Temperature but not ocean acidification affects energy metabolism and enzyme activities in the blue mussel, Mytilus edulis

1. In mosaic marine habitats, such as intertidal zones, ocean acidification (OA) is exacerbated by high variability of pH, temperature, and biological CO2 production. The nonlinear interactions among these drivers can be context-specific and their effect on organisms in these habitats remains largely unknown, warranting further investigation. 2. We were particularly interested in Mytilus edulis (the blue mussel) from intertidal zones of the Gulf of Maine (GOM), USA, for this study. GOM is a hot spot of global climate change (average sea surface temperature (SST) increasing by \u3e0.2°C/year) with \u3e60% decline in mussel population over the past 40 years. 3. Here, we utilize bioenergetic underpinnings to identify limits of stress tolerance in M. edulis from GOM exposed to warming and OA. We have measured whole organism oxygen consumption rates and metabolic biomarkers in mussels exposed to control and elevated temperatures (10 vs. 15°C, respectively) and current and moderately elevated PCO2 levels (~400 vs. 800 µatm, respectively). 4. Our study demonstrates that adult M. edulis from GOM are metabolically resilient to the moderate OA scenario but responsive to warming as seen in changes in metabolic rate, energy reserves (total lipids), metabolite profiles (glucose and osmolyte dimethyl amine), and enzyme activities (carbonic anhydrase and calcium ATPase). 5. Our results are in agreement with recent literature that OA scenarios for the next 100–300 years do not affect this species, possibly as a consequence of maintaining its in vivo acid-base balance

Combined effects of salinity and intermittent hypoxia on mitochondrial capacity and reactive oxygen species efflux in the Pacific oyster, Crassostrea gigas

Coastal environments commonly experience fluctuations in salinity and hypoxia-reoxygenation (H/R) stress that can negatively affect mitochondrial functions of marine organisms. Although intertidal bivalves are adapted to these conditions, the mechanisms that sustain mitochondrial integrity and function are not well understood. We determined the rates of respiration and reactive oxygen species (ROS) efflux in the mitochondria of oysters, Crassostrea gigas, acclimated to high (33 psu) or low (15 psu) salinity, and exposed to either normoxic conditions (control; 21% O2) or short-term hypoxia (24 h at <0.01% O2) and subsequent reoxygenation (1.5 h at 21% O2). Further, we exposed isolated mitochondria to anoxia in vitro to assess their ability to recover from acute (∼10 min) oxygen deficiency (<0.01% O2). Our results showed that mitochondria of oysters acclimated to high or low salinity did not show severe damage and dysfunction during H/R stress, consistent with the hypoxia tolerance of C. gigas. However, acclimation to low salinity led to improved mitochondrial performance and plasticity, indicating that 15 psu might be closer to the metabolic optimum of C. gigas than 33 psu. Thus, acclimation to low salinity increased mitochondrial oxidative phosphorylation rate and coupling efficiency and stimulated mitochondrial respiration after acute H/R stress. However, elevated ROS efflux in the mitochondria of low-salinityacclimated oysters after acute H/R stress indicates a possible tradeoff of higher respiration. The high plasticity and stress tolerance of C. gigas mitochondria may contribute to the success of this invasive species and facilitate its further expansion into brackish regions such as the Baltic Sea

Impact of Ocean Acidification on Energy Metabolism of Oyster, Crassostrea gigas—Changes in Metabolic Pathways and Thermal Response

Climate change with increasing temperature and ocean acidification (OA) poses risks for marine ecosystems. According to Pörtner and Farrell [1], synergistic effects of elevated temperature and CO2-induced OA on energy metabolism will narrow the thermal tolerance window of marine ectothermal animals. To test this hypothesis, we investigated the effect of an acute temperature rise on energy metabolism of the oyster, Crassostrea gigas chronically exposed to elevated CO2 levels (partial pressure of CO2 in the seawater ~0.15 kPa, seawater pH ~ 7.7). Within one month of incubation at elevated Pco2 and 15 °C hemolymph pH fell (pHe = 7.1 ± 0.2 (CO2-group) vs. 7.6 ± 0.1 (control)) and Peco2 values in hemolymph increased (0.5 ± 0.2 kPa (CO2-group) vs. 0.2 ± 0.04 kPa (control)). Slightly but significantly elevated bicarbonate concentrations in the hemolymph of CO2-incubated oysters ([HCO− 3]e = 1.8 ± 0.3 mM (CO2-group) vs. 1.3 ± 0.1 mM (control)) indicate only minimal regulation of extracellular acid-base status. At the acclimation temperature of 15 °C the OA-induced decrease in pHe did not lead to metabolic depression in oysters as standard metabolism rates (SMR) of CO2-exposed oysters were similar to controls. Upon acute warming SMR rose in both groups, but displayed a stronger increase in the CO2-incubated group. Investigation in isolated gill cells revealed a similar temperaturedependence of respiration between groups. Furthermore, the fraction of cellular energy demand for ion regulation via Na+/K+-ATPase was not affected by chronic hypercapnia or temperature. Metabolic profiling using 1H-NMR spectroscopy revealed substantial changes in some tissues following OA exposure at 15 °C. In mantle tissue alanine and ATP levels decreased significantly whereas an increase in succinate levels was observed in gill tissue. These findings suggest shifts in metabolic pathways following OA-exposure. Our study confirms that OA affects energy metabolism in oysters and suggests that climate change may affect populations of sessile coastal invertebrates such as mollusks

