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  • 1
    Digitale Medien
    Digitale Medien
    Endoplasmic microtubules connect the advancing nucleus to the tip of legume root hairs, but F-actin is involved in basipetal migration (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 27-36 
    Details
    ISSN: 0886-1544
    Schlagwort(e): nuclear migration ; microtubules ; F-actin ; root hairs ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A prominent feature of tip growth in filamentous plant cells is that the nucleus often migrates in step with the tip as it extends. We have studied this long-recognized but unexplained relationship in root hairs of the legume Vicia hirsuta by a variety of microscopic techniques. Using rhodaminyl lysine phallotoxin, and antitubulin antibodies, root hairs are shown to contain axial bundles of F-actin and a complex microtubular system. To the basal side of the nucleus the microtubules are cortical and net axial but in the region between nucleus and tip the arrangement is more complicated. Electron microscopic thin sections demonstrate that internal bundles of microtubles exist in addition to the plasma membrane-associated kind. Computerized deblurring of through-focal series of antitubulin stained hairs clarifies the three-dimensional organization: bundles of endoplasmic microtubules progress from the nuclear region toward the apical dome where they can be seen to fountain out upon the cortex.The relationship between nucleus and tip can be uncoupled with antimicrotubule herbicides. Time lapse video microscopy shows that these agents cause the nucleus to migrate toward the base. This contrary migration can be inhibited by adding cytochalasin D, which fragments the F-actin bundles.It is concluded that microtubules connect the nucleus to the tip but that F-actin is involved in basipetal migration as is known to occur when symbiotic bacteria uncouple the nucleus from the tip.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970080105
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  • 2
    Digitale Medien
    Digitale Medien
    Interaction of the insulin receptor kinase with serine/threonine kinases in vitro (1985)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 28 (1985), S. 171-182 
    Details
    ISSN: 0730-2312
    Schlagwort(e): insulin receptor ; tyrosine phosphorylation ; serine kinases ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Insulin causes rapid phosphorylation of the β subunit (Mr = 95,000) of its receptor in broken cell preparations. This occurs on tyrosine residues and is due to activation of a protein kinase which is contained in the receptor itself. In the intact cell, insulin also stimulates the phosphorylation of the receptor and other cellular proteins on serine and threonine residues. In an attempt to find a protein that might link the receptor tyrosine kinase to these serine/threonine phosphorylation reactions, we have studied the interaction of a partially purified preparation of insulin receptor with purified preparations of serine/threoine kinases known to phosphorylate glycogen synthase. No insulin-dependent phosphorylation was ob served when casein kinases I and II, phosphorylase kinase, or glycogen synthase kinase 3 was incubated in vitro with the insulin receptor. These kinases also failed to phosphorylate the receptor. By contrast, the insulin receptor kinase catalyzed the phosphorylation of the calmodulin-dependent kinase and addition of insulin in vitro resulted in a 40% increase in this phosphorylation. In the presence of calmodulin-dependent kinase and the insulin receptor kinase, insulin also stimulated the phosphorylation of calmodulin. Phosphoamino acid analysis showed an increase of phosphotyrosine content in both calmodulin and calmodulindependent protein kinase. These data suggest that the insulin receptor kinase may interact directly and specifically with the calmodulin-dependent kinase and calmodulin. Further studies will be required to determine if these phosphorylations modify the action of these regulatory proteins.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240280209
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  • 3
    Digitale Medien
    Digitale Medien
    Regulation of tissue transglutaminase gene expression as a molecular model for retinoid effects on proliferation and differentiation (1989)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 39 (1989), S. 293-304 
    Details
    ISSN: 0730-2312
    Schlagwort(e): retinoic acid ; transcriptional control ; antiproliteratiory differentiation ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Retinoids (structural and functional analogs of vitamin A) are potent antiproliferative agents whose mode of action is poorly understood. It has been suggested that the molecular events that underscore their action involve alterations in gene expression, but no gene has yet been shown to be directly regulated by these molecules. Several years ago, we found that retinoic acid caused an accumulation of the enzyme tissue transglutaminase in murine peritoneal macrophages and in human promyelocytic leukemia (HL-60) cells. We now report that this induction is caused by an increase in the mRNA for this enzyme. Retinoic acid is the only mediator of this induction, since its effects do not depend on the presence of serum proteins. The induction of tissue transglutaminase mRNA is not due to an increase in its stability but to an increase in the relative transcription rate of its gene. We present a model to correlate the retinoid induction of tissue transglutaminase with retinoid effects on cellular growth and differentiation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240390309
