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  • 1
    Electronic Resource
    Electronic Resource
    β -Endorphin and dynorphin control serum luteinizing hormone level in immature female rats (1981)
    [s.l.] : Nature Publishing Group
    Nature 294 (1981), S. 757-759 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Morphine, the enkephalins and /3-endorphin exert their actions in the MBH by modulating the LH secreting activity of the pituitary35. The tonic inhibition effected by the endorphins has been most convincingly documented in immature female rats: a dramatic (10-fold) increase in serum LH levels is ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/294757a0
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  • 2
    Electronic Resource
    Electronic Resource
    Selective development of tolerance without dependence in multiple opiate receptors of mouse vas deferens (1980)
    [s.l.] : Nature Publishing Group
    Nature 285 (1980), S. 242-243 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Mice (NMRI, 25 g) were treated chronically from osmotic minipumps with either DADL or sufentanyl. Vasa def erentia were removed from the animals and set up for electrical stimulation4. To prevent unmasking of opiate receptors, the bathing solution contained DADL or sufentanyl at the concentration ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/285242a0
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  • 3
    Electronic Resource
    Electronic Resource
    Hormone Profiles of Captive Striped Bass Morone saxatilis During Spermiation, and Long-Term Enhancement of Milt Production (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 29 (1998), S. 0 
    Details
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract— Plasma profiles of reproductive and thyroid hormones were studied in captive striped bass Morone saxatilis during an 11-wk period encompassing the spawning season, and the effect of a sustained-release gonadotropin-releasing hormone agonist (GnRHa)-delivery system (GnRHa-implant) on milt production was evaluated. The highest percentage of spermiating fish was observed between mid-April and mid-May, and mean total expressible milt ranged from 3.5 to 6.0 mL/kg. Plasma gonadotropin II (GtH II) increased significantly, though inconsistently, during the spermiation period, whereas testosterone and 11-ketotestosterone levels declined continually. Plasma 17,20β-dihydroxy-4-pregnen-3-one and 17,20β,21-dihydroxy-4-pregnen-3-one remained low and unchanged during the peak of the spermiation period, while thyroid hormones were high and fluctuated without exhibiting a trend consistent with spermiation. The observed endocrine profiles suggest that captivity can diminish plasma GtH II and triiodothyronine levels in striped bass. Transfer of spermiating males from large holding tanks to small spawning tanks reduced total expressible milt after 14 d, but treatment with a GnRHa-implant restored milt volume, presumably due to the prolonged elevation of plasma GnRHa and GtH II induced by the GnRHa-implant. Also, treatment with the GnRHa-implant induced a two- to four-fold elevation of expressible milt for at least 20 d compared to control fish, while resulting in only a 5 to 15% decrease in sperm density. It appears that captivity and hatchery operations can diminish milt production in striped bass, and that GnRHa-delivery systems, via sustained elevation of plasma GtH II, can induce long-term enhancement in milt volume without affecting sperm density greatly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-7345.1998.tb00662.x
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  • 4
    Electronic Resource
    Electronic Resource
    Potential of Total Reflection and Grazing Incidence XRF for Contamination and Process Control in Semiconductor Fabrication (2000)
    Springer
    Microchimica acta 133 (2000), S. 65-68 
    Details
    ISSN: 1436-5073
    Keywords: Key words: TXRF; VPD-ICP-MS; EFTEM; Si wafer; metal contamination.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract.  The actual detection limits of total reflection X-ray fluorescence (TXRF) are determined and compared to those of destructive physical analytical methods like secondary ion mass spectrometry (SIMS) and chemical methods like vapour phase decomposition in combination with inductively coupled plasma-mass spectrometry (VPD-ICP-MS). The elements Ca, Ti, Cr, Fe, Cu were analyzed on a Si wafer with 10 nm thermal oxide using TXRF and VPD-ICP-MS. The deviation of the TXRF and the VPD-ICP-MS results is less than 30%. The thickness, composition and density of a Co/Ti two-layer stack were determined using angle dependent total reflection and grazing incidence X-ray fluorescence (A-TXRF). The obtained data were compared with X-ray reflectometry (XRR) and energy filtered transmission electron microscopy (EFTEM). The agreement between TEM and A-TXRF is excellent for the determination of the thickness of the metal layers. From these results we conclude, that A-TXRF permits the accurate determination of composition, thickness and density of thin metallic layers. The results are discussed regarding detection efficiency, acquisition time, accuracy and reproducibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006040070073
