular tissue three different types of cells infected with MLO could be distinguished: (1) phloem parenchyma cells, (2) parenchyma cells separating the five vascular bundles of C. odorata and (3) cells in the outer region of the vascular system next to the cells looking like an endodermis. Within the cells of the types 2 and 3, MLO occurred in large numbers and at different morphological structures., Therefore, we assume that the MLO multiply in these cells.     

An in situ Freeze-Fracture Study of Spiroplasma citri and the Corn Stunt Spiroplasma

Spiroplasma citri and the corn stunt spiroplasma in sieve cells of Catharanthus roseus were investigated using freeze -fracture electron microscopy. Only the particle studded fracture faces of the plasmalemma could be exposed and not the surfaces of both the extraplasmatic and the plasmatic leaflet. The extraplasmatic fracture face (EF) shows a lower particle density than the plasmatic fracture face (PF). On the PF particle free areas could be observed, which are helically arranged in helical filaments. We suppose that the cytoplasmic fibrils, probably involved in motility processes and in maintaining the helical shape, underly the particle free area only.     

The evaluation of sixteen carcinogens in the rat using the micronucleus test.

Sixteen carcinogens were evaluated in rats for their ability to induce micronuclei. The direct acting agent, ethyl methanesulfonate and the procarcinogens/promutagens, cyclophosphamide and 4-nitroquinoline-1-oxide, induced dose-related increases in micronucleated polychromatophilic erythrocytes. Aflatoxin B1 also significantly increased the number of micronucleated polychromatophillic erythrocytes for 2 doses although no dose-response could be detected. Dimethylnitrosamine produced variable results. The remaining 11 compounds, 2-acetylaminofluorene, 4-aminobiphenyl, benzidine, diethylnitrosamine, dimethylbenzanthracene, 1,2-dimethylhydrazine, ethionine, ethyl carbamate, hexametapol, metronidazole, and beta-naphthylamine, failed to induce significantly increased numbers of micronuclei. The large number of false negative results obtained in the present investigations using the micronucleus test suggests that in vivo cytogenetic assays utilizing bone marrow may also lack the sensitivity needed to detect clastogenic effects of procarcinogens/promutagens which require tissue specific metabolic activation.     

Über die Pleomorphie von MLO in Catharanthus roseus (Vinca rosea)

About the pleomorphism of MLO in Catharanthus roseus (Vinca rosea) MLO of the flower greening (virescence)-type of Primula in the phloem of Catharanthus roseus (Vinca rosea) were fixed in two different ways. After prefixation with OsO4 they showed a diminished pleomorphic morphology, most MLO were spherical. With the fixation of KARNOVSKY (1965) and subsequent treatments with OsO4 and uranyl acetate, however, an extremely high pleomorphism was observed. Such pleomorphic MLO in single thin sections are probably the expression of a threedimensional network-like connection. The concentration of MLO in the sieve elements seems to influence the pleomorphism only insignificantly.     

Elektronenmikroskopische Untersuchungen der „Bakteroiden“ des Regenwurms Lumbricus terrestris L.

Ohne Zusammenfassung     

Application of an optimized marker amplification protocol in immunohistochemistry — a valuable tool for visualizing antigenic sites of low signal strength or sparse distribution

Amplification of immunohistochemical markers received considerable attention during the 1980s and 1990s. The amplification approach was largely abandoned following the development of antigen retrieval and reporter amplification techniques, because the latter were incorporated more easily into high throughput automated procedures in industrial and diagnostic laboratories. There remain, however, a number of instances where marker amplification still has much to offer. Consequently, we examined experimentally the utility of an optimized marker amplification technique in diagnostically relevant tissue where either the original signal strength was low or positive sites were visible, but sparsely distributed. Marker amplification in the former case not only improved the visibility of existing positive sites, but also revealed additional sites that previously were undetectable. In the latter case, positive sites were rendered more intense and therefore more easily seen during low magnification examination of large areas of tissue.     

