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  • 1
    Electronic Resource
    Electronic Resource
    Two saturable mechanisms of iron uptake from transferrin in human melanoma cells: The effect of transferrin concentration, chelators, and metabolic probes on transferrin and iron uptake (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 161 (1994), S. 160-168 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanisms of iron (Fe) and transferrin (Tf) uptake by the human melanoma cell line, SK-MEL-28, have been investigated using chelators and metabolic probes. These data provide evidence for two saturable processes of Fe uptake from Tf, namely, specific receptor-mediated endocytosis and a second nonspecific, non-receptor-mediated mechanism which saturated with respect to Fe uptake at a Tf concentration of approximately 0.3 mg/ml. In contrast to Fe uptake, Tf uptake increased linearly up to at least 1 mg/ml. Furthermore, under the culture conditions used, the second nonspecific, non-receptor-mediated mechanism was the most important process in terms of quantitative Fe uptake. Two concentrations of Tf-125I-59 Fe (0.01 and 0.1 mg/ml) were used in order to characterise the specific and nonspecific Fe uptake pathways. Membrane permeable chelators were equally effective at both Tf concentrations, whereas membrane impermeable chelators were significantly (P 〈 0.001) more effective at reducing the internalisation of Fe at the higher Tf concentration, consistent with a mechanism of Fe uptake which occurred at a site in contact with the extracellular medium. The oxidoreductase inhibitor, amiloride, only slightly inhibited Fe uptake at the higher Tf concentration, suggesting that the second nonspecific process was not mediated by a diferric Tf reductase. Three lysosomotrophic agents and the endocytosis inhibitor, phenylglyoxal, markedly reduced Fe uptake at both Tf concentrations, and it is concluded that a saturable process consistent with receptor-mediated endocytosis of Tf occurred at the lower Tf concentration, while the predominant mechanism of Fe uptake at high Tf concentrations was a second saturable process consistent with adsorptive pinocytosis. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041610119
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  • 2
    Electronic Resource
    Electronic Resource
    Elevated paraquat resistance can be used as a bioassay for longevity in a genetically based long-lived strain of Drosophila (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 12 (1991), S. 362-370 
    Details
    ISSN: 0192-253X
    Keywords: Aging ; genetics of aging ; biomarkers ; free radicals ; catalase ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A long-lived (L) strain of Drosophila melanogaster, derived from a normal-lived (R) strain by artificial selection, has a significantly different adult longevity. Previous work has shown that (1) the two strains age in the same manner, (2) the major genes responsible for much of the L strain's extended longevity are located on the 3rd chromosome, and (3) the extended longevity phenotype is significantly modulated by the larval environment. In this report, we investigate the resistance of the L and R strains to the lethal effects of dietary paraquat. We show that, within the limitations of our described chromosomal and environmental manipulations, the extended longevity phenotype always accompanies the phenotype of elevated paraquat resistance. In addition, reversed selection applied to the L strain results in the simultaneous decrease of both life span and paraquat resistance. Thus, the presence or absence of the latter phenotype may be used as a bioassay for the presence or absence of the extended longevity phenotype, without any necessary implication of causality. Use of this bioassay should greatly speed up the genetic analysis of this system by allowing us to identify long-lived animals at a young age. Finally, we show that the age-related loss of elevated paraquat resistance in both strains precedes all the other age-related functional decrements which we have previously noted in this system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020120505
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  • 3
    Electronic Resource
    Electronic Resource
    Behavioral and neurobiological implications of sex-determining factors in Drosophila (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 15 (1994), S. 275-296 
    Details
    ISSN: 0192-253X
    Keywords: Reproductive behavior ; courtship song ; Sex-specific internal anatomy ; doublesex mutants ; transformer mutants ; intersex mutant ; fruitless mutants ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The function of the central nervous system as it controls sex-specific behaviors in Drosophila has been studied with renewed intensity, in the context of genetic factors that influence the development of sexually differentiated aspects of this insect. Three categories of genetic variations that cause anomalies in courtship and mating behaviors are discussed: (1) mutants isolated with regard to courtship defects, of which putatively courtship-specific variants such as the fruitless mutant are a subset; (2) general behavioral and neurological variants (including sensory and learning mutants), whose defects include subnormal reproductive performance; and (3) mutations of genes within the sex-determination regulatory hierarchy of Drosophila, the analysis of which has included studies of reproductive behavior. Recent studies of mutations in two of these categories have provided new insights into the control of neuronally based aspects of sex-specific behavior. The doublesex gene, the final factor acting in the sex-determination