Photosynthetic traits of Australian wild rice (Oryza australiensis) confer tolerance to extreme daytime temperatures

Key message A wild relative of rice from the Australian savannah was compared with cultivated rice, revealing thermotolerance in growth and photosynthetic processes and a more robust carbon economy in extreme heat. Abstract Above ~ 32 °C, impaired photosynthesis compromises the productivity of rice. We compared leaf tissues from heat-tolerant wild rice (Oryza australiensis) with temperate-adapted O. sativa after sustained exposure to heat, as well as diurnal heat shock. Leaf elongation and shoot biomass in O. australiensis were unimpaired at 45 °C, and soluble sugar concentrations trebled during 10 h of a 45 °C shock treatment. By contrast, 45 °C slowed growth strongly in O. sativa. Chloroplastic CO2 concentrations eliminated CO2 supply to chloroplasts as the basis of differential heat tolerance. This directed our attention to carboxylation and the abundance of the heat-sensitive chaperone Rubisco activase (Rca) in each species. Surprisingly, O. australiensis leaves at 45 °C had 50% less Rca per unit Rubisco, even though CO2 assimilation was faster than at 30 °C. By contrast, Rca per unit Rubisco doubled in O. sativa at 45 °C while CO2 assimilation was slower, reflecting its inferior Rca thermostability. Plants grown at 45 °C were simultaneously exposed to 700 ppm CO2 to enhance the CO2 supply to Rubisco. Growth at 45 °C responded to CO2 enrichment in O. australiensis but not O. sativa, reflecting more robust carboxylation capacity and thermal tolerance in the wild rice relative.

Inverse problem of determining the coefficient and kernel in an integro - differential equation of parabolic type

This article is concerned with the study of the unique solvability of inverse boundary value problem for integro-differential heat equation. To study the solvability of the inverse problem, we first reduce the considered problem to an auxiliary system with trivial data and prove its equivalence (in a certain sense) to the original problem. Then using the Banach fixed point principle, the existence and uniqueness of a solution to this system is shown.

Numerical estimation of thermal ignition conditions for reactive medium with Gaussian distribution of activation energy

The article investigates the solutions of the one-dimensional stationary integro-differential heat equation. The source of heat release is determined through the Gaussian distribution function of the activation energy. In such a statement, the critical conditions for the existence of a bounded solution depend on the distribution variance. With the help of numerical methods, such dependences are obtained; for their explanation, the analytical approximations of the thermal explosion theory are used.

Novel Insights Into Heat Tolerance Using Microbiome and Metabolomics Analyses in Dairy Cows Rumen Fluid

Background: Heat stress is a key issue of growing concern for livestock industry worldwide due to its negative effects not only on milk production, fertility, health, welfare, and economic returns of dairy cows, but also on the microbial communities in the rumen. However, the underlying relationship between rumen microbiome and its associated metabolism with heat tolerance in cow have not been extensively described yet. Therefore, the main objective of this study was to investigate differential heat resistance in Holstein cows using rumen microbiome and metabolome analyses.Methods: We performed both principal component analysis and membership function analysis to select 7 heat-tolerant (HT) and 7 heat-sensitive (HS) cows. The ruminal fluid samples of two groups were collected at two hours post feeding on 7th day of heat stress period, for analyses including rumen fermentation parameters, rumen microbiome and nontargeted metabolomics.Results: Under heat stress conditions, the HT cows had a significantly higher propionic acid content than the HS cows; whereas measures of the respiratory rate (RR), rectal temperature (RT), acetic,butyric acid and acetic acid to propionic acid ratio (A:P) in the HT cows were lower compared with the HS cows. Omics sequencing revealed that the relative abundance of Rikenellaceae_RC9_gut_group, Succiniclasticum, Ruminococcaceae_NK4A214_group and Christensenellaceae_R-7_group were significantly higher in the HT than HS cows; whereas Prevotella_1, Ruminococcaceae_UCG-014, and Shuttleworthia were significantly higher in the HS cows compared to HT cows. Substances mainly involved in carbohydrate metabolism, including glycerol, mannitol, and maltose, showed significantly higher content in the HT cows compared to that in the HS cows. Simultaneously, RR was significantly correlated with both differential microorganisms and distinct metabolites, suggesting three metabolites could be potential biomarkers for determining heat resistance that require further research.Conclusion: Overall, distinct changes in the rumen microbiome and metabolomics in the HT cows may be associated with better adaptability to heat stress. These findings suggest their use as diagnostic tools of heat tolerance in dairy cattle breeding schemes.

