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  • 1
    Electronic Resource
    Electronic Resource
    Toxic oxygen: The radical life-giver (2002)
    [s.l.] : Nature Publishing Group
    Nature 420 (2002), S. 27-27 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The introduction of oxygen into the Earth's atmosphere was a double-edged sword. It provided a fuel that would allow the evolution of complex organisms with high energy demands, but also represented a new source of toxins. Oxygen-respiring eukaryotes needed not only to develop machinery to harness ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/420027a
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  • 2
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    Goldfish brain and heart are well protected from Ni2+-induced oxidative stress (2014)
    ELSEVIER SCIENCE INC
    In:  EPIC3Comparative Biochemistry and Physiology C-Toxicology & Pharmacology, ELSEVIER SCIENCE INC, 162, pp. 43-50, ISSN: 1532-0456
    Details
    Publication Date: 2014-08-25
    Description: After 96 h goldfish exposure to 10, 25 or 50 mg/L of Ni2 + no Ni accumulation was found in the brain, but lipid peroxide concentration was by 44% elevated in the brain, whereas carbonyl protein content was by 45–45% decreased in the heart. High molecular mass thiol concentration was enhanced by 30% in the heart, while in the brain low molecular mass thiol concentration increased by 28–88%. Superoxide dismutase activity was by 27% and 35% increased in the brain and heart, respectively. Glutathione peroxidase activity was lowered to 38% and 62% of control values in both tissues, whereas catalase activity was increased in the heart by 15–45%, accompanied by 18–29% decreased glutathione reductase activity. The disturbances of free radical processes in the brain and heart might result from Ni-induced injuries to other organs with more prominent changes in the heart, because of close contact of this organ with blood, whereas the blood–brain barrier seems to protect the brain.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
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    Euphausiid respiration model revamped. Latitudinal and seasonal shaping effects on krill respiration rates (2014)
    ELSEVIER SCIENCE BV
    In:  EPIC3Ecological Modelling, ELSEVIER SCIENCE BV, 291, pp. 233-241, ISSN: 0304-3800
    Details
    Publication Date: 2018-02-05
    Description: Euphausiids constitute a major biomass component in shelf ecosystems and play a fundamental role in the rapid vertical transport of carbon from the ocean surface to the deeper layers during their daily vertical migration (DVM). DVM depth and migration patterns depend on oceanographic conditions with respect to temperature, light and oxygen availability at depth, factors that are highly dependent on season in most marine regions. Here we introduce a global krill respiration ANN (artificial neural network) model including the effect of latitude (LAT), the day of the year (DoY), and the number of daylight hours (DLh), in addition to the basal variables that determine ectothermal oxygen consumption (temperature, body mass and depth). The newly implemented parameters link space and time in terms of season and photoperiod to krill respiration. The ANN model showed a better fit (r2 = 0.780) when DLh and LAT were included, indicating a decrease in respiration with increasing LAT and decreasing DLh. We therefore propose DLh as a potential variable to consider when building physiological models for both hemispheres. For single Euphausiid species investigated in a large range of DLh and DoY, we also tested the standard respiration rate for seasonality with Multiple Linear Regression (MLR) and General Additive model (GAM). GAM successfully integrated DLh (r2 = 0.563) and DoY (r2 = 0.572) effects on respiration rates of the Antarctic krill, Euphausia superba, yielding the minimum metabolic activity in mid-June and the maximum at the end of December. We could not detect DLh or DoY effects in the North Pacific krill Euphausia pacifica, and our findings for the North Atlantic krill Meganyctiphanes norvegica remained inconclusive because of insufficient seasonal data coverage. We strongly encourage comparative respiration measurements of worldwide Euphausiid key species at different seasons to improve accuracy in ecosystem modeling.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 4
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    Euphausiid respiration model revamped: latitudinal and seasonal shaping effects on krill respiration rates (2014)
    ELSEVIER SCIENCE BV
    In:  EPIC3Ecological Modelling, ELSEVIER SCIENCE BV, 291, pp. 233-241, ISSN: 0304-3800
    Details
    Publication Date: 2019-07-16
    Description: Euphausiids constitute a major biomass component in shelf ecosystems and play a fundamental role in the rapid vertical transport of carbon from the ocean surface to the deeper layers during their daily vertical migration (DVM). DVM depth and migration patterns depend on oceanographic conditions with respect to temperature, light and oxygen availability at depth, factors that are highly dependent on season in most marine regions. Here we introduce a global krill respiration ANN (Artificial Neural Network) model including the effect of latitude (LAT), the day of the year (DoY), and the number of daylight hours (DLh), in addition to the basal variables that determine ectothermal oxygen consumption (temperature, body mass and depth). The newly implemented parameters link space and time in terms of season and photoperiod to krill respiration. The ANN model showed a better fit (r2=0.780) when DLh and LAT were included, indicating a decrease in respiration with increasing LAT and decreasing DLh. We therefore propose DLh as a potential variable to consider when building physiological models for both hemispheres. For single Euphausiid species investigated in a large range of DLh and DoY, we also tested the standard respiration rate for seasonality with Multiple Linear Regression (MLR) and General Additive model (GAM). GAM successfully integrated DLh (r2= 0.563) and DoY (r2= 0.572) effects on respiration rates of the Antarctic krill, Euphausia superba, yielding the minimum metabolic activity in mid-June and the maximum at the end of December. We could not detect DLh or DoY effects in the North Pacific krill Euphausia pacifica, and our findings for the North Atlantic krill Meganyctiphanes norvegica remained inconclusive because of insufficient seasonal data coverage. We strongly encourage comparative respiration measurements of worldwide Euphausiid key species at different seasons to improve accuracy in ecosystem modelling.