Observation of universal dynamics in a spinor Bose gas far from equilibrium

The dynamics of quantum systems far from equilibrium represents one of the most challenging problems in theoretical many-body physics. While the evolution is in general intractable in all its details, relevant observables can become insensitive to microscopic system parameters and initial conditions. This is the basis of the phenomenon of universality. Far from equilibrium, universality is identified through the scaling of the spatiotemporal evolution of the system, captured by universal exponents and functions. Theoretically, this has been studied in examples as different as the reheating process in inflationary universe cosmology, the dynamics of nuclear collision experiments described by quantum chromodynamics, or the post-quench dynamics in dilute quantum gases in non-relativistic quantum field theory. Here we observe the emergence of universal dynamics by evaluating spatially resolved spin correlations in a quasi one-dimensional spinor Bose-Einstein condensate. For long evolution times we extract the scaling properties from the spatial correlations of the spin excitations. From this we find the dynamics to be governed by transport of an emergent conserved quantity towards low momentum scales. Our results establish an important class of non-stationary systems whose dynamics is encoded in time independent scaling exponents and functions signaling the existence of non-thermal fixed points. We confirm that the non-thermal scaling phenomenon involves no fine-tuning, by preparing different initial conditions and observing the same scaling behaviour. Our analog quantum simulation approach provides the basis to reveal the underlying mechanisms and characteristics of non-thermal universality classes. One may use this universality to learn, from experiments with ultra-cold gases, about fundamental aspects of dynamics studied in cosmology and quantum chromodynamics.Comment: 10 pages, 4 figures, 3 supplementary figure

Impact of ocean acidification on escape performance of the king scallop, Pecten maximus, from Norway

The ongoing process of ocean acidification already affects marine life, and according to the concept of oxygen and capacity limitation of thermal tolerance, these effects may be intensified at the borders of the thermal tolerance window. We studied the effects of elevated CO2 concentrations on clapping performance and energy metabolism of the commercially important scallop Pecten maximus. Individuals were exposed for at least 30 days to 4 °C (winter) or to 10 °C (spring/summer) at either ambient (0.04 kPa, normocapnia) or predicted future PCO2 levels (0.11 kPa, hypercapnia). Cold-exposed (4 °C) groups revealed thermal stress exacerbated by PCO2 indicated by a high mortality overall and its increase from 55 % under normocapnia to 90 % under hypercapnia. We therefore excluded the 4 °C groups from further experimentation. Scallops at 10 °C showed impaired clapping performance following hypercapnic exposure. Force production was significantly reduced although the number of claps was unchanged between normocapnia- and hypercapnia-exposed scallops. The difference between maximal and resting metabolic rate (aerobic scope) of the hypercapnic scallops was significantly reduced compared with normocapnic animals, indicating a reduction in net aerobic scope. Our data confirm that ocean acidification narrows the thermal tolerance range of scallops resulting in elevated vulnerability to temperature extremes and impairs the animal’s performance capacity with potentially detrimental consequences for its fitness and survival in the ocean of tomorrow

Naturally acidified habitat selects for ocean acidification–tolerant mussels

Ocean acidification severely affects bivalves, especially their larval stages. Consequently, the fate of this ecologically and economically important group depends on the capacity and rate of evolutionary adaptation to altered ocean carbonate chemistry. We document successful settlement of wild mussel larvae (Mytilus edulis) in a periodically CO2-enriched habitat. The larval fitness of the population originating from the CO2-enriched habitat was compared to the response of a population from a nonenriched habitat in a common garden experiment. The high CO2–adapted population showed higher fitness under elevated Pco2 (partial pressure of CO2) than the non-adapted cohort, demonstrating, for the first time, an evolutionary response of a natural mussel population to ocean acidification. To assess the rate of adaptation, we performed a selection experiment over three generations. CO2 tolerance differed substantially between the families within the F1 generation, and survival was drastically decreased in the highest, yet realistic, Pco2 treatment. Selection of CO2-tolerant F1 animals resulted in higher calcification performance of F2 larvae during early shell formation but did not improve overall survival. Our results thus reveal significant short-term selective responses of traits directly affected by ocean acidification and long-term adaptation potential in a key bivalve species. Because immediate response to selection did not directly translate into increased fitness, multigenerational studies need to take into consideration the multivariate nature of selection acting in natural habitats. Combinations of short-term selection with long-term adaptation in populations from CO2-enriched versus nonenriched natural habitats represent promising approaches for estimating adaptive potential of organisms facing global change