Combined effects of temperature and emersion-immersion cycles on metabolism and bioenergetics of the Pacific oyster Crassostrea (Magallana) gigas

Life on tidal coasts presents physiological major challenges for sessile species. Fluctuations in oxygen and temperature can affect bioenergetics and modulate metabolism and redox balance, but their combined effects are not well understood. We investigated the effects of intermittent hypoxia (12h/12h) in combination with different temperature regimes (normal (15 °C), elevated (30 °C) and fluctuating (15 °C water/30 °C air)) on the Pacific oyster Crassostrea (Magallana) gigas. Fluctuating temperature led to energetic costly metabolic rearrangements and accumulation of proteins in oyster tissues. Elevated temperature led to high (60%) mortality and oxidative damage in survivors. Normal temperature had no major negative effects but caused metabolic shifts. Our study shows high plasticity of oyster metabolism in response to oxygen and temperature fluctuations and indicates that metabolic adjustments to oxygen deficiency are strongly modulated by the ambient temperature. Co-exposure to constant elevated temperature and intermittent hypoxia demonstrates the limits of this adaptive metabolic plasticity

Heat hardening enhances mitochondrial potential for respiration and oxidative defence capacity in the mantle of thermally stressed Mytilus galloprovincialis

Ectotherms are exposed to a range of environmental temperatures and may face extremes beyond their upper thermal limits. Such temperature extremes can stimulate aerobic metabolism toward its maximum, a decline in aerobic substrate oxidation, and a parallel increase of anaerobic metabolism, combined with ROS generation and oxidative stress. Under these stressful conditions, marine organisms recruit several defensive strategies for their maintenance and survival. However, thermal tolerance of ectothermic organisms may be increased after a brief exposure to sub- lethal temperatures, a process known as "hardening". In our study, we examined the ability of M. galloprovincialis to increase its thermal tolerance under the effect of elevated temperatures (24, 26 and 28 °C) through the "hardening" process. Our results demonstrate that this process can increase the heat tolerance and antioxidant defense of heat hardened mussels through more efficient ETS activity when exposed to temperatures beyond 24 °C, compared to non-hardened individuals. Enhanced cell protection is reflected in better adaptive strategies of heat hardened mussels, and thus decreased mortality. Although hardening seems a promising process for the maintenance of aquacultured populations under increased seasonal temperatures, further investigation of the molecular and cellular mechanisms regulating mussels’ heat resistance is required

Stock discrimination of two European squids (Illex coindetii, Loligo forbesii) by statolith shape analysis

We evaluated the feasibility of classifying ommastrephid and loliginid squid species by statolith shape analysis into fisheries management units or stocks. Statoliths of Illex coindetii (Verany, 1839) and Loligo forbesii (Steenstrup, 1856) were studied from multiple areas of the North East Atlantic and Northern Mediterranean Sea during 2021–2022. I. coindetii and L. forbesii individuals were categorized into multiple stocks across the areas studied. Stocks migrating between fishing areas as well as multiple stocks in the same area, as identified for L. forbesii in this study, need to be considered for sustainable fisheries management

The Mitochondrial Contribution to Animal Performance, Adaptation, and Life-History Variation

We thank the National Science Foundation (grant IOS1738378 to W.R.H. and K.S.), SICB’s division of Comparative Physiology and Biochemistry and Comparative Endocrinology, the Company of Biologists, the Society of Experimental Biology, and the Canadian Society of Zoology for funding the symposium.  Peer reviewedPostprin