hierarchy, had been previously thought to regulate all aspects of sexual differentiation. Yet, it has been recently shown that doublesex does not control at least one neuronally-determined feature of sex-specific anatomy - a muscle in the male's abdomen, whose normal development is, however, dependent on the action of fruitless. These considerations prompted us to examine further (and in some cases re-examine) the influences exerted by sex-determination hierarchy genes on behavior. Our results - notably those obtained from assessments of doublesex mutations' effects on general reproductive actions and on a particular component of the courtship sequence (male “singing” behavior) - lead to the suggestion that there is a previously unrecognized branch within the sexdetermination hierarchy, which controls the differentiation of the male- and female- specific phenotypes of Drosophila. This new branch separates from the doublesex-related one immediately before the action of that gene (just after fransformer and transformer-2) and appears to control as least some aspects of neuronally determined sexual differentiation of males. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020150309
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  • 4
    Electronic Resource
    Electronic Resource
    Tubulin mRNA instability and stabilization by protein synthesis inhibitors are reproducible in nontranslating extracts from Chlamydomonas (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 14 (1993), S. 460-470 
    Details
    ISSN: 0192-253X
    Keywords: mRNA stability ; tubulin mRNA ; flagella ; Chlamydomonas ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In Chlamydomonas rein-hardtii, flagellar amputation stimulates an induction in the synthesis of flagellar proteins which allows the cells to rapidly regenerate their flagella. The induction involves the coordinate accumulation and rapid degradation of a large number mRNAs, including those encoding the tubulins. The post-induction degradation of induced tubulin mRNAs has been shown to differ from the consti-tutive turnover pathway in two ways: (1) the rate of degradation is accelerated, and (2) degradation is prevented by inhibition of protein synthesis. In this report, it is shown that the post-induction degradation of all deflagellation-induced mRNAs examined is prevented by cycloheximide (CX), suggesting they all may be degraded via the same pathway. A cell-free decay system has been developed to investigate the degradation pathway. At least two characteristics of tubulir mRNA degradation are reproducible in these extracts: (1) endogenous α-tubulin mRNA is less stable than constitutive mRNAs in the same extract and (2) α-tubulin mRNA in extracts prepared from CX-treated cells (CX ex-tracts) is significantly more stable than it is in extracts from untreated cells (control extracts). This indicates that the mechanism by which CX blocks rapid degradation of tubulin mRNA in vivo is not simply by preventing its translation and suggests the involvement of an altered trans-factor. The difference in tubulin mRNA stability in the two extracts is maintained when the extracts are prepared under conditions that dissociate ribosomes from mRNPs, indicating intact polysome structure is not necessary. Tubulin mRNA-containing polysomes isolated from control and CX extracts are equally stable when assayed alone. However, the poly-somes from control extracts are more sensitive to exogenous RNAse treatment than are those from CX extracts, indicating a structural difference. There are no detectable differences in soluble factors that influence tubulin mRNA degradation rate between control and CX extracts; addition of excess soluble factors to either control or CX extracts does not alter the tubulin mRNA degradation in the extract, nor does a simple one-to-one combination of the two extracts result in stabilization or destabilization of the whole population of tubulin mRNAs in the mixture. The deflagellation-induced mRNAs, as a group, are shown to be particularly susceptible to a nuclease activity in extracts, inhibitable by vanadyl ribonucleoside complexes, which does not appear to attack constitutive mRNAs. It is proposed that a structural difference in the tubulin mRNPs produced in the presence and absence of CX underlies their differences in stabilities, and that a common nuclease targets the induced flagellar protein mRNAs. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020140607
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  • 5
    Electronic Resource
    Electronic Resource
    Imaging fluid/solid interactions in hydrocarbon reservoir rocks (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 25 (1993), S. 465-473 
    Details
    ISSN: 1059-910X
    Keywords: ESEM ; Liquid hydrocarbons ; Hydrocarbon reservoirs ; Clay minerals ; Chlorite ; Illite/smectite ; Calcite ; Fluid sensitivity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The environmental scanning electron microscope (ESEM) has been used to image liquid hydrocarbons in sandstones and oil shales. Additionally, the fluid sensitivity of selected clay minerals in hydrocarbon reservoirs was assessed via three case studies: HCl acid sensitivity of authigenic chlorite in sandstone reservoirs, freshwater sensitivity of authigenic illite/smectite in sandstone reservoirs, and bleach sensitivity of a volcanic reservoir containing abundant secondary chlorite/corrensite. The results showed the suitability of using ESEM for imaging liquid hydrocarbon films in hydrocarbon reservoirs and the importance of simulating in situ fluid-rock interactions for hydrocarbon production programmes. In each case, results of the ESEM studies greatly enhanced prediction of reservoir/borehole reactions and, in some cases, contradicted conventional wisdom regarding the outcome of potential engineering solutions. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070250518