EFFECT OF VITAMIN E SUPPLEMENTATION AND PARTIAL SUBSTITUTION OF POLY- WITH MONO-UNSATURATED FATTY ACIDS IN PIG DIETS ON MUSCLE,AND MICROSOME EXTRACT a-TOCOPHEROL CONCENTRATION AND LIPID OXIDATION

The experiment was organized in a 3×2 factorial arrangement with three dietary fat blends and a basal (20 mg kg^?1 diet) or supplemented (220 mg kg^?1) level of α-tocopheryl acetate. Dietary vitamin E and monounsaturated to polyunsaturated fatty acid ratio (dietary MUFA/PUFA) affected muscle α-tocopherol concentration (α-tocopherol [log μg g^?1]=0.18 (±0.105)+0.0034 (±0.0003)·dietary α-tocopherol [mg kg^?1 diet] (P<0.0001)+0.39 (±0.122)·dietary MUFA/PUFA (P<0.0036)). An interaction between dietary α-tocopherol and dietary MUFA/PUFA exists for microsome α-tocopherol concentration (α-tocopherol [log μg g^?1]=1.14 (±0.169) (P<0.0001)+0.0056 (±0.00099)·dietary α-tocopherol [mg kg^?1 diet] (P<0.0001)+0.54 (±0.206)·dietary MUFA/PUFA (P<0.0131)?0.0033 (±0.0011)·dietary α-tocopherol [mg kg^?1)]×dietary MUFA/PUFA (P<0.0067)), and hexanal concentration in meat (hexanal [ng·g^?1]=14807.9 (±1489.8)?28.8 (±10.6) dietary α-tocopherol [mg·kg^?1] (P<0.01)?8436.6 (±1701.6)·dietary MUFA/PUFA (P<0.001)+24.0 (±11.22)·dietary α-tocopherol·dietary MUFA/PUFA (P<0.0416)). It is concluded that partial substitution of dietary PUFA with MUFA lead to an increase in the concentration of α-tocopherol in muscle and microsome extracts. An interaction between dietary α-tocopherol and fatty acids exists, in which at low level of dietary vitamin E inclusion, a low MUFA/PUFA ratio leads to a reduction in the concentration of α-tocopherol in microsome extracts and a concentration of hexanal in meat above the expected values.     

How the Spatial Position of Individuals Affects Their Influence on Swarms: A Numerical Comparison of Two Popular Swarm Dynamics Models

Schools of fish and flocks of birds are examples of self-organized animal groups that arise through social interactions among individuals. We numerically study two individual-based models, which recent empirical studies have suggested to explain self-organized group animal behavior: (i) a zone-based model where the group communication topology is determined by finite interacting zones of repulsion, attraction, and orientation among individuals; and (ii) a model where the communication topology is described by Delaunay triangulation, which is defined by each individual''s Voronoi neighbors. The models include a tunable parameter that controls an individual''s relative weighting of attraction and alignment. We perform computational experiments to investigate how effectively simulated groups transfer information in the form of velocity when an individual is perturbed. A cross-correlation function is used to measure the sensitivity of groups to sudden perturbations in the heading of individual members. The results show how relative weighting of attraction and alignment, location of the perturbed individual, population size, and the communication topology affect group structure and response to perturbation. We find that in the Delaunay-based model an individual who is perturbed is capable of triggering a cascade of responses, ultimately leading to the group changing direction. This phenomenon has been seen in self-organized animal groups in both experiments and nature.     

Quirks of dye nomenclature. 5. Rhodamines

Rhodamines were first produced in the late 19^th century, when they constituted a new class of synthetic dyes. These compounds since have been used to color many things including cosmetics, inks, textiles, and in some countries, food products. Certain rhodamine dyes also have been used to stain biological specimens and currently are widely used as fluorescent probes for mitochondria in living cells. The early history and current biological applications are sketched briefly and an account of the ambiguities, complications and confusions concerning dye identification and nomenclature are discussed.