Mononuclear phagocytes and eicosanoids: aspects of their synthesis and biological activities

Mononuclear phagocytes convert arachidonic acid and other unsaturated fatty acids from intracellular sources to a variety of oxygenated metabolites such as prostaglandins and leukotrienes which are secreted into the surrounding medium. Other oxidative products such as hydroxylinoleic acids are reacylated into cellular constituents. The underlying metabolic pathways are activated by numerous stimuli of exogenous or endogenous origin. Depending on the state of activation and cell differentiation, the organ of origin and the nature of the stimulus used, macrophages elaborate a distinct spectrum of oxidative arachidonic acid metabolites. The contribution of these metabolites to the proinflammatory properties of macrophages is twofold: As autocrine signals they modulate the synthesis of diverse macrophage products and they influence cellular functions of other cells such as T-lymphocytes.     

Baby hamster kidney (BHK-21/C13) cells can express striated muscle type proteins

When baby hamster kidney (BHK-21/C13) cell lines are subjected to low-serum medium, cell morphology changes from polygonal to elongated and occasionally fusion of cells is also observed. BHK-21 cells initially growing in Eagle's modified minimum essential medium (EMEM) containing 10% newborn bovine serum were induced to differentiate by changing the culture medium after the cells had grown to confluency. After this point the cells were grown in a low-serum medium (EMEM with 2% normal horse serum), for at least 4 days. The expression of different muscle-specific proteins (desmin, titin and skeletal muscle myosin) and of tropomyosins was studied in both polygonal and elongated BHK-21 cells using the indirect-immunofluorescence assay, two-dimensional (2D)-gel electrophoresis and immunoblotting. Filamentous staining was found with the desmin antisera in the polygonal cells and at all stages of BHK-cell elongation. While no reaction was seen with the titin and myosin antibodies in the polygonal cells, a punctate staining reaction for titin was detected 2 days after medium-change, although the cells had not yet elongated. After 4 days titin was found in a striated pattern. Filamentous staining was seen with the skeletal-muscle-specific myosin antibody at this stage. Confirmatory results were obtained from immunoblotting assays and 2D-gel electrophoresis of cytoskeletal preparations from undifferentiated and differentiated BHK cells. These latter experiments showed the initiation of tropomyosin expression only in the differentiated cells. The positive staining with antibodies to skeletal muscle myosin and titin indicates a striated-muscle nature of the (elongated) BHK-21/C13 cells.     

Heat-ethanol isolated serum albumin: discussion.

Albumin isolated by the Hagen/Münster heat-ethanol method is a remarkably stable solution of high purity and clinical compatibility. The simplicity of this method makes it a model fractionation procedure for the small transfusion service. Immunization studies carried out by us are compared with previous accounts of a "new" antigen occuring in plasma protein solution produced by partial heat denaturation. Clinical compatibility of cold-ethanol and heat-ethanol fractionated albumin solutions are also shortly discussed.     

Variation in monthly sizes of home-ranges of Hooded Vultures Necrosyrtes monachus in western,eastern and southern Africa

Tracking studies are often used to inform conservation plans and actions. However, species have frequently only been tracked in one or a few localities, whereas space use can be remarkably flexible, especially in long-lived species with advanced learning abilities. We assessed variability in space use in the Critically Endangered Hooded Vulture Necrosyrtes monachus by pooling movement data from three populations across the species’ sub-Saharan range (in South Africa, Botswana, Ethiopia, Kenya, The Gambia and Mozambique). We estimated minimum convex polygons and kernel density estimators (KDEs) and compared monthly home-range sizes between breeding and non-breeding seasons, age-classes and subspecies, accounting for uneven sampling within groups. Mean (± sd) monthly home-range sizes (95% KDEs) for adult Hooded Vultures from southern (12 453 ± 21 188 km², n = 82) and eastern Africa (3735 ± 3652 km², n = 24) were 103 and 31 times larger than those of conspecifics from western Africa (121 ± 98 km², n = 48). This may relate partly to subspecific differences, and individuals with small home-ranges in western Africa and Ethiopia were trapped in urban environments. Regional variation in space use by Hooded Vultures may be linked to flexibility in feeding behaviour (degree of commensalism) which may arise in response to resource availability and persecution in different areas. Age-class also affected monthly home-range sizes, with immature birds generally having larger monthly home-range size estimates than adults. Our results highlight the flexibility of Hooded Vultures in terms of their home-range sizes and suggest that home-range sizes differ between populations and individuals, depending on the extent of human commensalism. Our results also reaffirm the importance of international co-operation in conservation efforts aimed at protecting this wide-ranging, non-migratory species.     

