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  • gene expression  (65)
  • acidification  (57)
  • Springer  (122)
  • American Meteorological Society
  • Institute of Physics
  • 1995-1999  (122)
  • 1990-1994
  • 1995  (122)
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  • Springer  (122)
  • American Meteorological Society
  • Institute of Physics
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  • 1995-1999  (122)
  • 1990-1994
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Aquatic sciences 57 (1995), S. 81-89 
    ISSN: 1420-9055
    Schlagwort(e): Alpine lakes ; hydrochemistry ; acidification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract During a four-year study (1988–1991), 413 lakes in the Central Alps (Italy, Switzerland and Austria) were investigated to quantify their acidification. The ionic content of the lakes was generally low: 68% of them had alkalinity values of less than 200 µeq 1−1 and were regarded as sensitive to acidification. Moreover, 36% of the lakes showed alkalinity values of less than 50 µeq 1−1. Redundancy Analysis was used to relate the hydrochemistry of 187 lakes to their catchment characteristics. Calcite weathering was the main factor influencing lake chemistry. The same analysis, applied to a subset of 101 lakes lying in watersheds exclusively composed of silicic rocks, showed that lake chemistry was influenced by silicate weathering and nitrogen uptake. These processes were found to be mainly related to lake altitude and the fraction of the watershed not covered by vegetation, i.e. controlled by temperature. The importance of these relations to explain the pH shift produced by climatic variation is also discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 51 (1995), S. 1116-1123 
    ISSN: 1420-9071
    Schlagwort(e): Antisense RNA ; gene expression ; insertional mutagenesis ; physical mapping ; reporter genes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Over the past ten years, powerful molecular genetic techniques have been developed to analyze gene function inDictyostelium. DNA-mediated transformation using a variety of selections and vectors has allowed the introduction of wild-type or modified genes that are under various forms of transcriptional control. Homologous recombination is efficient and can be used to modify the genome in precise ways. In addition, it is now possible to clone genes based on their mutant phenotype alone, either by insertional mutagenesis, or by screening antisense expression cDNA libraries. Finally, a nearly complete physical map of the genome is available and so genes are easily mapped by physical techniques. We discuss many of these advances within the context of major research problems presently under study.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 51 (1995), S. 606-611 
    ISSN: 1420-9071
    Schlagwort(e): Metallothionein ; isometallothioneins ; gene expression ; rabbit kidney cell-line ; cadmium adaptation ; zinc adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract We explored the molecular genetics underlying the massive induction of isoMTs by Zn2+ or Cd2+ in metal tolerant rabbit kidney (RK-13) sub-line cells, using band shift assays and Southern blotting analysis. In sub-line cells accommodated to intermediate metal concentrations (100 μM Zn2+; 1–20 μM Cd2+) evidence suggested that the increase in the capacity for isoMT synthesis is brought about by an increased binding activity of the nuclear transcription factors MTF-1 and Sp1. Using quantitative band shift analysis with a mouse MRE-d oligonucleotide probe, the binding of both transcription factors was found to be enhanced two to three times over the binding activity measured in the unexposed parental RK-13 cells. Their increase in binding activity is probably the cause of the overexpression of MT genes and the development of metal tolerance in these cells. In cells tolerant to the highest concentrations of metal the analysis of Southern blot signals revealed MT gene amplification to be the most probable cause of the increased MT production. Thus, in cells of sub-lines growing in the presence of 350 μM Zn2+, two of the isoMT genes were coordinately triplicated and in cells tolerant to 150 μM Cd2+ one isoMT gene was amplified two-fold.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of paleolimnology 13 (1995), S. 51-63 
    ISSN: 1573-0417
    Schlagwort(e): acidification ; England ; Holocene ; Lake District ; paleolimnology ; testate amoebae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract Tests of testate amoebae extracted from samples of bottom sediments from 33 tarns in the English Lake District reveal a relationship between their distribution and physical-chemical parameters of the tarn waters.Nebela and several species ofDifflugia appear to prefer more acidic conditions, i.e., pH less than 6.2, while others such asCentropyxis, Lesquereusia and some species ofCyclopyxis andDifflugia are more common in lakes with pH's above that value. Using these data, and inferring rates of sedimentation from the densities of tests found in a 6-m core, a paleolimnological history for the past 11 000 years is presented for Ullswater (English Lake District). The record of testate amoebae, beginning shortly after deglaciation, depicts an uneven increase in acidity and a history of episodes of rapid and slow deposition that correlate reasonably well with paleoclimatological changes and anthropogenic alterations in the catchment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of paleolimnology 14 (1995), S. 185-223 
    ISSN: 1573-0417
    Schlagwort(e): taphonomy ; representativity ; diatoms ; acidification ; liming ; sediment traps
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract The representative quality of fossil diatom assemblages in the recent sediment of a lake is compared with its contemporary diatom flora. In April 1986 experimental liming of the catchment of a small acidified lake, Loch Fleet (Galloway, U.K.), produced immediate changes in water quality. Lakewater pH rose from a mean of approximately 4.5 to 6.5, and in the two year period following liming a consistently higher pH was maintained. The marked response of diatom species to changing water quality provided a means of tracing events from living communities to the fossil assemblages. Diatom periphyton and plankton were sampled during a 20 month period and archived material was used to characterise earlier diatom communities. A comparison is made between living diatom communities and diatom assemblages collected by sediment traps and from sediment cores taken during the same period. Following liming, the diatom communities were found to respond within days or weeks to the changes in water quality. There is an initial change from acidobiontic communities, dominated byTabellaria quadriseptata, to dominance by the acidophilous speciesEunotia incisa andPeronia fibula. However, in the epipsammic community the acidobiontic speciesTabellaria binalis fo.elliptica remains abundant after liming. Approximately one year after liming the abundances of species such asAchnanthes minutissima andBrachysira vitrea increase in the epilithon, epiphyton and epibryon, whilst in the epipsammonT. binalis fo.elliptica is replaced by smallEunotia spp. andAchnanthes altaica. During the latter part of 1987 and in 1988, despite a stable pH, fluctuating patterns of species abundances are seen in the epilithon, epiphyton and epibryon whilst the species composition of the epipsammon remains relatively stable. Spring blooms of the planktonic speciesSynedra acus andAsterionella formosa occur during 1988 and 1989 respectively. Sediment trapping, which began in April 1987, records shifts in species composition corresponding with those seen in the epilithon, epiphyton and epibryon and with the blooms of planktonic species. The signal from the smaller, and probably less easily transportable, epipsammic community is not so clearly discernible. Although the fundamental record of the sediment traps is one from living diatom communities, the appearance of taxa ‘extinct’ during the post-liming period reflects a low, but significant level of sediment resuspension. In contrast to the rapid response of living communities and their record in sediment traps, sediment cores do not begin to reflect changes in diatom composition until about 14 months after the initial liming. The first appearance of circumneutral taxa in significant abundance occurs only approximately 17 months after liming. The delayed reaction of sediment assemblages cannot be attributed principally to a slow rate of transport from the littoral to the profundal zone. Time-averaging processes within the sediment appear to be the main cause of the lag in core response. In contrast, blooms of planktonic species are quickly reflected in the stratigraphy of cores, but indicate that a considerable degree of downward mixing occurs. Comparison of the time trajectories of whole species assemblages in living communities, sediment traps and core surface sediments shows that the direction of change is similar in all three, but that the magnitude of change is attenuated in sediment assemblages.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 677-682 
    ISSN: 1573-2932
    Schlagwort(e): soils ; acidification ; ancient woodland ; nitrogen ; environmental change
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract This study outlines the results of analysis of soil samples collected from fixed quadrats located in a regular pattern across Wytham Wood. Oxfordshire, England. The site contains plots of mixed deciduous ancient woodland and more recent plantations. A previous soil study was undertaken in 1974 and samples archived. Soils were resampled in 1991 and some re-analysis of the 1974 samples was undertaken. Soils were of a wide range in types from sands to gravels with a pH range of 3.0–7.0. Results showed some decline in pH in lower horizons, but most striking was a large increase in soil nitrogen for all horizons and soil types.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 797-803 
    ISSN: 1573-2932
    Schlagwort(e): acidification ; recovery ; copper ; nickel ; lake ; rate ; alkalinity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract This paper describes the recovery pathways of two lakes situated near the Coniston nickel-copper smelter. These lakes were exposed to very intense airborne pollution, including SO2, H2SO4, Ni and Cu, during the 60 year operation of the smelter. After the closure of the Coniston smelter in 1972 and the subsequent improvement in air quality, the water quality in both lakes began to improve. Despite their proximity and exposure to similar inputs, the lakes differed both in the rate and magnitude of recovery. This study demonstrates the capacity of lakes to recover from chemical stresses over a very short period. Changes in Cu and Ni concentration could be predicted, while changes in pH, measured as H+, could not. The reasons for this discrepancy as well as the processes and lake parameters that control chemical recovery are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 889-894 
    ISSN: 1573-2932
    Schlagwort(e): acidification ; acid neutralizing capacity ; calcite ; fish ; liming ; mitigation ; ecosystems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract The Experimental Watershed Liming Study (EWLS) evaluated the application of CaCO3, to a forested watershed to mitigate the acidification of surface water. During October 1989, 6.9 Mg CaCC3/ha was applied by helicopter to two subcatchments of about 50% (102.5 ha) of the Woods Lake watershed area. The EWLS team investigated the response to treatment of soils (chemistry and microbial processes), vegetation, wetland, stream and lake waters, and phytoplankton and fish, and applied the Integrated Lake Watershed Acidification (ILWAS) model in predicting a watershed treatment duration of up to 50 years. Observations showed a gradual change in pH, acid neutralizing capacity (ANC) and Ca2+ in the water column; direct lake additions of CaCO3 (three different times) were characterized by abrupt changes following base addition and subsequent rapid reacidification. Moreover, the watershed treatment eliminated the snowmelt acidification of the near-shore region of the lake observed during direct lake treatments. Positive ANC water in the tributary and near-shore area improved conditions for fish reproduction and for a viable fish population. Budgets for 12-month periods before and after the watershed treatment showed that the lake shifted from a source of ANC to a sink due to retention of elevated inputs of Ca2+ from the watershed CaCO3 application.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 1539-1550 
    ISSN: 1573-2932
    Schlagwort(e): acidification ; air pollution impacts ; climate change ; global change ; integrated modeling ; sulfur deposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract This paper presents one of the first integrated analyses of acidification and climate change on a geographically-detailed basis, and the first linkage of integrated models for acid deposition (RAINS) and for climate change (IMAGE 2). Emphasis in this paper is on Europe. Trends in driving forces of emissions are used to compute anthropogenic SO2 emissions in 13 world regions. These emissions are translated into regional patterns of sulfur deposition in Europe and global patterns of sulfate aerosols using source-receptor matrices. Changes in climate are then computed based on changes in sulfate and greenhouse gases. Finally, we compute ecosystem areas affected by acid deposition and climate change based on exceedances of critical loads and changes in potential vegetation. Using this framework, information from global and regional integrated models can be used to link sulfur emissions with both their global and regional consequences. Preliminary calculations indicate that the size of European area affected by climate change in 2100 (58%) will be about the same as that affected by acid deposition in 1990. By the mid 21st century, about 14% of Europe's area may be affected by both acid deposition and climate change. Also, reducing sulfur emissions in Europe will have both the desirable impact of reducing the area affected by acid deposition, and the undesirable impact of enhancing climate warming in Europe and thus increasing the area affected by climate change. However, for the scenarios in this paper, the desirable impact of reducing sulfur emissions greatly outweighs its undesirable impact.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 1573-4919
    Schlagwort(e): vasoactive intestinal peptide ; ulcerative colitis ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The availability of colon provides a ready source of human neurons. Among the products of nerve cell bodies, vasoactive intestinal peptide is a neuropeptide that serves as a marker of non-adrenergic, non-cholinergic inhibitory nerves in colon. These nerves have been proposed to be involved in regulation of immune function, secretion, and smooth muscle function. In previous work, we identified decreased tissue levels of vasoactive intestinal peptide in a disorder of chronic colonic mucosal inflammation, ulcerative colitis. We hypothesized that diminished gene expression of vasoactive intestinal peptide could result in decreased tissue levels of this neuropeptide. Sigmoid colon was obtained at surgery from controls (n=6) and patients with ulcerative colitis (n=6). Vasoactive intestinal peptide mRNA was quantified by Northern blot hybridization and tissue levels of vasoactive intestinal peptide were determined by radioimmunoassay. Tissue vasoactive intestinal peptide was decreased only in the mucosalsubmucosal layer of ulcerative colitis (p=.02). There was a single 1.7 kbase vasoactive intestinal peptide transcript identified in both control colon and ulcerative colitis. Normalized vasoactive intestinal peptide mRNA levels were increased by 260% in ulcerative colitis compared to controls (p〈.01). These observations suggest that decreased vasoactive intestinal peptide gene expression or abnormal post-transcriptional processing are not primary defects in this disorder of chronic inflammation. The findings support the alternative hypothesis that axonal degeneration in ulcerative colitis could result in increased expression of neuronal vasoactive intestinal peptide mRNA.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    ISSN: 1573-4919
    Schlagwort(e): regucalcin ; calcium-binding protein ; insulin ; calcium ; gene expression ; rat liver
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The effect of refeeding on the expression of Ca2+-binding protein regucalcin mRNA in the liver of fasted rats was investigated. When rats were fasted overnight, the hepatic regucalcin mRNA level was reduced about 70% of that in feeding rats. Refeeding produced a remarkable elevation of hepatic regucalcin mRNA level (about 150–170% of fasted rats). Liver regucalcin concentration was appreciably increased by refeeding, although it was not altered by fasting. The oral administration of glucose (2 g/kg body weight) to fasted rats caused a significant increase in hepatic regucalcin mRNA level. Moreover, hepatic regucalcin mRNA level was clearly elevated by a single subcutaneous administration of insulin (10 and 100 U/kg) to fasted rats. The hormonal effect was not further enhanced by the simultaneous administration of calcium chloride (250 mg Ca/kg) to fasted rats, although calcium administration stimulated regucalcin mRNA expression in the liver. The present study suggests that the expression of hepatic regucalcin mRNA stimulated by refeeding is significantly involved in the action of insulin and/or calcium as stimulating factors.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 143 (1995), S. 67-71 
    ISSN: 1573-4919
    Schlagwort(e): regucalcin ; calcium-binding protein ; gene expression ; gene distribution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The existence and expression of gene encoding the Ca2+-binding protein regucalcin in various species and tissues were investigated with Southern and Northern hybridization analyses using regucalcin cDNA (0.9 kb of open reading frame). Genomic Southern hybridization analysis demonstrated that regucalcin gene was widely conserved among higher animals including human, monkey, rat, mouse, dog, bovine, rabbit and chicken. The gene was not found in yeast. The Northern blot analysis of poly (A)+RNAs extracted from the liver of various species showed that regucalcin mRNA was predominantly expressed in rat and mouse, although the expression was also seen in human, bovine and chicken. Furthermore, the enzyme-linked immunoadsorbent assay (ELISA) with rabbit-anti-regucalcin IgG indicated that hepatic regucalcin concentration was most pronounced in rat as compared with that of guinea pig, mouse and chicken. These observations show that the gene expression of regucalcin and its protein synthesis is unique in the liver of rats, suggesting the existence of a specific mechanism in demonstrating regucalcin synthesis from gene.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 143 (1995), S. 137-141 
    ISSN: 1573-4919
    Schlagwort(e): regucalcin ; calcium-binding protein ; estrogen ; gene expression ; rat liver
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The effect of nuclear receptor-related hormones on the expression of hepatic calcium-binding protein regucalcin mRNA in rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin cDNA (0.9 kb of open-reading frame). A single subcutaneons administration of 17β-estradiol (0.5, 1.0 and 2.0 mg/kg body weight) in rats induced a remarkable increase of regucalcin mRNA in liver; the level was about 200% of control at 24 h after the administration of 2.0 mg/kg. The increase showed about 350% even at 6 h after the administration. Meanwhile, hepatic regucalcin mRNA level was not appreciably altered by a single subcutaneous administration of thyroxine (T4) (20, 40 and 80 mg/kg) or hydrocortisone (10 and 30 mg/kg) in rats. The present study demonstrates that the expression of hepatic regucalcin mRNA is stimulated by estrogen action in the liver nuclei of rats.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 144 (1995), S. 105-108 
    ISSN: 1573-4919
    Schlagwort(e): fatty acid synthase ; gene expression ; and thyroid hormone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The effect of triiodothyronine (T3) on regulation of fatty acid synthase in chicken liver was investigated. In hypothyroid animals, enzyme activity was about one half of that in euthyroid animals. T3 treatment increased the enzyme activity in hypothyroid animals. There is little difference in both the mRNA concentration and the transcription rate between euthyroid and hypothyroid animals. T3 treatment markedly decreased both the mRNA concentration and the transcription rate in euthyroid and hypothyroid animals. These results suggested that T3 maintained the normal level of enzyme expression primarily by stimulating the post-transcriptional step, while the transcription of the gene was inhibited by hyperthyroidism.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 148 (1995), S. 45-57 
    ISSN: 1573-4919
    Schlagwort(e): manganese ; superoxide dismutase ; gene expression ; hyperoxide lung injury ; nuclear factor kappa B
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract TNFα and IL-1 each can activate NF-κB and induce gene expression of manganese superoxide dismutase (MnSOD), a mitochondrial matrix enzyme which can provide critical protection against hyperoxic lung injury. The regulation of MnSOD gene expression is not well understood. Since redox status can modulate NF-κB and potential κB site(s) exist in the MnSOD promoter, the effect of thiols (including NAC, DTT and 2-ME) on TNFα and IL-1 induced activation of NF-κB and MnSOD gene expression was investigated. Activation of NF-kB and increased MnSOD expression were potentiated by thiol reducing agents. In contrast, thiol oxidizing or alkylating agents inhibited both NF-κB activation and elevated MnSOD expression in response to TNFα or IL-1. Since protease inhibitors TPCK and TLCK can inhibit NF-κB activation, we also investigated the effect of these compounds on MnSOD expression and NF-κB activation. TPCK and TLCK each inhibited MnSOD gene expression and NF-κB activation. Since the MnSOD promoter also contains anAP-1 binding site, the effect of thiols and thiol modifying agents on AP-1 activation was investigated. Thiols had no consistent effect onAP-1 activation. Likewise, some of the thiol modifying compounds inhibited AP-1 activation by TNFα or IL-1, whereas others did not. Since diverse agents had similar effects on activation of NF-κB and MnSOD gene expression, we have demonstrated that activation of NF-κB and MnSOD gene expression are closely associated and that reduced sulfhydryl groups are required for cytokine mediation of both processes.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 146 (1995), S. 71-77 
    ISSN: 1573-4919
    Schlagwort(e): regucalcin ; calcium-binding protein ; gene expression ; rat kidney cortex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex, and this expression was clearly increased by a single intraperitoneal administration of calcium chloride solution (5–15 mg Ca/100 g body weight) in rats; this increase was remarkable at 60–120 min after the administration. Thyroparathyroidectomy (TPTX) caused a slight decrease of regucalcin mRNA levels in the kidney cortex. However, the administration of calcium (10 mg/100 g) in TPTX rats produced a clear increase of regucalcin mRNA levels in the kidney cortex. The subcutaneous administration of calcitonin (10–100 MRC mU/100 g) or parathyroid hormone [1–34] (1–10 U/100 g) in TPTX rats which received calcium (10 mg/100 g) administration did not cause an appreciable alteration of regucalcin mRNA levels in the kidney cortex, suggesting that the mRNA expression is not stimulated by calcium-regulating hormones. The administration of trifluoperazine (TFP; 5 mg/100 g), an inhibitor of Ca2+/calmodulin action, completely blocked the expression of regucalcin mRNA stimulated by calcium administration. Now, calcium content in the kidney cortex was significantly elevated by a single intraperitpneal administration of calcium (10 mg/100 g) in rats. The present study clearly demonstrates that the expression of regucalcin mRNA in the kidney cortex is stimulated by calcium administration in rats. This expression may be mediated through Ca2+/calmodulin action in the kidney cortex.