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  • 6
    Electronic Resource
    Electronic Resource
    Allografts of CNS tissue possess a blood-brain barrier: III. Neuropathological, methodological, and immunological considerations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 27 (1994), S. 471-494 
    Details
    ISSN: 1059-910X
    Keywords: Transplantation ; Central nervous system ; Endothelium ; Immunology ; Immunohistochemistry ; Blood vessels ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Development of a blood-brain barrier (BBB) within mammalian CNS grafts, placed either intracerebrally or peripherally, has been controversial. Published data from this laboratory have emphasized the presence or the absence of a BBB within solid mammalian tissue or cell suspension grafts is determined intrinsically by the graft and not by the surrounding host parenchyma (e.g., brain, kidney, testis, etc.). Nevertheless, correctly interpreting whether or not a BBB exists within brain grafts is manifested by methodologies employed to answer the question and by ensuing neuropathological and immunological consequences of intracerebral grafting. The present study addresses these issues and suggests misinterpretation for the absence of a BBB in brain grafts can be attributed to: (1) rupture of interendothelial tight junctional complexes in vessels of CNS grafts fixed by perfusion of the host; (2) damage to host vessels and BBB during the intracerebral grafting procedure; (3) graft placement in proximity to inherently permeable vessels (e.g., CNS sites lying outside the BBB) supplying the subarachnoid space/pial surface and circumventricular organs such as the median eminence, area postrema, and choroid plexus; and (4) graft rejection associated with antigen presenting cells and the host immune response. The latter is prevalent in xenogeneic grafts and exists in allogeneic grafts with donor-host mismatch in the major and/or minor histocompatibility complex. CNS grafts between non-immunosuppressed outbred donor and host rats of the same strain (e.g., Sprague Dawley or Wistar rats) can be rejected by the host; these grafts exhibit populations of immuonohistochemically identifiable major histopatibility complex class I+ and class II+ cells (microglia, macrophages, etc.) and CD4+ T-helper and CD8+ T-cytotoxic lymphocytes. PC12 cell suspension grafts placed within the CNS of non-immunosuppressed Sprague Dawley rats are rejected similarly. Donor cells from solid CNS grafts placed intracerebrally and stained immunohistochemically for donor major histocompatibility complex (MHC) class I expression are identified within the host spleen and lymph nodes; these donor MHC expressing cells may initiate the host immune response subsequent to the cells entering the general circulation through host cerebral vessels damaged during graft placement. Rapid healing of damaged cerebral vessels is stimulated with exogenously applied basic fibroblast growth factor, which may prove helpful in reducing the potential entry of donor cells to the host circulation. These results have implication clinically for the intracerebral grafting of human fetal CNS cell suspensions. © 1994 Wiley-Liss, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070270603
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  • 7
    Electronic Resource
    Electronic Resource
    Axial and paraxial influences on limb morphogenesis (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 208 (1991), S. 367-379 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies by Stephens and McNulty and Strecker and Stephens have demonstrated that foil barriers placed between the mesonephros and lateral plate at stages 12 to 15 inhibited limb development, but foil barriers placed between the neural tube and somites at stages 11 to 12 resulted in limbs with normal skeletal patterns. It was concluded that some influence present in the paraxial region of the embryo at stages 11 to 15 is necessary for normal limb development. The present study was undertaken to localize that influence more precisely. Foil barriers were placed in the lateral edge of the somites or segmental plate of stage 10 to 15 chick embryos. Barriers placed into stage 13 to 15 embryos resulted in chicks with normal limbs, but barriers placed into stage 10 to 11 embryos resulted in chicks with defective limbs. Barriers inserted just lateral to Hensen's node at stages 6 to 8 resulted in embryos with defective or absent wings. We also grafted stage 4 to 9 presumptive limb territories with and without Hensen's node. Explants without Hensen's node formed limb-like structures in 1% of the cases. Explants with Hensen's node formed limb-like structures in 27% of the cases. When barriers were implanted and a node was placed on the lateral side of the barrier, limbs formed in 40% of the cases. These data suggest a medial to lateral progression of some as yet unknown morphogenetic influence necessary for normal limb development and we hypothesized that the influence may initially emanate from Hensen's node.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052080310
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  • 8
    Electronic Resource
    Electronic Resource
