Stress Axis Research Articles

Analysis of proto-type Tarim Basin in the late Precambrian and the dynamic mechanism of its evolution.

Tarim Basin has undergone an intricate tectonic evolution history ever since its formation from two discrete terranes in Neoproterozoic rather than in the Paleoproterozoic. More precisely, the amalgamation is assumed to happen during 1.0-0.8 Ga based on plate affinity. As the beginning of a unified Tarim block, studies of Tarim Basin in the Precambrian are basic and important. After the amalgamation of south and north paleo-Tarim terranes, Tarim block was experiencing a complicated tectonic process of being affected by mantle plume related to the breakup of Rodinia supercontinent in the south, and compressed by the Circum-Rodinia Subduction System in the north. The breakup of Rodinia supercontinent finished in the late Sinian Period, leading Kudi Ocean and Altyn Ocean to open and separating Tarim block from itself. According to the residual strata thickness, drilling data, and lithofacies distribution, the proto-type basin and tectono-paleogeographic maps of Tarim Basin in the late Nanhua Period and Sinian Period are reconstructed. With these maps, the characteristics of the rifts are revealed. Two rift systems were developed inside the unified Tarim Basin in the Nanhua Period and Sinian Period, one back-arc rift system in the northern margin and the other aulacogen system in the southern margin. The azimuth distribution of the rifts in Quruqtagh showed a predominant NE-SW trend, and the rifts in Aksu trended mainly NW-SE, while the rifts in Tiekelike trended SW-NE. With a three-dimensional elastic FEM (Finite Element Method) model that includes all rifts and deposited areas in Tarim Basin, applying the southern subduction and northern mantle upwelling properly to get the paleotectonic mian stress axes and the differential stress field, the dynamic mechanisms of rifts evolution are proved to be related to the peripheral tectonic environment mentioned above.

The gp130/STAT3-endoplasmic reticulum stress axis regulates hepatocyte necroptosis in acute liver injury

The gp130/STAT3-endoplasmic reticulum stress axis regulates hepatocyte necroptosis in acute liver injury

Trajectories of stress axis biomarkers in police officers undergoing clinical interviewing for PTBS

Trajectories of stress axis biomarkers in police officers undergoing clinical interviewing for PTBS

The association between study conditions and hair cortisol in medical students in Germany – a cross-sectional study

BackgroundMedical students often experience high levels of stress due to adverse study conditions, which may have adverse health consequences. Hair cortisol concentration (HCC) has been described as a physiological marker for chronic stress and might thus help to identify students under stress and examine the study conditions being responsible for long-term physiological stress responses. This study therefore investigated the association between study conditions and HCC in a sample of medical students.MethodsFifty-five students from a medical school in Germany completed a paper-based questionnaire and had hair samples collected between July 2020 and July 2021. Study conditions were assessed with student versions of questionnaires based on the Job-Demand-Control-Support model (StrukStud, 25 items) and Effort-Reward Imbalance model (Student ERI, nine items). HCC of two centimeters closest to the scalp were determined by a cortisol luminescence immunoassay. Linear multiple regression analyses were performed to examine associations between study conditions and HCC.ResultsDemands (B = 0.23, p = 0.002), effort (B = 0.12, p = 0.029) and the effort-reward-ratio (B = 0.28, p = 0.007) were positively associated with HCC in separate regression analyses, adjusted for age and sex. Only the association between demands and HCC remained significant when all components of the respective questionnaire were considered in the same model (B = 0.22, p = 0.003).ConclusionThe results suggest that adverse study conditions may be associated with activation of the hypothalamic-pituitary-adrenal axis stress response as reflected by increased HCC. Longitudinal research is needed to confirm these cross-sectional results and examine effects of more prolonged stress due to adverse study conditions.

