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  • Cell & Developmental Biology  (2)
  • 5-hydroxytryptophan  (1)
  • 1990-1994  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Circadian rhythm of tryptophan hydroxylase activity in chicken retina (1991)
    Springer
    Cellular and molecular neurobiology 11 (1991), S. 511-527 
    Details
    ISSN: 1573-6830
    Keywords: serotonin ; melatonin ; tryptophan hydroxylase ; 5-hydroxytryptophan ; retina ; circadian rhythms ; serotoninN-acetyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Retinal tryptophan hydroxylase activity in chickens (1–4 weeks old and embryos) was estimated by determination of levels of 5-hydroxytryptophan (5HTP) in retinas at defined intervals after inhibition of aromatic L-amino acid decarboxylase withm-hydroxybenzylhydrazine (NSD1015). 2. The relationship of tryptophan hydroxylase activity to photoperiod was explored. In chickens maintained on a 12-hr light:12-hr dark cycle, a diurnal cycle in tryptophan hydroxylase activity was observed. Activity during middark phase was 4.4 times that seen in midlight phase. Cyclic changes in tryptophan hydroxylase activity persisted in constant darkness with a period of approximately 1 day, indicating regulation of the enzyme by a circadian oscillator. The phase of the tryptophan hydroxylase rhythm was found to be determined by the phase of the light/dark cycle. The relationship of the tryptophan hydroxylase rhythm to the light/dark cycle mirrors previously described rhythms of melatonin synthesis and serotoninN-acetyltransferase (NAT) activity in the retina. 3. Light exposure for 1 hr during dark phase suppressed NAT activity by 82%, while tryptophan hydroxylase activity was suppressed by only 30%. 4. Based on the differential responses of retinal NAT activity and tryptophan hydroxylase activity to acute light exposure during dark phase, it was predicted that exposure to light during dark phase would divert serotonin in the retina from melatonin biosynthesis to oxidation by MAO. In support of this, levels of 5-hydroxyindole acetic acid (5HIAA) in retina were found to be elevated approximately two-fold in chickens exposed to 30 min of light during dark phase. In pargyline-treated chickens, 2 hr of light exposure during dark phase was found to increase retinal serotonin levels by 64% over pargyline-treated controls. 5. Cyclic changes in tryptophan hydroxylase activity and NAT activity persisted for 2–3 days in constant light. Tryptophan hydroxylase activity at mid-night gradually decreased on successive days in constant light; on the first day of constant light, tryptophan hydroxylase activity at mid-night was 70% of activity seen during middark phase of the normal light/dark cycle and decreased further on subsequent days. In contrast, on each of 3 days of constant light, NAT activity at mid-night was approximately 15% of normal middark phase activity. 6. Cycloheximide completely inhibited the nocturnal increase in tryptophan hydroxylase activity when given immediately before light offset. The nocturnal increase in NAT activity was inhibited in a similar fashion. 7. Like the development of the NAT rhythm, cyclic changes of tryptophan hydroxylase activity in the retinas of chickens began on or immediately before the day of hatching. 8. The results indicate that retinal tryptophan hydroxylase activity is controlled by a circadian oscillator. The similarity of the circadian rhythm of tryptophan hydroxylase activity in chicken retina to the rhythms of retinal NAT activity and melatonin levels raises the possibility of a common oscillator regulating NAT and tryptophan hydroxylase activities, as well as involvement of tryptophan hydroxylase as a regulatory component in the melatonin synthetic pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00734813
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  • 2
    Electronic Resource
    Electronic Resource
    The role of β1 integrin in spreading and myofibrillogenesis in neonatal rat cardiomyocytes in vitro (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 87-100 
    Details
    ISSN: 0886-1544
    Keywords: myofibrils ; extracellular matrix ; cytoskeleton ; integrins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The influence of the extracellular matrix (ECM) on cell behavior, myofibrillogenesis and cytoarchitecture was investigated in neonatal rat cardiac myocytes in vitro. Cell behavior was examined by analyzing cell spreading on different ECM components under a variety of experimental conditions. Area measurements were made on digitized images of cells grown for various time intervals on fibronectin (FN), laminin (LN), collagens I and III (C I + III), plastic, and bovine serum albumin (BSA). The amount of spreading was varied on the different matrices and was maximal on FN 〉 LN 〉 C I+III 〉 plastic 〉 BSA. Addition of anti-β1 integrin antibodies to myocytes cultured on FN, LN and C I+III blocked spreading outward on the substrates and altered normal myofibrillogenesis, especially on LN. Concomitantly, the integrin antibodies induced the formation of giant pseudopodial processes which protruded upward from the substrates. These pseudopods contained actin polygonal networks which exhibited a regular geometrical configuration.Effects of the ECM on cytoarchitecture was examined by analyzing the temporal and spatial patterns of fluorescence and immunogold labeling of cytoskeletal and integrin proteins as myocytes spread in culture. The first indication of sarcomeric patterns was the appearance at 4 hours of striations formed by lateral alignment of α-actinin aggregates into Z bands. At later times, vinculin at 8 hours and β integrin at 22 hours became co-localized with α-actinin at the Z bands and focal adhesions. These data indicate that ECM components influence myocyte spreading and that myofibril assembly and/or stability is associated with ECM-integrin-cytoskeleton associations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970210202
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  • 3
    Electronic Resource
    Electronic Resource
    Distribution of vinculin in the Z-disk of striated muscle: Analysis by laser scanning confocal microscopy (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 145 (1990), S. 78-87 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vinculin is a major cytoskeletal component in striated muscle, where it has been reported to form a rib-like structure between the cell membrane and the Z-disk termed a costamere. This arrangement of vinculin has been purported to be involved in the alignment of the myofibrils. However, the three-dimensional arrangement of vinculin in relation to the Z-disk of the myofibril was not known. In the present study, we examined the distribution of vinculin in striated muscle with monospecific antibodies using immunofluorescence and laser scanning confocal microscopy. Isolated cardiac and skeletal muscle cells from a variety of species, tissue sections, and neonatal myocytes with developing myofibrils were examined. Optical sectioning in the X-Y and X-Z planes demonstrated that vinculin immunoreactivity was heaviest at the periphery of the cell; however, the immunoreactivity was also distributed within the Z-disk although at a relatively reduced level. This distribution is potentially significant in understanding the physiological significance of vinculin in striated muscle function and in myofi-brillogenesis.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041450112
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