Impact du dioxyde de carbone sur la levure Saccharomyces cerevisiae : caractérisation du transfert liquide/gaz et implications sur les métabolismes énergétiques

The aim of this work was to evaluate the impact of carbon dioxide (CO2) on the physiology of the yeast Saccharomyces cerevisiae, more precisely on the oxidative metabolism and on the onset of alcoholic fermentation. CO2 is involved in the interactions between transfer phenomena and biological phenomena in fermenters. The knowledge of the dissolved CO2 concentration and then of the CO2 liquid / gas mass transfer phenomena is required to assess the impact of this compound on the yeast physiology.Investigation of CO2 liquid / gas in biological reactors has been carried out using simulations and experiments taking into consideration both biological and transfer phenomena. CO2 supersaturation was observed in an intensive fed-batch culture of S.cerevisiae and may be caused by an asymmetric bubble size distribution of the gas phase. We demonstrated that CO2 liquid / gas transfer cannot be described based on O2 gas / liquid transfer and that CO2 concentration must be estimated through direct measurement.The impact of CO2 on the oxidative metabolism of S.cerevisiae was investigated using chemostat cultures submitted to different step-increases of the dissolved CO2 concentrations with direct measurement of the dissolved CO2 concentration. The yeast culture showed a transient response with an increase of the specific respiration rates ranging from with a +24 to +37 % during + 2.96 mM and+5.29 mM dissolved CO2 step-increases. This transient response was followed by a long-term response characterized by a decrease of the YATP value with increasing dissolved CO2 concentrations (down to -18% when the CO2 concentration increased from 1.6 mM to 17 mM).The impact of CO2 on the onset of the Crabtree effect in S.cerevisiae was investigated using the accelerostat technique with and without CO2 enrichment. The onset of alcoholic fermentation occurred at a much lower specific growth rate (0.122 h-1) and specific oxygen consumption rate (5.2 mmoleO2.gX-1.h-1) in CO2 enriched conditions than without CO2 enrichment (0.256h-1 and 8.65 mmoleO2.gX-1.h-1 respectively). These modifications may be linked with a decreased cellular adaptability to changing environmentL’objectif de ce travail est l’étude de l’impact du dioxyde de carbone (CO2) sur la physiologie et le métabolisme de la levure Saccharomyces cerevisiae, en particulier son impact sur le catabolisme oxydatif du glucose et son rôle dans le déclenchement de la transition respiro-fermentaire. Le CO2 est au coeur des interactions entre phénomènes biologiques et phénomènes physiques de transfert existant au sein d’un réacteur biologique. La compréhension de son impact sur la physiologie de la levure nécessite la connaissance de sa concentration en phase liquide et donc la maitrise des phénomènes de transfert interphasiques.Le transfert liquide / gaz du CO2 en fermenteur a été étudié par une approche couplant modélisation et expérimentation avec un effort particulier sur l’analyse intégrée des phénomènes biologiques et de transfert. En comparaison avec les hypothèses de transfert généralement admises une sursaturation du moût en CO2 dissous dans le moût a été observée lors de cultures de S.cerevisiae et attribuée à l‘existence d’une distribution asymétrique de tailles de bulles de la phase dispersée. Il a été démontré que le transfert liquide / gaz du CO2 lors d’une culture microbienne intensive ne peut être décrit par analogie avec le transfert gaz / liquide de l’oxygène et que la connaissance de la concentration en CO2 dissous ne peut être réalisée que par sa mesure directe.L’impact du CO2 sur le métabolisme oxydatif de la levure a été investigué par le suivi de la réponse dynamique de la réponse à différents incréments mesurés de la concentration en CO2 dissous en culture continue. Cette réponse est constituée d’une réponse transitoire et intense et d’une réponse à long-terme plus modérée Elle se caractérise par l’impact du CO2 sur l’énergétique cellulaire en augmentant la génération et la dissipation d’énergie ce qui est traduit à court-terme par une augmentation transitoire de +24 à +37 % des vitesses spécifiques de respiration lors d’échelons de la concentration en CO2 dissous de +2.96 et +5.29 mM et à long-terme par une diminution de 18% YATP de % lorsque la concentration en CO2 dissous augmente de 1.6 mM à 17 mM. L’effet du CO2 sur la transition respiro-fermentaire a été étudié en culture de type accélérostat en présence d’une concentration élevée en CO2 dissous. Dans ces conditions, la bascule vers le métabolisme réductif est obtenue pour un taux de croissance (0.122 h-1) et des vitesses spécifiques de respiration (5.2 mmoleO2.gX-1.h-1) inférieurs aux valeurs obtenues avec un accélérostat sans apport exogène de CO2 (0.256h-1 et 8.65 mmoleO2.gX-1.h-1) respectivement. Cette modification du métabolisme n’a pu être corrélée directement à un déficit de potentiel énergétique oxydatif et semble probablement liée à une perte de flexibilité d’adaptation à la dynamique de variation de l’environnement