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  • 4
    Digitale Medien
    Digitale Medien
    Surface structures of the antennular flagella of the hermit crab Pagurus alaskensis (Benedict): A light and scanning electron microscopy study (1974)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 144 (1974), S. 195-215 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The surface structures of the antennular flagella of Pagurus alaskensis are described in detail. Attention is directed towards the surface morphology of two types of possible sensilla: (1) exoskeletal pores (1.0-3.0 μm in diameter); (2) setae of various kinds. In addition, small (0.1-0.2 μm) pits occur in the exoskeleton which are not considered to be sensory in function. The exoskeletal pores are found at fairly specific locations on both the inner and outer flagella, particularly on the short segments of the outer flagella. Neither the inner nor the outer flagella are bilaterally symmetrical with respect to their setal armature. On the outer flagellum six groups of setae may be distinguished: lateralmesial; dorsal; ventral; accessory; aesthetasc; setae of the distal segment. On the inner flagellum setae of the mesial and lateral rows form distinctive groups. The morphology, orientation and locations of all the flagellar setae are defined and where possible the numbers of the various morphological types within the specific setal groups are given. It is noteworthy that many setal types have obvious apical pores and yet no pores could be found in the chemoreceptive aesthetasc setae. The functions of the various setae are discussed in relation to their topographical position and to existing electrophysiological and behavioral data. Some suggestions are made about future experiments to demonstrate the central connections of specific sensilla or groups of sensilla and to show their significance in the whole animal.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051440206
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  • 5
    Digitale Medien
    Digitale Medien
    Localization of 3H-estradiol in the reproductive organs of male and female baboons (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 172 (1982), S. 151-157 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The uptake and retention of radiolabeled estradiol by both the male and female reproductive organs were examined in the baboon. Two male and two female baboons were injected intracardially with 1 μg/kg body weight of 3H-estradiol and two animals, one male and one female, were injected with both labeled and 100 μg/kg body weight of unlabeled estradiol. One and a half hours after the injections, the animals were sacrificed and the uterus, cervix, vagina, oviduct, seminal vesicles, and prostate gland were removed and processed for autoradiography. The stratified squamous epithelia of the cervix and vagina demonstrated a light uptake of the label in the germinative, but not in the superficial cell layers. The columnar cells lining the oviduct and uterine glands were labeled, whereas the luminal epithelium of the uterus and the glandular epithelia of the seminal vesicles and prostate gland did not sequester the tritiated steroid. The interstitial cells of all the organs studied demonstrated a moderate to heavy uptake of the radioactivity, whereas the smooth muscle cells were lightly labeled except in the vagina, in which these cells displayed a moderate number of silver grains.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051720203
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  • 6
    Digitale Medien
    Digitale Medien
    The role of vitamin E in cellular energy metabolism in cultured adrenocortical cells (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 112 (1982), S. 207-216 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: AC1 cells, a bovine adrenocortical cell clone, are rapidly arrested and killed by 2 mM aminooxyacetate, an inhibitor of transmination reactions. Toxicity of aminooxyacetate to cultured bovine adrenocortical cells was previously linked to a high ratio of capacity for oxidation of glutamine relative to pyruvate and was reversible by adding excess glutamine. The toxic effects of aminooxyacetate were shown in the present study to be completely prevented by the simultaneous addition of low concentrations (〈100 nM) of d-α-tocopherol (vitamin E) or selenious acid or higher concentration of other tocopherols, antioxidants, and ubiquinones (coenzymes Q6 and Q10). When antioxidant analogs