AMPK-endoplasmic reticulum stress axis contributes to lipopolysaccharide-caused mitochondrial dysfunction by regulating mitochondria-associated membrane function in bovine hepatocytes

Mitochondrial homeostasis is closely associated with cellular homeostasis process, whereas mitochondrial dysfunction contributes to apoptosis and mitophagy. Hence, analyzing the mechanism of lipopolysaccharide (LPS)-caused mitochondrial damage is necessary to understand how cellular homeostasis is maintained in bovine hepatocytes. Mitochondria-associated membranes (MAM), a connection between endoplasmic reticulum (ER) and mitochondria, is important to control mitochondrial function. To investigate the underlying mechanisms of the LPS-caused mitochondrial dysfunction, hepatocytes isolated from dairy cows at ∼160 d in milk (DIM) were pretreated with the specific inhibitors of adenosine 5'-monophosphate-activated protein kinase (AMPK), ER stress, RNA-activated protein kinase-like ER kinase (PERK), inositol-requiring enzyme 1α (IRE1α), c-Jun N-terminal kinase, and autophagy followed by a 12 I1/4g/mL LPS treatment. The results showed that inhibiting ER stress with 4-phenylbutyric acid decreased the levels of autophagy and mitochondrial damage with AMPK inactivation in LPS-treated hepatocytes. The AMPK inhibitor compound C pretreatment alleviated LPS-induced ER stress, autophagy and mitochondrial dysfunction by regulating the expression of MAM-related genes, such as mitofusin 2 (MFN2), PERK, and IRE1α. Moreover, inhibiting PERK and IRE1α mitigated autophagy and mitochondrial dynamic disruption by regulating the MAM function. Additionally, blocking c-Jun N-terminal kinase, the downstream sensor of IRE1α, could reduce the levels of autophagy and apoptosis and restore the balance of mitochondrial fusion and fission by modulating the B cell leukemia 2 (BCL-2)/BCL-2 interacting protein 1 (BECLIN1) complex in the LPS-treated bovine hepatocytes. Furthermore, autophagy blockage with chloroquine could intervene in LPS-caused apoptosis to restore mitochondrial function. Collectively, these findings suggest that the AMPK-ER stress axis is involved in the LPS-caused mitochondrial dysfunction by mediating the MAM activity in bovine hepatocytes.

The Meran-Mauls Fault: Tectonic switching from compression to transpression along a restraining bend of the Periadriatic Fault

The WSW-ENE Meran-Mauls Fault (MMF) represents a break in the broadly E-W trending Periadriatic Fault (PAF), separating the Southern Alps from the N-verging wedge of the European Alps. Understanding the MMF evolution is mandatory to reconstruct the role of the entire PAF during the evolution of the belt since the late Cenozoic.Structural and microstructural analyses and paleostress calculations based on fault-slip data suggest the occurrence of four evolutionary stages for the MMF: 1) top-to-the-SE mylonites; 2) top-to-the-SE brittle faulting; 3) dextral faulting with re-activation of previous structures; 4) N–S compression associated with conjugate sets of mainly strike-slip fault systems. Paleostress reconstructions point to a σ2-σ3 permutation from stage 2 to stage 3, resulting in the switch from pure thrusting to strike-slip, followed by an anticlockwise rotation of the principal stress axes during stage 4, in a strike-slip regime related to N–S compression. Geochronological and thermochronological data point to 39-22 Ma age for stage 1, 22-17 Ma for stage 2, less than 17 Ma for stage 3. Our reconstruction strongly supports the interpretation of the MMF as a restraining bend of the PAF, which was weakly reactivated along its eastern portion as a dextral fault and later displaced by NNE-SSW left-lateral faults.

Tank color influences the response of tomato clownfish (Amphiprion frenatus) to an acute stress challenge.

The trade of aquarium organisms is growing worldwide. This market depends on a continuous supply of healthy and colorful aquatic animals, but this sector has few initiatives. However, in the last decade, there has been a growing interest in researching captive breeding of these animals, aiming to develop a more sustainable aquarium hobby. Larviculture is an important phase in the cultivation process because the larvae are more sensitive to stress and variations in the bulk of variables, such as temperature, salinity, nutritional management, light intensity and spectrum, and environmental background colors. Because background color could be a promoter variable of proper welfare, we tested whether it affects the endocrine response of tomato clownfish Amphiprion frenatus larvae to an acute stress challenge. We show that background color influences the endocrine stress axis responsiveness in tomato clownfish. When fish were subjected to a standard acute stressor of 61 days after hatching, only fish adapted to white walls increased the whole-body cortisol levels. From the results presented herein, we recommend that white tanks be avoided for A. frenatus larviculture. Both, the less stress level and the good welfare condition of larvae reared in colored tanks may have robust, practical applications since almost all clownfish in the ornamental aquarium trade come from captive breeding.