Thermal sensitivity of cell metabolism of different Antarctic fish species mirrors organism temperature tolerance

Despite cold adaptation, Antarctic fish show lower growth than expected from the van’t Hoff’s Q10 rule. Protein synthesis is one of the main energy-consuming processes, which is downregulated under energy deficiency. Considering the effect of temperature on growth performance, we tested if temperature-dependent cellular energy allocation to protein synthesis correlates with temperature-dependent whole-animal growth and thus thermal tolerance. Cell respiration and energy expenditure for protein synthesis were determined in hepatocytes of the circumpolar-distributed Antarctic eelpout Pachycara brachycephalum after warm acclimation (0 °C vs 5 °C) and, of two notothenioids the sub-Antarctic Lepidonotothen squamifrons and the high-Antarctic icefish Chionodraco hamatus. We used intermittent-flow respirometry to analyse cellular response to acute warming from 5 to 10 °C (P. brachycephalum) and from 1 to 5 °C (L. squamifrons, C. hamatus). Warming-induced rise in respiration was similar between 0- and 5 °C-acclimated P. brachycephalum and between L. squamifrons and C. hamatus. Irrespective of acclimation, warming decreased energy expenditure for protein synthesis in P. brachycephalum, which corresponds to reduced whole-animal growth at temperatures > 5 °C. Warming doubled energy expenditure for protein synthesis in L. squamifrons but had no effect on C. hamatus indicating that L. squamifrons might benefit from warmer waters. The species-specific temperature effect on energy expenditure for protein synthesis is discussed to mirror thermal sensitivity of whole-animal growth performance, thereby paralleling the degree of cold adaptation. Clearly more data are necessary including measurements at narrower temperature steps particularly for C. hamatus and an increased species’ number per ecotype to reinforce presented link between cellular and whole-animal thermal sensitivity

Lessons from two high CO2 worlds - future oceans and intensive aquaculture

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Exponentially rising CO2 (currently ~400 μatm) is driving climate change and causing acidification of both marine and freshwater environments. Physiologists have long known that CO2 directly affects acid-base and ion regulation, respiratory function and aerobic performance in aquatic animals. More recently, many studies have demonstrated that elevated CO2 projected for end of this century (e.g. 800-1000 μatm) can also impact physiology, and have substantial effects on behaviours linked to sensory stimuli (smell, hearing and vision) both having negative implications for fitness and survival. In contrast, the aquaculture industry was farming aquatic animals at CO2 levels that far exceed end-of-century climate change projections (sometimes >10 000 μatm) long before the term 'ocean acidification' was coined, with limited detrimental effects reported. It is therefore vital to understand the reasons behind this apparent discrepancy. Potential explanations include 1) the use of 'control' CO2 levels in aquaculture studies that go beyond 2100 projections in an ocean acidification context; 2) the relatively benign environment in aquaculture (abundant food, disease protection, absence of predators) compared to the wild; 3) aquaculture species having been chosen due to their natural tolerance to the intensive conditions, including CO2 levels; or 4) the breeding of species within intensive aquaculture having further selected traits that confer tolerance to elevated CO2 . We highlight this issue and outline the insights that climate change and aquaculture science can offer for both marine and freshwater settings. Integrating these two fields will stimulate discussion on the direction of future cross-disciplinary research. In doing so, this article aimed to optimize future research efforts and elucidate effective mitigation strategies for managing the negative impacts of elevated CO2 on future aquatic ecosystems and the sustainability of fish and shellfish aquaculture.The authors wish to acknowledge the funding that has contributed to ideas within this manuscript. This includes a United Kingdom Ocean Acidification Research Program (UKOARP) Project (NE/H01750X/1 to R.W.W.) cofunded by the Natural Environment Research Council (NERC), the Department for Environment, Food and Rural Affairs (Defra) and the Department of Energy and Climate Change (DECC), together with various BBSRC-funded projects (BB/J00913X/1, BB/N013344/1 and BB/M017583/1 to R.W.W.)