A digital seismogram archive of nuclear explosion signals, recorded at the Borovoye Geophysical Observatory, Kazakhstan, from 1966 to 1999

Seismologists from Kazakhstan, Russia, and the United States have rescued the Soviet-era archive of nuclear explosion seismograms recorded at Borovoye in northern Kazakhstan during the period 1966–1996. The signals had been stored on about 8000 magnetic tapes, which were held at the recording observatory. After hundreds of man-years of work, these digital waveforms together with significant metadata are now available via the project URL, namely http://www.ldeo.columbia.edu/res/pi/Monitoring/Data/ as a modern open database, of use to diverse communities. Three different sets of recording systems were operated at Borovoye, each using several different seismometers and different gain levels. For some explosions, more than twenty different channels of data are available. A first data release, in 2001, contained numerous glitches and lacked many instrument responses, but could still be used for measuring accurate arrival times and for comparison of the strengths of different types of seismic waves. The project URL also links to our second major data release, for nuclear explosions in Eurasia recorded in Borovoye, in which the data have been deglitched, all instrument responses have been included, and recording systems are described in detail. This second dataset consists of more than 3700 waveforms (digital seismograms) from almost 500 nuclear explosions in Eurasia, many of them recorded at regional distances. It is important as a training set for the development and evaluation of seismological methods of discriminating between earthquakes and underground explosions, and can be used for assessment of three-dimensional models of the Earth’s interior structure

Heat hardening enhances metabolite-driven thermoprotection in the Mediterranean mussel Mytilus galloprovincialis

Introduction: Temperature affects organisms’ metabolism and ecological performance. Owing to climate change, sea warming constituting a severe source of environmental stress for marine organisms, since it increases at alarming rates. Rapid warming can exceed resilience of marine organisms leading to fitness loss and mortality. However, organisms can improve their thermal tolerance when briefly exposed to sublethal thermal stress (heat hardening), thus generating heat tolerant phenotypes.Methods: We investigated the “stress memory” effect caused by heat hardening on M. galloprovincialis metabolite profile of in order to identify the underlying biochemical mechanisms, which enhance mussels’ thermal tolerance.Results: The heat hardening led to accumulation of amino acids (e.g., leucine, isoleucine and valine), including osmolytes and cytoprotective agents with antioxidant and anti-inflammatory properties that can contribute to thermal protection of the mussels. Moreover, proteolysis was inhibited and protein turnover regulated by the heat hardening. Heat stress alters the metabolic profile of heat stressed mussels, benefiting the heat-hardened individuals in increasing their heat tolerance compared to the non-heat-hardened ones.Discussion: These findings provide new insights in the metabolic mechanisms that may reinforce mussels’ tolerance against thermal stress providing both natural protection and potential manipulative tools (e.g., in aquaculture) against the devastating climate change effects on marine organisms

Genome-wide significant association with seven novel multiple sclerosis risk loci

Objective: A recent large-scale study in multiple sclerosis (MS) using the ImmunoChip platform reported on 11 loci that showed suggestive genetic association with MS. Additional data in sufficiently sized and independent data sets are needed to assess whether these loci represent genuine MS risk factors. Methods: The lead SNPs of all 11 loci were genotyped in 10 796 MS cases and 10 793 controls from Germany, Spain, France, the Netherlands, Austria and Russia, that were independent from the previously reported cohorts. Association analyses were performed using logistic regression based on an additive model. Summary effect size estimates were calculated using fixed-effect meta-analysis. Results: Seven of the 11 tested SNPs showed significant association with MS susceptibility in the 21 589 individuals analysed here. Meta-analysis across our and previously published MS case-control data (total sample size n=101 683) revealed novel genome-wide significant association with MS susceptibility (p<5×10−8) for all seven variants. This included SNPs in or near LOC100506457 (rs1534422, p=4.03×10−12), CD28 (rs6435203, p=1.35×10−9), LPP (rs4686953, p=3.35×10−8), ETS1 (rs3809006, p=7.74×10−9), DLEU1 (rs806349, p=8.14×10−12), LPIN3 (rs6072343, p=7.16×10−12) and IFNGR2 (rs9808753, p=4.40×10−10). Cis expression quantitative locus effects were observed in silico for rs6435203 on CD28 and for rs9808753 on several immunologically relevant genes in the IFNGR2 locus. Conclusions: This study adds seven loci to the list of genuine MS genetic risk factors and further extends the list of established loci shared across autoimmune diseases