Studies On The Physiology And Biochemistry Of Selenium-enriched Rice And The Antioxidant Activities Of Selenium-containing Proteins

Selenium is an important element in humans and animals.Its beneficial and toxic effects depend on the dose,morphology and biological effectiveness.At present,many selenium-enriched products increase their selenium content through exogenous selenium application,but their effective absorption and utilization for selenium is far less than selenium-enriched materials.In this paper,selenium-enriched rice was chosen as the research material to study the relationship between selenium and protein of selenium-enriched and non-selenium-enriched materials and the differential expression level between proteome and metabolome,and animal modeling experiments were made to systematically study the physiological and biochemical characteristics of selenium-enriched rice and the antioxidant activity of selenoprotein,aiming at providing a scientific basis for the safe use of selenium in agricultural production and the development and utilization of rice selenoprotein.The main conclusions of this study are as follows:1.Selenium content in different parts of rice grains is positively correlated with protein content.Selenium content in the embryos of selenium-enriched rice is highest,and selenium content in other parts is gradually decreasing from the outer to the inner.The molecular weight of Z3057 B protein in selenium-enriched rice is mainly distributed in 13.6~122.6 kDa.The protein of each molecular weight is bound to selenium,but the binding amount of selenium is negatively correlated with the molecular weight of protein.The content of the protein with the molecular weight of 13.4kDa is the highest,accounting for 38.7% of total protein content.67.5% of the selenium is bound to the protein with a molecular weight of not more than 38.8 kDa.2.The quantitative proteomics and metabolomics research methods of rice based on iTRAQ technology were used to find out the difference in expression levels between proteome and metabolome for selenium-enriched rice(Z3057B)and non-selenium-enriched rice(Chenghui 727).There were 401 differential proteins between selenium-enriched rice and non-selenium-enriched rice,among which there were 193 up-regulated differential proteins and 208 down-regulated differential proteins.77 target differential proteins were obtained by bioinformatics analysis,which were mainly divided into oxidoreductase,transferase,isomerase,heat shock protein,lyase,hydrolase,ligase,synthetase,tubulin and actin.Differential metabolites include flavonoids,amino acids,catechins,organic acids,nucleotides,proanthocyanidins,sugars,and plant hormones and so on.By bioinformatics analysis of differential proteins and differential metabolites,it was found that anti-stress,anti-oxidation,active oxygen metabolism,carbohydrate and amino acid metabolism of selenium-enriched rice were stronger than those of non-selenium-enriched rice,but their effect involving in starch synthesis route was weaker than that of non-selenium-enriched rice.CYS and metE may be the two key proteins that cause amino acid differences between the two types of rice.OsAPx02,CatC,riPHGPX and HSP70,HSP90 may be key genes regulating the antioxidant and anti-stress effects of the two types of rice.3.Selenium-rich rice,non-selenium-rich rice and inorganic selenium source were treated in elderly mouse model to explore the difference between selenium-rich rice and inorganic selenium on animal body.The high selenium caused high total antioxidant capacity(T-AOC),high superoxide dismutase(SOD),low methane dicarboxylic aldehyde(MDA)and the increase glutathione peroxidase(GSH-Px)in livers of mice.The study aims to explore the gene alterations in hearts of elderly mice exposed to selenium by using the RNA-Seq technique.Between non-selenium rich white rice and selenium-rich polished rice groups,53 genes were significantly differentially expressed.Gene ontology(GO)analysis suggested that cellular process,binding,biological regulation and catalytic activity accounted for the majority of differentially expressed genes.Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis indicated that Se might be involved in 123 pathways,such as colorectal cancer,prostate cancer,small cell lung cancer,longevity regulating pathway and PI3K-AKT signaling pathway.4.The selenium protein extracted from selenium-enriched rice(Z3057B)was used as the research object.The four proteins including water-soluble protein,salt-soluble protein,alcohol-soluble protein and alkali-soluble protein were extracted successively by continuous extraction method.The scavenging effect of four kinds of selenium-containing proteins on hydroxyl radicals and DPPH free radicals were measured by modified salicylic acid method.The results showed that the antioxidant capacity of selenoprotein was closely related to the selenium content,and the antioxidant capacity was followed by water-soluble protein > alkali soluble protein > salt soluble protein > alcohol soluble protein.The rice selenoprotein was mainly water-soluble protein.Selenium protein has certain effects on the immune system;its effects on the activities of T-AOC,GSH-Px and SOD in serum and liver of aging mice are significantly enhanced;it makes the content of MDA decreased.When the selenoprotein content of rice is 25?g/(kg.day),the damage of D-galactose to the liver can be significantly alleviated.In summary,as a supplement source of selenium,selenium-enriched rice meets the human demand for selenium,and it is safe to the human body and friendly to the environment.When non-selenium-enriched rice was selected for selenium application and enrichment treatment on leaf surfaces,it will be necessary to select the varieties sensitive to selenium and control the concentration of exogenous selenium application.Selenium protein extracted from selenium-enriched rice can be used as an anti-aging health food with great development potential.