Brain-bacteria-gut axis and oxidative stress mediated by intestinal mucosal microbiota might be an important mechanism for constipation in mice.

Intestinal microbiota disorder was associated with constipation. This study investigated the microbiota-gut-brain axis and oxidative stress mediated by intestinal mucosal microbiota in mice with spleen deficiency constipation. The Kunming mice were randomly divided into the control (MC) group and the constipation (MM) group. The spleen deficiency constipation model was established by gavage with Folium sennae decoction and controlled diet and water intake. The body weight, spleen and thymus index, 5-Hydroxytryptamine (5-HT) and Superoxide Dismutase (SOD) content were significantly lower in the MM group than the MC group, the content of vasoactive intestinal peptide (VIP) and malondialdehyde (MDA) content were significantly higher than the MC group. The Alpha diversity of intestinal mucosal bacteria was not changed but beta diversity was changed in mice with spleen deficiency constipation. Compared to the MC group, the relative abundance of Proteobacteria was an upward trend and the Firmicutes/Bacteroidota (F/B) value was a downward trend in the MM group. There was a significant difference in the characteristic microbiota between the two groups. In the MM group, Brevinema, Akkermansia, Parasutterella, Faecalibaculum, Aeromonas, Sphingobium, Actinobacillus, and other pathogenic bacteria were enriched. Meanwhile, there was a certain relationship between the microbiota and gastrointestinal neuropeptide and oxidative stress indicators. The community structure of intestinal mucosal bacteria in mice with spleen deficiency constipation was changed, which was characterized by the reduction of F/B value and enrichment of Proteobacteria. Microbiota-gut-brain axis may be important for spleen deficiency constipation.

Septohippocampal cholinergic system at the intersection of stress and cognition: Current trends and translational implications.

Deficits in hippocampus-dependent memory processes are common across psychiatric and neurodegenerative disorders such as depression, anxiety and Alzheimer's disease. Moreover, stress is a major environmental risk factor for these pathologies and it exerts detrimental effects on hippocampal functioning via the activation of hypothalamic-pituitary-adrenal (HPA) axis. The medial septum cholinergic neurons extensively innervate the hippocampus. Although, the cholinergic septohippocampal pathway (SHP) has long been implicated in learning and memory, its involvement in mediating the adaptive and maladaptive impact of stress on mnemonic processes remains less clear. Here, we discuss current research highlighting the contributions of cholinergic SHP in modulating memory encoding, consolidation and retrieval. Then, we present evidence supporting the view that neurobiological interactions between HPA axis stress response and cholinergic signalling impact hippocampal computations. Finally, we critically discuss potential challenges and opportunities to target cholinergic SHP as a therapeutic strategy to improve cognitive impairments in stress-related disorders. We argue that such efforts should consider recent conceptualisations on the dynamic nature of cholinergic signalling in modulating distinct subcomponents of memory and its interactions with cellular substrates that regulate the adaptive stress response.

Digital‐Twin‐Driven Diagnostics of Crack Propagation in a Single LiNi0.7Mn0.15Co0.15O2 Secondary Particle during Lithium Intercalation

AbstractCrack propagation has been extensively spotlighted as a main reason for the degradation of secondary‐particle‐type active materials, including LiNixMnyCo1−x−yO2 (NMC). Numerous experimental analyses and 3D‐modeling‐based investigations have been conducted to unravel this complicated phenomenon, especially for nickel‐rich NMCs, which experience substantial crack propagation during high‐voltage, high‐temperature, or high‐depth‐of‐discharge operations. To fundamentally clarify this unavoidable degradation factor and permit its suppression, a digital‐twin‐guided electro–chemo–mechanical (ECM) model of a single few‐micrometer‐sized LiNi0.7Mn0.15Co0.15O2 (NMC711) particle is developed in this study using a 3D reconstruction technique. Because the digital twin technique replicates a real pore‐containing NMC711 secondary particle, this digital‐twin electrochemical model simulates voltage profiles even at 8C‐rate within an error of 0.48% by fitting two key parameters: diffusion coefficient and exchange current density. The digital‐twin‐based ECM model is developed based on the verified electrochemical parameters and mechanical properties such as lithium‐induced strain from axis lattice parameters and stress–strain curve measured by nanoindentation. Using this model, the electrochemical‐reaction‐induced mechanical properties including strain, stress, and strain energy density are also visualized in operando in a single NMC711 particle. Finally, the advanced operando ECM analysis allows for the diagnosis of crack formation, highlighting the effectiveness of this platform in elucidating crack formation in active materials.

