Uncoupling Thermotolerance and Growth Performance in Chinook Salmon: Blood Biochemistry and Immune Capacity

Ocean warming and extreme sea surface temperature anomalies are threatening wild and domesticated fish stocks in various regions. Understanding mechanisms for thermotolerance and processes associated with divergent growth performance is key to the future success of aquaculture and fisheries management. Herein, we exposed Chinook salmon (Oncorhynchus tshawytscha) to environmentally relevant water temperatures (19–20 °C) approaching their upper physiological limit for three months and sought to identify blood biomarkers associated with thermal stress and resilience. In parallel, blood biochemical associations with growth performance were also investigated. Temperature stress-activated leukocyte apoptosis induced a minor immune response, and influenced blood ion profiles indicative of osmoregulatory perturbation, regardless of how well fish grew. Conversely, fish displaying poor growth performance irrespective of temperature exhibited numerous biomarker shifts including haematology indices, cellular-based enzyme activities, and blood clinical chemistries associated with malnutrition and disturbances in energy metabolism, endocrine functioning, immunocompetence, redox status, and osmoregulation. Findings provide insight into mechanisms of stress tolerance and compromised growth potential. Biochemical phenotypes associated with growth performance and health can potentially be used to improve selective breeding strategies.

Helium in the Earth's foreshock: a global Vlasiator survey

<p>The foreshock is a region of space in front of the Earth's bow shock, extending along the interplanetary magnetic field. It is permeated by ions and electrons reflected at the shock, low-frequency waves, and various plasma transients. The ion foreshock is dominated by a number of proton populations such as field-aligned beams, gyrating distributions and diffuse ions, as well as proton-excited waves. As the solar wind can contain a significant fraction of helium, it is of great interest to investigate how alpha-particles (He<sup>2+</sup>) are reflected into forming their own foreshock. We investigate the extent of the helium foreshock in relation to foreshock ultra-low frequency waves and protons using Vlasiator, a global hybrid-Vlasov simulation. We confirm a number of historical spacecraft observations at the foreshock regions associated with field-aligned beams, gyrating ion distributions, and specularly reflected particles, performing the first numerical global survey of the helium foreshock. We present wavelet analysis at multiple positions within the foreshock and evaluate the dynamics of gyrating ion populations in response to the transverse and compressive wave components. We also present Magnetosphere Multiscale (MMS) spacecraft crossings of the foreshock edge and compare Hot Plasma Composition Analyzer (HPCA) measurements of energetic ions with our simulation data, showing the variability of the foreshock edge suprathermal ion profiles.</p>

Phenotypic and physiological responses to salt exposure in Sorghum reveal diversity among domesticated landraces

ABSTRACTSoil salinity negatively impacts plant function, development, and yield. Sorghum bicolor is a staple crop known to be drought tolerant, to have adapted to a variety of conditions, and to contain significant standing genetic diversity, making it an exemplary species to study phenotypic and physiological variation in salinity tolerance. In our study, a diverse group of sorghum landraces and accessions was first rank-ordered for salinity tolerance and then individuals spanning a wide range of response were analyzed for foliar proline and ion accumulation. We found that, while proline is often a good indicator of osmotic adjustment and is historically associated with increased salt tolerance, proline accumulation in sorghum reflects stress-response injury rather than acclimation. When combining ion profiles with growth responses and stress tolerance indices, the variation observed in tolerance was similarly not a sole result of Na+ accumulation, but rather reflected accession-specific mechanisms that may integrate these and other metabolic responses. When we compared variation in tolerance to phylogenetic relationships, we conclude that the most parsimonious explanation for the variation observed among accessions is that salinity tolerance was acquired early during domestication and was subsequently maintained or lost in diverged lineages during improvement in areas that vary in soil salinity.

High chloride, sulphate and fluoride concentrations in clay-rich aquitard porewater, the North China Plain: evidence of geochemical behavior

The focus of this investigation was to constrain the porewater chemistry from tracer and ion profiles in a 128 m thick clay-rich sequence of Quaternary sediments comprising the clay, silt and fine sand formation in the North China Plain. Porewater are much more saline (1.1-71.0 g/L) than the lower confined groundwaters (0.3-1.3g/L). Chloride profiles from aqueous extraction (AE) (ranging from 117 to 3260 mg/L) generally keep good consistent with that obtained from squeezing test (ST). However, the sulphate and fluoride concentrations by AE (ranging from 340 to 48,700 mg/L and from 8.8 to 144 mg/L, respectively) are far greater than that by ST. Dissolution of evaporites may be responsible for the high Cl/Br ratios greater than 1000, probably indicating recharge occurred during much wetter periods. The original stable isotopic and chemical compositions in the aquitard porewater have been modified by transpiration and evaporation processes concentrating Cl and causing isotopic enrichment during their formation periods. Dissolution of fluorite, hieratite, and cryolite caused by weathering behavior and ion-exchange reactions should be responsible for the high fluoride concentrations in the aquitard porewater. High sulphate levels found in aqueous samples may arise from pyrite oxidation during sampling, storage and/or porewater extraction procedure.