Plasma Membrane Alterations and Cytoskeletal Changes in Apoptosis

During apoptosis, one of the first membrane changes that can be detected is exposure of phosphatidylserine residues at the outer plasma membrane leaflet, while early apoptosis is also accompanied by changes in the cytoskeletal organization. In this study we investigated the relationship between these two phenomena during olomoucine- and roscovitin-induced apoptosis in human lung cancer and neuroblastoma cell lines. Loss of membrane asymmetry was detected by biotin-labeled or FITC-labeled annexin V binding to negatively charged phosphatidylserine, while cytoskeletal components were visualized by immunocytochemistry. The apoptotic, annexin V-positive, cells were analyzed by flow cytometry, confocal scanning laser microscopy, and Western blotting. We report that cytokeratin and vimentin aggregation in early apoptosis occurs simultaneously with phosphatidylserine exposure and chromatin condensation. In contrast to these intermediate filament proteins, which were disassembled and proteolytically cleaved in early apoptosis, microfilaments and microtubuli were not proteolytically degraded but were found to be present as aggregated filaments in the apoptotic bodies. We also show that loss of membrane asymmetry and cytokeratin aggregation are independent processes, sinceN-ethylmaleimide-induced phosphatidylserine exposure does not cause cytokeratin disassembly. Vice versa, phorbol 12-myristate 13-acetate-induced cytokeratin filament aggregation does not result in phosphatidylserine exposure.     

NUTRITIONAL REQUIREMENTS OF FRAXINUS CALLUS CULTURES

A satisfactory synthetic medium has been developed for continuous growth of Fraxinus pennsylvanica Marsh. callus cultures. The medium contains modified Reinert and White (1956) inorganic nutrient solution with 5 mg/liter Fe as NaFe-EDTA and supplemented with myoinositol 10 mg/liter, pyridoxine HCl 0.1 mg/liter, 2,4-dichlorophenoxyacetic acid 0.04 mg/liter, kinetin 1 mg/liter, sucrose 20 g/liter, and agar 10 g/liter. myo-Inositol, pyridoxine and an auxin are essential. α-Naphthaleneacetic acid is an effective alternate auxin. Kinetin and to some extent gibberellic acid improve the yields. Thiamine has no effect.     

Serine-71 phosphorylation of rac1 modulates downstream signaling

The Rho GTPases Rac1 and Cdc42 regulate a variety of cellular functions by signaling to different signal pathways. It is believed that the presence of a specific effector at the location of GTPase activation determines the route of downstream signaling. We previously reported about EGF-induced Ser-71 phosphorylation of Rac1/Cdc42. By using the phosphomimetic S71E-mutants of Rac1 and Cdc42 we investigated the impact of Ser-71 phosphorylation on binding to selected effector proteins. Binding of the constitutively active (Q61L) variants of Rac1 and Cdc42 to their specific interaction partners Sra-1 and N-WASP, respectively, as well as to their common effector protein PAK was abrogated when Ser-71 was exchanged to glutamate as phosphomimetic substitution. Interaction with their common effector proteins IQGAP1/2/3 or MRCK alpha was, however, hardly affected. This ambivalent behaviour was obvious in functional assays. In contrast to Rac1 Q61L, phosphomimetic Rac1 Q61L/S71E was not able to induce increased membrane ruffling. Instead, Rac1 Q61L/S71E allowed filopodia formation, which is in accordance with abrogation of the dominant Sra-1/Wave signalling pathway. In addition, in contrast to Rac1 transfected cells Rac1 S71E failed to activate PAK1/2. On the other hand, Rac1 Q61L/S71E was as effective in activation of NF-kappaB as Rac1 Q61L, illustrating positive signal transduction of phosphorylated Rac1. Together, these data suggest that phosphorylation of Rac1 and Cdc42 at serine-71 represents a reversible mechanism to shift specificity of GTPase/effector coupling, and to preferentially address selected downstream pathways.     

Adrenocorticotropin and beta-endorphin are colocalized in the nervous system of rat duodenum

Adrenocorticotropin and beta-endorphin-like immunoreactivities were visualized by an immunohistochemical method on adjacent serial sections of the nervous system of the rat duodenum. Perikarya lying in the myenteric plexus and stained alternately for ACTH or beta-endorphin, showed on two adjacent serial sections a co-existence of these two peptides within one and the same perikarya. A co-localization of beta-endorphin and ACTH is not demonstrated with certainty in the submucous plexus. These results may be evidence for a common occurrence of the two peptides within perikarya of the rat duodenum.