Associations of SLC6A4 methylation with salivary cortisol, salivary alpha-amylase, and subjective stress in everyday life

Dysregulations of the hypothalamic-pituitary-adrenal (HPA) and sympatho-adrenal medullary (SAM) axis are associated with mental and somatic illness. However, there is lack of knowledge regarding the molecular mechanisms underlying these effects. Epigenetic states in the serotonin transporter gene (SLC6A4) were shown to be associated with stress in various forms. We hypothesized that levels of DNA methylation (DNAm) of SLC6A4 would be associated with altered SAM- and HPA regulation in daily life. N = 74 healthy persons participated in the study. An ecological momentary assessment (EMA) approach was used to assess indicators of stress in daily life. Each day included six concurrent assessments of saliva, to quantify cortisol (sCort; HPA axis) and alpha-amylase (sAA; SAM axis), and to assess self-reports on subjective stress. To assess SLC6A4 DNAm, peripheral blood was drawn and analyzed via bisulfite pyrosequencing. All data were assessed in two waves three months apart, each including two days of EMA and the assessment of SLC6A4 DNAm. Data were analyzed using multilevel models. On the between-person level, higher average levels of SLC6A4 DNAm were associated with higher average levels of sAA, but not with average levels of sCort. On the within-person level, higher levels of SLC6A4 DNAm were associated with lower levels of sAA and sCort. There were no associations of subjective stress with SLC6A4 DNAm. The results help to clarify the association between environmental stress and stress axes regulation, pointing towards an important role of differential within- and between-person effects of SLC6A4 DNAm, which might shape this association.

GATA6 coordinates cross-talk between BMP10 and oxidative stress axis in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening condition characterized by a progressive increase in pulmonary vascular resistance leading to right ventricular failure and often death. Here we report that deficiency of transcription factor GATA6 is a shared pathological feature of PA endothelial (PAEC) and smooth muscle cells (PASMC) in human PAH and experimental PH, which is responsible for maintenance of hyper-proliferative cellular phenotypes, pulmonary vascular remodeling and pulmonary hypertension. We further show that GATA6 acts as a transcription factor and direct positive regulator of anti-oxidant enzymes, and its deficiency in PAH/PH pulmonary vascular cells induces oxidative stress and mitochondrial dysfunction. We demonstrate that GATA6 is regulated by the BMP10/BMP receptors axis and its loss in PAECs and PASMC in PAH supports BMPR deficiency. In addition, we have established that GATA6-deficient PAEC, acting in a paracrine manner, increase proliferation and induce other pathological changes in PASMC, supporting the importance of GATA6 in pulmonary vascular cell communication. Treatment with dimethyl fumarate resolved oxidative stress and BMPR deficiency, reversed hemodynamic changes caused by endothelial Gata6 loss in mice, and inhibited proliferation and induced apoptosis in human PAH PASMC, strongly suggesting that targeting GATA6 deficiency may provide a therapeutic advance for patients with PAH.