    Materialart: Digitale Medien
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  • 17
    ISSN: 1573-4919
    Schlagwort(e): neutrophil ; N-formyl-methionyl-leucyl-phenylalanine ; glycolysis ; pHi ; acidification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract A chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP), induced an acidification of cytosol by about 0.05 pH units in 30 sec followed by an alkalinization in human neutrophils. The quantitative contribution of acid production to the acidification was studied. The superoxide (O2 −) production stimulated by fMLP was not involved in the acidification because the production of acids in neutrophils from patients with chronic granulomatous disease who do not produce O2 −, was the same as that in normal neutrophils. The intracellular acidification was completely inhibited by deoxyglucose, suggesting that energy metabolism enhanced upon stimulation by fMLP might be the main source of the acidification. Although enhancement of the lactate formation by fMLP was 0.8 nmol/106 cells, which could lower intracellular pH by 0.08 pH units, the lactate production could not explain the initial acidification because the production of lactate started at 1 min after the stimulation while the intracellular acidification began immediately after the stimulation. Mitochondrial respiratory inhibitors such as KCN and rotenone had no effects on the fMLP-induced intracellular acidification. The fMLP-induced production of CO2 in 30 sec through the hexose monophosphate shunt was only 2.6 pmol/106 cells, which was calculated to decrease intracellular pH by only 0.0014. Thus, changes of energy metabolism induced by fMLP does not explain the acidification.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 629-634 
    ISSN: 1573-2932
    Schlagwort(e): acidification ; monitoring ; calibrated catchments ; lakes ; rivers ; ground water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Surface and ground water monitoring in Norway is designed to give a regional coverage with most of the stations in areas with acidification and some stations in unpolluted areas that give background values. Surface water (weekly sampling) and precipitation (daily measurement) are monitored at 6 calibrated catchments, 5 located in southern Norway and 1 in northernmost Norway close to the Russian border. Ground water (weekly sampling) is monitored in 4 reservoirs in Southern Norway. 73 lakes located all over Norway are surveyed each fall. Nineteen rivers in western and southern Norway are monitored by monthly sampling. All sites are considered sensitive to acidification and are chosen to minimise the effects of anthropogenic catchment based impacts. Results from the monitoring over the period 1980–1994 show that there is a reduction of sulphate of about 25–35% in surface waters which is related to a 30–45% reduction in sulphate concentration in precipitation. An improvement in water quality as measured as increase in ANC has only been apparent since 1990. Due to heavy seasalt episodes in the most coastal catchments like Birkenes and the rivers in western Norway, there has been no improvement of ANC since 1980. Deposition of nitrogen has not changed over the last 10 years, and there is no change in the levels of nitrate in the monitored surface waters.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 943-948 
    ISSN: 1573-2932
    Schlagwort(e): acidification ; liming ; phytoplankton ; zooplankton ; humic lake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Liming resulted in an immediate and transitory decrease of plankton biomass and phytoplankton primary production in the limed part of an acidified humic lake. In the longer term liming has changed species composition and dominance of phyto- and zooplankton. Due to increased transparency and improved oxygen conditions plankton biomass peaked deeper in the water column after liming. During the three years post-liming period phyto- and zooplankton communities have changed less than reported in several other studies. This is largely because liming was carried out well before the collapse of perch population, which has controlled zooplankton both in the pre- and post-treatment period.
    Materialart: Digitale Medien
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  • 20
    ISSN: 1573-2932
    Schlagwort(e): acidification ; Virginia ; fish response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract The “Shenandoah National Park: Fish in Sensitive Habitats” (SNP:FISH) project is a response to declining pH and acid neutralizing capacity in Shenandoah National Park (SNP) streams. SNP receives more atmospheric sulfate than any other USA national park, and pH had decreased to the point where early negative effects on fish were expected. SNP provides the opportunity to study the early stages of acidification effects on fish. Three different classes of geological formations yield streams with low-ANC (0 μEq/L), intermediate-ANC (60–100 μEq/L) or high-ANC (150–200 μEq/L) waters in SNP. This allows a comparison of responses across a water quality gradient in a small geographic area receiving similar deposition. Both chronic and episodic acidification occur in SNP streams. Biological effects are apparent in fish species richness, population density, condition factor, age, size, and bioassay survival. A primary project objective was to provide the necessary data for development and testing models for forecasting changes in fish communities resulting from changes in stream chemistry. Monitored variables include several which are predictive of acidification effects on SNP fish communities.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 481-486 
    ISSN: 1573-2932
    Schlagwort(e): critical loads ; nitrogen deposition ; sulphur deposition ; acidification ; mountain lakes ; Tatra National Park
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract An overall level as well as seasonal changes of acidification of Tatra Mountains surface waters have been studied. Measurements carried out in the Tatra Mountains National Park were concentrated on two lakes: Dlugi Staw and Zielony Staw, situated in the crystalline, granitic part of the mountains. These lakes differ from each other in altitude (1784 m and 1632 m a.s.l. respectively) as well as in quantity and variety of flora and fauna living in and around them. The wet deposition of acidifying compounds of sulphur and nitrogen, and their seasonal variability in the area of the lakes were measured and compared with the critical loads of sulphur and nitrogen for these lakes and their catchments. Results showed that the critical loads of both sulphur and nitrogen in Dlugi Staw were exceeded all over the year and in Zielony Staw the acid deposition was roughly equal to critical load. A surprisingly high concentration of nitrogen compounds in acid deposition, well above the absorption ability of both the lakes and their catchments were ascertained. Nitrogen retention coefficients calculated for the lakes were as follows: Dlugi Staw — approximately 10%, Zielony Staw — approximately 50%. Seasonal variability in nitrate ions concentration in the lakes' waters reflected their prominent acidification caused by nitrogen compounds corresponding to stages 2 and 3 in the scale proposed recently by Stoddard (Stoddard, 1994).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 493-498 
    ISSN: 1573-2932
    Schlagwort(e): remote lakes ; water chemistry ; critical load ; acidification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Water chemistry data on which all the investigations in the AL:PE 1 (Acidification of Mountain Lakes: Palaeolimnology and Ecology) and AL:PE 2 (Remote Mountain Lakes as Indicators of Air Pollution and Climate Change) projects are based, are available for 28 lakes in U.K. (Scotland), Italy, Norway and France (AL:PE 1) and in Svalbard (Norway), Ireland, Austria, Spain, Portugal, Poland, Slovakia, Slovenia and Russia (AL:PE 2). The results show high sulphate concentrations in some mountain lakes in all the countries. Nitrate and sulphate concentrations have different distribution patterns among the sites. A gradient in acidification from north (Norway) to central Europe (via U.K. to Italy) is identified for the AL:PE lakes by means of multivariate data analysis. Critical loads and their exceedance are calculated, where sufficient information is available, both according to the leaching of S, and of S plus N from the catchment. The pattern of critical load exceedance demonstrates an increasing importance of nitrate from Norway via U.K. to Italy. Leaching of N was of considerable importance to the acidification of lakes in the Italian Alps. The projects receive financial support from the European Union.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 315-320 
    ISSN: 1573-2932
    Schlagwort(e): Fish populations ; perch ; roach ; growth ; reproduction ; water chemistry ; acidification ; recover
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Acid-induced fish damage in small lakes in southern Finland was studied in a fish status survey of eighty lakes from 1985–1987. Later, twenty of these lakes were selected for further monitoring. A sampling of these lakes from 1988–1989 showed that the decrease in some perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) populations still continued. The results from the same lakes in 1992 showed that successful reproduction had taken place with many of the perch populations that had been close to extinction in 1985. In contrast, no signs of recovery in the roach populations were detected. The explanation for the appearance of new cohorts of perch could have been the decrease in acid deposition but the exceptional hydrological conditions of winters in the early 1990s may also have affected them. The different responses of the perch and roach populations were interpreted as a consequence of the different sensitivity of these two species to acidification. Even a slight improvement in the water quality has resulted in the appearance of strong new year-classes of perch, but not of roach. Therefore, more improvement in water quality is needed until a sensitive species like roach can reproduce again.
    Materialart: Digitale Medien
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  • 24
    ISSN: 1573-2932
    Schlagwort(e): acidification ; arable soils ; trace elements (Cd, Ni, Zn, Cu, Mn, Cr, Al, Se) ; plant uptake ; field study
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Soil pH is one of the main factors influencing the solubility and availability of trace elements in arable soils. Thus pH can affect the trace element contents of agricultural crops and thereby indirectly influence human health. The aim of this study was to determine Cd, Ni, Zn, Cu, Mn, Cr, Al and Se contents in spring wheat, potatoes and carrots (Cd, Ni and Zn) and estimate their correlations with certain soil factors (surface and subsurface soil pH and organic matter content) governing the plant availability of these elements. Commercial fields were sampled in Sweden in order to cover a wide range of soil types with respect to pH, soil texture and organic matter content. Concentrations of Zn, Mn, Ni (grain) and Cd (straw) in spring wheat (n=43); Cd, Ni, Zn, Mn, Cu and Al in potatoes (n=69); and Cd, Ni and Zn in carrots (n=36) showed significant negative correlations with surface soil pH (0–25 cm). The Se content of potatoes and Cr content of spring wheat straw were positively correlated with soil pH. Stepwise multiple regressions including a combination of soil pHs (0–25 and 25–50 cm) and organic matter contents (0–25 cm) showed that the organic matter content as well as the surface and subsurface soil pH significantly influenced concentrations of several trace elements in one or more of the studied crops. It was concluded that, if acid deposition together with other acidifying processes (fertilisation, harvest of biomass, etc.) are not balanced by a sufficient amount of liming there might be a decrease in the pH of arable soils, which, in turn will lead to decreased levels of Se in edible crops but an overall increase concentrations of other trace elements.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 153-165 
    ISSN: 1573-2932
    Schlagwort(e): air pollutants ; effect on materials ; acidification ; cultural monuments ; sulphur dioxide ; nitrogen oxides ; ozone ; economic calculations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Damage caused to materials exposed in the atmosphere constitutes one of the most important direct effects of acidifying air pollutants. Systematic field and laboratory investigations performed in the recent decade in many countries have contributed to a considerable increase in the knowledge on the mechanisms of the effects of pollutants, on the quantification of damage and on the assessment of the cost of damage. Beside the very important role of SO2 for several materials also studies of the direct or synergistic effect of NOx and O3 have contributed to the understanding of the complex pollution effects. Even if there are still considerable gaps of knowledge it seems that NOx and O3 may contribute in an important way to the deterioration of several materials also in indoor environments which are important for i.a. electronic equipment, storage conditions and museums. Important knowledge has been gained from the International Cooperation Project within UK ECE which is an extensive field exposure on 39 test sites. Dose-response relations have been obtained after 4-year exposure showing the effect of dry and wet deposition on corrosion of several material groups. Also the effect of micro- and mesoclimate on corrosion of building materials like plaster and bricks in different positions on buildings and locations within an urban area has been subject to systematic studies. Results from the studies are used i.a. for assessment of so called acceptable corrosion levels and for mapping areas where the levels are exceeded at different pollution scenarios, as well as for calculation of economic damage. Based on model studies for some city areas tentative calculations of damage cost have been performed for the European region. The indirect effects consist of increased corrosion due to water and soil acidification which are of importance in geologically sensitive areas. Structures which are in contact with soil and water represent a very great capital investment and are of vital importance to the community.