were tested, it was found that structural features of the molecules that increase antioxidant potency increased potency for prevention of aminooxyacetate toxicity. α-Tocopherol-supplemented AC1 cells were found to be significantly less sensitive than nonsupplemented cells to growth inhibition by rotenone but not by fluorocitrate or dinitrophenol. Dinitrophenol (100 m̈M) stimulated substrate oxidation fivefold but had relatively slight effects on growth, either with or without α-tocopherol, indicating that limitation of the maximal activity of the tricarboxylic acid cycle and respiratory chain is probably not responsible for the sensitivity to aminooxyacetate and rotenone in cells not supplemented with α-tocopherol. Sensitivity to growth inhibition by rotenone and the prevention by ubiquinones of aminooxyacetate toxicity suggest a restriction of electron flow at the NADH-ubiquinone step. The resultant higher NADH/NAD+ ratio would result in a lowered capacity for metabolism of pyruvate with consequent dependence for tricarboxylic acid cycle function and energy production on 2-oxoglutarate from glutamine by the transmination pathway. Vitamin E and other antioxidants may restore efficient function of ubiquinone by preventing side reactions involving lipid peroxidation. Selenium may have a similar effect as cofactor for glutathione peroxidase. A high ratio of capacity for oxidation of glutamine relative to pyruvate and accompanying sensitivity to aminooxyacetate may reflect a deficiency of vitamin E and selenium in adrenocortical cells in culture.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041120208
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  • 7
    Digitale Medien
    Digitale Medien
    Maturation of human promyelocytic leukemia cells induced by nicotinamide: Evidence of a regulatory role for ADP-ribosylation of chromosomal proteins (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 121 (1984), S. 334-340 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We have studied the role of ADP-ribosylation of chromosomal proteins in the regulation of myeloid cell maturation using the HL-60 cell line as a model. Nuclei isolated from this human promyelocytic leukemia cell line contained (ADP-ribose)n synthetase activity, whereas little or no enzymatic activity was detectable in normal human blood neutrophils. Furthermore, the activity of (ADP-ribose)n synthetase was decreased in HL-60 cells when they were induced to mature with retinoic acid (RA). To determine whether reduced (ADP-ribose)n synthetase activity is simply a result of induced maturation or whether it is a necessary precedent event for the maturation process, we evaluated the effects of nicotinamide (NAm) and its methyl derivative, N′-methylnicotinamide (N′-Met-NAm), agents which decrease ADP-ribosylation. Treatment of HL-60 cells with these drugs caused the cells to undergo maturation and to acquire certain of the morphologic, functional, and biochemical characteristics of normal neutrophils. N′-Met-NAm was more potent than NAm in inducting maturation; at a concentration of 0.8 mM, it caused greater than 80% of the cells to mature, whereas a tenfold greater concentration of NAm was required to induce a similar degree of maturation. NAm and N′-Met-NAm also potentiated the maturation of HL-60 cells induced by RA. Exposure of cells to noninducing concentrations of these compounds caused a leftward shift in the dose-response curve for RA; maturation was observed at 10-11 M RA in the presence of either 2 mM NAm or 0.2 mM N′-Met-NAm while 10-9 M RA was required to induce maturation in their absence. A leftward shift in the dose response curve for maturation in the presence of low doses of NAm or N′-Met-NAm did not occur with another inducer, dimethyl formamide (DMF). Two enzymes, NAD glycohydrolase and tissue transglutaminase, that are abundant in macrophages, were induced by RA but not by NAm. N′-Met-NAm decreased by about 75% the amount of endogenous (ADP-ribose)n in a selected fraction of chromosomal proteins which included histone H1 and the nonhistone high mobility group proteins. The results of this study support the concept that ADP-ribosylation of chromosomal proteins influences the regulation of human myeloid cell maturation.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041210210
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  • 8
    Digitale Medien
    Digitale Medien