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of light-harvesting complexes of photosystem II in Scenedesmus (1994)
    Springer
    Planta 193 (1994), S. 398-405 
    Details
    ISSN: 1432-2048
    Keywords: Gene expression (Lhc) ; Light and gene expression ; Light-harvesting complex ; Mutant ; Scenedesmus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The patterns of accumulation of photosynthetic pigments, mRNAs transcribed from the genes encoding chlorophyll a/b-binding proteins (Lhc mRNAs), and light-harvesting complex (LHC) apoproteins have been compared in dark- and light-grown cells of wild-type (WT) Scenedesmus obliquus and the mutants WT-LHC1, C-6D, C-6E, C-2A′, C-2A′-LHC1 and C-2A′-LHC2. In contrast to the WT, which developed the complete photosynthetic apparatus in darkness, mutant strains exhibited either a lack of chlorophyll (Chl) b, carotenoids or LHC formation, or a light requirement for the synthesis of Chls or carotenoids. Accumulation of LHC apoproteins strictly depended on the presence of Chl a and carotenoids. The formation of a functional light-harvesting complex additionally required Chl b. Amounts of Lhc mRNAs of dark-grown mutant cells exceeded those of the WT. Thus, accumulation of Lhc mRNAs was independent of Chl and carotenoid synthesis and of chloroplast development. Transcripts of 1.4 and 1.6 kb accumulated constitutionally during growth in darkness. Illumination increased the amounts of these mRNAs and, additionally, a 1.8-kb Lhc mRNA appeared. Hence, light altered the expression of Lhc genes both quantitatively and qualitatively. Ratios of Chl a/Lhc mRNA, Chl a/LHC apoprotein and Lhc mRNA/LHC apoprotein were identical in the greening mutants C-6D, C-2A′, C-2A′-LHC1, and C-2A′-LHC2 after 8 h illumination. Light-independent accumulation of Lhc mRNAs, by contrast, was not correlated with the amounts of either Chl a or LHC apoproteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201819
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  • 6
    Electronic Resource
    Electronic Resource
    Formation of light-harvesting complexes of photosystem II in Scenedesmus (1994)
    Springer
    Planta 193 (1994), S. 406-412 
    Details
    ISSN: 1432-2048
    Keywords: Greening ; Gene expression (Lhc) ; Lightharvesting complex ; Light and gene expression ; Scenedesmus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Time courses of the accumulation of chlorophyll (Chl) a, Chl b, of mRNA transcribed from the genes encoding the Chl a/b-binding proteins of the light-harvesting complexes (LHCs) (Lhc mRNAs) and LHC apoproteins have been investigated in Scenedesmus wild type (WT) and the mutant C-2A′ upon transfer from darkness to light. The WT develops the complete photosynthetic apparatus in darkness, whereas C-2A′ exhibits a light-dependent formation of Chls and functional chloroplasts. Accumulation kinetics of Chls and LHC apoproteins were paralleled in green (WT) and greening (C-2A′) cells. Illumination induced a steady increase in these compounds which was only moderate in the WT but pronounced in C-2A′. Accumulation of Lhc mRNAs, however, was strongly enhanced by light in both WT and C-2A′ cells and showed a transient time course with a maximum after 4 h illumination. Amounts of Lhc mRNAs and LHC approproteins were correlated only during the initial 4 h of greening of C-2A′. In green cells (WT and later stages of greening of C-2A′), amounts of Lhc mRNAs and LHC apoproteins diverged markedly. These findings and results provided by in-vitro translation of polysomal RNA lead to the following conclusion: the light-regulation of Lhc-gene expression in Scenedesmus takes place mainly at the transcriptional level in greening cells and at the post-translational level in green cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201820
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  • 7
    Electronic Resource
    Electronic Resource
    The bidirectional hydrogenase of Synechocystis sp. PCC 6803 works as an electron valve during photosynthesis (2000)
    Springer
    Archives of microbiology 173 (2000), S. 333-338 
    Details
    ISSN: 1432-072X
