Rescue effects of Se-enriched rice on physiological and biochemical characteristics in cadmium poisoning mice.

Cadmium (Cd) is an element injurious for human health and is possibly toxic to organisms at minor concentrations. While some of other trace metallic elements have antagonistic features to it. One of them is the interaction between selenium (Se) and Cd in plant different organs. Literature review disclosed that the intake of Se to some extent can reduce the accumulation of Cd in plants, while the research on of trace metallic elements (Cd) and Se-enriched food (rice) in the living body has rarely been reported. This study intended to explore whether there was a mitigating effect of Se-enriched rice on mice poisoned with Cd. A mouse model of low-dose and high-dose Cd poisoning was established (supplemented with cadmium chloride(CdCl2·2½H20)), followed by feeding two groups (1) Se-enriched rice and (2) setting an equal amount of inorganic Se group. After that, the impact of Se-enriched rice on the antioxidant activity was evaluated. The Se-enriched diet enhanced the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and enzyme activities of GSH peroxidase (GSH-Px) in mice livers and kidney whereas significantly decreased the malondialdehyde (MDA) contents. Moreover, the degree of physiological damage in mice with low cadmium poisoning was significantly alleviated, and the expression of antioxidant genes (Nrf-2, GPX1, TrxR2, TNF-2) was increased. In conclusion, the Se-enriched diet has a positive effect on the biological effects in mice, and it can be used as a daily diet to resist damage to the body's low Cd state and support enzymatic antioxidant systems by eliminating oxidative injury.

Impact of selenium, zinc and their interaction on key enzymes, grain yield, selenium, zinc concentrations, and seedling vigor of biofortified rice.

Selenium (Se) is an essential micronutrient and important component of oxidase which protects cell membranes, eliminate the role of free radicals in the human body. Se is necessary for low Se rice genotypes and Se deficient areas. Zinc (Zn) is a micro-battalion that affects the growth, development, aging, drought resistance, disease resistance, and many other aspects for rice. The effects of Se and Zn fertilization on Se and Zn concentrations were evaluated including the response of superoxide dismutase (SOD), catalase (CAT) enzymes activity, and grain yield under single Se, Zn, and combined Se-Zn application using R725 rice variety in pot experiment with 8 treatments (0, Zn5, Zn10, Zn15, Se1, Zn5 + Se1, Zn10 + Se1, and Zn15 + Se1) mg/kg of soil and three replications. Moreover, germination% and seedling growth of resulted seeds from this experiment were evaluated for the agronomical benefit of farmers. The results revealed that Se and Zn had a cumulative effect on each other, but more Se increase was activated than Zn under the combined Se-Zn application. Zinc application had the small effect on Zn concentration in the different fractions but the positive effect on carotenoids and the yield (both applied alone and in combination with Se). Single Se application resulted in a positive effect on Zn accumulation in grain and husk with the high effectiveness of Se accumulation and loss during processing. Combined Se-Zn application had positive effect on carotenoids, CAT, grain yield, and total dry matter. Moreover, single Zn and combined Se-Zn application had a positive effect on germination% and seedling growth. Agronomic biofortification with combined Se-Zn supply provided both agronomic and nutritional benefits for rice in the current pot trail. However, as Se preferably accumulated in the edible part as compared to Zn, 1 mg Se/kg fertilization was unsafe for edible purposes according to the national standard of China (0.04-0.3 mg/kg) but could be recommended as medicine.

Dissecting the Potential of Selenoproteins Extracted from Selenium-Enriched Rice on Physiological, Biochemical and Anti-Ageing Effects In Vivo.

Ageing is an irreversible phenomenon and the processes which can delay it are under consideration for a long time by the scientific community. Selenium is an important candidate for it, but the impact of selenoprotein on nutritional changes and ageing has not been reported well. In this regard, antioxidant activities and free radical scavenging effect of selenoproteins extracted from selenium-rich rice were studied. Mice were administered a subcutaneous abdominal injection of D-galactose to induce the ageing model and fed with different selenoprotein dosage diet. Deviations among biochemical activities (total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and malondialdehyde (MDA)) in liver and serum of the mice were assessed. The degree of liver injury, antioxidant genes and protein relative expression were estimated. The protein content, selenium content, hydroxyl scavenging and DPPH radicals were accessed in selenoprotein components. The selenoprotein constituent had protein and selenium contents in different components as water-soluble proteins > alkali-soluble proteins > salt-soluble proteins > ethanol-soluble proteins. The enzymatic activity (total antioxidant capacity, GSH-Px and SOD) in liver and serum of mice was significantly enhanced in selenoprotein diet groups. D-Galactose-induced liver injury was significantly reduced by selenoprotein diet of 25 µg/(kg day). Real-time qPCR and Western blot disclosed the enhanced relative expression of antioxidant genes (SOD2, GPX1, TrxR2 and Nrf2) and HO-1 protein in the positive control (Vc) and selenoprotein diet groups. In conclusion, selenoprotein treatment was found to have a positive influence on liver hepatocytes and biochemical features in mice. It might be used as a potential diet in scavenging oxidative injury and supporting enzymatic antioxidant system.

Quick selenium accumulation in the selenium-rich rice and its physiological responses in changing selenium environments.

