ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

Hits per page

hits 1 - 4 | 4 hits

Sorting

Electronic Resource

Intracellular guanosine-5′-0-(3-thiotriphosphate) blocks chemotactic motility of Dictyostelium discoideum amoebae (1993)

Schlatterer, Christina ; Malchow, Dieter

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 25 (1993), S. 298-307

add to mindlist on the mindlist

Details

ISSN: 0886-1544

Keywords: guanine nucleotides ; calcium ; chemotaxis ; pseudopods ; membrane traffic ; BAPTA ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Starving amoebae of the cellular slime mold Dictyostelium discoideum react chemotactically towards the attractant cAMP. In this study, the effect of nonhydrolyzable analogs of GTP and GDP on the chemotactic behavior was analyzed with light microscopic techniques. Guanosine-5′-0-(2-thiotriphosphate) (GTPβS) or guanosine-5′-0-(2-thiodiphosphate) (GDPβS) was scrape-loaded into the cytoplasm of cells, together with a fluorescent marker. Stimulation with a cAMP-filled glass capillary revealed a reduced capacity of loaded cells to migrate to wards the capillary tip. Most cells still protruded filopods in the direction of the capillary tip, but full extension of pseudopods was inhibited in a dose-dependent and reversible manner. This indicates that in the presence of the analogs, chemotactic sensing still occurs, and that a more distal step of the cascade of events leading to the formation of the pseudopod is impaired.In cells loaded with the analogs together with the calcium indicator fura-2, stimulation with 10 μM cAMP led to a transient change in the intracellular free calcium concentration ([Ca2+]i), which was detectable in 28% of the cells. Furthermore, large vacuoles were found containing high amounts of calcium. On the other hand, clamping of [Ca2+]i at low levels with 1,2-bis(2-aminophenoxy) ethane N,N,N′,N′-tetraacetic acid (BAPTA) also inhibited motility, with neither filopods nor pseudopods formed.The data suggest that chemotactic migratory activity involves GTP-dependent processes that participate in the regulation of the Ca2+ homeostasis of the cell and in the regulation of membrane traffic that contributes to the directed locomotion. © 1993 Wiley-Liss, Inc.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cm.970250309

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Interaction of lung surfactant protein a with alveolar macrophages (1993)

Ohmer-Schröck, Daniela ; Schlatterer, Christina ; Plattner, Helmut ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Microscopy Research and Technique 26 (1993), S. 374-380

add to mindlist on the mindlist

Details

ISSN: 1059-910X

Keywords: C1q ; Calcium ; Specific binding ; SP-A ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Natural Sciences in General

Notes: We analyzed the binding mechanism of human recombinant lung surfactant protein A (SP-A) to rat alveolar macrophages using anti-SP-A antiserum and protein A coated onto gold particles. Results were compared with our recent data on binding and uptake of SP-A-coated colloidal gold particles. The rationale for the current approach was to avoid any possible steric effects on SP-A binding to the cell surface. Binding of unlabeled SP-A depends on the presence of calcium ions in the medium and involves a mannose-specific mechanism. Binding is partly inhibited by the collagenase-resistent fragment of SP-A, representing mainly the globular part of SP-A. Taken together, these facts indicate binding of SP-A via the carbohydrate binding site on the globular region of SP-A. On the other hand, a partial inhibition of SP-A binding by fragments of C1q (representing the collagenous region of C1q) indicates a second binding site for SP-A by the collagen-like portion to the C1q receptor of macrophages. We conclude that two different mechanisms are probably involved in SP-A binding to alveolar macrophages. Specificity of the binding was shown with fluorescein-labeled SP-A. Binding was inhibited by an excess of unlabeled SP-A. Binding and uptake of SP-A are seen only with alveolar macrophages and not with other macrophage populations isolated from rat, such as liver macrophages (Kupffer cells), resident peritoneal macrophages, and peritoneal macrophages activated by Corynebacterium parvum. Therefore, binding sites for SP-A occur exclusively on alveolar macrophages. In addition, the intracellular Ca2+ concentration of the lung macrophages was determined by using the fluorescent dye fura-2/AM. Intracellular [Ca2+] increased immediately after addition of SP-A. This indicates immediate activation of macrophages by SP-A. © 1993 Wiley-Liss, Inc.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jemt.1070260505

Permalink