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Simple Summary: In this study, the effects of fish oil supplementation on the growth performance, physiological and biochemical indicators, immune function, and liver cell health of the Chinese stripe-necked turtle (Mauremys sinensis) were examined. Increasing the level of fish oil in the diet improved the growth performance of M. sinensis and increased the lipid content in the body, but it induced oxidative stress in the liver. Furthermore, it decreased the immune function of M. sinensis, increased instances of apoptosis in liver cells, and caused liver damage. These results highlight the importance of identifying the appropriate lipid supplementation level to promote growth and maintain health. Dietary lipids provide energy for animals and can also be converted into other nutrients (such as non-essential amino acids), which play a role in saving protein. The Chinese stripe-necked turtle is a protected and endangered species that has been bred in captivity; however, basic data on lipid requirements remain unavailable. In this study, 360 Mauremys sinensis (body weight of 65.32 ± 0.15 g) were randomly divided into six groups with three replicates per group; the turtles were fed experimental diets supplemented with various levels of fish oil (i.e., 1% (control group, CG), 3.5% (HF-1), 6% (HF-2), 8.5% (HF-3), 11% (HF-4), and 13.5% (HF-5)) for 10 weeks. The results showed that compared with CG, increasing the fish oil level promoted the growth performance of turtles, and the HF-3 group achieved the best effect. The HF-4 group showed the highest increases in the hepatosomatic index and viscerosomatic index. In addition, increased lipid levels also increased the crude lipid content and reduced the crude protein content in muscle tissue. Oil red O staining showed that the liver lipid content increased with the level of supplemented fish oil, which is consistent with the results of the hepatosomatic index. Compared with CG, triglyceride, total cholesterol, and low-density lipoprotein cholesterol increased significantly in both the liver and serum when fish oil levels exceeded 8.5% (p < 0.05), while high-density lipoprotein cholesterol decreased significantly. Aspartate transaminase and cerealthirdtransaminase levels in serum increased significantly when fish oil levels exceeded 8.5% (p < 0.05). Moreover, the activities of antioxidant enzymes (GSH-Px, SOD, T-AOC, and CAT) and MDA showed similar results, indicating that high fish oil levels (8.5–13.5%) caused liver tissue damage in M. sinensis. Increased fish oil levels significantly upregulated the expression levels of cytokines (IFN-γ, TNF-α, TGF-β1, IL-10, and IL-12) (p < 0.05), downregulated the expression levels of antioxidant enzyme-related genes (cat, mn-sod, and gsh-px), and increased apoptosis of liver cells. Supplementation of the diet with 3.5–6% fish oil improved the growth performance of M. sinensis, and the turtles maintained a beneficial immune status. The results provide a scientific basis for optimizing the commercial feed formula of M. sinensis. [ABSTRACT FROM AUTHOR]

Forests are the largest carbon sink in terrestrial ecosystems, and the impact of nitrogen (N) deposition on this carbon sink depends on the fate of external N inputs. However, the patterns and driving factors of N retention in different forest compartments remain elusive. In this study, we synthesized 408 observations from global forest 15N tracer experiments to reveal the variation and underlying mechanisms of 15N retention in plants and soils. The results showed that the average total ecosystem 15N retention in global forests was 63.04 ± 1.23%, with the soil pool being the main N sink (45.76 ± 1.29%). Plants absorbed 17.28 ± 0.83% of 15N, with more allocated to leaves (5.83 ± 0.63%) and roots (5.84 ± 0.44%). In subtropical and tropical forests, 15N was mainly absorbed by plants and mineral soils, while the organic soil layer in temperate forests retained more 15N. Additionally, forests retained more N15H4+$$ {}^{15}\mathrm{N}{\mathrm{H}}_4^{+} $$than N15O3−$$ {}^{15}\mathrm{N}{\mathrm{O}}_3^{-} $$, primarily due to the stronger capacity of the organic soil layer to retain N15H4+$$ {}^{15}\mathrm{N}{\mathrm{H}}_4^{+} $$. The mechanisms of 15N retention varied among ecosystem compartments, with total ecosystem 15N retention affected by N deposition. Plant 15N retention was influenced by vegetative and microbial nutrient demands, while soil 15N retention was regulated by climate factors and soil nutrient supply. Overall, this study emphasizes the importance of climate and nutrient supply and demand in regulating forest N retention and provides data to further explore the impacts of N deposition on forest carbon sequestration. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the direct effects of pain-induced depression and anxiety, as well as the mediating role of psychological resilience, on the psychological distress associated with rheumatoid arthritis. The method involved a sample of 196 patients with rheumatoid arthritis and applied the Hospital Anxiety and Depression Scale, Connor–Davidson Resilience Scale, and visual analog scale for pain. Bivariate and path analyses were performed, and a multiple mediational model was utilized. Results showed that all correlations among study variables were significant (p < 0.01). A partial mediation effect of psychological resilience was observed, and direct effects among the variables (pain, psychological resilience, anxiety, and depression) were statistically significant, including the direct effect of psychological resilience on depression and anxiety. The indirect effects of pain through psychological resilience on depression and anxiety were also significant. Thus, the results suggest that psychological resilience partially mediates the effects of pain-induced anxiety and depression in patients with rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

Elevated nitrogen (N) deposition and changes in reduced or oxidized component contribution greatly affect soil acidification. China has experienced a significant transformation of N deposition components from NHx to NOy over the past 40 years, but the effects of component transformation on soil acidification are poorly understood. Therefore, long‐term monitoring data and literature on N deposition, combined with the results of isotope experiments, were used to explore the contributions of different N forms on soil acidification in China's forests. Here, all processes related to NHx and NOy, including the transformation to NH4+ and NO3− and subsequent N cycling in the soil, were considered. We found that N‐induced soil acidification in 80% area of China's forests was dominated by NHx deposition, and the other areas (South China) were dominated by NOy deposition in 2010s. From 1980 to 2019, the average contribution of NHx was higher than that of NOy but the latter contribution continued to increase. Meanwhile, the results showed that soil acidification increased with the decrease of the ratio of NHx to NOy (RNHx/NOy), which is mainly because NOy is more easily leached in the form of NO3− than that of NHx under the influence of different plant preferences and soil retention rates, resulting in a higher net proton production of NOy. Our research has powerful implications for policymaking, provides a theoretical basis for formulating different N reduction policies in different regions, and points out that the synergistic effect of RNHx/NOy changes should be considered to alleviate soil acidification. Key Points: Most forest soil was dominated by the contribution of NHx deposition, causing soil acidificationThe contribution of NOy deposition to soil acidification increased continuously during 1980–2019Decreased ratio of NHx to NOy deposition has led to aggravated forest soil acidification [ABSTRACT FROM AUTHOR]