No Glycation Required: Interference of Casein in AGE Receptor Binding Tests

For the determination of the binding of heated cow’s milk whey proteins such as β-lactoglobulin to the receptors expressed on immune cells, inhibition ELISA with the soluble form of the receptor for advanced glycation end products (sRAGE) and scavenger receptor class B (CD36) has been successfully used in the past. However, binding to heated and glycated caseins in this read-out system has not been tested. In this study, inhibition ELISA was applied to measure the binding of cow’s milk casein alone, as well as all milk proteins together, which underwent differential heat treatment, to sRAGE and CD36, and we compared those results to a dot blot read out. Moreover, binding to sRAGE and CD36 of differentially heated milk protein was measured before and after in vitro digestion. Casein showed binding to sRAGE and CD36, independent from the heat treatment, in ELISA, while the dot blot showed only binding to high-temperature-heated milk protein, indicating that the binding is not related to processing but to the physicochemical characteristics of the casein. This binding decreased after passage of casein through the intestinal phase.

Study on a New Process and its Kinetics of Iron Recovery and Glass-ceramics Preparation from Desulfurization Slag

The melting point and phase of slag was calculated with Factsage thermodynamics software, and base on this, taking desulfurization slag as the main raw material, which is leached by ammonium chloride as pretreatment. The composition of target slag system was adjusted with high aluminum powder coal ash and glass cullet, and then the reducing slag and metallic iron were separated by high temperature carbon thermal reaction. The prepared glass-ceramics with main crystal phases of diopside and nepheline were obtained by heat treatment, which shows that the new process is feasible. The crystallization activation energy was calculated by using Kissinger, Ozawa and Augis-Bennett method base on the differential heat curve. The results show that the crystallization activation energy is relatively high, and the crystal growth index n are all less than 3, which means that the crystallization capacity of the glass-ceramics is low. At the heating rate of 5 K/min, the n value of sample No. 3 is the largest, which is 2.7, and the mode of volumetric crystallization changes from two-dimensional to one-dimensional with the increase of heating rate, therefore, nucleating agent is needed in the preparation of glass-ceramics.

How do the sea and the land conditions affect the coastal breezes? 20 days analysed from WRF simulations in the Gulf of Cádiz (Iberian Peninsula)

<p>Sea breezes are common and recurrent thermally-driven winds formed in coastal areas under conditions of weak synoptic forcing, due to the differential heat capacity of the sea and the land. Their accurate forecast is key because of the impacts on maxima near-surface temperatures, humidity (and then thermal comfort), pollutants distribution, convective-systems formation, etc., being crucial for the wind energy sector and because they develop in areas that are normally densely populated.</p><p>Some studies have investigated the impacts of the surface conditions in coastal breezes in different regions around the world. Their findings are diverse, mostly attributed to differences in the marine boundary layer stability, which can favour or inhibit the vertical mixing. This is needed to vertically distribute thermal changes in the land or the sea surfaces to deeper atmospheric layers, and thus to modify the horizontal surface pressure gradients. In this work, we use the Weather Research and Forecasting (WRF) model to investigate how the coastal breezes are affected by changes in the surface representation in the Gulf of Cádiz, in the Atlantic coast of the Southwestern Iberian Peninsula. We focus on artificial and realistic changes in land use, soil moisture and sea surface temperature. The analysis is performed for a case study of 20 days in August 2020, characterised by many coastal-breeze events in the area analysed and by a gradual decrease in the sea surface temperature. The model is evaluated with observational data at different coast locations, inland and on the ocean, as well as using wind speed transects from satellite altimetry.</p>