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  • 1
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cupula of the supraorbital neuromast in the lateral line canal of the clown knifefish contains vertical columns. In the central region of the cupula overlying the macula, these columns are densely packed, are relatively constant in size, and run from the base of the cupula to the surface of the cupula which is exposed to canal fluid. There are two types of columns, dark and light, which form elliptical compartments in planes of section that cut across the columns; the cupula therefore has the appearance of mosaic tile in such sections. The dark compartments contain tubules that extend from the base of the cupula at the junction with the macula to the top of the cupula. Each tubule is associated with the kinocilium of a single hair cell. The lateral parts of the cupula, not overlying the macula, also contain compartments, but these compartments differ in size and structure from those in the central region. In addition to the compartments, the central region of the cupula also contains spherical aggregates of droplets. These small aggregates, termed mora, are found principally in a layer within the central region of the cupula, but are also found outside this layer. Because of their light-reflecting properties, the mora can be used for noninvasive optical measurements in vivo of the motion of the cupula.
    Additional Material: 9 Ill.
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  • 2
    ISSN: 0730-2312
    Keywords: forskolin ; cholera toxin ; pertussis toxin ; interleukin-2 ; T lymphocyte ; G protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The Nb2 T lymphoma is unique in that these lymphocytes proliferate in response to prolactin as well as in response to interleukin-2. In this study, we have examined the responsiveness of the adenylate cyclase system in Nb2 cells and the role of this signaling system in regulating proliferation and protein phosphorylation. An analog of cAMP inhibited prolactin-stimulated proliferation and blocked a prolactin-induced decrease in protein phosphorylation. Forskolin, a potent activator of adenylate cyclase in T lymphocytes, did not elevate cAMP levels in Nb2 cells and was not an effective inhibitor of prolactin-induced proliferation. In fact, one preparation of forskolin stimulated proliferation of quiescent Nb2 cells. Like forskolin, prostaglandin E2 did not stimulate cAMP production in Nb2 cells even though, it increased cAMP in a preparation of rat peripheral blood lymphocytes. Cholera toxin appeared to ADP-ribosylate a stimulatory guanine nucleotide-binding protein in Nb2 cells, but the toxin did not increase intracellular levels of cAMP nor was it a potent anti-mitogenic agent. Pertussis toxin, an agent that can increase cAMP production through suppression of the inhibitory guanine nucleotide-binding protein, exerted only minor anti-proliferative actions on prolactin-stimulated Nb2 cells. These data suggest that cAMP inhibits Nb2 cell proliferation and prolactin-induced changes in protein phosphorylation but that the adenylate cyclase system in our clone of Nb2 cells responds poorly to agents that normally increase cAMP.
    Additional Material: 8 Ill.
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  • 3
    ISSN: 0730-2312
    Keywords: 2D-PAGE ; human tumors ; HEp-3 ; subcellular fractionation ; negative regulators ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human epidermoid carcinoma (HEp-3) cells are highly tumorigenic and metastatic in vivo, but their metastatic phenotype is progressively and uniquely lost upon serial passage in vitro. The nonmetastatic phenotype is fully reversible to the highly metastatic state when HEp-3 cells are passaged back in vivo.To study the complex process of metastasis and its possible negative regulation by specific gene products, the expression of specific proteins between the highly metastatic and nonmetastatic HEp-3 cells was investigated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and subsequent computer assisted analyses. Concomitant with the in vitro loss of metastatic potential of HEp-3 cells is the elevated expression of a subset of low abundance proteins detectable in 2D-PAGE but not apparent in high resolution one dimensional PAGE. When the HEp-3 cells revert to the metastatic state, the expression of these proteins declines. The increased abundance of four distinct proteins directly correlates with the loss of the metastatic phenotype: two of the four proteins are associated with isolated cellular membranes (36kD, pl 5.7; 22kDa, pl 5.6), on protein fractionates with the cytoplasm (65kD, pl 6.2), and one protein is enriched in the nuclei fraction (32kD, pl 5.8). These data indicate that computer-assisted analysis of highly sensitive, large-format, 2D-PAGE can be used to identify specific proteins in subcellular compartments that are candidates for negative regulators of the metastatic process. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 69 (1941), S. 481-498 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 23-31 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lifelike models of the oscillating legs treated as three-segment systems show the course of kinetic and potential energy over the locomotor cycle for a cheetah, pronghorn, jackrabbit, and elephant running at speeds approaching their maxima. The models can be adjusted to eliminate differences among the animals in time intervals, mass or length of limb, and joint angles. This facilitates analysis of the influence on total energy of each of these variables and of the distribution of mass among leg segments. Fast-cycling legs of the carnivore type have significantly more energy than those of the hoofed type. This may contribute to the lesser endurance that is usual for carnivores that hunt using a high-speed dash.
