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Lake Baikal is the only freshwater reservoir inhabited by deep-water fauna, which originated mostly from shallow-water ancestors. Ommatogammarus flavus and O. albinus are endemic scavenger amphipods (Amphipoda, Crustacea) dwelling in wide depth ranges of the lake covering over 1300 m. O. flavus had been previously collected close to the surface, while O. albinus has never been found above the depth of 47 m. Since O. albinus is a promising model species for various research, here we tested whether O. albinus is less metabolically adapted to atmospheric pressure than O. flavus. We analyzed a number of energy-related traits (contents of glucose, glycogen and adenylates, as well as lactate dehydrogenase activity) and oxidative stress markers (activities of antioxidant enzymes and levels of lipid peroxidation products) after sampling from different depths and after both species’ acclimation to atmospheric pressure. The analyses were repeated in two independent sampling campaigns. We found no consistent signs of metabolic disturbances or oxidative stress in both species right after lifting. Despite O. flavus surviving slightly better in laboratory conditions, during long-term acclimation, both species showed comparable reactions without critical changes. Thus, the obtained data favor using O. albinus along with O. flavus for physiological research under laboratory conditions.

The previously undescribed dynamics of the heat shock protein HSP70 and subsequent lipid peroxidation products have been assessed alongside lactate dehydrogenase activity for

Tracking physiological parameters in different organs within the same organism simultaneously and in real time can provide an outstanding representation of the organism's physiological status. The state-of-the-art technique of using encapsulated fluorescent molecular probes (microencapsulated biomarkers) is a unique tool that can serve as a platform for the development of new methods to obtain in vivo physiological measurements and is applicable to a broad range of organisms. Here, we describe a novel technique to monitor the pH of blood inside the gill capillaries and interstitial fluid of muscles by using microencapsulated biomarkers in a zebrafish model. The functionality of the proposed technique is shown by the identification of acidification under anesthesia-induced coma and after death. The pH in muscles reacts to hypoxia faster than that in the gill bloodstream, which makes both parameters applicable as markers of either local or bodily reactions., Summary: An optical technique for the simultaneous in vivo monitoring of pH in the blood of gill capillaries and interstitial fluid of muscles developed and tested in zebrafish.

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.