    Materialart: Digitale Medien
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  • 26
    ISSN: 1573-2932
    Schlagwort(e): Rhinichthys atratulus ; condition factor ; whole-body sodium ; Shenandoah National Park ; acidification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Condition factor, “K”, was measured for 1202 blacknose dace (Rhinichthys atratulus) from three streams in Shenandoah National Park (USA) of different acid neutralizing capacities (ANCs). “K” is a ratio of weight standardized to length; it is an indication of the health of the individuals in a population. R. atratulus condition factor in the low-ANC stream was found to be significantly lower (11%) than that of dace measured for fish from the intermediate- and high-ANC streams. This difference, according to the results of related investigations, is likely to be biologically significant. Whole-body sodium concentrations were measured as an additional test of sublethal stress in these streams. During summer base flow conditions, mean whole-body sodium concentrations of adult R. atratulus maintained in cages were found to be highest in the low-ANC stream and lowest in the high-ANC stream. The lower condition factor of dace in the low-ANC stream may be related to whole-body sodium concentration and ion regulation. Ion regulation in the low-ANC stream may be more metabolically costly because of chronic sublethal pH stress. R. atratulus may maintain high body Na+ concentrations in low ANC- and ionic strength waters in order to provide a buffer against large episodic pH depressions. The metabolic cost of this ionoregulatory over-compensation may necessitate the diversion of energy from somatic growth and explain the poorer condition of fish from such waters.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 383-388 
    ISSN: 1573-2932
    Schlagwort(e): acidification ; fish population extinctions ; physiological stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Investigation of Heeney Lake, 21.7 ha, revealed a small population of white sucker, Catostomus commersoni. Only four age-classes were represented in this normally abundant and long-lived species. By 1984 only one new age-class had been recruited into the population. As these fish spawned in the outlet stream in early spring, the potential toxicity of these waters was assessed at two snow-melt events. Rainbow trout, Oncorhynchus mykiss, of hatchery origin were held in the outlet stream as pH declined from 6.5 to 4.7 during a snow melt, late February. Trout showed a loss of 19% in plasma Na and 24% in Cl concurrent with gill Al concentration increasing from 10 to 250 μg'g−1 dry wt. At the mid-April snow melt, pH fell to 4.1, and rainbow trout held in the outlet showed a decline in plasma sodium of 42% and gill Al increased from 10 to 415 μg'g−1 dry wt. Control rainbow trout held in Harp L. at pH 6.3 showed no significant change in plasma and muscle ion concentrations, or in gill Al concentration. White sucker from nearby waters were held in Heeney Lake outlet, late April, and muscle Na and Cl declined significantly as gill Al concentration increased from 11 to 50 μg'g−1 dry wt during 48 hr exposure. White sucker hekl in Heeney L. outlet, mid-May, showed no significant change in plasma ions. No white sucker have been captured in Heeney L. since 1984 and the population is presumed to be extinct. Acid deposition has declined in recent years but lake and stream pH have not recovered and fish populations may still decline or disappear.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 389-394 
    ISSN: 1573-2932
    Schlagwort(e): fish community ; colonization ; extinction ; acidification ; temporal patterns
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Fish communities in four lakes sampled over several years were compared against a reference data set of forty-nine lakes in south-central Ontario. Two of the temporal-comparison lakes (Crosson and Grindstone) exhibit significant changes in their fish communities relative to the reference set. This was due to the extirpation of various fish species (white sucker Catostomus commersoni, lake trout Salvelinus namaycush, and blacknose shiner Notropis heterolepis) during the intervening years. A control lake in the temporal comparison (Poorhouse) showed little change in species composition over time and no loss of species. The fourth temporal lake, Plastic Lake, also showed little change likely as a consequence of the previously documented extinctions in this lake. White suckers within Crosson Lake have demonstrated intermittent recruitment and a 89% reduction in population abundance due to acid-induced reproductive constraints in their spawning stream. Similar conditions contributed to the loss of sucker populations and additional species in Grindstone and Plastic Lakes also. Various species in many of the lakes represent metapopulations. Given the barriers imposed by outflow drainage conditions, these accelerated rates of local extinctions have not been balanced by colonizations from other lakes within the watershed. As a consequence the underlying fish communities have been changed and will remain so without active rehabilitation.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 407-412 
    ISSN: 1573-2932
    Schlagwort(e): Stream ; acidification ; aluminium ; invertebrates ; insects ; accumulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Acidified surface waters often show elevated aluminium (Al) levels, detrimental to fish and some invertebrates. Whether Al can accumulate in benthic invertebrates, with time and/or along the food chain, is not clear. To test this, benthic invertebrates, representing different functional feeding groups, were collected in spring from streams, with different acidity and Al concentrations. Weight-specific Al content was determined with an AAS. At localities with pH ≈ 4, high Al contents (≈ 1 mg inorg-Al g−1 af dw) were found in shredders and/or deposit feeders (Asellus aquaticus, Nemoura sp., and limnephilids), while the predator Isoperla grammatica contained only ≈ 0.3 mg Al g−1, and the “filtering predator” Plectrocnemia conspersa almost no Al. Also at pH ≈ 6 Nemoura sp. and limnephilids showed significantly higher Al contents than did the predators Isoperla grammatica and Rhyacophila nubila, Al concentrations of the animals were often higher at pH 4 than at pH 6. Thus, no evidence of any food chain accumulation (or biomagnification) of Al could be validated. Accordingly, this study gives no support that the high concentrations of Al in fish and birds are due to their feeding on benthic invertebrates at low pH conditions. It was also found that animals that inhabit and/or consume benthic detritus as food contain highest Al levels.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 419-424 
    ISSN: 1573-2932
    Schlagwort(e): acidification ; acid episodes ; critical load ; mountain ; streams ; benthic fauna ; fish
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Investigations in the southern part of the Scandinavian mountain range have shown a direct correlation between snowpack pH and the lowest pH in small streams. In streams with catchments 〈100 km2 a snowpack pH below 4.8 resulted in a stream pH below 5.5. As the snowpack pH in the southern mountain range is 4.0–4.6, lower values to the south and at high altitudes, large areas are affected by acid deposition. The acidity of the snowpack is released almost directly into the streams during thaw, due to the large snowpack, rapid thaw, steep terrain and thin soils. The acidification of the snow has lead to an extensive fauna depletion, especially in smaller streams without upstream lakes. The abundance of benthos in acidified streams in the municipality of Härjedalen (11.000 km2) is today only one tenth of the abundance before acidification. Fish populations have declined to the same extent, and several acid-sensitive species have been lost. It is concluded that mountain streams and fauna are extremely sensitive to acidification, and that even large reductions of emissions will be insufficient.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 445-450 
    ISSN: 1573-2932
    Schlagwort(e): Brook trout ; acidification ; Virginia ; early life history
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Shenandoah National Park receives more atmospheric sulfate loading than any other USA national park. pH has been gradually declining in low-ANC streams for more than 10 years. We have completed four 1-to-3 month-long field bioassays in three streams differing in acid neutralizing capacity (ANC), using a total of 18,000 hatchery brook trout eyed-eggs through fry. In three of the four bioassays, embryos/fry showed poorer survivorship in the low-ANC stream, compared to the high-ANC stream. Substantial mortalities occurred under different hydrological conditions, including steady rain plus significant rain events (fall 1992), low rainfall followed by a significant rain event (spring 1993), and steady light rain and snowmelt with no large rain events (spring 1994). In a fourth bioassay (fall 1993), poor survivorship occurred in all three streams due to drought conditions. Trout placed in the intermediate-ANC stream showed variable survivorship, in two bioassays as high as in the high-ANC stream, and in one bioassay as poor as in the low-ANC stream. Baseflow ANC in the intermediate-ANC stream is 40–100 ueq/L, and pH never falls below 6.0. However, during episodes, pH in this stream sometimes fluctuates rapidly in the range of 6.0 to 7.0, and this fluctuation itself may be a source of physiological stress.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 1197-1202 
    ISSN: 1573-2932
    Schlagwort(e): Scots pine ; Pinus sylvestris ; deposition ; element budget ; soil solution ; soil chemistry ; alkaline dust ; pH ; acidification ; sulfur release
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Since 1993 we are studying three Scots pine ecosystems along a deposition gradient in north-eastern Germany (formerly GDR). Dramatic reductions of pollutant emissions are reported for the period since 1989/90. S-deposition is high at the sites Roesa and Taura (25 kg S ha−1yr−1) compared to Neuglobsow. Inputs of basic cations, especially Ca, by alkaline dust immissions decrease in the order Roesa 〉 Taura 〉 Neuglobsow. The soil solution data show high concentrations of Ca and SO4 at Roesa decreasing drastically along the deposition gradient. The elevated pH values reflect the impact of alkaline dust deposition particularly in the organic surface layer at Roesa. The site Taura received less base cation deposition and is marked by the lowest pH values throughout the soil profile combined with increased Al concentrations in the solution of the mineral soil. Thus, the composition of the soil solutions clearly reflects the different deposition regimes of the past. The element budgets show that large amounts of base cations, sulfur, and, at Taura, also aluminum are actually released from the soils that were previously stored.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    ISSN: 1573-2932
    Schlagwort(e): acidification ; buffering ; groundwater ; monitoring ; precipitation ; seasalt ; soil ; soilwater ; throughfall
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Chemical time trends for precipitation, throughfall, and soilwater (1986–1992), and groundwater (1980–1993) at Birkenes, southern Norway, are compared to gain insights into possible causes for the recent increase in groundwater acidification there. Precipitation and throughfall trends do not show evidence for an increase in anthropogenic acids (e.g. sulphate), but seasalt deposition (e.g. chloride) has been marginally greater in 1990–1992 than in most previous years on record. Soilwater composition partly indicates increasing acidification in recent years (pH, Al and ANC), but hardness and sulphate content are decreasing. Soilwater ANC became negative in 1989, revealing a lasting deficit in its potential to buffer acidity. Groundwater shows clear signs of intensifying acidification (pH, Al, ANC, hardness and sulphate), and this may result partly from climatic conditions (mild winters, ‘seasalt episodes’) and partly from the deterioration of an acid buffering system within the soil cover. Acidification via sulphate deposition certainly is not a direct cause. The declining hardness of soilwater suggests that the ion-exchange buffer in the soil may have ceased to function properly. The necessity for obtaining long-term time-series of water chemistry is underscored by this study.
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    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 151 (1995), S. 55-60 
    ISSN: 1573-4919
    Schlagwort(e): regucalcin ; calcium ; gene expression ; kidney damage ; rat kidney cortex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The alteration of Ca2+-binding protein regucalcin mRNA expression in the kidney cortex of rats administered cisplatin and cephaloridine, which can induce kidney damage, was investigated. Cisplatin (0.25, 0.5 and 1.0 mg/100 g body weight) or cephaloridine (25, 50 and 100 mg/100 g) was intraperitoneally administered in rats, and 1, 2 and 3 days later they were sacrificed. The alteration in serum findings after the administration of cisplatin (1.0 mg/100 g) or cephaloridine (50 and 100 mg/100 g) demonstrated chemically induced kidney damage; blood urea nitrogen (BUN) concentration increased markedly and serum inorganic phosphorus or calcium concentration decreased significantly. Moreover, the administration of cisplatin (1.0 mg/100 g) or cephaloridine (100 mg/100 g) caused a remarkable increase of calcium content in the kidney cortex of rats, indicating kidney damage. The expression of regucalcin mRNA in the kidney cortex was markedly reduced by the administration of cisplatin or cephaloridine in rats, when the mRNA levels were analyzed by Northern blotting using rat liver regucalcin cDNA (0.9 kb). The mRNA decreases were seen with the used lowest dose of cisplatin or cephaloridine. The present study clearly demonstrates that the mRNA expression of Ca2+-binding protein regucalcin in the kidney cortex of rats is decreased by chemically induced kidney damage.
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 152 (1995), S. 131-141 
    ISSN: 1573-4919
    Schlagwort(e): gene expression ; mRNA ; proto-oncogenes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract Polyomavirus large T-antigen transgenic mice develop cardiac hypertrophy characterized by an increase in atrial natriuretic factor and β-myosin heavy chain isoform expression. The aim of this study was to examine changes in proto-oncogene expression in hypertrophied hearts from the transgenic mice. Expression of early growth response-1 (Egr-1) mRNA was detected in hearts from all 15 transgenic mice, but was not detectable in 13 control mice. Reverse transcriptase-polymerase chain reaction experiments usingEgr-1-specific primers confirmed the increase inEgr-1 mRNA in enlarged hearts from the transgenic mice. Expression of c-jun,junD and Ha-ras mRNAs was increased in the transgenic hearts 3, 17 and 2.8-fold, respectively. Western blots showed an increase in c-myc, c-jun and ras protein in hypertrophied transgenic hearts. Immunofluorescence analyses confirmed an increase in Egr-1 and c-jun protein in transgenic cardiomyocytes. Proliferating cell nuclear antigen, Ki-ras and HSP 90 mRNAs were decreased 22, 2.7 and 3-fold, respectively in the transgenic hearts. Not altered in most hypertrophied hearts was expression of c-fos, junB, p53, c-neu, c-myc, HSP70, HSP27, TGF-β or IGF-1 mRNAs. Proto-oncogene and growth factor gene expression in hypertrophy induced by PVLT expression is modulated, with some proto-oncogenes increased and others decreased in expression.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    ISSN: 1573-5028
    Schlagwort(e): β-fructofuranosidase ; invertase ; gene expression ; gene structure ; flower buds ; Daucus carota
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Three genomic clones (Inv *Dc1, Inv *Dc2 and Inv *Dc3) were isolated by using the cDNA for carrot cell wall β-fructofuranosidase as a probe. The expression patterns of the three genes differed markedly. High levels of Inv *Dc1 transcripts were found in leaves and roots of young carrot, whereas in plants with developing tap roots no transcripts were detected. A high level of mRNA of Inv *Dc1 was also present in suspension-cultured cells. In developing reproductive organs, only low levels of transcripts of Inv *Dc1 were found in flower buds and flowers and none at later stages of development. In contrast, Inv *Dc2 and Inv *Dc3 were not expressed in vegetative plant organs. Invb1 *Dc1 was exclusively and strongly expressed in flower buds, and Inv *Dc3 at a very low level in suspension-cultured cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    ISSN: 1573-5028
    Schlagwort(e): fruit ; gene expression ; promoter ; ripening ; tomato ; transgenic plant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The 1.4 kb 5′ polygalacturonase (PG) gene-flanking region has previously been demonstrated to direct ripening-specific chloramphenicol acetyl transferase (CAT) expression in transgenic tomato plants. The steady state level of CAT mRNA in these plants was estimated to be less than 1% of the endogenous PG mRNA. Further constructs containing larger PG gene-flanking regions were generated and tested for their ability to direct higher levels of reporter gene expression. A 4.8 kb 5′-flanking region greatly increased levels of ripening-specific reporter gene activity, while a 1.8 kb 3′ region was only shown to have a positive regulatory role in the presence of the extended 5′ region. Transgenic plants containing the CAT gene flanked by both of these regions showed the same temporal pattern of accumulation of CAT and PG mRNA, and steady-state levels of the transgene mRNA were equivalent to 60% of the endogenous PG mRNA on a per gene basis. The proximal 150 bp of the PG promoter gave no detectable CAT activity. However, the distal 3.4 kb of the 4.8 kb 5′ PG promoter was shown to confer high levels of ripening-specific gene expression when placed in either orientation upstream of the 150 bp minimal promoter. The DNA sequence of the 3.4 kb region revealed a 400 bp imperfect reverse repeat, and sequences which showed similarity to functionally significant sequences from the ripening-related, ethylene-regulated tomato E8 and E4 gene promoters. The possible roles of the flanking regions in regulating PG gene expression are discussed.
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  • 38
    ISSN: 1573-5028
    Schlagwort(e): acetohydroxyacid synthase ; gene organization ; gene expression ; herbicide resistance ; cotton ; Gossypium hirsutum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The acetohydroxyacid synthase (AHAS) gene family of the cotton AD allotetraploid Gossypium hirsutum has been cloned and characterized. We have identified six different AHAS genes from an analysis of genomic clones and Southern blots of genomic DNA. Four of the six genes are organized as tandem pairs, in which the genes are separated by only 2–3 kb. Conservation of restriction fragment length polymorphisms between G. hirsutum and A-genome and D-genome-containing diploid cottons was sufficient to assign the single genes in clones A5 and A19 to the A and D subgenomes, respectively. Each diploid genome has one tandem pair, but in these cases we could not make specific subgenomic assignments. DNA and deduced amino acid sequences were determined for the A5 and A19 genes, and an AHAS cDNA clone isolated from a leaflibrary. The sequence of the A19 gene matches that of the cDNA clone, while the A5 gene is 97.8% similar. The four genes comprising the tandem pairs are much less similar to the cDNA clone. The deduced amino acid sequences of the mature polypeptides encoded by the A5 and A19 genes are collinear with the housekeeping forms of AHAS from Arabidopsis thaliana, Nicotiana tabacum and Brassica napus. The constitutive expression of A5 and A19 was confirmed with RNase protection assays and northern blots. We conclude that these genes encode the main house-keeping froms of AHAS in G. hirsutum. Among the four AHAS genes comprising the two tandem pairs, at least two are functional. These genes exhibit either low-level constitutive expression (one or both of the ‘downstream’ genes of each pair), or highly specific expression in reproductive tissue (one or both of the ‘upstream’ genes of each pair). The AHAS gene family of G. hirsutum is more complex than that of other plants so far examined.
