Study On The Effects Of Typical Inorganic Selenium On Earthworm Metabolism And Bioavailability

Chapter 1: Selenium is an essential micronutrient for human beings and animals.This mainly introduces its basic properties and dual biological effects,existing forms and distribution in nature,development status of Selenium-rich agriculture and possible ecological problems.The toxicological research progress of earthworms(Eisenia foetida)and the application of metabonomics in toxicological research were briefly summarized.Chapter 2: An ultra-performance liquid chromatography-electrospray ionization-mass spectrometry(UPLC-ESI-MS)method was developed for the determination of the seleno amino acids in earthworms.Selenomethione(Se Met)and methylselenocysteine(Me Se Cys)were extracted from earthworms by oscillating and ultrasound assisted enzymatic hydrolysis.These two seleno amino acids were isolated and determined by HPLC-ESI-MS with the positive ion and multiple reaction monitoring(MRM)mode.External standard method was used to quantify.Our results indicated that both Se Met and Me Se Cys had a good calibration curve in a range of 4-600 ng·m L-1,with R2 > 0.9999.The method detection limits of Se Met and Me Se Cys were 0.49 ?g·g-1 and 0.67 ?g·g-1,respectively.The recoveries of standard addition were 81.1-112.4%,with relative standard deviation(RSD)values less than 3.1%.This detection method was preferred over others as it had eliminated the cumbersome procedures,such as pre-column derivatization and the opposite direction gas addition.Chapter 3: After exposure to different concentrations of sodium selenite in artificial soil for 14 days,the contents of leucine,alanine,glycine,valine,lysine,phenylalanine and tyrosine metabolites in earthworms were determined by ultra-performance liquid chromatography electrospray ionization mass spectrometry(UPLC-ESI-MS).Principal component analysis(PCA),contribution value,change rate and growth inhibition rate of these metabolites were analyzed.The results showed that the change rate of metabolites at sodium selenite concentrations of 3 mg·kg-1 and 70 mg·kg-1 were significantly different from those of the control group.Chapter 5: After exposure to different concentrations of sodium selenite,the metabolites,total selenium and selenium amino acids in earthworms were measured and analyzed.It was found that different concentrations of sodium selenite affected the metabolism of earthworms.Furthermore,different concentrations of sodium selenite could affect the bioavailability and absorption ability of selenium for biota.