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Antarctic shallow water benthos under glacier retreat forcing (2014)
    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Marine Ecology-An Evolutionary Perspective, WILEY-BLACKWELL PUBLISHING, ISSN: 0173-9565
    Details
    Publication Date: 2015-06-21
    Description: The West Antarctic Peninsula is one of the fastest warming regions on Earth. Faster 20 glacier retreat and related calving events lead to more frequent iceberg scouring, 21 fresh water input and higher sediment loads, which in turn affect shallow water 22 benthic marine assemblages in coastal regions. In addition, ice retreat creates new 23 benthic substrates for colonization. We investigated three size classes of benthic 24 biota (microbenthos, meiofauna and macrofauna) at three sites in Potter Cove (King 25 George Island, West Antarctic Peninsula) situated at similar water depths but 26 experiencing different disturbance regimes related to glacier retreat. Our results 27 revealed the presence of a patchy distribution of highly divergent benthic assemblages within a relatively small area (about 1 km2). In areas with frequent ice 29 scouring and higher sediment accumulation rates, an assemblage mainly dominated 30 by macrobenthic scavengers (such as the polychaete Barrukia cristata), vagile 31 organisms, and younger individuals of sessile species (such as the bivalve Yoldia 32 eightsi) was found. Macrofauna were low in abundance and very patchily distributed 33 in recently ice-free areas close to the glacier, whereas the pioneer nematode genus 34 Microlaimus reached a higher relative abundance in these newly exposed sites. The 35 most diverse and abundant macrofaunal assemblage was found in areas most 36 remote from recent glacier influence. By contrast the meiofauna showed relatively 37 low densities in these areas. The three benthic size classes appeared to respond in 38 different ways to disturbances likely related to ice retreat, suggesting that the 39 capacity to adapt and colonize habitats is dependent on both body size and specific 40 life traits. We predict that, under continued deglaciation, more diverse, but less 41 patchy, benthic assemblages will become established in areas out of reach of glacier-42 related disturbance.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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  • 6
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    Pitfalls in invertebrate proteasome assays (2013)
    COMPANY OF BIOLOGISTS LTD
    In:  EPIC3Journal of Experimental Biology, COMPANY OF BIOLOGISTS LTD, 216, pp. 1351-1354, ISSN: 0022-0949
    Details
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
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    Spatial compartmentalization of free radical formation and mitochondrial heterogeneity in bivalve gills revealed by live-imaging techniques (2016)
    BIOMED CENTRAL LTD
    In:  EPIC3Frontiers in Zoology, BIOMED CENTRAL LTD, 13(1), pp. 1, ISSN: 1742-9994
    Details
    Publication Date: 2016-08-10
    Description: Background Reactive oxygen (ROS) and nitrogen (RNS) species are produced during normal unstressed metabolic activity in aerobic tissues. Most analytical work uses tissue homogenates, and lacks spatial information on the tissue specific sites of actual ROS formation. Live-imaging techniques (LIT) utilize target-specific fluorescent dyes to visualize biochemical processes at cellular level. Results Together with oxidative stress measurements, here we report application of LIT to bivalve gills for ex-vivo analysis of gill physiology and mapping of ROS and RNS formation in the living tissue. Our results indicate that a) mitochondria located in the basal parts of the epithelial cells close to the blood vessels are hyperpolarized with high Δψm, whereas b) the peripheral mitochondria close to the cilia have low (depolarized) Δψm. These mitochondria are densely packed (mitotracker Deep Red 633 staining), have acidic pH (Ageladine-A) and collocate with high formation of nitric oxide (DAF-2DA staining). NO formation is also observed in the endothelial cells surrounding the filament blood sinus. ROS (namely H2O2, HOO• and ONOO− radicals, assessed through C-H2DFFDA staining) are mainly formed within the blood sinus of the filaments and are likely to be produced by hemocytes as defense against invading pathogens. On the ventral bend of the gills, subepithelial mucus glands contain large mucous vacuoles showing higher fluorescence intensities for O2 •- than the rest of the tissue. Whether this O2 •- production is instrumental to mucus formation or serves antimicrobial protection of the gill surface is unknown. Cells of the ventral bends contain the superoxide forming mucocytes and show significantly higher protein carbonyl formation than the rest of the gill tissue. Conclusions In summary, ROS and RNS formation is highly compartmentalized in bivalve gills under unstressed conditions. The main mechanisms are the differentiation of mitochondria membrane potential and basal ROS formation in inner and outer filament layers, as well as potentially antimicrobial ROS formation in the central blood vessel. Our results provide new insight into this subject and highlight the fact that studying ROS formation in tissue homogenates may not be adequate to understand the underlying mechanism in complex tissues.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