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 28 (1995), S. 859-870 
    ISSN: 1573-5028
    Schlagwort(e): Brassica ; phosphate starvation ; gene expression ; β-glucosidase ; mineral nutrition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Differential gene expression at the transcriptional level was examined as an initial step in the investigation of the Pi starvation response of Brassica nigra suspension cells. Total RNA was extracted from 7-day old cells grown in media containing either no Pi, 1.25 mM or 10 mM Pi., In vitro translation was carried out using their respective poly(A)+ RNA isolates and the resultant polypeptides were separated on a high-resolution SDS-PAGE gel. Scanning densitometry identified four polypeptides (ca. 31.7, 32.3, 52.5 and 64.8 kDa) present only in the Pi-starved samples. Screening by differential hybridization was performed on a cDNA library constructed from mRNA isolated from Pi-starved cells. Probes prepared from mRNA from Pi-deficient and Pi-sufficient cells identified a number of clones representing mRNA species that were preferentially transcribed under Pi deficiency. These phosphate starvation-responsive (psr) clones were placed into eleven groups as determined by cross-hybridization. Northern blots showed that the corresponding genes are inducible in both mild and severe Pi starvation conditions. Preliminary sequencing identified one of the clones as being homologous to β-glucosidases from several plant species. The possible role of β-glucosidase during Pi starvation and the identities of the other psr genes are discussed.
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  • 40
    ISSN: 1573-5028
    Schlagwort(e): linked gene ; gene expression ; peroxidase ; Populus kitakamiensis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A genomic library was prepared from Populus kitakamiensis and screened with the cDNA for an anionic peroxidase from P. kitakamiensis. One genomic clone was isolated that contained two tandemly oriented genes for anionic peroxidases, prxA3a and prxA4a. Both genes consisted of four exons and three introns; the introns had consensus nucleotides, namely, GT and AG, at their 5′ and 3′ ends, respectively. The prxA3a and prxA4a genes encoded 347 and 343 amino acid residues, respectively, including putative signal sequences at the amino-termini. Putative promoters and polyadenylation signals were found in the flanking regions of both genes. The sequence of the coding region of prxA3a was completely identical to that of the cDNA clone pA3, whereas the sequence of the coding region of prxA4a was only 73% identical to that of the cDNA clone pA3. Northern blot analysis showed that the patterns of expression of the mRNAs that corresponded to prxA3a and prxA4a differed in stems of P. kitakamiensis.
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  • 41
    ISSN: 1573-5028
    Schlagwort(e): anthocyanin ; Compositae ; corolla ; dfr ; flower development ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In the ornamental cut flower plant Gerbera hybrida the spatial distribution of regulatory molecules characteristic of differentiation of the composite inflorescence is visualized as the various patterns of anthocyanin pigmentation of different varieties. In order to identify genes that the plant can regulate according to these anatomical patterns, we have analysed gene expression affecting two enzymatic steps, chalcone synthase (CHS) and dihydroflavonol-4-reductase (DFR), in five gerbera varieties with spatially restricted anthocyanin pigmentation patterns. The dfr expression profiles vary at the levels of floral organ, flower type and region within corolla during inflorescence development according to the anthocyanin pigmentation of the cultivars. In contrast, chs expression, although regulated in a tissue-specific manner during inflorescence development, varies only occasionally. The variation in the dfr expression profiles between the varieties reveals spatially specific gene regulation that senses the differentiation events characteristic of the composite inflorescence.
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 27 (1995), S. 441-456 
    ISSN: 1573-5028
    Schlagwort(e): HSP70 ; HSC70 ; seed development ; imbibition ; chaperone ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Eukaryotes express several cytoplasmic HSP70 genes, and their encoded proteins participate in diverse cellular processes. Three cDNAs encoding highly expressed cytoplasmic HSP70 homologues from Pisum sativum were cloned and characterized. They were designated PsHSP71.2, PsHSC71.0, and PsHSP70b. These HSP70 genes have different expression profiles in leaves: PsHSP71.2 is observed only in response to heat stress, PsHSC71.0 is present constitutively, and PsHSP70b is weakly constitutively expressed, but induced strongly in response to heat stress. In addition to being heat induced, the PsHSP71.2 mRNA is also expressed in zygotic, but not maternal organs of developing pea seeds, while PsHSC71.0 and PsHSP70b mRNAs are present in maternal and zygotic organs throughout seed development. Immunoblot analysis of parallel protein samples detects a 70 kDa polypeptide in all samples, and a 72 kDa polypeptide that corresponds to the PsHSP71.2 gene product is observed in cotyledons beginning at mid-maturation and in axes beginning between late maturation and desiccation. This polypeptide is not detected in the seed coat. The 72 kDa polypeptide remains abundant in both cotyledons and axes through germination, but declines substantially between 48 and 72 h after the onset of imbibition. Differential control of HSP70 expression during heat stress, seed maturation, and germination is consistent with the hypothesis that there are functional distinctions between cytoplasmic HSP70s.
    Materialart: Digitale Medien
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 27 (1995), S. 487-497 
    ISSN: 1573-5028
    Schlagwort(e): Cucumis sativus ; gene expression ; glyoxylate cycle ; glyoxysome ; isocitrate lyase ; seed germination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The cucumber (Cucumis sativus L.) genome contains only a single gene encoding the glyoxylate cycle enzyme isocitrate lyase (ICL). The cucumber icl gene has been isolated and sequenced, revealing only two small introns. The predicted amino acid sequence is more than 85% identical to ICL from other higher plants, and contains the C-terminal tripeptide Ser-Arg-Met which resembles a peroxisomal targeting sequence. The icl gene is coordinately expressed with the malate synthase (ms) gene after seed germination in both the light and the dark, suggesting that these genes may contain similar DNA elements regulating transcription. The start of transcription of the icl gene was determined and the DNA sequences upstream compared with the region of the ms gene promoter known to regulate transcription. This comparison revealed a highly conserved DNA sequence at similar positions in each gene.
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  • 44
    ISSN: 1573-5028
    Schlagwort(e): Alfalfa ; cell division cycle ; chromosomal location ; cyclin ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cyclins in association with the protein kinase p34cdc2and related cyclin-dependent protein kinases (cdks) are key regulatory elements in controlling the cell division cycle. Here, we describe the identification and characterization of a full-length cDNA clone of alfalfa mitotic cyclin, termed CycIIIMs. Computer analysis of known plant cyclin gene sequences revealed that this cyclin belongs to the same structural group as the other known partial alfalfa cyclin sequences. Genetic segregation analysis based on DNA-DNA hybridization data showed that the CycIIIMs gene(s) locates in a single chromosomal region on linkage group 5 of the alfalfa genetic map between RFLP markers UO89A and CG13. The assignment of this cyclin to the mitotic cyclin class was based on its cDNA-derived sequence and its differential expression during G2/M cell cycle phase transition of a partially synchronized alfalfa cell culture. Sequence analysis indicated common motifs with both the A- and B-types of mitotic cyclins similarly to the newly described B3-type of animal cyclins.
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 647-662 
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; peroxidase ; powdery mildew ; splicing ; Triticum aestivum L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A PCR-based screening approach was used to isolate genomic clones from wheat encoding peroxidase isozymes. Three complete genes (pox1, pox2 and pox4) and one truncated gene (pox3) were characterized. The nucleotide sequences predicted mature proteins of 31 kDa, in which all the highly conserved motifs of secreted plant peroxidases were preserved. The coding regions showed 73–83% DNA sequence identity, with the highest level of similarity noted for the tandemly oriented pox2 and pox3. Expression of respective pox genes in various tissues of wheat was assessed by the RT-PCR technique, which showed that all four genes are active. The primary pox1 mRNA was spliced to remove three introns, whereas processing of the other pox transcripts involved only two intervening sequences. Splicing occurred at consensus GU/AG splice sites except for the first introns of pox1, pox2 and pox4 transcripts, where processing took place at unusual GC donor sites. The RNA analysis suggested that the pox1, pox2 and pox4 genes are predominantly expressed in roots. Lower levels of expression were found for pox4 and pox3 in leaves. Infection of wheat by the powdery mildew fungus selectively induced expression of pox2 in leaves.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 1211-1221 
    ISSN: 1573-5028
    Schlagwort(e): ferredoxin ; Citrus ; ethylene ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The sequence and expression of mRNA homologous to a cDNA encoding a non-photosynthetic ferredoxin (Fd1) from Citrus fruit was investigated. The non-photosynthetic nature of this ferredoxin was deduced from: (1) amino acid sequence alignments showing better scores with non-photosynthetic than with photosynthetic ferredoxins, (2) higher expression in tissues containing plastids other than chloroplast such as petals, young fruits, roots and peel of fully coloured fruits, and (3) the absence of light-dark regulation characteristic of photosynthetic ferredoxins. In a phylogenetic tree constructed with higher-plant ferredoxins, Citrus fruit ferredoxin clustered together with root ferredoxins and separated from the photosynthetic ferredoxins. Non photosynthetic (root and fruit) ferredoxins, but not the photosynthetic ferredoxins, have their closest homologs in cyanobacteria. Analysis of ferredoxin genomic organization suggested that non-photosynthetic ferredoxins exist in Citrus as a small gene family. Expression of Fd1 is developmentally regulated during flower opening and fruit maturation, both processes may be mediated by ethylene in Citrus. Exogenous ethylene application also induced the expression of Fd1 both in flavedo and leaves. The induction of non-photosynthetic ferredoxins could be related with the demand for reducing power in non-green, but biosynthetically active, tissues.
    Materialart: Digitale Medien
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  • 47
    ISSN: 1573-4978
    Schlagwort(e): MAR ; SCS ; insulation ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The flanking sequences of several genes have been shown to direct a position independent expression of transgenes. Attempts to completely identify the insulating sequences have failed so far. Some of these sequences contain a matrix attached region (MAR) located in the flanking part of the genes. This article will show that the MARs in cultured cells located in the 3' OH region of the human apolipoprotein B100 (Apo B100) and within the SV40 genome were unable to stimulate and insulate transgene expression directed by the promoters from a rabbit whey acidic protein (WAP) gene or from human cytomegalovirus (hCMV) early genes. In transgenic mice, the MAR from the Apo B100 and SV40 genes did not enhance the expression of a transgene containing the rabbit whey acid protein (WAP) promotor, the late gene SV40 intron (VP1 intron), the bovine growth hormone (bGH) cDNA and the SV40 late gene terminator. This construct was even toxic for embryos. Similarly, the specialized chromatin structure (SCS) from the Drosophila 87A7 HSP70 gene reduced chloramphenicol acetyl transferase (CAT) activity when added between a cytomegalovirus (CMV) enhancer and a Herpes simplex thymidine kinase (TK) gene promoter. This inhibitory action was almost complete when a second SCS sequence was added before the CMV enhancer. Sequences from the firefly luciferase and from the human gene cathepsin D cDNA used as control unexpectedly showed a similar inhibitory effect when added to the CMVTKCAT construct instead of SCS. When added before the CMV enhancer and after the transcription terminator in the CMVTKCAT construct, the SCS sequence was unable to insulate the integrated gene as seen by the fact that the level of CAT in cell extracts were by no means correlated with the number of copies in individual clones. From these data, it is concluded that i) a MAR containing the canonical AT rich sequences does not amplify the expression of all gene constructs ii) AT rich MAR sequences do not have per se an insulating effect iii) Drosophila SCS from the 87A7 HSP70 gene has no insulating effect in all gene constructs (at least in mammalian cells) iv) and the addition of a DNA fragment between an enhancer and a promoter in a gene construct cannot be used as a reliable test to evaluate its insulating property.
    Materialart: Digitale Medien
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  • 48
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; embryo sac ; ovule ; Petunia hybrida ; protein ; kinase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The mitogen activated protein (MAP) kinase pathway of eukaryotes is stimulated by many growth factors and is required for the integration of multiple cellular signals. In order to study the function of MAP kinases during plant ovule development we have synthesized a Petunia hybrida ovule-specific cDNA library and screened for MAP protein kinase-related sequences using a DNA probe obtained by PCR. A full-length cDNA clone was identified (PMEK for Petunia hybrida MAP/ERK-related protein kinase) and shown to encode a protein related to the family of MAP/ERK protein kinases. Southern blot analysis showed that PMEK is a member of a small multigene family in P. hybrida. The cDNA codes for a protein (PMEK1) of 44.4 kDa with an overall sequence identity of 44% to the products of the mammalian ERK/MAP kinase gene, and the budding yeast KSS1 and FUS3 genes. PMEK1 displays 96 and 80% identity respectively with the tobacco NTF3 and Arabidopsis ATMPK1 kinases, and only 50% to the more distantly related plant MAP kinase MsERK1 from alfalfa. The two phosphorylation sites found in the loop between subdomain VII and VIII in all the other MAP kinases are also present in PMEK1. RNA gel blot and RT-PCR analyses demonstrated that PMEK1 is expressed in vegetative organs and preferentially accumulated in female reproductive organs of P. hybrida. In situ hybridization experiments showed that in the reproductive organs PMEK1 is expressed only in the ovary and not in the stamen.
    Materialart: Digitale Medien
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  • 49
    ISSN: 1573-5028
    Schlagwort(e): ADP-glucose pyrophosphorylase (small and large subunit) ; DNA sequence ; gene expression ; starch synthesis ; sugar beet (Beta vulgaris L.)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The cDNA cloning of a small and a large subunit of ADP-glucose pyrophosphorylase (AGPase) from sugar beet is reported. The deduced amino acid sequences are highly homologous to previously identified AGPase polypeptides from other plant species. Both subunits are encoded by low copy genes. When RNA gel blot experiments were performed, strongest expression was detected in sink and source leaves of greenhouse-grown sugar beet plants. A lower expression was found in other tissues tested, i.e. in the hypocotyl, the tap root and roots. In these tissues, slightly higher transcript levels were found for the small subunit gene than for the large subunit gene.
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  • 50
    ISSN: 1573-5028
    Schlagwort(e): glycine betaine ; betaine aldehyde dehydrogenase ; osmotic stress ; gene expression ; plant hormone ; abscisic acid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract When subjected to salt stress or drought, some vascular plants such as barley respond with an increased accumulation of the osmoprotectant glycine betaine (betaine), being the last step of betaine synthesis catalyzed by betaine aldehyde dehydrogenase (BADH). We report here cloning and characterization of BADH cDNA from barley, a monocot, and the expression pattern of a BADH transcript. An open reading frame of 1515 bp encoded a protein which showed high homology to BADH enzymes present in other plants (spinach and sugar-beet) and in Escherichia coli. Transgenic tobacco plants harboring the clone expressed high levels of both BADH protein and its enzymatic activity. Northern blot analyses indicated that BADH mRNA levels increased almost 8-fold and 2-fold, respectively, in leaves and roots of barley plants grown in high-salt conditions, and that these levels decreased upon release of the stress, whereas they did not decrease under continuous salt stress. BADH transcripts also accumulate in response to water stress or drought, indicating a common response of the plant to osmotic changes that affect its water status. The addition of abscisic acid (ABA) to plants during growth also increased the levels of BADH transcripts dramatically, although the response was delayed when compared to that found for salt-stressed plants. Removal of plant roots before transferring the plants to high-salt conditions reduced only slightly the accumulation of BADH transcripts in the leaves.