    Additional Material: 4 Ill.
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  • 6
    ISSN: 0730-2312
    Keywords: genome ; calmodulin ; smooth muscle ; immunohistochemistry ; heart ; development ; protein kinase ; tissue selective ; calcium ; signal transduction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We report that the genetic locus that encodes vertebrate smooth muscle and nonmuscle myosin light chain kinase (MLCK) and kinase-related protein (KRP) has a complex arrangement and a complex pattern of expression. Three proteins are encoded by 31 exons that have only one variation, that of the first exon of KRP, and the genomic locus spans approximately 100 kb of DNA. The three proteins can differ in their relative abundance and localization among tissues and with development. MLCK is a calmodulin (CaM) regulated protein kinase that phosphorylates the light chain of myosin II. The chicken has two MLCK isoforms encoded by the MLCK/KRP locus. KRP does not bind CaM and is not a protein kinase. However, KRP binds to and regulates the structure of myosin II. Thus, KRP and MLCK have the same subcellular target, the myosin II molecular motor system. We examined the tissue and cellular localization of KRP and MLCK in the chicken embryo and in adult chicken tissues. We report on the selective localization of KRP and MLCK among and within tissues and on a differential distribution of the proteins between embryonic and adult tissues. The results fill a void in our knowledge about the organization of the MLCK/KRP genetic locus, which appears to be a late evolving regulatory paradigm, and suggest an independent and complex regulation of expression of the gene products from the MLCK/KRP genetic locus that may reflect a basic principle found in other eukaryotic gene clusters that encode functionally linked proteins. J. Cell. Biochem. 70:402-413, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 7
    ISSN: 0730-2312
    Keywords: gene regulation ; 2,3,7,8-tetrachlorodibenzo-p-dioxin ; cytochrome P1-450 ; receptor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) dioxin, produces a diverse set of biological responses which, in some cases, reflects the altered expression of specific genes. An intracellular receptor protein binds TCDD saturably and with high affinity and mediates several of TCDD's biological effects. In mouse hepatoma cells, TCDD induces aryl hydrocarbon hydroxylase activity by activating the transcription of the cytochrome P1-450 gene. Studies of receptor-defective variant cells indicate that the activation of cytochrome P1-450 gene transcription requires functional TCDD receptors. Analysis of the DNA that flanks the 5′-end of the mouse cytochrome P1-450 gene reveals at least three control regions: a promoter, an inhibitory element, and a dioxin-responsive element (DRE). Therefore, expression of the cytochrome P1-450 gene represents a balance between negative and positive control. The DRE contains two discrete, non-overlapping DNA domains that respond to TCDD. Each TCDD-responsive domain acts independently of the other, each requires TCDD receptors for function, and each has the properties of a transcriptional enhancer. For example, the function of the DREs is relatively independent of both their location and their orientation with respect to the promoter. Together, the DREs and the TCDD-receptor complex constitute a dioxin-responsive enhancer system. Exposure of cells to TCDD results in the protection of a specific DNA domain from exonuclease digestion. This protection requires TCDD receptors. The protected domain maps to a DRE. This observation implies that the TCDD-receptor complex interacts with the DRE to activate the transcription of the cytochrome P1-450 gene.
