Oxidative stress occurs in the process of egg storage. Antioxidants as feed additives can enhance egg quality and extend the shelf life of eggs. Selenium-enriched Cardamine violifolia (SEC) has strongly antioxidant properties. The objective of this study was to assess the effects of dietary supplementation with SEC on egg quality and the yolk antioxidant capacity of eggs stored at 4 °C and 25 °C. Four hundred fifty 65-week-old, Roman hens that were similar in laying rate (90.79 ± 1.69%) and body weight (2.19 ± 0.23 kg) were divided into 5 groups. The birds were fed diets supplemented with 0 mg/kg selenium (Se) (CON), 0.3 mg/kg Se from sodium selenite (SS), 0.3 mg/kg Se from Se-enriched yeast (SEY), 0.3 mg/kg Se for selenium-enriched Cardamine violifolia (SEC) or 0.3 mg/kg Se from Se-enriched Cardamine violifolia and 0.3 mg/kg Se from Se-enriched yeast (SEC + SEY) for 8 weeks. The eggs were collected on the 8th week and were analyzed for egg quality and oxidative stability of yolk during storage at 4 °C or 25 °C for 0, 2, 4, or 6 weeks. Dietary SEC and SEC + SEY supplementation increased the Haugh unit (HU) and albumen foam stability in eggs stored at 4 °C and 25 °C (p < 0.05). SS and SEC supplementation increased the yolk index in eggs stored at 25 °C (p < 0.05). SEC or SEC + SEY slowed down an increase in albumen pH and gel firmness in eggs stored at 4 °C and 25 °C (p < 0.05). Moreover, SEC or SEC + SEY alleviated the increase in malonaldehyde (MDA), and the decrease in total antioxidant capacity (T-AOC) level and total superoxide dismutase (T-SOD) activity in yolks stored at 4 °C and 25 °C (p < 0.05). These results indicate that SEC mitigated egg quality loss and improved the antioxidant capacity of yolks during storage. SEC supplementation would be advantageous to extend the shelf life of eggs.
Abstract Cardamine violifolia is a selenium (Se)‐enriched plant found in China. In this study, the Se‐enriched peptides of C. violifolia (CP) were isolated using a 1 kDa ultrafiltration membrane after enzymatic hydrolysis by alkaline and neutral proteases. The peptides were separated by DEAE‐Sepharose FF anion‐exchange chromatography and purified using preparative high‐performance liquid chromatography (prep‐HPLC). The component with the highest antioxidant activity, CPR13, was identified by comparing the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH•), hydroxyl (•OH), 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS + •), and superoxide ( ) radical scavenging ability of each fraction. At a concentration of 0.1 mg/mL, the DPPH•, •OH, , and ABTS + • scavenging activities of CPR13 were 89.2%, 26.3%, 40.6%, and 42.9%, respectively. Amino acid sequences were obtained by liquid chromatography combined with mass spectrometry as follows: GRVGSSSC, GRAGGSYM, GHPNFKLNCSGG, GTKSCKA, ASSNARDMI, TAGGCYIPI, and KNCALQ. The seleno‐amino acids were identified as selenomethionine, methylselenocysteine, and selenocysteine. Correlation analysis among organic Se content, peptide content, and antioxidant activity revealed that organic Se plays a greater role in free radical scavenging than peptides, and that the organic Se content of the Se‐enriched peptides was positively correlated with their antioxidant ability ( P < 0.05). It indicated that CP has a great potential as natural functional materials for dietary supplement.
A well-constructed ecological security pattern (ESP) can promote linkages between ecological sources, mitigate the degradation of ecosystems, and facilitate sustainable urban development. However, when determining the ecological sources for ESPs, previous studies have less frequently or insufficiently considered the ecosystem service trade-offs. Our research aims to fill this research gap to improve the assessment of ESPs. Through a case study in a rapidly urbanizing region—the Jianghuai Ecological Economic Zone in China—we demonstrate the application possibilities of the proposed framework. Ecosystem services in the study area were evaluated using the Integrated Valuation of Ecosystem Services and Tradeoffs model, ecological sources were screened using the ordered weighted averaging method; then, an ESP was constructed using the minimum cumulative resistance model and circuit theory. The results indicated that crop production and water purification were higher in the east and lower in the west, while the water yield showed the opposite trend. Habitat quality and carbon storage were higher in the south and lower in the north. Eleven scenarios were set to determine ecological sources based on ecosystem service trade-offs. By comparing service efficiency, scenario 5 was selected as our optimal scenario, and the service efficiencies of ecological sources for crop production, water yield, habitat quality, carbon storage and water purification were 1.35, 1.15, 1.21, 1.06 and 0.92, respectively. There were no significant ecological sources in the developed eastern and central regions due to rapid urbanization and drastic land use changes in the area. There were 31 major ecological sources located in the western and northwestern parts of the study area, where water bodies and wetlands were well developed. There was a total of 70 ecological corridors in the study area, with 53 key ecological corridors. Based on these results, we proposed three measures to improve the sustainability of ecosystems to cope with the rapid urbanization while providing ecological quality. This study can provide implications for ecosystem security in other fast-growing cities.
Abstract Broussonetia papyrifera, a valuable feed resource, is known for its fast growth, wide adaptability, high protein content and strong selenium enrichment capacity. Selenomethionine (SeMet), the main selenium form in selenium fortification B. papyrifera, is safe for animals and this enhances its nutritional value as a feed resource. However, the molecular mechanisms underlying SeMet synthesis remain unclear. This study identified three homocysteine S-methyltransferase genes from the B. papyrifera genome. The phylogenetic tree demonstrated that BpHMTs were divided into two classes, and BpHMT2 in the Class 2-D subfamily evolved earlier and possesses more fundamental functions. On the basis of the correlation between gene expression levels and selenium content, BpHMT2 was identified as a key candidate gene associated with selenium tolerance. Subcellular localization experiments confirmed the targeting of BpHMT2 in nucleus, cell membrane and chloroplasts. Moreover, three BpHMT2 overexpression Arabidopsis thaliana lines were confirmed to enhance plant selenium tolerance and SeMet accumulation. Overall, our finding provides insights into the molecular mechanisms of selenium metabolism in B. papyrifera, highlighting the potential role of BpHMT2 in SeMet synthesis. This research contributes to our understanding of selenium-enriched feed resources, with increased SeMet content contributing to the improved nutritional value of B. papyrifera as a feed resource.
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