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 27 (1995), S. 317-325 
    ISSN: 1573-5028
    Schlagwort(e): chloroplasts ; gene expression ; heat bleaching ; photosynthesis ; transcription
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A shift in the ratio of chlorophyll (Chl) a and Chl b is an early indicator of heat bleaching in Euglena gracilis. This observation prompted us to consider whether or not changes in steady-state levels of chloroplast transcripts and in transcriptional activity could limit the synthesis of Chl a-binding proteins in bleaching plastids. We found that the mature transcripts for CP47 and CP43, the Chl a-binding apoproteins of the proximal antenna of photosystem II, decline sharply very early during bleaching. Our study also shows that transcription of psbB and psbC, the chloroplast genes encoding CP47 and CP43, remains essentially unchanged during the same interval. We conclude that posttranscriptional events, such as mRNA stability, could play a major role in initiating an irreversible loss of chloroplast function in Euglena at a moderately elevated temperature. Lack of these transcripts would eventually impair the assembly of photosystem II in thylakoids.
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  • 52
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; gene family ; higher plants ; Hordeum vulgare ; metabolic regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have amplified and cloned DNA sequences derived from a gene encoding a SNF1 (sucrose-non-fermenting 1)-related protein kinase which differs from that previously reported from barley. Northern blot and polymerase chain reaction (PCR) analysis of RNA populations, using specific probes and oligonucleotide primers, indicated that the two SNF1-related genes are differentially regulated. One is expressed in all tissues, whereas the other is expressed at high levels in the seed endosperm and aleurone, but at levels undetectable by northern blot analysis in other tissues. Comparisons with other plant SNF1-related protein kinase genes suggest that the form which is expressed at greatly enhanced levels in the seed is less similar to the other plant homologues which have been reported and may be unique to cereals.
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  • 53
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; light regulation ; nitrate reductase ; phytochrome ; signal transduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have explored the possible involvement of the phosphoinositide (PI) cycle and protein kinase C (PKC) in the phytochrome (Pfr)-mediated light signal transduction pathway using nitrate reductase (NR) and phytochrome-I (PhyI) genes as model systems. We have shown earlier that phorbol myristate acetate (PMA) completely replaces the red light effect in stimulating nitrate reductase activity and transcript levels in maize. In this paper, we present detailed evidence to show that PMA mimics the red light effect and follows similar kinetics to enhance NR steady-state transcript accumulation in a nitrate-dependent manner. We also show that PMA inhibits phyI steady-state transcript accumulation in a manner similar to red light, indicating that a PKC-type enzyme(s) may be involved in mediating the light effect in both cases. Serotonin or 5-hydroxytryptamine (5-HT), a stimulator of PI turnover, was also found to mimic the red light effect in enhancing NR transcript levels and inhibiting phyI transcript accumulation, indicating the role of the PI cycle in generating second messengers for regulating the two genes. These results indicate that phytochrome-mediated light regulation of NR and phyI gene expression may involve certain common steps in the signal transduction pathway such as the PI cycle and protein phosphorylation by a PKC-type enzyme.
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  • 54
    ISSN: 1573-5028
    Schlagwort(e): auxin ; DNA binding factor ; gene expression ; glutathione S-transferase ; Nicotiana tabacum ; signal transduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have analysed the promoter regions of two closely related auxin-regulated glutathione S-transferase genes. All active deletion constructs tested showed expression of the reporter gene β-glucuronidase (gusA) in root tips of young seedlings and newly developing lateral roots. Auxin treatment greatly enhanced the level of expression. The Nt103-1 promoter region −370/−276 was found to be necessary, at least as a quantitative element to confer auxin-responsiveness to a reporter gene, and sequences responsible for the auxin-responsiveness must be located downstream of −370. The region −651/−370 contains sequence information necessary for uninduced expression. The Nt103-35 promoter manifested its auxin-responsiveness within the −504/−310 region. Electrophoretic mobility shift analysis, using nuclear extracts from tobacco leaves and suspension cells, identified a factor binding to a sequence (ap103, TGAGTCT) at position −560 of the Nt103-1 promoter, which shows homology to the mammalian AP-1 site. A second factor was found to bind a sequence (as103, ATAGCTAAGTGCTTACG) with homology to the CaMV 35S promoter as-1 element. The as103 element is present in both promoters and positioned around −360, so within the region determined to be indispensable for the response to auxin. A third factor was found binding to the −276/−190 region of both promoters. Combined, these data point to the relevance of a 90 bp region for auxin-induced activity of both tobacco genes. The ASF-1 like factor binding to the as103 element within this region might be involved in mediating the auxin response.
    Materialart: Digitale Medien
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  • 55
    ISSN: 1573-5028
    Schlagwort(e): differential screening ; gene expression ; Lycopersicon esculentum ; rin ; ripening inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A tomato fruit cDNA library was differentially screened to identify mRNAs present at higher levels in fruit of the tomato ripening mutant rin (ripening inhibitor). Complete sequencing of a unique clone ERT D1 revealed an open reading frame with homology to several glutamate decarboxylases. The deduced polypeptide sequence has 80% overall amino acid sequence similarity to a Petunia hybrida glutamate decarboxylase (petGAD) which carries a calmodulin-binding site at its carboxyl terminus and ERT D1 appears to have a similar domain. ERT D1 mRNA levels peaked at the first visible sign of fruit colour change during normal tomato ripening and then declined, whereas in fruit of the ripening impaired mutant, rin, accumulation of this mRNA continued until at least 14 days after the onset of ripening. This mRNA was present at much lower levels in other tissues, such as leaves, roots and stem, and was not increased by wounding. Possible roles for GAD, and its product γ-aminobutyric acid (GABA) in fruit, are discussed.
    Materialart: Digitale Medien
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  • 56
    ISSN: 1573-5028
    Schlagwort(e): carotenoids ; cleavage site ; gene expression ; melon ; phytoene synthase ; ripening
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A cDNA clone (MEL5), encoding a protein homologous to phytoene synthase (PSY), has been isolated from a climacteric melon fruit cDNA library, using the tomato cDNA clone TOM5 [34] as a heterologous probe. MEL5 hybridised to a transcript of 1.65 kb which suggested that the 1.36 kb clone, isolated originally, was not full-length. The missing 5′ end was isolated by a reverse transcriptase-polymerase chain reaction (RT-PCR)-based method. This enabled the full sequence of the protein to be deduced and the cleavage site of the transit peptide for chromoplast import to be predicted. Northern analysis of RNA extracted from fruit samples of different ripening stages as well as from roots, leaves and flower petals was used to examine the expression pattern of the corresponding mRNA. The transcript corresponding to MEL5 is present at low quantities in unripe (green) fruit, reaches its highest levels when the fruit turns from green to orange and persists at lower levels during later ripening stages. A similar transcript was also detected in flower petals and in trace amounts in leaves and roots. Genomic Southern analysis indicates that the clone is homologous to a low-copy-number gene family. Sequence analysis showed a high degree of conservation among plant PSYs.
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 11-23 
    ISSN: 1573-5028
    Schlagwort(e): drought ; flooding ; freezing tolerance ; gene expression ; salt
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Six cDNAs representing unique cold-induced sequences have been cloned from the hardy citrus relative Poncirus trifoliata. Among these, pBCORc115 and pBCORc119 were found to belong to the same gene family. Sequencing data indicated that pBCORc115 and pBCORc119 each contained an open reading frame, coding for a 19.8 kDa protein (COR19) and a smaller 11.4 kDa protein (COR11) respectively. Inspection of the deduced amino acid sequences revealed three large repeats in COR19, but only one was present in the COR11. Two elements: a Q-clustered tract and a K-rich motif were identified in each repeat. The K-rich motifs were similar to those of cotton D-11 and Group 2 LEA proteins. A Serine-cluster, a common feature in many Group 2 LEA-like proteins, was also found in these proteins, but it was in an unusual position at the carboxy-terminus. A bipartite motif of basic residues, similar to known nuclear targeting sequences, was also present in COR19 and COR11, suggesting that members of this protein family may have a nuclear targeting function. The expression of COR19 mRNA in response to cold acclimation, drought, flooding, and salinization was examined. COR19 expression in leaf tissue was induced in response to cold acclimation, but repressed during drought and flooding stress.
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 367-377 
    ISSN: 1573-5028
    Schlagwort(e): Avena sativa ; gene expression ; PHYA ; light regulation ; mRNA degradation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Gene-preferential oligonucleotide probes were used to determined the relative abundance and half-lives of distinct oat phytochrome A (PHYA) mRNAs. Oat PHYA mRNAs are highly conserved in the 5′-untranslated region and the coding region, but the 3′-untranslated region has an overall lower sequence conservation and was the source of gene-preferential probes. PHYA3 mRNA was estimated to be ca. 61% of the oat PHYA mRNA pool present in poly(A)+ RNA from dark-grown seedlings. The half-lives for PHYA3 and PHYA4 mRNAs were both estimated to be ca. 30 min, and a similar short half-life was estimated for the average PHYA mRNA. Sequence comparisons of PHYA mRNAs from four grass species identified conserved sequences within the 5′- and 3′-untranslated regions that might be important for PHYA mRNA degradation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 479-489 
    ISSN: 1573-5028
    Schlagwort(e): Ascorbate peroxidase ; Arabidopsis thaliana ; gene expression ; guaiacol peroxidase ; ozone ; sulfur dioxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effects of ozone or sulfur dioxide on antioxidant enzymes were investigated in Arabidopsis thaliana. Plants were fumigated with 0.1–0.15 ppm ozone or sulfur dioxide up to about 1 week in an environment-controlled chamber. Both pollutants increased the activities of ascorbate peroxidase and guaiacol per-oxidase in leaves, but had little effect on the activities of superoxide dismutase, catalase, monodehydroascorbate reductase, dehydroascorbate reductase or glutathione reductase. Ozone was more effective than sulfur dioxide in increasing the activities of the peroxidases. Ascorbate peroxidase activity increased 1.8-fold without a lag period during fumigation with 0.1 ppm ozone, while guaiacol peroxidase activity increased 4.4-fold with a 1-day lag. Expression of the APX1 gene encoding cytosolic ascorbate peroxidase was further investigated. Its protein levels in leaves exposed to 0.1 ppm ozone for 4 or 8 days were 1.5-fold higher than in controls. Both ozone and sulfur dioxide elevated APX1 mRNA levels in leaves at 4 and 7 days, whereas at 1 day only ozone was effective. The induction of APX1 mRNA levels by ozone (3.4- to 4.1-fold) was more prominent than that by sulfur dioxide (1.6-to 2.6-fold). The APX1 mRNA level increased by day and decreased by night. Exposure of plants to 0.1 ppm ozone enhanced the APX1 mRNA level within 3 h, which showed a diurnal rhythm similar to that of the control. These results demonstrate that near-ambient concentrations of ozone as well as similar concentrations of sulfur dioxide can induce APX1 gene expression in A. thaliana.
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 823-831 
    ISSN: 1573-5028
    Schlagwort(e): afterripening ; aldose reductase ; Avena fatua ; gene expression ; LEA ; seed dormancy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To analyze the patterns of gene expression associated with seed dormancy in wild oat (Avena fatua), we have isolated cDNA clones corresponding to genes that are differentially expressed in dormant and afterripened line M73 embryos. Gene transcripts of these clones were maintained in embryos of imbibed dormant caryopses, but declined rapidly in afterripened embryos after imbibition. GA3 treatment of dormant caryopses, which breaks dormancy, could lower the transcript levels in dormant embryos. When the germination of afterripened caryopses was inhibited by high temperature (35 °C), the decline in abundance of the transcripts in afterripened embryos was arrested. These genes were expressed to various degrees in water-stressed, but not in unstressed, 7-day-old seedlings. The expression of the genes was also ABA-inducible in afterripened embryos. The expression patterns in non-dormant line SH430 wild oat were similar to those of afterripened M73. DNA sequence analyses indicated that some of the cDNA clones encode LEA (late embryogenesis-abundant) proteins and aldose reductase. The significance of the expression of these genes in maintaining seed dormancy or longevity is discussed.
    Materialart: Digitale Medien
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  • 61
    ISSN: 1573-5028
    Schlagwort(e): carbon catabolite repression ; cDNA ; gene expression ; stress-induced genes ; glucose-starvation ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to isolate glucose-starvation-related cDNAs in maize (Zea mays L.) root tips, a cDNA library was constructed with poly(A)+ mRNA from 24 h starved root tips. After differential screening of the library, we isolated six different cDNAs (named pZSS2 and pZSS7) which were expressed during glucose starvation. Time course analysis revealed that maximum expression of five of these genes occurs 30 h after the onset of the starvation treatment. On the contrary, the expression of mRNAs corresponding to pZSS4 was maximal at an early stage of starvation and then dramatically decreased. The expression of this gene did not seem to be specific for glucose starvation. The pattern of induction of the genes corresponding to pZSS2, pZSS3, pZSS5, pZSS6 and pZSS7 revealed that non-metabolizable sugars such as L-glucose and mannitol induce mRNA transcription similarly to glucose starvation. When D-glucose or any other metabolizable sugar was supplied, the level of transcripts was reduced. Nucleotide sequence analyses of the six cDNAs allowed identification of five of them by comparison with sequence data bases. The protein encoded by clone pZSS2 is analogous to a wound-induced protein from barley. Clones pZSS4 to pZSS7 encode, respectively, a transmembrane protein, a cysteine protease, a metallothionein-like protein and a chymotrypsin/subtilisin-like protease inhibitor. Clone pZSS3 shares no significant homology with any known sequence.
    Materialart: Digitale Medien
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 28 (1995), S. 647-656 
    ISSN: 1573-5028
    Schlagwort(e): abscission ; gene expression ; polygalacturonase ; ethylene ; auxin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Abscission, organ separation, is accompanied by cell wall breakdown in separation layer cells. In tomato (Lycopersicon esculentum), ethylene-induced abscission is correlated with an increase in polygalacturonase (PG) and endo-β-1,4-D-glucanase (cellulase) activity. We have identified a putative, abscission-specific cDNA clone for PG, pTAPG1. The TAPG1 cDNA has 43% identity at the amino acid level with the tomato fruit PG. Genomic blot analysis suggests that the gene for TAPG1 is a member of a small subfamily of PG genes that is distinct from the tomato fruit PG. The TAPG1 cDNA hybridizes to mRNA expressed during the course of ethylene-induced leaf and flower abscission. A high level of PG transcript accumulation coincides with the occurrence of abscission. Auxin, an abscission inhibitor, and silver thiosulfate, an ethylene action inhibitor, suppressed accumulation of mRNA in leaf abscission zones complementary to the TAPG1 cDNA. Expression of TAPG1 transcripts is several-fold higher in flower abscission zones than in leaf abscission zones. The identification of cDNAs that encode abscission-specific PG provide and additional tool to study the regulation of abscission and cell wall dissolution in separation layer cells.
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 28 (1995), S. 667-676 
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; promoter ; glyceraldehyde-3-phosphate dehydrogenase ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Transient expression experiments show that the maize GapA1 promoter exhibits a requirement for sequences contained within intron 1 and surrounding exon border regions for expression in maize Black Mexican Sweet cells. Maize GapA1-promoter constructs lacking intron 1 are inactive. Intron 1 and its exon border sequences, when reintroduced into constructs lacking introns, restore gene activity whereas intron 2 and its exon borders to not. The minimal promoter so defined encompasses roughly 250 bp upstream of the in vivo transcription start and appears also to include intron 1. An octameric sequence was identified in intron 1 of maize GapA1 which is similar to sequence motifs found in other maize introns known to increase transient expression. Partial restoration of gene expression in GapA1 constructs lacking intron 1 was achieved through insertion of the identified octameric sequence.
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 28 (1995), S. 739-750 
    ISSN: 1573-5028
    Schlagwort(e): alcohol dehydrogenase ; fermentation ; gene expression ; pollen ; pyruvate decarboxylase ; respiration ; tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We characterized the genes coding for the two dedicated enzymes of ethanolic fermentation, alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC), and show that they are functional in pollen. Two PDC-encoding genes were isolated, which displayed reciprocal regulation: PDC1 was anaerobically induced in leaves, whereas PDC2 mRNA was absent in leaves, but constitutively present in pollen. A flux through the ethanolic fermentation pathway could be measured in pollen under all tested environmental and developmental conditions. Surprisingly, the major factor influencing the rate of ethanol production was not oxygen availability, but the composition of the incubation medium. Under optimal conditions for pollen tube growth, approximately two-thirds of the carbon consumed was fermented, and ethanol accumulated into the surrounding medium to a concentration exceeding 100 mM.