The formation of orthogonal joint systems and cuboidal blocks: New insights gained from flat-lying limestone beds in the region of Havre-Saint-Pierre (Quebec, Canada)

Vertical orthogonal joints are a common feature in shallow crustal rocks. There are several competing theories for their formation despite the ubiquity. We examined the exceptional exposures of orthogonal joints in flat-lying Ordovician limestone beds from the Havre-Saint-Pierre Region in Quebec, Canada (north shore of Saint-Lawrence River) to test conceptual models of joint formation in a natural setting. In the region, the spacing of cross-joints is consistently larger than the spacing of systematic joints by a factor of 1.5 approximately. The joint-spacing-to-bed-thickness ratios (s/t) are much larger in these beds (s/t = 4.3 for systematic joints, and 6.4 for cross-joints) than those in higher strained strata along the south shore of the Saint-Lawrence River (s/t = 1), highlighting the effect of tectonic strain in decreasing fracture spacing and block size. The high values of s/t indicate that cross-joint formation was unlikely caused by a switch from compression to tension once a critical s/t ratio for systematic joints was reached (as hypothesized in previous studies). We proposed a new model for the formation of orthogonal joint systems where the principal stress axes locally switch during the formation of systematic fractures. The presence of ladder-shaped orthogonal joints suggests a state of effective stress with σ1∗≫0 > σ2∗>σ3∗ and where σ2∗-σ3∗ is within the range of fracture strength variability at the time of fracture. This research provides a new mechanical model for the formation of orthogonal joint systems and cuboidal blocks.

Placenta DNA methylation levels of the promoter region of the leptin receptor gene are associated with infant cortisol

The intrauterine environment and early life stress regulation are widely recognized as an early foundation for lifelong physical and mental health. Methylation of CpG sites in the placenta represents an epigenetic modification that can potentially affect placental function, influence fetal development, and ultimately impact the health of offspring by programming the hypothalamic-pituitary-adrenal (HPA) axis stress response during prenatal development. Leptin, an adipokine produced by the placenta, is essential for energy homeostasis. It is also epigenetically regulated by promoter DNA methylation. Mounting evidence suggests that leptin also affects the stress response system. Though heterogeneity in the early stress response system may influence life-long mental and physical health, few studies explicitly examine the heterogeneity in the newborn stress response system. Less is known about leptin's association with the human hypothalamic-pituitary-adrenocortical (HPA) axis early in life. This study sought to serve as a proof of concept study investigating the relationship between newborn cortisol output trajectories and placental leptin DNA methylation in 117 healthy newborns from socioeconomically and racially- and ethnically-diverse families. We characterized heterogeneity in newborn cortisol output during the NICU Network Neurobehavioral Scales exam in the first week of life with latent growth mixture models. We then evaluated whether leptin promoter (LEP) methylation in placental samples was associated with newborn cortisol trajectories. Our findings suggest that increased placental LEP methylation, which corresponds to decreased leptin production, is associated with infant cortisol trajectories marked by increased cortisol output in the NNNS exam. These results provide important insights into the role of placental leptin DNA methylation in human newborn HPA axis development and subsequent developmental origins of health and disease processes.

Spatial–Temporal Distribution and Focal Mechanisms for the Shallow Earthquakes in the Rongchang-Luxian Region in Southern Sichuan Basin, China

AbstractAn Ms 6.0 earthquake struck the Luxian County in southern Sichuan basin, China, on 15 September 2021, which was the largest local event thus far and caused heavy casualties and serious property losses. Using data of 107 temporary and six permanent stations from five months before to four and a half months after the time of the mainshock in the Rongchang-Luxian region, we utilize the machine learning-based workflow for phase picking, earthquake detection and relocation, and obtain precise hypocenter data for 22,806 events. We found that earthquakes increase significantly since July 2021, showing north-northeast-, northeast-, east-northeast- and east-southeast-directed seismic strips. Almost all events are located within the sedimentary layers at 1–7 km depth above the crystalline basement, and more than half of them occurred in Silurian and Ordovician formations. The Ms 6.0 Luxian earthquake sequence occurred in an area where no clear seismicity was observed before the mainshock. On map view, the aftershock zone shows a convex polygon with an overall strike of 112°. The focal depths of aftershocks southwest to the mainshock are distributed in a narrower range of 4–7 km and extend to a wider range of 2–7 km on the northeast side. It is speculated that the seismogenic fault is a blind thrust fault dipping to the southwest at 2–7 km depth. The focal mechanisms of 13 ML 3.0+ earthquakes show either pure reverse faulting or reverse faulting dominated mechanisms with a strike-slip component. The centroid depths fall in the range of 1.95–6.75 km. The maximum and middle principal stress axes are nearly horizontal; the azimuth of the maximum horizontal stress is about 120° and the stress shape ratio is 0.78. These results provide an important reference for reunderstanding the local seismic risk and for detailed studies on the seismological aspects about the unusual Luxian earthquake in the future.

