Thermal acclimation

Habitats vary in temperature both spatially and temporally.  Variation in thermal habitat introduces challenges to organisms and may reduce fitness unless organisms can physiologically adjust to such changes.  Theory predicts that thermal variability should influence the capacity for acclimation such that increased variation should favor a reduction in the thermal sensitivity of physiological traits.  IN this study, we investigated acclimation to constant and variable conditions in populations of the salamander Desmognathus brimleyorum from the Ouachita Mountains of Arkansas, USA.  We exposed salamanders to constant and variable temperature regimes for 8 weeks in the laboratory.  We then tested salamanders for acclimation of thermal tolerance, and the thermal sensitivities of swimming performance and standard metabolic rate.  Our results indicate limited capacity for thermal acclimation to constant and variable conditions in D. brimleyorum.  Instead, variation in physiological traits is dominated by differences among populations.  Population differences do not appear to be correlated with observed variation in the thermal conditions of the streams, but are likely a consequence of structural and ecological differences.  Due to the mixed support for theoretical predictions for acclimation to thermal environments, further consideration should be given to revising and expanding current theoretical models.

This paper presents the study of a new solar and thermoelectric heat pump and its implementation in a container house architecture. Design and thermodynamic exchanges of the different subsystem in the different required configurations have been evaluated according to both Industry 4.0 Digital Twin model holistic optimization process and constructal law in the direction of increasing its efficiency. First law estimation and second law analysis have performed. The building system has been energetically optimized in the location of Bologna (Italy). An accurate solar design of the building is presented by analyzing the monthly behaviour of the building and the solar gains from the transparent elements. The results produce a building which benefits of three qualifying elements: sandwich walls that include high-efficiency Vacuum Insulated Panels (VIP) for minimizing heat dispersions; highly optimized transparent elements including seasonal shading; an innovative cogeneration heat pump that couples solar energy and heating-cooling by mean of thermoelectric effect with heat recovery from photovoltaic systems. The acclimatization is realized by a new generation heat pump using solar thermal and photovoltaic sources, which are coupled with a dual-mode heating/cooling heat pump by Peltier cells and heat recovery (during winter) from photovoltaic modules. A complete analysis and dimensioning of the building and heat pump are provided.

In the face of global warming, both the absolute thermal tolerance of an ectotherm, and its ability to shift its tolerance level via acclimation, are thought to be fundamentally important. Understanding the links between tolerance and its plasticity is therefore critical to accurately predict vulnerability to warming. Previous studies in a number of ectotherm taxa suggest trade-offs in the evolution of thermal tolerance and its plasticity, something which does not, however, apply to Deronectes diving beetles, where these traits are instead positively correlated. Here we revisit the relationship between thermal tolerance and plasticity in these beetles, paying attention to a recently discovered morphological adaptation supporting under water respiration - setal tracheal gills. Hollow setae on the elytra interconnect with the beetle's tracheal system, providing a gas exchange surface that allows oxygen to be extracted directly from the water. This enables individuals to stay submerged for longer than their subelytral air stores would allow. We show that hypoxia reduced heat tolerance, especially when individuals were denied access to air, forcing them to rely solely on aquatic gas exchange. Species with higher densities of these gas-exchanging setae exhibited improved cold tolerance, but reduced heat tolerance and lower plasticity of heat tolerance. Differences in setal tracheal gill density across species were also related to habitat use: species with low gill density were found mainly in intermittent, warmer rivers, where underwater gas exchange is more problematic and risks of surfacing may be smaller. Moreover, when controlling for differences in gill density we no longer found a significant relationship between heat tolerance and its plasticity, suggesting that the previously reported positive relationship between these variables may be driven by differences in gill density. Differences in environmental conditions between the preferred habitats could simultaneously select for characteristic differences in both thermal tolerance and gill density. Such simultaneous selection may have resulted in a non-causal association between cold tolerance and gill density. For heat tolerance, the correlations with gill density could reflect a causal relationship. Species relying strongly on diffusive oxygen uptake via setal tracheal gills may have a reduced oxygen supply capacity and may be left with fewer options for matching oxygen uptake to oxygen demand during acclimation, which could explain their reduced heat tolerance and limited plasticity. Our study helps shed light on the mechanisms that underpin thermal tolerance and plasticity in diving air-breathing ectotherms, and explores how differences in thermal tolerance across species are linked to their selected habitat, morphological adaptations and evolutionary history.

Using a proteomic approach, we characterized different protein expression profiles in anterior gills of the Chinese mitten crab, Eriocheir sinensis, after cadmium (Cd) exposure. Two experimental conditions were tested: (i) an acute exposure (i.e. 500μgCdl−1 for 3 days) for which physiological, biochemical and ultrastructural damage have been observed previously; (ii) a chronic exposure (i.e. 50μgCdl−1 for 30 days) resulting in

Effects of soil water availability on seedling growth, dry matter production and allocation were determined for Gympie (humid coastal) and Hungry Hills (dry inland) provenances of Eucalyptus cloeziana F. Muell. and for E. argophloia Blakely (dry inland) species. Seven-...

Effects of soil water availability on seedling growth, dry matter production and allocation were determined for Gympie (humid coastal) and Hungry Hills (dry inland) provenances of Eucalyptus cloeziana F. Muell. and for E. argophloia Blakely (dry inland) species. Seven-...