    Keywords: Hydrogen metabolism hoxH Photosynthesis Respiration Electron transport Complex I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The activity of the bidirectional hydrogenase of the cyanobacterium Synechocystis sp. PCC 6803 was found not to be regulated in parallel to respiration but to photosynthesis. A mutant with a deletion in the large hydrogenase subunit gene (hoxH), which contains the active site, was impaired in the oxidation of photosystem I (PSI) when illuminated with light, which excites either PSI alone or both photosystems. The fluorescence of photosystem II (PSII) of this mutant was higher than that of wild-type cells. The transcript level of the photosynthetic genes psbA, psaA and petB was found to be different in the hydrogenase-free mutant cells compared to wild-type cells, which indicates that the hydrogenase has an effect on the regulation of these genes. Collectively, these results suggest that the bidirectional hydrogenase functions as a valve for low-potential electrons generated during the light reaction of photosynthesis, thus preventing a slowing down of electron transport. This conclusion is supported by growth curves demonstrating that the mutant cells need more time to adapt to changing light intensities. Investigations of the wild-type and ΔhoxH strains strongly suggest that Synechocystis contains only the bidirectional hydrogenase, which seems to be essentially insensitive to oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030000139
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of light on the NADPH-protochlorophyllide oxidoreductase of Arabidopsis thaliana (1991)
    Springer
    Plant molecular biology 16 (1991), S. 615-625 
    Details
    ISSN: 1573-5028
    Keywords: light-dependent Pchlide reductase ; Arabidopsis thaliana ; chloroplast development ; chlorophyll biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA encoding the NADPH-protochlorophyllide oxidoreductase (Pchlide reductase) of Arabidopsis thaliana has been isolated and sequenced. The cDNA contains the complete reading frame for the precursor of the Pchlide reductase. The deduced amino acid sequence of the Arabidopsis enzyme closely resembles the corresponding sequences of barley and oat. The cDNA has been used as a template for the synthesis of the enzyme protein in Escherichia coli. An antiserum was raised against this enzyme protein and both the antiserum and the cDNA were used as experimental tools to study the effects of light on the Pchlide reductase in A. thaliana. When etiolated seedlings of Arabidopsis were exposed to light the enzyme activity and the concentration of the enzyme protein rapidly declined. Similar light effects have been described previously for other angiosperms. In contrast to most of these species, however, in Arabidopsis only minor changes in Pchlide reductase mRNA content could be observed when etiolated seedlings were exposed to light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023426
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  • 9
    Electronic Resource
    Electronic Resource
    Expression of atrial natriuretic peptide in thymic macrophages after dexamethasone treatment of rats (1992)
    Springer
    Cell & tissue research 268 (1992), S. 397-399 
    Details
    ISSN: 1432-0878
    Keywords: Atrial natriuretic peptide (ANP) ; Macrophages ; Thymus ; Dexamethasone ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rat thymus represents a site of synthesis of atrial natriuretic peptide (ANP); the immunosuppressor dexamethasone strikingly increases ANP-expression in this immune organ. The presented data suggest that this increase can be attributed to macrophages. By means of immunohistochemistry and Northern blot analysis these immune cells were found to express ANP-immunoreactivity as well as mRNA coding for ANP. In contrast, macrophages of control thymi displayed only weak ANP-immunoreactivity. Thus, ANP appears to be a constituent of rat thymic macrophages, and its synthesis in the thymus is strongly elevated by acute exposure of the animals to glucocorticoids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318809
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  • 10
    Electronic Resource
    Electronic Resource
    Salmon gonadotropin (sGTH) immunoreactivity and 11-oxotestosterone secretion of mature rainbow trout (Salmo gairdneri) testes in vitro: an alternative to radio-receptor assay for sGTH-binding studies (1988)
    Springer
    Cell & tissue research 251 (1988), S. 665-669 
    Details
    ISSN: 1432-0878
    Keywords: Testis ; Androgen secretion ; Gonadotropic hormone ; Trout (Salmo gairdneri)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary After three intraperitoneal injections of salmon gonadotropin (sGTH) or bovine serum albumin (BSA), testicular tissue of fully mature rainbow trout was prepared for in vitro incubation with or without sGTH. The secretion of 11-oxotestosterone was measured and the tissue was fixed for light-microscopical localization of sGTH immunoreactivity (ir). Tissue from sGTH-treated males showed an increased basal secretion and sGTH-stimulated androgen secretion but the stimulated versus control ratio was higher without sGTH treatment in vivo. When the tissue had had contact with exogenous sGTH, sGTH-ir showed similar distribution patterns regardless of the sGTH treatment regimes. The extralobular compartment showed a staining of interstitial cells and capillary walls. The staining in the intralobular compartment was less clear. Many Sertoli-cells carried a faint nuclear label, whereas intralobular germ cells appeared to be unlabeled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214015
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