Polypeptides of cerebral subcellular fractions of differentially-housed mice

Summary The difference in protein of cerebral nerve-ending fractions caused by differential housing of male mice is of a quantitative nature and might reflect a change in the number of nerve-endings.This work was supported in part by Centro Nacional Ramón y Cajal (de la Seguridad Social) and Fundación Juan March and was conducted in part at the Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan Italy, while Dr F. P. Conde was on a research fellowship. Thanks are due to Mr Riccardo Gelati for technical assistance and to Mr Mario Azzini for the photography.     

The biology of cell locomotion within three-dimensional extracellular matrix

Cell migration in three-dimensional (3-D) extracellular matrix (ECM) is not a uniform event but rather comprises a modular spectrum of interdependent biophysical and biochemical cell functions. Haptokinetic cell migration across two-dimensional (2-D) surfaces consists of at least three processes: (i) the protrusion of the leading edge for adhesive cell-substratum interactions is followed by (ii) contraction of the cell body and (iii) detachment of the trailing edge. In cells of flattened morphology migrating slowly across 2-D substrate, contact-dependent clustering of adhesion receptors including integrins results in focal contact and stress fiber formation. While haptokinetic migration is predominantly a function of adhesion and deadhesion events lacking spatial barriers towards the advancing cell body, the biophysics of the tissues require a set of cellular strategies to overcome matrix resistance. Matrix barriers force the cells to adapt their morphology and change shape and/or enzymatically degrade ECM components, either by contact-dependent proteolysis or by protease secretion. In 3-D ECM, in contrast to 2-D substrate, the cell shape is mostly bipolar and the cytoskeletal organization is less stringent, frequently lacking discrete focal contacts and stress fibers. Morphologically large spindle-shaped cells (i.e., fibroblasts, endothelial cells, and many tumor cells) of high integrin expression and strong cytoskeletal contractility utilize integrin-dependent migration strategies that are coupled to the capacity to reorganize ECM. In contrast, a more dynamic ameboid migration type employed by smaller cells expressing low levels of integrins (i.e., T lymphocytes, dendritic cells, some tumor cells) is characterized by largely integrin-independent interaction strategies and flexible morphological adaptation to preformed fiber strands, without structurally changing matrix architecture. In tumor invasion and angiogenesis, migration mechanisms further comprise the migration of entire cell clusters or strands maintaining stringent cell-cell adhesion and communication while migrating. Lastly, cellular interactions, enzyme and cytokine secretion, and tissue remodeling provided by reactive stroma cells (i.e. fibroblasts and macrophages) contribute to cell migration. In conclusion, depending on the cellular composition and tissue context of migration, diverse cellular and molecular migration strategies can be developed by different cell types.     

Acceleration of red cell glycolysis by citrate due to intracellular pH enhancement

Zusammenfassung Nachweis, dass in Konsequenz der intra- und extrazellulären pH-Differenz, das Citrat die Erythrocyten Glycolyse beschleunigt.     

Filaments of the vertebrate lens

Summary Filaments of an average diameter of 10–12 nm have been identified in the eye lens fibre cells of representative species of each vertebrate order. These filaments presumably serve a cytoskeletal role in the lens fibre cells.This study was supported by research grant Ey 0141 of the National Institutes of Health, Bethesda, Maryland, USA.     

Chain-proteins of the vertebrate lens

Some lens proteins exist in a chain-like form in the vertebrate lens fibre cells. They consist of globular proteins arranged on a filamentous backbone.     

Chain-proteins of the vertebrate lens

Summary Some lens proteins exist in a chain-like form in the vertebrate lens fibre cells. They consist of globular proteins arranged on a filamentous backbone.This study was supported by research grant EY-01417 of the National Institutes of Health, Bethesda, Maryland, USA.     

Particle aggregates in plasma and intracellular membranes of toad bladder (granular cell)

Summary Freeze-fracture of granular cells of toad urinary bladder (Bufo marinus) reveals the presence, hitherto undescribed, of intramembranous particle aggregates in intracytoplasmic structures (tubules, vacuoles and vesicles) both in resting and vasopressin-stimulated epithelia.This work was supported by grants No. 3.553.75, 3.120.77 and 3.1300.73 from the Swiss National Science Foundation.The authors are indebted to Mrs Marthe Sidler-Ansermet, Miss Jacqueline Rial and Mr Michel Bernard for valuable technical assistance.     

Changes in intracellular pH and cell volume during the early phase of DMSO-induced differentiation of friend erythroleukemia cells

Summary Changes in intracellular pH and water volume were measured after treatment of Friend erythroleukemia cells with 1.5% DMSO. It was found that a continuous decrease in pH_i occurred, beginning 1 h after induction and a decline in pH_i of 0.18 was measured after 9 h. In addition a decline in cellular water volume, of 12% only 15 min after induction, and 23% after 9 h, was observed.11 December 1986Acknowlegments. This work was supported by the Deutsche Forschungsgemeinschaft.     

