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  • 1
    ISSN: 0886-1544
    Keywords: tubulin ; Drosophila ; β-ecdysterne ; differentiating ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Drosophila Kc cells exposed to physiological doses of the moulting hormone, β-ecdysone, elongate, become motile, and subsequently aggregate. This pattern of morphogenesis was found to require the assembly of a microtubular cytoskeleton. Tubulin content was significantly increased in hormone-treated cells when compared to controls, as measured by a 3H-colchicine-binding assay. However, determinations of rates of tubulin synthesis and breakdown revealed no difference between control and hormone-treated cells for either parameter. When tubulin content was assayed by methods that do not depend on colchicine-binding activity, no difference between hormone-treated and control cells was observed. These results are discussed in terms of a model in which β-ecdysone affects the distribution of tubulin in “assembly-active” and “assembly-inactive” pools.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0730-2312
    Keywords: discoidins I and II ; lectins ; surface-localized ; aggregation-defective mutants ; cell cohesion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The endogenous lectins discoidins I and II are believed to be primary components of the morphogenetic cell cohesion system of D discoideum. We have developed two immunochemical methods to analyze the association of the discoidins with the cell surface. One method is a two-stage specific antibody binding assay in which intact cells are incubated on ice with rabbit serum (either control serum or antidiscoidin I and II), washed, then incubated with 125I-Protein A. Specific antibody binding is defined as the difference between percent radioactivity bound with antidiscoidin versus control serum during the first stage. Substantial specific binding was observed with developed A3 cells but not with vegetative cells, and nearly all of the activity could be removed by pread-sorption of the antiserum with discoidin-Sepharose. As a complementary method, quantitative immunoadsorption analysis was performed in which we tested the ability of intact cells to remove antibodies reactive with purified 125I-discoidin I or II. Developed cells, but not vegetative cells, were capable of adsorbing antibodies reactive with discoidin I as well as those reactive with discoidin II. This represents the first demonstration that both lectins are present on the surface of cohesive cells.These procedures, coupled with other methods to analyze soluble discoidin in cell extracts, were used to study discoidin expression in wild type cells and in two newly isolated aggregation-defective mutants. Strain EB-32 fails to aggregate and displays little or no discoidin in cell extracts or at the cell surface. On the other hand, strain EB-18 forms loose amorphous mounds, and expresses substantial quantities of the discoidins, both in cell extracts and at the cell surface. These mutants should prove valuable in studying the organization and regulation of discoidins I and II at the surface of aggregating cells.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 7 (1983), S. 169-177 
    ISSN: 0148-7280
    Keywords: porcine ; sperm ; adenylate cyclase ; phosphodiesterase ; female secretions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Adenylate cyclase activities were studied in porcine sperm in the presence and absence of Mn++ before and after incubation in vivo and in vitro. Incubation of sperm in vivo for 30 min increased the Mg++-stimulated adenylate cyclase activity from 35.1 pmoles cyclic AMP formed per mg protein per 10 min to 50.4 pmoles. The activity stimulated by Mg++ and Mn++ increased from 392 to 729 pmoles after 30 min of in vivo incubation. Activity after incubation in vivo for 120 min was not different from activity after 30 min. In vitro incubation of porcine sperm in Ca++-free Ringer-fructose resulted in no change, but incubation in oviductal and uterine flushings obtained from gilts soon after ovulation increased Mg++-stimulated activity by 24% and Mg++-+ Mn++-stimulated activity by 49%. In vitro incubations in preovulatory flushings plus follicular fluid or in bovine serum albumin also increased adenylate cyclase activity.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 210 (1984), S. 393-405 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The anatomic relationships of the carpal radioscapholunate ligament to its contiguous structures were analyzed by studying (1) 12 grossly dissected fresh adult wrists, and (2) multiple histologic sections from six adult wrists. Observations indicate that the radioscapholunate ligament originates from the prominence between the scaphoid and lunate articular facets on the distal articular surface of the radius, and from the palmar margin of the distal radius, deep and medial to the origin of the radiotriquetral and radiocapitate ligaments. The primary insertion of the radioscapholunate ligament is the medial margin of the proximal pole of the scaphoid. The ligament secondarily inserts into the lateral margin of the lunate and significantly contributes to the proximal portion of the scapholunate interosseous ligament. The radioscapholunate ligament is distinguished morphologically from the other palmar radiocarpal ligaments by its loosely organized collagen fibers and relatively high degree of vascularity. The radiotriquetral and radiocapitate ligaments are composed of densely fasciculated collagen fibers surrounded by perpendicularly oriented perifascicular and epiligamentous fibers. A fibrous capsular layer covers the most superficial aspect of each carpal ligament. On the deep surfaces of these ligaments, a condensation of epiligamentous fibers forms a synovial capsular layer. The palmar radiocarpal ligaments are truly intracapsular structures, as they are interposed between the fibrous and synovial capsular layers. No histologic evidence of elastin is present within the substance of these ligaments.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The binding and internalization of fluorescein isothiocyanate-conjugated insulin by nonactivated and phytohemagglutinin-activated circulating human lymphocytes was measured by flow cytometry. In confirmation of previous results, negligible binding or internalization was observed for unstimulated cells, while activated lymphocytes showed significant insulin binding. The majority of this insulin was demonstrated to be internalized via receptor-mediated endocytosis and acidified within 60 min after addition of insulin. Dual-fluorescence flow cytometry, using antibodies specific for human T cell subsets, was used to show that the expression of insulin binding sites occurs for at least some cells from both the helper/inducer and cytotoxic/suppressor T cell subsets. Insulin internalization is not an artifact of in vitro stimulation, since more than 90% of the unstimulated lymphocytes from a patient with a helper T cell leukemia are positive for insulin internalization. The usefulness of flow cytometric analysis for measuring lymphocyte activation in unstimulated populations and the therapeutic potential of the reported findings for control of lymphocyte proliferation are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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