BACKGROUND: The element selenium (Se) deficiency is thought to be a global human health problem, which could disperse by daily-supplement from Se-rich food. Increasing the accumulation of Se in rice grain is an approach matched to these nutrient demands. Nonetheless, Se is shown to be essential but also toxic to plants, with a narrow margin between deficiency and toxicity. Notably, the regulatory mechanism balancing the accumulation and tolerance of Se in Se-rich rice plants remains unknown. RESULTS: In this study, we investigated the phenotypical, physiological, and biochemical alterations of Se-rich rice in the exposure to a variety of Se applications. Results showed that the Se-rich rice was able to accumulate more abundance of Se from the root under a low Se environment comparing to the Se-free rice. Besides, excessive Se led to phytotoxic effects on Se-rich rice plants by inducing chlorosis and dwarfness, decreasing the contents of antioxidant, and exacerbating oxidative stresses. Furthermore, both phosphate transporter OsPT2 and sulfate transporters OsSultr1;2 may contribute to the uptake of selenate in rice. CONCLUSIONS: Se-rich red rice is more sensitive to exogenous application of Se, while and the most effective application of Se in roots of Se-rich rice was reached in 20 µM. Our findings present a direct way to evaluate the toxic effects of Se-rich rice in the Se contaminated field. Conclusively, some long-term field trial strategies are suggested to be included in the evaluation of risks and benefits within various field managements.

Cross-Talk between Cadmium and Selenium at Elevated Cadmium Stress Determines the Fate of Selenium Uptake in Rice.

Cadmium (Cd) is a well-known metal imposing threats to human health, and it can be accumulated in polished rice over the permitted range of 0.2 mg kg-1 (GB 2762-2017). It has been reported that selenium (Se) application decreases Cd uptake. Se-rich diets have gained attention recently, but the potential of Se-rich rice in mitigating Cd stress needs further investigation. In this study, a pot experiment in the field was conducted to assess the influence of environmental factors and exogenous split application of Se on the nutritional status of rice under Cd stress. The results indicated that the increased fertilizer treatment in soil bulk linearly increased the metal content in rice grains. Approximately 50-70% of metal was recovered in rice tissues, while 5-20% of the metal that was applied leached down into the soil. A Se concentration of 0.4 mg kg-1 could significantly improve the total Se content in grain and mitigate Cd toxicity (1 mg kg-1) below the permitted range. Panicles and roots were more active for total Se accumulation in Se-rich and non-Se-rich rice, respectively. Polishing and milling operations can significantly reduce the Cd content, as rice bran in rice tissues accumulated most of the metal's residues. The late matured rice cultivars consumed more heat units, and more metal contents were found in them. Collectively, it was found that Se can mitigate Cd toxicity, but the rice cultivation at T2 (high Cd; 2 mg kg-1 and Se; 1 mg kg-1) increased the metal uptake capability and health-risk index in polished rice, with its Se content heightened over permitted range of 0.04 to 0.30 mg kg-1 (GB/T 22499-2008). However, further molecular studies are required, in order to completely access the inverted Se accumulation behavior in rice tissues at high Cd soil stress.

Alterations in transcriptome and antioxidant activity of naturally aged mice exposed to selenium-rich rice.

Selenium (Se) is a vital element which leads to strong antioxidation in animals and humans. However, the mechanism underlying natural cereal Se-induced biological changes is not well understood. This study intended to explore the gene differential expression in naturally aged mice exposed to selenium by RNA-Seq technique. A total spectrum of 53 differentially expressed genes was quantified in mice heart tissues treated with Se-rich and general rice. The GO functional annotation of differentially expressed genes disclosed the enrichment of cellular process, ionic binding, biological regulation, and catalytic activity. One hundred twenty-three differential pathways (cardiovascular diseases, immune system, transport and catabolism, longevity regulating, and PI3K-AKT signaling) were identified according to KEGG metabolic terms. Afterwards, the effect of Se-rich rice on the antioxidant activity was assessed. The selenium-rich diet increased the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in mice serum and livers while significantly reduces methane dicarboxylic aldehyde (MDA) contents. FOXO1 and FOXO3 genes, which acted as the regulators of apoptosis and the antioxidant enzyme, were significantly enhanced in mice when fed with Se-rich rice. In short, the present findings disclosed the alluring insights of organic and inorganic selenium sources on certain biological processes and antioxidant activity of living bodies. However, long-term trials are still required to draw a definitive conclusion, including risks and benefit analysis for various management strategies.

Accumulation, mobilization, and transformation of selenium in rice grain provided with foliar sodium selenite.

BACKGROUND: Selenium is an indispensable trace element for humans and its deficiency can lead to serious health complications. Nearly 70% of the area of China faces selenium deficiency. To deal with this problem, selenium-enriched rice has been increasingly incorporated into everyday diets. However, there is a lack of in-depth studies of the absorption, translocation, and transformation of selenium in the different parts of the rice plant when sprayed with sodium selenite. RESULTS: Foliar sodium selenite applied at critical growth stages can significantly improve the total and organic selenium content of plants. Application of 10 mg L-1 sodium selenite led to the most organic selenium (0.03 mg kg-1 ) in polished rice. Correlation studies of sodium selenite applied to leaves and other plant parts showed that total selenium accumulated most in glume, followed by rice bran, then polished rice, and finally embryo. The behavior of organic selenium was different. Organic selenium accumulated most in polished rice, then embryo, then rice bran, and finally glume. Moreover, 75-85% of the Se found in polished rice and embryo was organic in nature. CONCLUSIONS: We propose that 10 mg L-1 sodium selenite can be recommended as appropriate for foliar fertilization in the organic selenium biofortification of Se-free rice. © 2018 Society of Chemical Industry.