Effect of the glucocorticoid receptor antagonist PT150 on acquisition and escalation of fentanyl self-administration following early-life stress.

There is comorbidity between posttraumatic stress disorder (PTSD) and opioid use disorder (OUD), perhaps because PTSD-like stressful experiences early in life alter the hypothalamic-pituitary-adrenal stress axis to increase the risk for OUD. The present study determined if the glucocorticoid receptor antagonist PT150 reduces the escalation of fentanyl intake in rats exposed to a "two-hit" model of early-life stress (isolation rearing and acute stress). Male and female rats were raised during adolescence in either isolated or social housing and then were given either a single acute stress (restraint and cold-water swim) or control treatment in young adulthood. Rats were then treated daily with PT150 (50 mg/kg, oral) or placebo and were tested for acquisition of fentanyl self-administration in 1-hr sessions, followed by escalation across 6-hr sessions. Regardless of PT150 treatment or sex, acquisition of fentanyl self-administration in 1-hr sessions was greater in isolate-housed rats compared to social-housed rats; the acute stress manipulation did not have an effect on self-administration even though it transiently increased plasma corticosterone levels. During the 6-hr sessions, escalation of fentanyl was observed across all treatment groups; however, there was a significant PT150 Treatment × Sex interaction. While males self-administered more than females overall, PT150 decreased intake in males and increased intake in females, thus negating the sex difference. Although PT150 may serve as an effective treatment for reducing the risk of OUD following early-life stress in males, further work is needed to determine the mechanism underlying the differential effects of PT150 in males and females. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Polygonum sibiricum polysaccharides exert the antidepressant-like effects in chronic unpredictable mild stress-induced depressive mice by modulating microbiota-gut-brain axis.

Polygonum sibiricum polysaccharides (PSP) are one of the main active components of Polygonatum sibiricum, which is a traditional Chinese medicine with food and drug homologies. Recent studies have revealed the antidepressant-like effects of PSP. However, the precise mechanisms have not been clarified. Therefore, the present study was conducted to explore that whether PSP could exert the antidepressant-like effects via microbiota-gut-brain (MGB) axis in chronic unpredictable mild stress (CUMS)-induced depressive mice by transplantation of fecal microbiota (FMT) from PSP administration mice. FMT markedly reversed the depressive-like behaviors of CUMS-induced mice in the open field, the sucrose preference, the tail suspension, the forced swimming, and the novelty-suppressed feeding tests. FMT significantly increased the levels of 5-hydroxytryptamine and norepinephrine, decreased the levels of the pro-inflammatory cytokines in the hippocampus and reduced the levels of corticosterone, an adrenocorticotropic-hormone, in the serum of CUMS-induced mice. In addition, administration of PSP and FMT significantly increased the expressions of ZO-1 and occludin in the colon and decreased the levels of lipopolysaccharide and interferon-γ in the serum of CUMS-induced mice. Moreover, administration of PSP and FMT regulated the signaling pathways of PI3K/AKT/TLR4/NF-κB and ERK/CREB/BDNF. Taken together, these findings indicated that PSP exerted antidepressant-like effects via the MGB axis.

Palaeostress analysis using fault-slip data from the Xiangdong tungsten deposit in the central south China continent: Evolution of intraplate stress in the Middle Mesozoic

In the central South China continent, the Xiangdong tungsten deposit associated with Late-Jurassic granitic intrusion offers an opportunity to examine the evolution of intraplate stress between the Late Jurassic and Early Cretaceous, which was a time of transition from regional shortening to regional extension. NE–ENE-striking, steeply-dipping, opening-mode tungsten-bearing quartz veins constitute the deposit. Favorable conditions for vein formation where densely spaced arrays have non-curving tips occur under remote stress with a large stress difference and hence in this case probably aligned with the horizontal maximum principal stress axis. Palaeostress analysis using fault-slip data measured on the side walls of underground mine levels yielded the optimal solution of two stresses characterized by an NNW–SSE-shortening strike-slip regime and an NNW–SSE extensional regime. Based on field observations, the first tectonic phase existed during meso- and epi-thermal mineralization, probably owing to the collision between the Siberia and Mongolia–Sino-Korean continents far to the north at the time, and the second tectonic phase appeared after hydrothermal mineralization, as a result of Cretaceous regional rifting. Therefore, multiple strike-slip deformations would have involved the study area during hypo- and epi-thermal mineralization in the Late Jurassic. This evidence does not support the mainstream extension model for Mesozoic tungsten mineralization in central South China.