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    Simulated leakage of high pCO2 water negatively impacts bivalve dominated infaunal communities from the Western Baltic Sea (2016)
    Nature Publishing Group
    In:  EPIC3Scientific Reports, Nature Publishing Group, 6(31447)
    Details
    Publication Date: 2016-11-24
    Description: Carbon capture and storage is promoted as a mitigation method counteracting the increase of atmospheric CO2 levels. However, at this stage, environmental consequences of potential CO2 leakage from sub-seabed storage sites are still largely unknown. In a 3-month-long mesocosm experiment, this study assessed the impact of elevated pCO2 levels (1,500 to 24,400 µatm) on Cerastoderma edule dominated benthic communities from the Baltic Sea. Mortality of C. edule was significantly increased in the highest treatment (24,400 µatm) and exceeded 50%. Furthermore, mortality of small size classes (0-1 cm) was significantly increased in treatment levels ≥6,600 µatm. First signs of external shell dissolution became visible at ≥1,500 µatm, holes were observed at 〉6,600 µatm. C. edule body condition decreased significantly at all treatment levels (1,500-24,400 µatm). Dominant meiofauna taxa remained unaffected in abundance. Densities of calcifying meiofauna taxa (i.e. Gastropoda and Ostracoda) decreased in high CO2 treatments (〉6,600 µatm), while the non - calcifying Gastrotricha significantly increased in abundance at 24,400 µatm. In addition, microbial community composition was altered at the highest pCO2 level. We conclude that strong CO2 leakage can alter benthic infauna community composition at multiple trophic levels, likely due to high mortality of the dominant macrofauna species C. edule.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    Anatomy of a glacial meltwater discharge event in an Antarctic Cove (2018)
    ROYAL SOC
    In:  EPIC3Philosophical Transactions of the Royal Society A-Mathematical Physical and Engin, ROYAL SOC, 376, ISSN: 1364-503X
    Details
    Publication Date: 2019-05-13
    Description: Glacial meltwater discharge from Antarctica is a key influence on the marine environment, impacting ocean circulation, sea level, and productivity of the pelagic and benthic ecosystems. The responses elicited depend strongly on the characteristics of the meltwater releases, including timing, spatial structure and geochemical composition. Here we use isotopic tracers to reveal the time-varying pattern of meltwater during a discharge event from the Fourcade Glacier into Potter Cove, northern Antarctic Peninsula. The discharge is strongly dependent on local air temperature, and accumulates into an extremely thin, buoyant layer at the surface. This layer showed evidence of elevated turbidity, and responded rapidly to changes in atmospherically-driven circulation to generate a strongly pulsed outflow from the cove to the broader ocean. These characteristics contrast with those further south along the Peninsula, where strong glacial frontal ablation is driven oceanographically by intrusions of warm deep waters from offshore. The Fourcade Glacier switched very recently to being land-terminating; if retreat rates elsewhere along the Peninsula remain high and glacier termini progress strongly landward, the structure and impact of the freshwater discharges are likely to increasingly resemble the patterns elucidated here.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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  • 10
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    Interdecadal variability of phytoplankton biomass accumulation along the coastal West Antarctic Peninsula (2018)
    ROYAL SOC
    In:  EPIC3Philosophical Transactions of the Royal Society A-Mathematical Physical and Engin, ROYAL SOC, 376(2122), ISSN: 1364-503X
    Details
    Publication Date: 2018-10-11
    Description: The West Antarctic Peninsula (WAP) is a climatically-sensitive region where periods of strong warming have caused significant changes in marine ecosystem and food web processes. Tight coupling between phytoplankton and higher trophic levels implies that the coastal WAP is a bottom-up controlled system, where changes in phytoplankton dynamics may largely impact other food web components. Here, we analyzed the interdecadal time series of year-round chlorophyll-a (Chl) collected from three stations along the coastal WAP, Carlini Station at Potter Cove (PC) on King George Island, Palmer Station on Anvers Island, and Rothera Station on Adelaide Island. There were trends toward increased phytoplankton biomass at Carlini Station (PC) and Palmer Station, while phytoplankton biomass declined significantly at Rothera Station over the studied period. The impacts of two relevant climate modes to the WAP, the El Niño-Southern Oscillation and the Southern Annular Mode, on winter and spring phytoplankton biomass appear to be different among three sampling stations, suggesting a possibly more important role of local-scale forcing than large-scale forcing on phytoplankton dynamics at each station. The interannual variability of seasonal bloom progression derived from considering all three stations together captured ecologically meaningful, seasonally co-occurring bloom patterns which were primarily constrained by water-column stability strength. Our findings highlight a coupled link between phytoplankton and physical and climate dynamics along the coastal WAP, understanding of which is crucial in predicting overall WAP food web responses to climate change and variability.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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