    Sensilla on the mouthparts and antennae of the elephant louse, Haematomyzus elephantis piaget (Phthiraptera: Haematomyzidae) (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 214 (1992), S. 333-340 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The labial palpus of the elephant louse Haematomyzus elephantis has six sensilla that represent three different types: trichoid, basiconic, and styloconic. Two rows of basiconic sensilla are situated on the dorsal and ventral surfaces of the rostrum, and each row consists of three sensilla. Male and female antennae have 15-17 trichoid sensilla situated on the scape, pedicel, and three antennal annuli. Both sexes have two sensilla basiconica on the dorsal surface of the pedicel near the junction of the scape and pedicel. Two coeloconic (tuft) sensilla are situated on the antennae of both sexes, one sensillum on each of the last two annuli. There are three plate organs, two on the last annulus and one on the penultimate annulus of the male and female antennae. Sexual dimorphism is exhibited in the male and female antennae, in that the male has about twice as many sensilla basiconica on the apex of the last annulus as does the female. The total number of sensilla basiconica on the apex of the male antennae is at least two times the number that is known to be present in any other species of lice. © 1992 Wiley-Liss, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052140308
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  • 9
    Electronic Resource
    Electronic Resource
    Phorbol ester-induced transcription of an immediate-early response gene by human T cells is inhibited by co-treatment with calcium ionophore (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 54 (1994), S. 135-144 
    Details
    ISSN: 0730-2312
    Keywords: ETR101 ; Jurkat cells ; transcriptional regulation ; chromosome localization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human T cells require two discrete signals to initiate their proliferation. In Jurkat T cells the first signal can be provided by the phorbol ester TPA and the second by the calcium ionophore A23187. We have isolated a cDNA from Jurkat T cells representing mRNA induced by TPA but inhibited by simultaneous treatment of the cells with antibody, lectin, or A23187. Sequencing revealed identity of the Jurkat clone to a cDNA, termed ETR101, recently isolated from HL60 promyelocytic leukaemia cells and shown to be an immediate early gene expressed upon TPA stimulation of these cells [Shimizu et al.: J Biol Chem 266:12157, 1991]. The gene is also induced very rapidly upon TPA treatment of Jurkat cells and is superinduced by co-treatment with cycloheximide. The predicted amino acid sequence encoded by ETR101 has weak homology to JunB and JunD, therefore it is of some interest that these three genes share the chromosomal localization, 19p13.2. The divergent effects of TPA treatment upon cell proliferation and differentiation in different circumstances allow some speculation about a possible role for the ETR101 gene product upon cellular differentiation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240540202
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  • 10
    Electronic Resource
    Electronic Resource
    Neuraminidase-induced thrombocytopenia in mice: Effects on thrombopoiesis (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 147 (1991), S. 7-16 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies to examine the effects of thrombocytopenia on thrombopoiesis have generally utilized immune-mediated platelet depletion. We have developed a nonimmune model to exclude the possibility that adverse immune-mediated effects have been misinterpreted as the physiological response to stimulation of thrombopoiesis. Thrombopoiesis was examined in mice after induction of thrombocytopenia with a single injection of the nonimmunologic agent neuraminidase (Ndase). Utilizing electron microscopy, we examined platelets and megakaryocytes (MK) obtained 8, 12, 24, 48, 72, 96, and 120 hr after administration of Ndase. Eight to 48 hr after induction of acute, severe throm-bocytopenia (mean platelet count 〈 50,000/μl), the medians of the platelet sectional area distributions, as measured morphometrically, were significantly greater than the median platelet sectional area of pooled controls. The maximum median value for platelet sectional area was observed at 24 hr. The largest platelets in these samples contained more profiles of endoplasmic reticulum and Golgi cisternae, and a lower concentration of surface-connected canalicular system, as compared with normal platelets. By 72 hr post-injection of Ndase, virtually all platelets exhibited normal size and organelle complement. Mean platelet volumes, determined by electrical impedance analysis, paralleled the serial changes in platelet sectional areas. MK frequency and ploidy, measured by two-color fluorescence activated flow cytometry, were unchanged 12 and 24 hr following Ndase. At 48 hr, total MK frequency increased significantly (P 〉0.01) from 0.11% to 0.17%, and MK ploidy distribution shifted with a reduction in 16N MK (P 〉0.005) and an increase in 32N MK (P 〉0.01). MK ploidy was maximally altered from normal at 72 hr with increased 32N MK frequency (32.0%, P 〈0.001) and increased 64N MK frequency (2.4%, P 〉0.005). Morphologic and morphometric examination of MK at all time points did not reveal detectable changes from normal in cytoplasmic appearance or size, respectively. Therefore, we have demonstrated marked alterations of morphology and size of platelets, and of MK ploidy, using this nonimmunologic model. These studies further support our previous observations that megakaryocyte ploidy and platelet volume are independently regulated in response to depletion of the circulating platelet mass, and they show that these changes are not dependent upon the mechanism of thrombocytopenia.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041470103
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