Welfare effects of environmental hypercapnia quantified by indicators based on morphology and allostatic load in Atlantic salmon (Salmo salar)

Water supply is a limited resource in most salmon hatcheries, which is compensated by reduced water flow and oxygenation. However, reduced water exchange can lead to accumulation of CO2, resulting in environmental hypercapnia, which may have negative impacts on fish welfare. Thus, environmental hypercapnia can be a common welfare problem for salmon in hatcheries, and particularly in recirculating systems (RAS).In this experiment, Atlantic salmon were exposed to chronic environmental hypercapnia during the last 68 days of the freshwater phase, whereupon effects on physiological stress coping mechanisms and morphological welfare indicators were investigated. Effects on stress coping mechanisms were quantified by measuring changes in brain serotonergic chemistry and plasma cortisol at basal levels and in response to a standardized acute stress test. The results show that exposure to elevated CO2 saturation in the water compromised stress responsiveness of brainstem serotonergic activity, altered osmotic homeostasis, and suppressed growth indicating that fish experience allostatic overload. However, no effects on morphological welfare indicators were observed. This accentuates the need for physiological measures, including physiological responses to controlled challenges to activate the stress axis, when investigating the welfare status of fish reared in systems with potential high CO2.

Coseismic and post-seismic characteristics of the 2021 Ganaveh earthquake along the Zagros foredeep fault based on InSAR data

SUMMARY The Ganaveh earthquake on 2021 April 18 (Mw 5.8) occurred in the southwest of the Dezful embayment of the Zagros Mountain belt, Iran, as a mainly compressive event. The InSAR coseismic displacement maps reveal a maximum of 17 cm of surface displacement in the satellite line of sight direction. InSAR inversion indicates a low-angle NE-dipping causative fault plane with a maximum slip of 95 cm at ∼6 km depth. It highlights the occurrence of the Ganaveh earthquake within the competent layers of the Zagros sedimentary cover, beneath the Gachsaran formation. A slight sinistral slip component (2.9 cm) is retrieved which is compatible with the USGS focal mechanism. Time-series analysis of SAR images after the main shock until the end of 2021 indicates a maximum of 7 cm of post-seismic surface displacement with a similar strike and pattern as the coseismic phase. This similarity and the distribution of aftershocks suggest an afterslip mechanism for the post-seismic phase. The inversion of post-seismic cumulative displacement evaluates a maximum of 30 cm slip at a depth of ∼5 km along the coseismic causative fault. A regional compressional stress regime (N041°E for the direction of the σ1 stress axis) is constrained by using the focal mechanisms of 39 earthquakes occurring between 1968 and 2021, including the Ganaveh main shock and its five larger aftershocks. Applying this direction of compression on the Ganaveh fault plane also results in a minor sinistral movement, consistent with the geodetic results. The relocated main shock and aftershocks as well as our InSAR coseismic displacement situations on the hanging wall of the Zagros Foredeep fault highlight it as the causative fault of the Ganaveh earthquake. To fit the geometry of the Ganaveh rupture plane with the Zagros Foredeep fault, we modelled a listric fault plane and its slip distribution using the available geological data. The retrieved slip variation on the listric plane is in close agreement with the slip pattern on the modelled planar geometry. The low dip angle of the rupture plane combined with a listric geometry highlights the thin-skin characteristics of the Zagros Foredeep fault as the causative fault of the Ganaveh earthquake. The occurrence of this moderate magnitude earthquake on the Zagros Foredeep fault underlines its role as the western structural boundary for the recurrence of Mb > 5 events in the Dezful embayment.