    Materialart: Digitale Medien
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 28 (1995), S. 811-820 
    ISSN: 1573-5028
    Schlagwort(e): β-oxidation ; gene expression ; fruit ripening ; Mangifera indica ; peroxisomes ; thiolase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Fruit ripening is a complex, developmentally regulated process. A series of genes have been isolated from various ripening fruits encoding enzymes mainly involved in ethylene and cell wall metabolism. In order to aid our understanding of the molecular basis of this process in a tropical fruit, a cDNA library was prepared from ripe mango (Mangifera indica L. cv. Manila). By differential screening with RNA poly(A)+ from unripe and ripe mesocarp a number of cDNAs expressing only in ripe fruit have been isolated. This paper reports the characterization of one such cDNA (pTHMF 1) from M. indica which codes for a protein highly homologous to cucumber, rat and human peroxisomal thiolase (EC 2.3.1.16), the catalyst for the last step in the β-oxidation pathway. The cDNA for the peroxisomal mango thiolase is 1305 bp in length and codes for a protein of 432 amino acids with a predicted molecular mass of 45 532 Da. Mango thiolase is highly homologous to cucumber thiolase (80%), the only other plant thiolase whose cloning has been reported, and to rat and human thiolases (55% and 55% respectively). It is shown by northern analysis that during fruit ripening THMF 1 is up-regulated. A similar pattern of expression was detected in tomato fruit. Wounding and pathogen infection do not appear to affect THMF 1 expression. The possible involvement of thiolase in fatty acid metabolism during fruit ripening will be discussed. To our knowledge this is the first report cloning of a plant gene involved in fatty acid metabolism showing an induction during fruit ripening.
    Materialart: Digitale Medien
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  • 66
    ISSN: 1573-5028
    Schlagwort(e): pyruvate kinase ; plastid ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Clones encoding two different forms of plastid pyruvate kinase (PKp; EC 2.7.1.40) have been isolated from both castor and tobacco seed cDNA libraries. One form, designated PKpA, from castor was described in a previous report, and the tobacco homologue of PKpA has now been isolated. In addition, a second cDNA, designated PKpG, has been identified and sequenced in both species. Western blot analysis, using antibodies raised against protein overexpressed from these clones, indicates that they encode the two predominant polypeptides of plastid pyruvate kinase from developing castor endosperm. In castor, both PKpA and PKpG are encoded by single genes. In the allotetraploid Nicotiana tabacum, there are two copies of each, one derived from each of the progenitors of this species. The expression of the genes for PKpA and PKpG was examined in various tissues from both castor and tobacco. In castor, both forms are expressed in developing and germinating endosperm and in the root but neither is expressed in the leaf. In tobacco, both forms are expressed in developing seeds but in mature tissues, PKpA is most abundant in roots and PKpG in leaves.
    Materialart: Digitale Medien
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  • 67
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 27 (1995), S. 327-338 
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; multi-gene family ; phenylalanine ammonia-lyase ; phenylpropanoids ; promoters ; secondary metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Phenylpropanoid derivatives are a complex class of secondary metabolites that have many important roles in plants during normal growth and in responses to environmental stress. Phenylalanine ammonialyase (PAL) catalyzes the first step in the biosynthesis of phenylpropanoids, and is usually encoded by a multi-gene family. Genomic clones for three Arabidopsis thaliana PAL genes containing the entire protein-coding region and upstream and downstream sequences have been obtained and completely sequenced. Two A. thaliana PAL genes (PAL1 and PAL2) are structurally similar to PAL genes that have been cloned from other plant species, with a single intron at a conserved position, and a long highly conserved second exon. Previously identified promoter motifs plus several additional sequence motifs were found in the promoter regions of PAL1 and PAL2. Expression of PAL1 and PAL2 is both qualitatively and quantitatively similar in different plant organs and under various inductive conditions. A third A. thaliana PAL gene, PAL3, differs significantly from PAL1 and PAL2 and other sequenced plant PAL genes. PAL3 contains an additional intron, and its deduced amino acid sequence is less homologous to other PAL proteins. The PAL3 promoter region lacks several sequence motifs conserved between A. thaliana PAL1 and PAL2, as well as motifs described in other genes involved in phenylpropanoid metabolism. A. thaliana PAL3 was expressed at very low levels under the conditions examined.
    Materialart: Digitale Medien
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  • 68
    ISSN: 1573-5028
    Schlagwort(e): cis factor ; gene expression ; promoter ; transgenic rice ; wheat histone H3
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Type I element (CCACGTCACCGATCCGCG) is a well-conserved regulatory element found in proximal promoter region of a certain class of plant histone genes, that is composed of two independent cis-acting elements of the hexamer (ACGTCA) and the reverse-oriented octamer (GATCCGCG) motifs. To investigate functional role(s) of the type I element in regulation of a wheat histone H3 gene (TH012) promoter activity in vivo, base substitution mutations were introduced into the element and activities of the mutated promoters were examined in cultured rice cells, and in regenerated roots and anther walls of transgenic rice plants by employing a GUS reporter system. Mutations of each or both of the hexamer and the octamer motifs caused a reduction in the promoter activity in protoplasts transfected transiently or stably transformed calli. The mutation of the octamer motif with or without the mutation of the hexamer motif caused a marked reduction of the promoter activity in the root meristem of transgenic rice although the mutation of the hexamer motif alone caused a weak reduction. In contrast to these results, no effect of the mutations of either the hexamer or the octamer motif was found in the anther wall in which replication-independent activity of the H3 promoter was observed. Our results suggested that the hexamer and the octamer motifs may play important role(s) in regulation of replication-dependent but not of replication-independent expression of the wheat histone H3 gene.
    Materialart: Digitale Medien
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 27 (1995), S. 743-752 
    ISSN: 1573-5028
    Schlagwort(e): plant hormone ; gibberellic acid ; GA-responsive ; gene expression ; HCA ; hydrophobic cluster analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A multiple gene family of at least four members, related to a GA-stimulated transcript (GAST1) from tomato, was characterized in Arabidopsis thaliana by analysing four related cDNAs, named GASA1 to GASA4. The corresponding peptides display comparable structural features: (1) a putative signal peptide of 18 to 23 residues; (2) a highly divergent hydrophilic region of about 22 amino acids; (3) a conservative 60 amino acid C-terminal domain containing 12 cysteines. This organization has also bean shown in two related peptides from tomato, GAST1 found in shoots and RSI-1 found in early lateral roots. Southern blot hybridization patterns showed single-copy genes for all four members of the GASA family. Accumulation of the various transcripts, monitored by northern blot hybridization, indicated that the various genes are expressed differentially in plant organs. Specific mRNAs were mostly detected in flower buds and immature siliques in the case of GASA1, in siliques and dry seeds in the case of GASA2 and 3, and in growing roots and flower buds in the case of GASA4. At least two of the GASA genes are activated in GA-deficient mutant ga5, as early as 4 to 8 h after spraying with 50 μM GA3. The complex patterns of expression and regulation of the various genes suggest that the related peptides are involved in a developmental regulation process in Arabidopsis.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 27 (1995), S. 953-967 
    ISSN: 1573-5028
    Schlagwort(e): calcium-dependent protein kinase ; gene expression ; protein phosphorylation ; rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have isolated, from a cDNA library constructed from rice coleoptiles, two sequences, OSCPK2 and OSCPK11, that encode for putative calcium-dependent protein kinase (CDPK) proteins. OSCPK2 and OSCPK11 cDNAs are related to SPK, another gene encoding a rice CDPK that is specifically expressed in developing seeds [20]. OSCPK2 and OSCPK11-predicted protein sequences are 533 and 542 amino acids (aa) long with a corresponding molecular mass of 59436 and 61079 Da respectively. Within their polypeptide chain, they all contain those conserved features that define a plant CDPK; kinase catalytic sequences are linked to a calmodulin-like regulatory domain through a junction region. The calmodulin-like regulatory domain of the predicted OSCPK2 protein contains 4 EF-hand calcium-binding sites while OSCPK11 has conserved just one canonical EF-hand motif. In addition, OSCPK2-and OSCPK11-predicted proteins contain, at their N-terminal region preceding the catalytic domain, a stretch of 80 or 74 residues highly rich in hydrophilic amino acids. Comparison of the NH2-terminal sequence of all three rice CDPKs so far identified (OSCPK2, OSCPK11 and SPK) indicates the presence of a conserved MGxxC(S/Q)xxT motif that may define a consensus signal for N-myristoylation. OSCPK2 and OSCPK11 proteins are both encoded by a single-copy gene and their polyadenylated transcripts are 2.4 and 3.5 kb long respectively. OSCPK2 and OSCPK11 mRNAs are equally abundant in rice roots and coleoptiles. A 12 h white light treatment of the coleoptiles reduces the amount of OSCPK2 mRNA with only a slight effect on the level of OSCPK11 transcript. With anoxic treatments, OSCPK2 mRNA level declined significantly and promptly while the amount of OSCPK11 transcript remained constant.
    Materialart: Digitale Medien
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  • 71
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; cyanobacterium ; nitrite reductase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nitrite reductase (NiR) gene (nirA) has been isolated and sequenced from the filamentous, thermophilic non-N2-fixing cyanobacterium Phormidium laminosum. Putative promoter-like and Shine-Dalgarno sequences appear at the 5′ end of the 1533 bp long nir-coding region. The deduced amino acid sequence of NiR from P. laminosum corresponds to a 56 kDa polypeptide, a size identical to the molecular mass previously determined for the pure enzyme, and shows a high identity with amino acid sequences from ferredoxin-dependent NiR. This cyanobacterial NiR gene has been efficiently expressed in Escherichia coli DH5α from the E. coli lac promoter and probably from the P. laminosum NiR promoter.
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 27 (1995), S. 1183-1188 
    ISSN: 1573-5028
    Schlagwort(e): differential screening ; maize ; pith ; trpA ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A cDNA derived from an abundant maize pith mRNA transcript and its corresponding genomic equivalent have been isolated and characterized. High transcript levels are seen in the pith and young leaves of maize plants, while no transcript is detected in seed tissue of any age. The protein encoded by the isolated gene has considerable homology with tryptophan synthase alpha subunit (trpA) from other organisms and the cDNA clone can complement an E. coli trpA mutant. These data support the conclusion that this cDNA and the corresponding genomic clone encode a maize trpA protein.
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 91-98 
    ISSN: 1573-5028
    Schlagwort(e): Arabidopsis thaliana ; gene expression ; hypersensitive response ; oxidative stress ; ozone ; pathogenesis-related proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have used a reverse transcriptase polymerase chain reaction procedure (differential display) to isolate cDNAs corresponding to transcripts that accumulate in ozone-treated Arabidopsis thaliana. In this report we describe the characterization of an ozone-induced transcript, AtOZI1. AtOZI1 mRNA in untreated plants was detected at low levels in cotyledons, leaves, and flower buds and at higher levels in roots and mature flowers. AtOZI1 mRNA accumulation was transiently induced in leaves 3- to 5-fold within the first 6 h of ozone treatment. AtOZI1 mRNA accumulation was also transiently induced 3- to 6-fold by photopathogenic Pseudomonas strains. Sequence analysis of AtOZI1 revealed that it encodes a 8.6 kDa basic protein that contains a putative signal peptide and two potential phosphorylation sites. Our results suggest that AtOZI1 represents a novel stress-related protein that accumulates in response to the production of active oxygen species.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 135-148 
    ISSN: 1573-5028
    Schlagwort(e): chromophyte ; Chrysophyceae ; light-harvesting complex protein gene ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have isolated a gene from a library of nuclear DNA for a chlorophyll a/c-binding protein (named Cac for chl a/c by analogy with Cab for chl a/b) of a chromophyte alga, Giraudyopsis stellifer, and sequenced it. The comparison of the deduced amino acid sequence with other chl a/c-and chl a/b-binding protein sequences shows that structural and functional features, i.e. the arrangement ‘en X’ of the two A and B transmembrane helices and the putative chl a-binding sites, are shared by both Chlorophyta and Chromophyta. Moreover, in contrast to Chlorophyta, a very strong identity is found among Chromophyta in the C helix, suggesting a major function associated to this specific region. Nevertheless, the primary structure of the apoprotein does not seem affected by the pigment composition in Chromophyta. As in the few other examples currently known, we confirm that the cac genes are nuclear-encoded and are part of a multigenic family. Northern blots, performed on poly(A)+ mRNA from G. stellifer, give evidence that the cac gene is light-induced at a transcriptional level and that no expression can be observed in the dark.
    Materialart: Digitale Medien
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  • 75
    ISSN: 1573-5028
    Schlagwort(e): cathepsin B ; gene expression ; Nicotiana ; thiol protease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Sequence analysis of a 1.33 kb clone from a root cDNA library of Nicotiana rustica revealed an open reading frame encoding a protein of 356 amino acids. The deduced protein has high levels of homology to human cathepsin B protease and a cathepsin B-like cysteine protease from wheat but much lower levels of homology with other plant cysteine proteinases. Southern blotting experiments suggest a limited number of cathepsin B-like genes are present in the genome of N. rustica and also that of N. tabacum. RNA analysis involving a range of tissues, harvested from both Nicotiana species 4–5 h after the beginning of a 16 h photoperiod, revealed the cathepsin B-like gene was being expressed strongly in roots, stem and developing flowers but weakly in mature leaves. Further analysis of RNA extracted from leaf tissue of N. tabacum revealed the gene showed rhythmic expression and also that its expression increased in response to wounding. Analysis of leaf tissues harvested during the latter part of a 16 h photoperiod (11 and 16 h after illumination commenced) showed that transcript levels were two three times higher than in leaf tissue harvested either towards the end of the dark period or 5 h after illumination commenced. When leaf tissue was wounded at 11:00 (5 h after plants were illuminated), and harvested for RNA extraction 6 h later, the level of cathepsin B-like transcript in mesophyll tissue was found to be increased ca. 2-fold relative to the level detected in unwounded controls.
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  • 76
    ISSN: 1573-5028
    Schlagwort(e): Arabidopsis thaliana ; chloroplast ; gene expression ; ω-3 fatty acid desaturase ; promoter ; transgenic plants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Arabidopsis FAD7 gene encodes a chloroplast ω-3 fatty acid desaturase that catalyzes the desaturation of lipid-linked dienoic fatty acids (18:2 and 16:2). An 825 bp FAD7 promoter fragment upstream from the transcriptional start point contained several short sequences which were homologous to the cis-elements (box II, G-box, etc.) conserved in many light-responsive genes. We introduced the FAD7 promoter fused to the β-glucuronidase (GUS) or the luciferase (LUC) reporter gene into tobacco plants. The −825 promoter sequence conferred tissue-specific and light-responsive expression to both these reporter genes in transgenic tobacco, indicating that these expressions of the FAD7 gene were regulated mainly at the transcriptional level. Histochemical GUS staining showed that the activity of the FAD7 promoter is restricted to the tissues with chloroplast-containing cells although the staining was noticeably absent in the chloroplast-containing cells associated with vascular systems. The 5′ deletion experiments of the promoter revealed that the −362/ −166 region, containing two putative box II sequences, was responsible for the tissue-specific and light-responsive expression of the FAD7 gene.
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  • 77
    ISSN: 1573-5028
    Schlagwort(e): tomato ; polygalacturonase ; pectin methylesterase ; heat stress ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effects of extended heat stress on polygalacturonase (PG; EC 3.2.1.15) and pectin methylesterase (PME; EC 3.1.1.11) gene expression at mRNA, protein and activity levels in ripening tomato fruits were investigated. Steady state levels of PG mRNA declined at temperatures of 27°C and above, and a marked reduction in PG protein and activity was observed at temperatures of 32°C and above. Exogenous ethylene treatment did not reverse heat stress-induced inhibition of PG gene expression. Transfer of heat-stressed fruits to 20°C partly restored PG mRNA accumulation, but the rate of PG mRNA accumulation declined exponentially with duration of heat stress. Heat stress-induced inhibition of PME mRNA accumulation was recoverable even after 14 days of heat stress. In fruits held at 34°C, both PG and PME protein and activity continued to accumulate for about 4 days, but thereafter PG protein and activity declined while little change was observed in PME protein and activity. In spite of increases in mRNA levels of both PG and PME during the recovery of heat-stressed fruit at 20°C, levels of PG protein and activity declined in fruits heat-stressed for four or more days while PME protein and activity levels remained unchanged. Collectively, these data suggest that PG gene expression is being gradually and irreversibly shut off during heat stress, while PME gene expression is much less sensitive to heat stress.