    Selenium deficiency in cultured adrenocortical cells: Restoration of glutathione peroxidase and resistance to hydroperoxides on addition of selenium (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 123 (1985), S. 33-38 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Cultured bovine adrenocortical cells were previously shown to be functionally deficient in selenium and vitamin E when grown in medium supplemented with fetal bovine serum. In the present experiments, the lack of significant bioavailable amounts of selenium in the medium was demonstrated by the finding of only low levels of glutathione peroxidase in the cultured cells (0.008 U/mg protein compared with 0.045 U/mg protein in fresh adrenocortical tissue). When 20 nM selenium as selenite was added to the cultured adrenocortical cells, glutathione peroxidase activity increased continuously over 72 h, with a total increase of about eightfold over this period. Over the same time-course, the highest concentration of cumene hydroperoxide tolerated by the cells without cell death increased progressively from 10 μM to 50 μM. Addition of 1μM α-tocopherol also increased the amount of cumene hydroperoxide tolerated to 50 μM. Cell death was measured by cloning efficiency after removal of cumene hydroperoxide. Addition of either selenium or α-tocopherol had little effect on the growth rate of the cells over six passages, even when residual vitamin E was removed from the serum by extraction with ether and residual low molecular weight selenium compounds were removed by dialysis. It is concluded that combined deficiency of selenium and vitamin E, at least in the presence of other components of fetal bovine serum, has little effect on the ability of the cells to survive under normal conditions, as evidenced by continued long-term proliferation. However, the low levels of glutathione peroxidase resulting from selenium deficiency cause an increase susceptibility to peroxide-mediated toxicity. The combined deficiency of selenium and vitamin E impairs the ability of cells to survive under adverse conditions, as well as altering mitochondrial functions, as previously demonstrated.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041230106
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  • 9
    Digitale Medien
    Digitale Medien
    The effect of endotoxin on murine stem cellsThis study supported in part by grants from National Heart and Lung Institute HL 7542, and HL 5600 and from the General Research Branch NIH FE 5587. (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 82 (1973), S. 239-244 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Previous studies showed that after 5 μg of Salmonella typhosa endotoxin there was an increase in colony stimulating factor temporally related to a fall in murine marrow in vitro colony forming cells (CFC). This was followed by differentiation along the marrow granulocytic pathway. The present studies showed that after 5 μg of endotoxin the peripheral blood CFC fell by approximately 50% at one hour, rose to a level ten fold that of control at six hours and then returned to control values by 48 hours. There was a progressive increase in the number of splenic CFC to ten fold that of control from 24 to 72 hours after endotoxin. These data imply a migration of CFC from the marrow to the spleen along with an in-situ increase in splenic CFC. Thus, either migration or differentiation may explain the fall in marrow CFC after endotoxin.Spleen colony forming units (CFU) in the marrow were measured by a transplantation technique and the transplantation fraction (f Fx) determined. A decrease in marrow CFU at 24 hours after endotoxin was secondary to a change in the f Fx. from 11.1% to 7.6%. There was however, an increased percentage of CFU in DNA synthesis in the interval of 6-48 hours after endotoxin, as judged by the hydroxyurea technique. As the marrow CFC fell within 20 minutes of endotoxin administration, the data suggest the CFC may be affected initially and that changes in the generative cycle of the CFU may be of a secondary nature.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1040820212
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  • 10
    Digitale Medien
    Digitale Medien
    Expression of angiotensin-converting enzyme activity in cultured pulmonary artery endothelial cells (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 108 (1981), S. 337-345 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Angiotensin-converting enzyme (EC 3.4.15.1) is a carboxyterminal dipeptidyl peptidase. The enzyme catalyzes the conversion of the decapeptide angiotensin I to the octapeptide angiotensin II. In addition, the enzyme catabolizes bradykinin. Because of these actions, the enzyme is of pivotal importance in blood pressure homeostasis. Numerous investigators have demonstrated the presence of the enzyme in association with endothelial cells but relatively little is known concerning the factors controlling the expression of enzyme activity by endothelial cells in culture. We have demonstrated that endothelial cells in culture do not express significant amounts of enzyme activity until several days after growth ceases due to high cell density. This is important because it demonstrates a change in function with stage of growth in culture and a possible difference in functional capabilities between nondividing endothelial cells and cells that are dividing in response to injury. Since density-dependent expression of differentiated traits does not appear to be unique to endothelial cells an understanding of the mechanisms underlying this phenomenon may provide a general explanation for the expression of differentiated traits by cultured cells.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041080307
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