61 research outputs found

    Salinity modulates thermotolerance, energy metabolism and stress response in amphipods Gammarus lacustris

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    Temperature and salinity are important abiotic factors for aquatic invertebrates. We investigated the influence of different salinity regimes on thermotolerance, energy metabolism and cellular stress defense mechanisms in amphipods Gammarus lacustris Sars from two populations. We exposed amphipods to different thermal scenarios and determined their survival as well as activity of major antioxidant enzymes (peroxidase, catalase, glutathione S-transferase) and parameters of energy metabolism (content of glucose, glycogen, ATP, ADP, AMP and lactate). Amphipods from a freshwater population were more sensitive to the thermal challenge, showing higher mortality during acute and gradual temperature change compared to their counterparts from a saline lake. A more thermotolerant population from a saline lake had high activity of antioxidant enzymes. The energy limitations of the freshwater population (indicated by low baseline glucose levels, downward shift of the critical temperature of aerobic metabolism and inability to maintain steady-state ATP levels during warming) was observed, possibly reflecting a trade-off between the energy demands for osmoregulation under the hypo-osmotic condition of a freshwater environment and protection against temperature stress

    The hybrid spatialities of transition: capitalism, legacy, and uneven urban economic restructuring

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    This paper conceptualises post-socialist urban economic geographies through the notion of hybrid spatialities that emerge from the mutual embeddedness of neoliberalism and socialist legacies. While the dismantling of state socialism was a massive moment towards the exacerbation of uneven development, ironically it is the socialist-era spatial legacy that has become the single major differentiating factor for the economic status of cities. This superficial overdetermination, however, masks the root causes of uneven development that must be seen in the logic of capitalism and its attendant practices which subsume legacy, recode its meaning, and recast the formerly equalitarian spaces as an uneven spatial order. The authors argue that the socialist legacy, rather than being an independent carrier of history, has been alienated from its history to become an infrastructure of neoliberalisation, conducive to capitalist process. The paper draws specifically on the experiences of Russia, although its reflections should reverberate much more broadly

    CHANGES IN ACTIVITY OF ANTIOXIDANT ENZYMES UNDER INCREASED SALINITY IN PALEARCTIC AMPHIPODS GAMMARUS LACUSTRIS SARS

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    The aim of the present study was to evaluate activity of antioxidant en­zymes (peroxidase, catalase, glutathione S-transferase) in Palearctic amphipod species Gammarus lacustris Sars under increased salinity. Activity of peroxidase and catalase was stable under combined influence of increased salinity and temperature. Opposite to this, activity of glutathione S-transferase decreased in the same conditions. Prob­ably, here we demonstrated possible participation of antioxidant enzymes in adaptation mechanisms to environmental changes in widespread amphipods G. lacustris

    Salinity modulates thermotolerance, energy metabolism and stress response in amphipods Gammarus lacustris

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    Temperature and salinity are important abiotic factors for aquatic invertebrates. We investigated the influence of different salinity regimes on thermotolerance, energy metabolism and cellular stress defense mechanisms in amphipods Gammarus lacustris Sars from two populations. We exposed amphipods to different thermal scenarios and determined their survival as well as activity of major antioxidant enzymes (peroxidase, catalase, glutathione S-transferase) and parameters of energy metabolism (content of glucose, glycogen, ATP, ADP, AMP and lactate). Amphipods from a freshwater population were more sensitive to the thermal challenge, showing higher mortality during acute and gradual temperature change compared to their counterparts from a saline lake. A more thermotolerant population from a saline lake had high activity of antioxidant enzymes. The energy limitations of the freshwater population (indicated by low baseline glucose levels, downward shift of the critical temperature of aerobic metabolism and inability to maintain steady-state ATP levels during warming) was observed, possibly reflecting a trade-off between the energy demands for osmoregulation under the hypo-osmotic condition of a freshwater environment and protection against temperature stress

    Determination of Lake Baikal endemic amphipod Eulimnogammarus verrucosus (Gerstf., 1858) thermal optima limits by changes in its metaboliс markers

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    In present study the determination of cellular metabolic markers under exposure of Lake Baikal endemic amphipod Eulimnogammarus verrucosus (Amphipoda, Crustacea) in a wide range of ambient temperatures was carried out. The metabolic data was compared with species termopreferendum data obtained in our previous studies. It was found that exposure of amphipods under increased temperatures resulted in increase of HSP70 content and lactate, activating of antioxidant enzymes (catalase and peroxidase), as well as reduction of lactate dehydrogenase and glutathione S-transferase activities. Exposure of E. verrucosus at low temperatures resulted in decrease of HSP70 content, increase of lactate level, peroxidase and lactate dehydrogenase activation, and reduction of glutathione S-transferase activity. It was noted that the most expressed changes of metabolism markers in the species observed when temperature threshold was exceeded 11°C or then temperature dropped below 4°C. The temperature range 4-11°C represented the area of ​​stability of cellular metabolic markers in E. verrucosus and correlated with a preferred temperature limits, previously obtained in behavioral experiments. Thus, for a first time with Lake Baikal amphipods we showed that the zone of stability of cellular metabolism in E. verrucosus closely related to their behavioral thermal preference zones and is likely to reflect thermal optima limits of the species
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