Changes in intracellular pH and cell volume during the early phase of DMSO-induced differentiation of Friend erythroleukemia cells

Changes in intracellular pH and water volume were measured after treatment of Friend erythroleukemia cells with 1.5% DMSO. It was found that a continuous decrease in pHi occurred, beginning 1 h after induction and a decline in pHi of 0.18 was measured after 9 h. In addition a decline in cellular water volume, of 12% only 15 min after induction, and 23% after 9 h, was observed.     

Isolation of filaments of the chick lens

Summary A preparation of intermediate filaments isolated from the chicken lens is enriched with a 50,000 dalton polypeptide.This study was supported by research grant EY 01417 of the National Institutes of Health, Bethesda, Maryland, USA.     

Isolation of filaments of the chick lens

A preparation of intermediate filaments isolated from the chicken lens is enriched with a 50,000 dalton polypeptide.     

Effects of intracellular or extracellular application of tetraethylammonium on the action potential in cultured chick embryonic heart muscle cell

Summary The effects of tetraethylammonium (TEA) on the action potential in cultured chick embryonic heart muscle cells were investigated. The onset of prolongation of the action potential occurred within 10 min following intracellular iontophoretic application of TEA, but after more than 50 min following extracellular application. These facts suggest that the major site of action of TEA is on the inner surface of the membrane in these cells.     

Adhesion receptors and cell invasion: mechanisms of integrin-guided degradation of extracellular matrix

The integrins are a large family of heterodimeric cell adhesion receptors mediating cell-matrix and cell-cell adhesion. They seem to play a central role in cell migration and invasion and are therefore essential in processes such as healing of tissue injuries and the progression of human cancer. Integrins function in cell invasion by mediating cell movement on matrix molecules and also by regulating the expression of matrix-degrading enzymes, namely the matrix metalloproteinases. Here we review recent findings on the mechanisms by which integrins regulate matrix degradation. A novel, multistep model of integrin-guided collagen degradation is proposed.     

Polypeptides and Leuches' anhydrides from carbamic acid derivatives of C-activated amino acids

Zusammenfassung Durch katalytische Hydrierung von C-aktivierten Carbobenzoxyaminosäurederivaten, z. B. von gemischten Anhydriden und aktivierten Estern, werden via die Carbaminsäurederivate die entsprechenden Leuchsschen Anhydride und Polypeptide erhalten.

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This work was supported by grants from the National Institutes of Health, U.S. Public Health Service (G.M. 06579 and G.M. 08795).     

Viral journeys on the intracellular highways

Viruses are obligate intracellular pathogens that are dependent on cellular machineries for their replication. Recent technological breakthroughs have facilitated reliable identification of host factors required for viral infections and better characterization of the virus–host interplay. While these studies have revealed cellular machineries that are uniquely required by individual viruses, accumulating data also indicate the presence of broadly required mechanisms. Among these overlapping cellular functions are components of intracellular membrane trafficking pathways. Here, we review recent discoveries focused on how viruses exploit intracellular membrane trafficking pathways to promote various stages of their life cycle, with an emphasis on cellular factors that are usurped by a broad range of viruses. We describe broadly required components of the endocytic and secretory pathways, the Endosomal Sorting Complexes Required for Transport pathway, and the autophagy pathway. Identification of such overlapping host functions offers new opportunities to develop broad-spectrum host-targeted antiviral strategies.     

Impact of biofilm matrix components on interaction of commensal Escherichia coli with the gastrointestinal cell line HT-29

Commensal Escherichia coli form biofilms at body temperature by expressing the extracellular matrix components curli fimbriae and cellulose. The role of curli fimbriae and cellulose in the interaction of commensal E. coli with the intestinal epithelial cell line HT-29 was investigated. Expression of curli fimbriae by the typical commensal isolate E. coli TOB1 caused adherence and internalization of the bacteria and triggered IL-8 production in HT-29 cells. In particular, induction of IL-8 production was complex and involved curli-bound flagellin. While cellulose alone had no effect on the interaction of TOB1 with HT-29 cells, co-expression of cellulose with curli fimbriae decreased adherence to, internalization and IL-8 induction of HT-29 cells. Investigation of a panel of commensal isolates showed a partial correlation between expression of curli fimbriae and enhanced internalization and IL-8 production. In addition, a high immunostimulatory flagellin was identified. Thus, the consequences of expression of extracellular matrix components on commensal bacterial-host interactions are complex.