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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular 999 (1989), S. 12-18 
    ISSN: 0167-4838
    Keywords: (Dromedary) ; Anion binding ; Hemoglobin ; NMR, ^3^5Cl^--
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0778
    Keywords: 5-HT3 receptor ; large scale ; reactor ; Semliki Forest virus ; suspension process ; transient expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The expression of recombinant proteins with the Semliki Forest Virus (SFV) system has been scaled up to bioreactor scale. As a model protein for this study the human 5-HT3 receptor was chosen. The gene for the receptor was subcloned into the SFV expression plasmid pSFV1. Virus production by in vivo packaging and production of the recombinant protein was scaled up, the latter to a reactor volume of 11.5 l. A VibromixTM agitation system was chosen to overcome aggregation problems of BHK cells in suspension. In the process, cells were first grown to a density of 106 cells/ml, the medium was then exchanged with fresh medium and the culture was infected with the recombinant virus at an estimated multiplicity of infection of 30. 24 h post infection we measured an expression level of 3 million functional 5-HT3 receptors per cell. For harvesting, the cells were pelleted by centrifugation. The receptor protein was purified in a single step (Hovius et al., 1998) by exploiting the hexa-His tag at minimal protein loss (51% yield). Experiments to optimise expression resulted in yields up to 8 million receptors per cell, when the pH of a suspension culture was controlled at pH 7.3. Rapid virus generation and protein production, high protein yields as well as successful large scale application have made the SFV expression system attractive to produce large quantities of recombinant protein in a very short time. After optimisation of the expression conditions (in particular by setting the pH at 7.3), yields were increased twofold.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2020-02-12
    Description: Here we present a tephrostratigraphic record (core Co1202) recovered from the northeastern part of Lake Ohrid (Republics of Macedonia and Albania) reaching back to Marine Isotope Stage (MIS) 6. Overall ten horizons (OT0702-1 to OT0702-10) containing volcanic tephra have been recognised throughout the 14.94 m long sediment succession. Four tephra layers were visible at macroscopic inspection (OT0702-4, OT0702-6, OT0702-8 and OT0702-9), while the remaining six are cryptotephras (OT0702-1, OT0702-2, OT0702-3, OT0702-5, OT0702-7 and OT0702-10) identified from peaks in K, Zr and Sr intensities, magnetic susceptibility measurements, and washing and sieving of the sediments. Glass shards of tephra layers and cryptotephras were analysed with respect to their major element composition, and correlated to explosive eruptions of Italian volcanoes. The stratigraphy and the major element composition of tephra layers and cryptotephras allowed the correlation of OT0702-1 to AD 472 or AD 512 eruptions of Somma-Vesuvius, OT0702-2 to the FL eruption of Mount Etna, OT0702-3 to the Mercato from Somma-Vesuvius, OT0702-4 to SMP1-e/Y-3 eruption from the Campi Flegrei caldera, OT0702-5 to the Codola eruption (Somma-Vesuvius or Campi Flegrei), OT0702-6 to the Campanian Ignimbrite/Y-5 from the Campi Flegrei caldera, OT0702-7 to the Green Tuff/Y-6 eruption from Pantelleria Island, OT0702-8 to the X-5 eruption probably originating from the Campi Flegrei caldera, OT0702-9 to the X-6 eruption of generic Campanian origin, and OT0702-10 to the P-11 eruption from Pantelleria Island. The fairly well-known ages of these tephra layers and parent eruptions provide new data on the dispersal and deposition of these tephras and, furthermore, allow the establishment of a chronological framework for core Co1202 for a first interpretation of major sedimentological changes.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/article
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  • 4
    Publication Date: 2020-02-12
    Description: The reliability of Arctic climate predictions is currently hampered by insufficient knowledge of natural climate variability in the past. A sediment core from Lake El’gygytgyn (NE Russia) provides a continuous high-resolution record from the Arctic spanning the past 2.8 Ma. The core reveals numerous “super interglacials” during the Quaternary, with maximum summer temperatures and annual precipitation during marine benthic isotope stages (MIS) 11c and 31 ~4-5°C and ~300 mm higher than those of MIS 1 and 5e. Climate simulations show these extreme warm conditions are difficult to explain with greenhouse gas and astronomical forcing alone, implying the importance of amplifying feedbacks and far field influences. The timing of Arctic warming relative to West Antarctic Ice Sheet retreats implies strong interhemispheric climate connectivity.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/article
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  • 5
    Publication Date: 2020-02-12
    Description: Rock magnetic, biochemical and inorganic records of the sediment cores PG1351 and Lz1024 from Lake El'gygytgyn, Chukotka peninsula, Far East Russian Arctic, were subject to a hierarchical agglomerative cluster analysis in order to refine and extend the pattern of climate modes as defined by Melles et al. (2007). Cluster analysis of the data obtained from both cores yielded similar results, differentiating clearly between the four climate modes warm, peak warm, cold and dry, and cold and moist. In addition, two transitional phases were identified, representing the early stages of a cold phase and slightly colder conditions during a warm phase. The statistical approach can thus be used to resolve gradual changes in the sedimentary units as an indicator of available oxygen in the hypolimnion in greater detail. Based upon cluster analyses on core Lz1024, the published succession of climate modes in core PG1351, covering the last 250 ka, was modified and extended back to 350 ka. Comparison to the marine oxygen isotope (δ18O) stack LR04 (Lisiecki and Raymo, 2005) and the summer insolation at 67.5° N, with the extended Lake El'gygytgyn parameter records of magnetic susceptibility (κLF), total organic carbon content (TOC) and the chemical index of alteration (CIA; Minyuk et al., 2007), revealed that all stages back to marine isotope stage (MIS) 10 and most of the substages are clearly reflected in the pattern derived from the cluster analysis.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 6
    Publication Date: 2020-02-12
    Description: To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El’gygytgyn in northeast Arctic Russia. Sedi- ments from this lake contain a paleoclimate record of glacial- interglacial cycles during the last three million years. Low- resolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical param- eters are used to infer past climatic conditions thus provid- ing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Follow- ing this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differ- ences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/article
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  • 7
    Publication Date: 2020-02-12
    Description: The Last Interglacial Period (LIP) is often regarded as a good analogue for potential climatic conditions under predicted global warming scenarios. Despite this, there is still debate over the nature, duration and frequency of climatic changes during this period. One particularly contentious issue has been the apparent evidence of climatic instability identified in many marine cores but seemingly lacking from many terrestrial archives, especially within the Arctic, a key region for global climate change research. In this paper, geochemical records from Lake El’gygytgyn, north-eastern Russia, are used to infer past climatic changes during the LIP from within the high Arctic. With a sampling resolution of ~ 20 - ~ 90 years, these records offer the potential for detailed, high-resolution paleoclimate reconstruction. This study shows that the LIP commenced in central Chukotka ~ 129 thousand years ago (ka), with the warmest climatic conditions occurring between ~ 128-127 ka before being interrupted by a short-lived cold reversal. Mild climatic conditions then persisted until ~ 122 ka when a marked reduction in the sedimentation rate suggests a decrease in precipitation. A further climatic deterioration at ~ 118 ka marks the return to glacial conditions. This study highlights the value of incorporating several geochemical proxies when inferring past climatic conditions, thus providing the potential to identify signals related to environmental change within the catchment. We also demonstrate the importance of considering how changes in sedimentation rate influence proxy records, in order to develop robust paleoenvironmental reconstructions.
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/article
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