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 29 (1995), S. 1143-1155 
    ISSN: 1573-5028
    Schlagwort(e): gene family ; gene expression ; photoreceptor ; phytochrome ; tomato
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Data presented here define five tomato phytochrome genes (PHY) and indicate the existence of additional PHY in the tomato genome. Portions of each gene, encoding amino acids 203 through 315 in a consensus amino acid sequence, were amplified by polymerase chain reaction. Four of these genes, PHYA, PHYB1, PHYB2 and PHYE, are members of previously identified PHY subfamilies, while the fifth, PHYF, is identified as a member of a new PHY subfamily. PHYA, PHYB1, PHYB2 and PHYE fragments encode amino acid sequences that share 88% to 98% sequence identity with their Arabidopsis counterparts. The PHYF fragment, however, encodes a polypeptide that shares only 65% to 74% sequence identity with previously identified Arabidopsis phytochromes. A phylogenetic analysis suggests that PHYF arose soon after, or perhaps prior to, the origin of angiosperms. This analysis leads to the prediction that PHYF might be widespread among angiosperms, including both monocotyledons and dicotyledons. Each of the five tomato PHY is expressed as a transcript of sufficient size to encode a full-length phytochrome apoprotein. Two PHYF transcripts, 4.4 and 4.7 kb in length, have been detected in 9-day-old light-grown seedlings, consistent with either multiple transcription start sites or differential processing. Analyses of genomic Southern blots hybridized with radiolabelled RNA probes derived from the five tomato PHY, as well as Arabidopsis PHYC, indicate that the tomato genome contains as many as 9 to 13 PHY. The tomato PHY family is apparently not only different from, but also larger than, the PHY family presently described for Arabidopsis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 79
    ISSN: 1573-9368
    Schlagwort(e): human α1AT ; CAT ; transgenic mice ; gene expression ; liver
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The tissue-specific and developmental pattern of expression controlled by the proximal promoter (position −348 to+15) derived from the human α-1-antitrypsin (hα1AT) gene was studied in transgenic mice. The short promoter segment was linked to the chloramphenicol acetyltransferase (CAT) reporter gene. The transgene showed highly specific expression in the liver and the correct developmental pattern of regulation. Interestingly, this short promoter targets expression to the liver with a greater specificity than that reported for larger α1AT promoter fragments.
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Transgenic research 4 (1995), S. 397-405 
    ISSN: 1573-9368
    Schlagwort(e): gene expression ; transgenic mice ; thyroid hormone ; thyroid hormone response element ; muscle ; heart
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract During development in the murine ventricle, there is a switch in myosin heavy chain gene (MyHC) transcription. The β-MyHC is expressed in the ventricles during foetal development, but is shut down at or around birth, at which time α-MyHC transcription is activated. This antithetical switch is thought to be mediated by circulating levels of thyroid hormone (TH) and both low and high affinity thyroid response elements (TREs) have been identified in the proximal promoter region of the murine α-MyHC. Myosin gene expression in the atria is relatively unaffected by the TH status. Previously, we used site-directed mutagenesis of the promoter in a transgenic analysis to define those elements responsible for high levels of transcriptionin vivo. These analyses focused on the role(s) of twocis elements, TRE1 and TRE2 that are located at −129 to −149 and −102 to −120, respectively, on the α-MyHC promoter. Although the elements' ablation had differential effects on transgene expression, neither single mutation abolished transgene expression completely. Here, we show that mutating both elements results in a complete inactivation of the transgene in both ventricles and atria under euthyroid conditions. However, expression still can be detected in the hyperthyroid state, implying that, although the TRE1 and TRE2 elements are critical elements for high levels of α-MyHC transcriptionin vivo, other promoter sites can mediate at least some degree of transcriptional activation.
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  • 81
    ISSN: 1573-5117
    Schlagwort(e): acidification ; macroinvertebrate communities ; running waters ; Vosges Mountains
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Les caractéristiques physico-chimiques et les peuplements de macroinvertébrés benthiques de six ruisseaux drainant un bassin versant granitique du massif vosgien ont été étudiés. Parmi les cours d'eau, cinq sont caractérisés par des faibles valeurs moyennes de pH (4.90 à 5.90), et d'alcalinité (HCO inf3 sup− : 0–16 µeq l−1) et par des concentrations moyennes en aluminium élevées (154–278 µg l−1) Seul un ruisseau apparaît typique du massif (pH: 6.90; aluminium: 79 μg l−1 et HCO inf3 sup− : 152 µeq l−1). Les peuplements de macroinvertébrés des ruisseaux acidifiés sont sévèrement affectés. La richesse, l'abondance et la diversité (indice de Shannon) sont alors significativement plus faibles que dans le cours d'eau non acidifié. Tous les groupes faunistiques majeurs sont touchés, mais les Mollusques et les Ephémèroptères sont les organismes les plus sensibles à l'acidification, tandis que les Plécoptères et les Oligochètes sont dominants. Toutefois, il a été mis en évidence une recolonisation possible des rivières acidifiées par certaines espèces, durant la période d'étiage estivale quand la qualité de l'eau s'améliore.
    Notizen: Abstract The physico-chemical characteristics and the macroinvertebrate communities of six streams draining a small granitic catchment located in the Vosges mountains (northeastern France) have been studied. Among the streams, five were affected by acidification and characterised by low pH (mean pH: 4.90 to 5.90), low HCO inf3 sup− concentrations (mean concentration: 0–16 µeq l−1) and elevated aluminium concentrations (mean concentration: 154–278 µg l−1). Only one stream was typical of waters draining granitic bedrock (mean pH: 6.90; mean aluminium concentration: 79 µg 1−1; mean HCO inf3 sup− concentration: 152 µeq l−1). The macroinvertebrates communities of the acidified streams were strongly affected compared to the non-acidified one. Richness, abundance and diversity (Shannon index) were significantly lower when acidification occurred. All the major taxonomic groups were affected, but Molluscs and Ephemeroptera were the most acid-sensitive or organisms, whereas Plecoptera and Oligochaetes were dominant. However, recolonization of acidified streams was possible during summer low flow when the global water quality slightly increased.
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  • 82
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 313-314 (1995), S. 333-340 
    ISSN: 1573-5117
    Schlagwort(e): Seathwaite Tarn ; acid lake ; acidification ; fertilisation ; rotifers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Seathwaite Tarn, in the English Lake District, was used as an experimental site to test the feasibility of increasing the pH of an acidified waterbody by adding a phosphorus-based fertiliser solution. The impact of this experiment on the planktonic rotifer community was assessed by monitoring for two years before treatment (1990–1991), and for a further two years once treatment had begun (1992–1993). The pH of the water rose by 0.5 pH units over the period of fertilisation, and the lake became very eutrophic. This had little effect on the species composition of the rotifer assemblage, which continued to reflect the acid, oligotrophic nature of the untreated lake. However, there were marked changes in the levels of abundance of most planktonic species. Population densities of Keratella serrulata and Trichocerca longiseta increased in early spring, compared to pre-treatment levels, apparently due to the rises in chlorophyll-a concentrations. In contrast, Polyarthra dolichoptera became very scarce after fertilisation began. The treatment seemed to have little effect on the population dynamics of the dominant openwater rotifer, Polyarthra remata. In 1993, very high densities of Bosmina coregoni (up to 250 × 103 ind M−3 ) developed in response to the eutrophication programme. This seemed to suppress the rotifer community in the summer months.
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 168-169 (1995), S. 353-363 
    ISSN: 1573-5036
    Schlagwort(e): acidification ; leaching losses ; needlefall ; nitrogen saturation ; Pseudotsuga menziesii (Mirb.) Franco ; throughfall
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The effects on growth and nutrient status of an increased availability of all major nutrients was studied in a 40 year old Douglas fir stand. The nutrient amounts were applied by daily sprinkling and were in fixed, optimal proportions to the estimated annual uptake of N. Irrigation was included to avoid drought stress. The nutrient applications were also done in combination with a lower NH4 load, realized under a roof that was placed above the ground. According to nutritional standards nitrogen supply was optimal and was related to the moderately high atmospheric N inputs. Nutrition of P, K and in some years Ca seemed critical. In all four studied growing seasons water additions resulted in a growth increase, of 30 to 40%. Irrigation decreased needle fall. Nutrient applications increased the needle concentrations of P and K considerably, but this did not result in a growth enhancement. Fertilization also increased K and P in shedded needles. Only minor leaching losses were calculated. The recovery in trees of fertilizer K and P was maximally 15%. Input-output budgets suggested that P was strongly retained in the soil. The decrease in NH4 load had slightly decreased N availability and soil acidification, and seemed to enhance tree growth. The use of tree growth as a parameter to evaluate the effects of an improved nutritional balance is discussed.
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  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 168-169 (1995), S. 167-172 
    ISSN: 1573-5036
    Schlagwort(e): acidification ; fine roots ; forest decline ; Picea abies ; tree vitality ; triphenyl tetrazolium chloride
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The vitality of fine roots in a Norway spruce stand subjected to application of ammonium sulphate (NS), wood ash (A) and nitrogen-free fertilizer (V) respectively, was investigated using i) vitality classification of fine roots based on morphological characteristics and ii) the triphenyl tetrazolium chloride (TTC) method of estimating dehydrogenase activity. Although the NS-treated areas showed a 30% increase in above-ground production in response to the NS-application, the vitality of the fine-root system in the humus layer appeared to be in a state of deterioration, as indicated by a decrease in fine-root biomass, an increased amount of dead fine (0–1 mm) and small (1–2 mm) roots, a decreased specific root length (SRL = fine root length/fine root dry weight) and an increased dehydrogenase activity. The impact of the the A and V treatments was reflected in a decrease in fine-root biomass and an increase in SRL. The results make it clear that in order to study the vitality of forest trees, both fine-root studies and studies of above-ground tree parts are necessary.
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  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 171 (1995), S. 245-253 
    ISSN: 1573-5036
    Schlagwort(e): acidification ; Alfisol ; aluminum toxicity ; cowpea ; exchangeable acidity ; maize ; manganese toxicity ; nitrogen fertilization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Increased use of N fertilizer and more intensive cropping due to the rising food demand in the tropics requires design and evaluation of sustainable cropping systems with minimum soil acidification. The objectives of this study were to quantify acidification of an Oxic Kandiustalf with different types of N fertilizer in two cropping systems under no-tillage and its effect on crop performance. Chemical soil properties in continuous maize (Zea mays L.) and maize-cowpea (Vigna unguiculata (L.) Walp) rotation were determined with three N sources (urea (UA), ammonium sulfate (AS) and calcium ammonium nitrate (CAN)) in Nigeria, West Africa, during five years. Chemical soil properties were related to grain yield and diagnostic plant nutrient concentrations. For the three N sources, the rate of decline in soil pH in maize-cowpea rotation was 57±7.5% of that in continuous maize, where double the amount of N fertilizer was applied. The rate of soil acidification during the five years was greater for AS than for UA or CAN in continuous maize, and not different for UA and CAN in both cropping systems. With AS, soil pH decreased from 5.8 to 4.5 during five years of continuous maize cropping. Exchangeable acidity increased with N fertilization, but did not reach levels limiting maize or cowpea growth. Return of residues to the soil surface may have reduced soluble and exchangeable Al levels by providing a source of organic ligands. Soil solution Mn concentrations increased with N fertilization to levels likely detrimental for crop growth. Symptoms of Mn toxicity were observed on cowpea leaves where AS was applied to the preceding maize crop, but not on maize plants. Soil acidification caused significant reductions in exchangeable Ca and effective CEC. Main season maize yield with N fertilization was lower with AS than with UA or CAN, but not different between UA and CAN during the six years of cropping. The lower maize grain yield with AS than with the other N sources was attributed to lower pH and a greater extractable Mn concentration with AS. When kaolinitic Alfisols are used for continuous maize cropping, even under no-tillage with crop residues returned as mulch, the soil may become acidifed to pH values of 5.0 and below after a few years. The no-till cereal-legume rotation with judicial use of urea or CAN as N sources for the cereal crop is a more suitable system for these poorly buffered, kaolinitic soils than continuous maize cropping. The use of AS as N source should be avoided. H Marschner Section editor
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  • 86
    ISSN: 1573-5036
    Schlagwort(e): acidification ; aluminium ; forest vitality ; Norway spruce ; sea salts ; Sitka spruce
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Studies on biogeochemical cycling of elements are performed in even aged forest ecosystems of Norway spruce, Sitka spruce and beech at several locations in Denmark. Episodes with high sea salt deposition and unusual low water surplus percolation caused extreme salt concentrations in the soil solutions. The changes were smallest beneath beech stands and most pronounced at the most salt-affected Sitka spruce stands. Contemporary, the pH drops and the Al3+ concentration increased above 20 mg L-1 owing to cation exchange with Na+. The Cl- and Al3+ concentrations reached levels reported as toxic for Norway spruce, but not for Sitka spruce and beech. The changes in the soil water chemistry must be considered as important factors for the reduced vitality in Norway spruce ecosystems in Denmark.
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  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 407-414 
    ISSN: 1573-6881
    Schlagwort(e): Glycine decarboxylase ; mitochondria ; photorespiration ; gene expression ; light control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Physik
    Notizen: Abstract The four component proteins of the glycine decarboxylase multienzyme complex (the P-, H-, T-, and L-proteins) comprise over one-third of the soluble proteins in mitochondria isolated from the leaves of C3 plants. Together with serine hydroxymethyltransferase, glycine decarboxylase converts glycine to serine and is the site of photorespiratory CO2 and NH3 release. The component proteins of the complex are encoded on nuclear genes with N-terminal presequences that target them to the mitochondria. The isolated complex readily dissociates into its component proteins and reassociates into the intact complexin vitro. Because of the intimate association between photosynthesis and photorespiration, the proteins of the complex are present at higher levels in leaves in the light. The expression of these genes is controlled at the transcriptional level and the kinetics of expression are closely related to those of the small subunit of Rubisco. Deletion analysis of fusions between the promoter of the H-protein of the complex and the reporter gene β-glucuronidase in transgenic tobacco has identified a region responsible for the tissue specificity and light dependence of gene expression. Gel shift experiments show that a nuclear protein in leaves binds to this region. Glycine decarboxylase has proven to be an excellent system for studying problems in plant biochemistry ranging from protein-protein interactions to control of gene expression.
    Materialart: Digitale Medien
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  • 88
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular neurobiology 15 (1995), S. 79-88 
    ISSN: 1573-6830
    Schlagwort(e): gonadotropin-releasing hormone ; gene expression ; tissue-specific expression ; steroid hormone ; peptide hormone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary 1. Gonadotropin-releasing hormone (GnRH) is the hypothalamic releasing factor that controls pituitary gonadotropin subunit gene expression and indirectly gametogenesis and steroidogenesis from the gonad, which results in reproductive competence. 2. GnRH is synthesized in only about 1000 neurons in the hypothalamus and released in an episodic fashion down the median eminence to regulate gonadotropin biosynthesis. 3. Although much is known about the secretory dynamics of GnRH release, little is known about the pretranslational control of GnRH biosynthesis due to lack of appropriate model systems. The recent availability of immortalized neuronal cell lines that produce GnRH allows investigators for the first time to begin to dissect the factors that directly regulate GnRH gene expression. 4. This article reviews the current state of knowledge concerning the mechanisms that direct tissue-specific and peptide hormone control of GnRH biosynthesis.