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0730-2312
    Keywords: EGF receptor ; multidrug-resistance ; human neuroblastoma ; binding assay ; immunoprecipitation ; transformation/differentiation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Multidrug-resistant human neuroblastoma cell lines obtained by selection with vincristine or actinomycin D from two independent clonal lines, SH-SY5Y and MCIXC, have 3- to 30-fold more cell surface epidermal growth factor (EGF) receptors than the drug-sensitive parental cells as indicated by EGF binding assays and immunoprecipitation, affinity-labeling, and phosphorylation studies. Reversion to drug sensitivity in one line was accompanied by a return to the parental level of EGF receptor. SH-EP cells, a clone derived from the same neuroblastoma cell line as SH-SY5Y but which displays melanocyte rather than neuronal lineage markers, also express significantly more EGF receptor than SH-SY5Y cells. By nucleic acid hybridization analysis with a molecularly cloned probe, increased receptor level in multidrug-resistant cells was shown to be the result of higher levels of EGF receptor mRNA in drug-resistant than in drug-sensitive cells. The increased steady state amount of specific RNA did not result from amplification of receptor-encoding genes. A small difference was observed in the electrophoretic mobility under denaturing conditions of EGF receptor immunoprecipitated from drug-resistant and drug-sensitive cells. Quantitative and qualitative modulation of the EGF receptor might reflect alterations in the transformation and/or differentiation phenotype of the resistant cells or might result from unknown selective pressures associated with the development of multidrug resistance.
    Additional Material: 3 Ill.
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  • 9
    ISSN: 0730-2312
    Keywords: steroid receptor ; oviduct ; avian tissues ; protein ; acceptor site ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The avian oviduct receptor binding factor-1 (RBF-1) is a 10 kDa nuclear matrix protein that was originally identified through its ability to effect high affinity interaction of activated progesterone receptor (PR) with chromatin. In the present study, the RBF-1 is shown to not be restricted to reproductive tissues (e.g., oviduct) but present in all avian tissues examined by Western blot analysis with a monoclonal antibody prepared against purified RBF-1. The heart and pancreas had the highest and lowest RBF-1 levels, respectively; the concentration ranging by ∼ 50-fold in these tissues. The 10 kDa size of the RBF-1 detected in all tissues suggests no significant tissue-specific differences in the protein. This was consistent with the finding that purified hepatic and oviductal RBF-1 have identical amino-terminal sequence. Using a recently isolated cDNA to RBF-1, the levels of RBF-1 mRNA were found to correlate well with the ubiquitous presence of the protein as well as tissue-specific differences in concentration. The presence of RBF-1 in non-progesterone responsive tissues suggests the possibility that RBF-1 may not be specifically involved in PR-DNA interactions but may play a more diverse role, possibly involving other steroid receptors such as the glucocorticoid receptor. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0730-2312
    Keywords: 5-(N, N-hexamethylene)-amiloride (HMA) ; 12-O-tetradecanoylphorbol-13-acetate (TPA) ; chelerythrine ; protein kinase C (PKC) ; serum withdrawal ; internucleosomal DNA cleavage ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Changes in intracellular ion concentrations have been correlated with the activation of an endogenous endonuclease and thus internucleosomal DNA cleavage during apoptosis in many cell types. We investigated whether intracellular pH could play a significant role in apoptotic initiation and progression in C3H-10T1/2 cells, a cell strain that does not exhibit double-stranded DNA cleavage during apoptosis. Protein kinase C and the Na+/H+ antiporter, known regulators of intracellular pH, also were assessed for their involvement in apoptosis of C3H-10T1/2 cells. When a H+ ionophore was used to clamp intracellular pH to 6.0 or below, a significant level of apoptosis was induced in these cells within 6 h, whereas clamping at pH 6.75 did not induce significant amounts of apoptosis until 36 h after acidification. The acidified cells exhibited classic apoptotic morphology and chromatin condensation, similar to serum withdrawn cells, but failed to show internucleosomal DNA cleavage with electrophoresis of genomic DNA. Our results also suggest that the 12-O-tetradecanoylphorbol-13-acetate (TPA)-mediated inhibition of apoptosis in serum withdrawn C3H-10T1/2 cells functions through a sequential activation of protein kinase C and the Na+/H+ antiporter; thus, an alkalinization or an inhibition of acidification is involved in this apoptotic block. Serum withdrawal itself does not appear to act through a negative effect on either protein kinase C or the Na+/H+ antiporter. TPA was also capable of inhibiting the apoptosis induced by specific inhibitors of protein kinase C and the Na+/H+ antiporter, but the inhibition was successful only if the TPA was administered at least 20 min prior to the addition of the enzyme inhibitor. These results indicate that apoptosis in C3H-10T1/2 cells follows a pathway that involves intracellular acidification, but is independent of detectable endonuclease activity. J. Cell. Biochem. 67:231-240, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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