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  • UmuC  (2)
  • Oceanography: general (Arctic and Antarctic oceanography; water masses)  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Water mass distribution in Fram Strait and over the Yermak Plateau in summer 1997 (2000)
    Springer
    Annales geophysicae 18 (2000), S. 687-705 
    Details
    ISSN: 0992-7689
    Keywords: Oceanography: general (Arctic and Antarctic oceanography; water masses) ; Oceanography: physical (general circulation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The water mass distribution in northern Fram Strait and over the Yermak Plateau in summer 1997 is described using CTD data from two cruises in the area. The West Spitsbergen Current was found to split, one part recirculated towards the west, while the other part, on entering the Arctic Ocean separated into two branches. The main inflow of Atlantic Water followed the Svalbard continental slope eastward, while a second, narrower, branch stayed west and north of the Yermak Plateau. The water column above the southeastern flank of the Yermak Plateau was distinctly colder and less saline than the two inflow branches. Immediately west of the outer inflow branch comparatively high temperatures in the Atlantic Layer suggested that a part of the extraordinarily warm Atlantic Water, observed in the boundary current in the Eurasian Basin in the early 1990s, was now returning, within the Eurasian Basin, toward Fram Strait. The upper layer west of the Yermak Plateau was cold, deep and comparably saline, similar to what has recently been observed in the interior Eurasian Basin. Closer to the Greenland continental slope the salinity of the upper layer became much lower, and the temperature maximum of the Atlantic Layer was occasionally below 0.5 °C, indicating water masses mainly derived from the Canadian Basin. This implies that the warm pulse of Atlantic Water had not yet made a complete circuit around the Arctic Ocean. The Atlantic Water of the West Spitsbergen Current recirculating within the strait did not extend as far towards Greenland as in the 1980s, leaving a broader passage for waters from the Atlantic and intermediate layers, exiting the Arctic Ocean. A possible interpretation is that the circulation pattern alternates between a strong recirculation of the West Spitsbergen Current in the strait, and a larger exchange of Atlantic Water between the Nordic Seas and the inner parts of the Arctic Ocean.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-000-0687-5
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Analysis of chimeric UmuC proteins: identification of regions in Salmonella typhimurium UmuC important for mutagenic activity (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 121-129 
    Details
    ISSN: 1617-4623
    Keywords: Key words Escherichia coli ; Salmonella typhimurium ; SOS mutagenesis ; Chimeric proteins ; UmuC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Unlike Escherichia coli, the closely related bacterium Salmonella typhimurium is relatively unresponsive to the mutagenic effects of DNA-damaging agents. Previous experiments have suggested that these phenotypic differences might result from reduced activity of the S. typhimurium UmuC protein. To investigate this possibility, we have taken advantage of the high degree of homology between the UmuC proteins of E. coli and S. typhimurium and have constructed a series of plasmid-encoded chimeric proteins. The possibility that the phenotypic differences might be due to differential expression of the respective UmuC proteins was eliminated by constructing chimeric proteins that retained the first 25 N-terminal amino acids of either of the UmuC proteins (and presumably the same translational signals), but substituting the remaining 397 C-terminal amino acids with the corresponding segments from the reciprocal operon. Constructs expressing mostly E. coli UmuC were moderately proficient for mutagenesis whereas those expressing mostly S. typhimurium UmuC exhibited much lower frequencies of mutation, indicating that the activity of the UmuC protein of S. typhimurium is indeed curtailed. The regions responsible for this phenotype were more precisely localized by introducing smaller segments of the S. typhimurium UmuC protein into the UmuC protein of E. coli. While some regions could be interchanged with few or no phenotypic effects, substitution of residues 212–395 and 396–422 of E. coli UmuC with those from S. typhimurium resulted in reduced mutability, while substitution of residues 26–59 caused a dramatic loss of activity. We suggest, therefore, that the primary cause for the poor mutability of S. typhimurium can be attributed to mutations located within residues 26–59 of the S. typhimurium UmuC protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02172909
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Analysis of chimeric UmuC proteins: identification of regions inSalmonella typhimurium UmuC important for mutagenic activity (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 121-129 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Salmonella typhimurium ; SOS mutagenesis ; Chimeric proteins ; UmuC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract UnlikeEscherichia coli, the closely related bacteriumSalmonella typhimurium is relatively unresponsive to the mutagenic effects of DNA-damaging agents. Previous experiments have suggested that these phenotypic differences might result from reduced activity of theS. typhimurium UmuC protein. To investigate this possibility, we have taken advantage of the high degree of homology between the UmuC proteins ofE. coli andS. typhimurium and have constructed a series of plasmid-encoded chimeric proteins. The possibility that the phenotypic differences might be due to differential expression of the respective UmuC proteins was eliminated by constructing chimeric proteins that retained the first 25 N-terminal amino acids of either of the UmuC proteins (and presumably the same translational signals), but substituting the remaining 397 C-terminal amino acids with the corresponding segments from the reciprocal operon. Constructs expressing mostlyE. coli UmuC were moderately proficient for mutagenesis whereas those expressing mostlyS. typhimurium UmuC exhibited much lower frequencies of mutation, indicating that the activity of the UmuC protein ofS. typhimurium is indeed curtailed. The regions responsible for this phenotype were more precisely localized by introducing smaller segments of theS. typhimurium UmuC protein into the UmuC protein ofE. coli. While some regions could be interchanged with few or no phenotypic effects, substitution of residues 212–395 and 396–422 ofE. coli UmuC with those fromS. typhimurium resulted in reduced mutability, while substitution of residues 26–59 caused a dramatic loss of activity. We suggest, therefore, that the primary cause for the poor mutability ofS. typhimurium can be attributed to mutations located within residues 26–59 of theS. typhimurium UmuC protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02172909
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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