    Materialart: Digitale Medien
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  • 89
    ISSN: 1573-5117
    Schlagwort(e): Turbellaria ; Dugesia ; homeobox ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To identify potential pattern control and cell determination and/or differentiation genes in the freshwater planarian Dugesial (G.) tigrina, we searched for homeobox genes of different types in the genome of this primitive metazoan. We applied two basic approaches: 1) Screening the cDNA library with degenerate oligonucleotides corresponding to the most conserved amino acid sequence from helix-3 of the homeodomain of each family; and 2) PCR amplification of genomic DNA or cDNA, using two sets of degenerated oligonucleotides corresponding to helices 1 and 3 of the homeodomain or two specific domains of the POU family. Using the first strategy we have identified and characterized two tissue-specific cell determination and/or differentiation NK-type homeobox genes. Using the second strategy we have identified several homeobox genes that belong to the HOM/Hox, paired (prd) or POU families.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    Springer
    World journal of microbiology and biotechnology 11 (1995), S. 71-84 
    ISSN: 1573-0972
    Schlagwort(e): Archaea ; gene expression ; genetics ; replication ; thermophile
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract The molecular biology of extremophiles has recently attracted much interest, both in terms of cell adaptation to extreme environmental conditions and the development of manipulative genetic techniques. Although molecular genetic techniques have been successfully applied to halophiles and methanogens, their use with hyperthermophiles is limited by the extreme growth conditions that these organisms require. Much information on the thermophilic Archaea, has been obtained by studying the key enzymes involved in fundamental cell processes, such as transcription and replication, and by the cloning, sequence comparison and heterologous expression of structural genes. The development of viral vectors and systems for transformation, mutant production and screening will permit increased genetic manipulation of these organisms.
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  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Antonie van Leeuwenhoek 67 (1995), S. 181-200 
    ISSN: 1572-9699
    Schlagwort(e): β-lactam antobiotics ; biosynthetic enzymes ; penicillin ; cephalosporin ; cephamycin ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genespcbAB,pcbC andpenDE encoding enzymes involved in the biosynthesis of penicillin have been cloned fromPenicillium chrysogenum andAspergillus nidulans. They are clustered in chromosome I (10.4 Mb) ofP. chrysogenum, but they are located in chromosome II ofPenicillium notatum (9.6 Mb) and in chromosome VI (3.0 Mb) ofA. nidulans. Expression studies have shown that each gene is expressed as a single transcript from separate promoters. Enzyme regulation studies and gene expression analysis have provided useful information to understand the control of gene expression leading to overexpression of the genes involved in penicillin biosynthesis. Cephalosporin genes have been studied inCephalosporium acremonium and also in cephalosporin-producing bacteria. InC. acremonium the genes involved in cephalosporin biosynthesis are separated in at least two clusters. Cluster I (pcbAB-pcbC) encodes the first two enzymes of the cephalosporin pathway which are very similar to those involved in penicillin biosynthesis. Cluster II (cefEF-cefG), encodes the last three enzymatic activities of the cephalosporin pathway. It is unknown, at this time, if thecefD gene encoding isopenicillin epimerase is linked to any of the two clusters. In cephamycin producing bacteria the genes encoding the entire biosynthetic pathway are located in a single cluster extending for about 30 kb inNocardia lactamdurans, and inStreptomyces clavuligerus. The cephamycin clusters ofN. lactamdurans andS. clavuligerus include a genelat which encodes lysine-6-aminotransferase an enzyme involved in formation of the precursor α-aminoadipic acid. TheN. lactamdurans cephamycin cluster includes, in addition, a β-lactamase (bla) gene, a penicillin binding protein (pbp), and a transmembrane protein gene (cmcT) that is probably involved in secretion of the cephamycin. Little is known however about the mechanism of control of gene expression in the different β-lactam producers. The availability of most of the structural genes provides a good basis for further studies on gene expression. This knowledge should lead in the next decade to a rational design of strain improvement procedures. The origin and evolution of β-lactam genes is intriguing since their nucleotide sequences are extremely conserved despite their restricted distribution in the microbial world.
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  • 92
    Digitale Medien
    Digitale Medien
    Springer
    Antonie van Leeuwenhoek 67 (1995), S. 377-383 
    ISSN: 1572-9699
    Schlagwort(e): Campylobacter jejuni ; flagella ; flagellin genes ; flaA ; flaB ; phase variation ; gene expression ; sigma 28 ; sigma 54 ; repressor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Flagella production inCampylobacter jejuni 81116 is subject to phase variation; the bacterium is able to switch its flagellum synthesis, and thereby its motility, on and off. Under standard laboratory growth conditions flagellar phase variants can be maintained as stable, pure cultures. We found conditions that efficiently induced a phase shiftin vitro. TheflaA gene but not theflaB gene is subject to the on and off switch. Minor amounts of FlaB are still present in aflagellate cells. We previously showed that flagellin gene expression in phase variants was regulated at the transcriptional level. Here, sequence data prove that abolishment offlaA transcription is not caused by DNA rearrangements or mutations within the flagellin locus. SinceflaA is preceeded by a typical σ28 promoter aC. jejuni σ28 homolog could play a role in regulation offlaA gene expression but such a gene or protein could not be detected. However,in vitro transcription could be detected using σ28-holoenzyme preparations fromBacillus subtilis. Possible regulatory mechanisms that may control flagellar phase variation in Campylobacter are discussed.
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  • 93
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 28 (1995), S. 69-91 
    ISSN: 1573-515X
    Schlagwort(e): Acid neutralizing capacity ; acidification ; aluminum ; dissolved organic carbon ; lake ; watershed
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Cone Pond is one of the few acidic, clear-water ponds in the White Mountains of New Hampshire, a region dominated by high inputs of strong acids from atmospheric deposition and low base content of bedrock. Monitoring was conducted for 13 months to compare and contrast the acid-base chemistry of the terrestrial and aquatic portions of the watershed. Variations in Al concentration and speciation in drainage waters were correlated with changes in the supply of naturally occurring organic ligands. During the study period, the pond retained 28% of Al inputs, including nearly half of the inputs of organically complexed Al. Chemical equilibrium calculations indicated that the entire water-column was oversaturated with respect to the solubility of synthetic gibbsite during summer, as was the hypolimnion during winter. Retention of Al resulted from an increase in pH in the hypolimnion concomitant with SO4 2− reduction, and from loss of organic anions in epilimnetic waters. Acid neutralizing capacity (ANC) generated in the pond primarily through SO4 2− reduction and base cation (C B ) release was balanced by ANC consumed as a result of Al retention.
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular neurobiology 15 (1995), S. 43-78 
    ISSN: 1573-6830
    Schlagwort(e): luteinizing hormone-releasing hormone ; genetic targeting ; neuronal cell lines ; migration ; morphology ; implantation ; prohormone processing ; coculture ; pulsatile release ; secretion ; gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary 1. Two LHRH neuronal cell lines were developed by targeted tumorigenesis of LHRH neuronsin vivo. These cell lines (GN and GT-1 cells) represent a homogeneous population of neurons. GT-1 cells have been further subcloned to produce the GT1-1, GT1-3, and GT1-7 cell lines. While considerable information is accumulating about GT-1 cells, very little is currently known about the characteristics and responses of GN cells. 2. By both morphological and biochemical criteria, GT-1 cells are clearly neurons. All GT-1 cells immunostain for LHRH and the levels of prohormone, peptide intermediates, and LHRH in the cells and medium are relatively high. 3. GT-1 cells biosynthesize, process, and secrete LHRH. Processing of pro-LHRH appears to be very similar to that reported for LHRH neuronsin vivo. At least four enzymes may be involved in processing the prohormone to LHRH. 4. LHRH neurons are unique among the neurons of the central nervous system because they arise from the olfactory placode and grow back into the preoptic-anterior hypothalamic region of the brain. Once these neurons reach this location, they send their axons to the median eminence. With respect to the immortalized neurons, GN cells were arrested during their transit to the brain. In contrast, GT-1 cells were able to migrate to the preoptic-anterior hypothalamic region but were unable correctly to target their axons to the median eminence. These problems in migration and targeting appear to be due to expression of the simian virus T-antigen. 5. While GT-1 cells are a homogeneous population of neurons, they are amenable to coculture with other types of cells. Coculture experiments currently under way should help not only to reveal some of the molecular and cellular cues that are important for neuronal migration and axonal targeting, but they should also highlight the nature of the cellular interactions which normally occurin situ. 6. GT-1 cells spontaneously secrete LHRH in a pusatile manner. The interpulse interval for LHRH from these cells is almost identical to that reported for release of LH and LHRHin vivo. GT-1 cells are interconnected by both gap junctions and synapses. The coordination and synchronization of secretion from these cells could occur through these interconnections, by feedback from LHRH itself, and/or by several different compounds that are secreted by these cells. One such compound is nitric oxide. 7. GT-1 cells have Na+, K+, Ca2+, and Cl− channels. Polymerase chain reaction experiments coupled with Southern blotting and electrophysiological recordings reveal that GT-1 cells contain at least five types of Ca2+ channels. R-type Ca2+ channels appear to be the most common type of channel and this channel is activated by phorbol esters in the GT-1 cells. 8. LHRH is secreted from GT-1 cells in response to norepinephrine, dopamine, histamine, GABA (GABA-A agonists), glutamate, nitric oxide, neuropeptide Y, endothelin, prostaglandin E2, and activin A. Phorbol esters are very potent stimulators of LHRH secretion. Inhibition of LHRH release occurs in response to LHRH, GABA (GABA-B agonists), prolactin, and glucocorticoids. 9. Compared to secretion studies, far fewer agents have been tested for their effects on gene expression. All of the agents which have been tested so far have been found either to repress LHRH gene expression or to have no effect. The agents which have been reported to repress LHRH steady-state mRNA levels include LHRH, prolactin, glucocorticoids, nitric oxide, and phorbol esters. While forskolin stimulates LHRH secretion, it does not appear to have any effect on LHRH mRNA levels.
    Materialart: Digitale Medien
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  • 95
    ISSN: 1573-6830
    Schlagwort(e): astrocytes ; glioma ; gene expression ; growth factors ; reverse transcription ; polymerase chain reaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary 1. Although glial cells in culture are known to secrete growth factors and are also known to be responsive to some of them, detailed comparisons are difficult because the bulk of information was based on various animals of origin, developmental stages, growth properties, culture age, and culture conditions. 2. To present a unified picture of the growth factors and their receptors found in glial cells, we surveyed the expression of messenger RNAs of a panel of growth factors and receptors, using reverse transcription-polymerase chain reaction (RT-PCR), in three common glial cell types: rat astrocytes in primary culture, rat glioma line C6, and human glioma line A172. 3. We observed that normal and neoplastic glial cells in culture express multiple growth factors and also possess most of the receptors to these factors, suggesting multiple autocrine functions. In addition, glia produce growth factors known to be capable of acting on neurons, implicating paracrine function involving glia-neuron interaction. Glial cells also produce growth factors and receptors that are capable of communicating with hematopoietic cells, suggesting neuroimmunologic interaction. What is most interesting is that glial cells express receptors for growth factors previously thought to be acting on neurons only. 4. The current study demonstrates the feasibility of screening from a small sample a large number of growth factors and receptors. The method portends future clinical application to biopsy or necropsy samples from brain tumors or pathologic brains suffering from degenerative diseases such as Alzheimer's or Parkinson's disease.
    Materialart: Digitale Medien
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  • 96
    ISSN: 1573-515X
    Schlagwort(e): acidification ; alkalinity generation ; metaphyton ; sulfur ; sulfate reduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Experimental acidification of a softwater lake to below pH 5 fundamentally changed the sulfur cycle and lowered internal alkalinity generation (IAG). Prior to reaching pH 4.5, the balance of sulfur reduction and oxidation reactions within the lake was in favour of reduction, and the lake was a net sink for sulfate. In the four years at pH 4.5 the balance of reduction and oxidation reactions was in favour of oxidation, and there was a net production of sulfate (SO4 2−) within the lake. Evidence indicating a decrease in net SO4 2− reduction at pH 4.5 was also obtained in an anthropogenically acidified lake that had been acidified for many decades. In both lakes, the decrease in net SO4 2− reduction appeared to be linked not to a simple inhibition of SO4 2− reduction but rather to changes in benthic ecosystem structure, especially the development of metaphytic filamentous green algae, which altered the balance between SO4 2− reduction and sulfur oxidation. At pH's above 4.5, net SO4 2− reduction was the major contributor to IAG in the experimental lake, as it is in many previously studied lakes at pH 5 and above. At pH 4.5, the change in net annual SO4 2− reduction (a decrease of 110%) resulted in a 38% decrease in total IAG. Because of the important role of net SO4 2− reduction in acid neutralization in softwater lakes, models for predicting acidification and recovery of lakes may need to be modified for lakes acidified to pH 〈5.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 2319-2324 
    ISSN: 1573-2932
    Schlagwort(e): sensitivity ; buffering ; acidification ; vegetation effects ; soil ; Al toxicity ; GIS ; mapping ; nutrient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Acidic deposition is considered a problem in Europe and North America but the potential for ecosystem damage from this pollution is also increasing rapidly in many developing countries. It is therefore important to assess current and future risks of ecosystem effects due to acidic deposition in these areas. It is possible to indicate risk areas by linking an assessment of sensitivity to net acidic input rates derived from deposition estimates for sulphur and nitrogen compounds and base cations. A method to assess and map a relative scale of terrestrial ecosystem sensitivity using international datasets is presented. The assessment relies on the determination of buffering mechanisms that prevent effects related to acidic deposition. Land-cover data, edaphic and climate datasets are combined using a GIS. Large areas are assessed as highly sensitive to acidic deposition in tropical regions of Asia, South and Central America and Africa, and also in the Boreal forests of northern Asia. Sensitive areas cover forest and non-forest ecosystems and some areas of agricultural production. Critical loads are not evaluated in this project but initial estimates will be applied to sensitivity classes at a further stage which will allow estimation of areas at risk by comparison with deposition.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 2389-2394 
    ISSN: 1573-2932
    Schlagwort(e): atmospheric deposition ; base cations ; Europe ; acidification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Atmospheric deposition of base cations in Europe is mapped on a 10×20 km grid using the inferential modeling technique. Deposition fields are found to resemble the geographic variability of sources, climate and land use. In large parts of southern Europe, more than 50% of the potential acid deposition is found counteracted by deposition of base cations. In central and northwestern Europe, however, base cation deposition usually amounts less than 25% of the acid input. An uncertainty analysis to assess the quality of the base cation deposition maps revealed that for an average grid cell the deviation from the estimated value can be as large as 140%.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    ISSN: 1573-2932
    Schlagwort(e): Surface waters ; north-west Scotland ; acidification ; critical loads ; sea-salts ; palaeolimnology ; diatoms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Recent critical loads assessments suggest that sensitive surface waters in the north-west of Scotland have acidified, whereas earlier surveys indicate little chemical or biological evidence of acidification. It has been suggested that regionally high sea-salt inputs are affecting either critical loads calculations or the susceptibility of surface waters to acidification. We use palaeolimnological techniques to test the hypothesis that the critical load exceedances in north-west Scotland are real. Pre-industrial and present day loch-water pH are inferred from diatom assemblages in sediment cores from 21 lochs in order to estimate recent pH change. The results indicate consistent post-1800 declines in loch-water pH, although the magnitude of this decline is small (〈0.4 pH unit) and in most cases within the error of the technique. It is concluded that although slight acidification might have taken place, this has not been of sufficient magnitude to significantly effect most biological communities (e.g. higher plants, invertebrates and fish).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 85 (1995), S. 2443-2448 
    ISSN: 1573-2932
    Schlagwort(e): critical loads ; freshwaters ; geology ; soil ; land use ; sensitivity ; acidification ; catchments
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Using information on geology, soils and land use, a map has been generated for Great Britain which indicates five classes of sensitivity of surface waters to acidification. This map has been used for designing sampling strategies for mapping critical loads of acidity for freshwaters. This paper evaluates the freshwater sensitivity map using a data set of water chemistry collected as part of the UK critical loads programme. Discriminant analysis was used to predict five critical load classes from information on geology and soil sensitivity for freshwater sites. This showed geology and soil information can correctly predict approximately 50% of all critical loads classes. In addition, 77% of sites fall within one critical loads class of that predicted. Predictions may be improved by including other variables eg altitude and geographical location. Differences between lake, stream and reservoir sites are also examined. Ranges of critical loads values were determined for each of the five classes of surface water sensitivity. While a trend in critical load values was evident between classes, there was significant overlap. A simplified sensitivity map with only three classes related more closely to critical loads values. The paper demonstrates the usefulness of the surface water sensitivity map for assessing acidification at a national scale, but highlights the difficulties of predicting critical loads for individual sensitive catchments using national data.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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