Ce(III) Acts On Several Bioinorganic Chemical Behaviors Of Horseradish Cells

As rare earth elements(REEs) have excellent optical, electrical and magnetic properties, etc., they have been widely used in high-tech fields such as new energy, new material, biology, informatics, aeronautics and oceanology. Meanwhile, REEs have also been used in agricultural production. The widespread use of REEs has resulted in the accumulation of REEs in environment and organisms. It is harmful to the food safety, environmental safety and human health. Therefore, the in-depth investigation of REEs'biological effects and mechanism, especially revealing the cytological mechanism of REEs affecting organisms from the viewpoint of botanic inorganic chemistry is urgently needed. In this paper, horseradish (Armoracia rusticna), which is an economic plant for export, was selected as the experimental materials, the several bioinorganic chemical behavior of Ce(?) acting on horseradish cells was investigated by the optimal combination methods of cytochemistry (cellular radiochemistry and cellular histochemistry) and biophysical chemistry (microscopy, flow cytometry, laser confocal microscope, electrochemistry, computer simulation, patch clamp, scanning electron microscopy(SEM) equipped with X-ray energy dispersive spectrometer, X-ray photoelectron spectroscopy (XPS). The main results were shown as follows:(1) The intracellular behavior of Ce(?) acting on horseradish was observed by using electron microscope autoradiography (EMARG). Ce(?) in low concentration was anchored on plasma membrane as nano-particles and could not enter into cells. Ce(?) in high concentration was distributed on/in plasma membrane as well as entered into cells by unusual endocytosis, then it formed nanosphere (80-200 nm) by self-assembly in cells. We also observed that the endocytosis of horseradish cells could be activated by Ce(?) in either low or high concentration by using total internal reflection microscopy established by Gibiansky.(2) It was discovered that Ce(?) could affect the cellular behavior of K+ and Ca2+ by using patch clamp, non-electrical activity of ion detection device, flow cytometry and laser confocal microscope. Ce(?) in low concentration promoted the K+ and Ca2+ migration out of and into the cells while Ce(?) in high concentration inhibited the intracellular K+ migration out of the cells and promoted the extracellular K+ migration into the cells, and it could also promote the outward migration of intracellular Ca2+ and the release of intracellular calcium store which induced the intracellular Ca2+ overload. Meanwhile, it was indicated by molecular dynamics simulation that the property of Ce(?) is similar to that of Ca2+, therefore, Ce(?) could partly displace the Ca in CaM.(3) The change in the cytochemical behavior of Ce(?) and the cellular behavior of K+ and Ca2+ induced a series of complicated cytobiological and cytochemical responses from the extracellular to the intracellular space. Ce(?) in low concentration increased the expression of mannose residues out of.plasma membrane, improved the content of plasma membrane proteins and unsaturated fatty acids, increased the content of intracellular nutrient elements and DNA, inhibited the activity of intracellular antioxidant enzyme, and then promoted the cellular growth and development. Ce(?) in high concentration inhibited the expression of mannose residues out of plasma membrane, decreased the content of plasma membrane proteins and unsaturated fatty acids, decreased the content of intracellular nutrient elements and DNA, increased the activity of intracellular antioxidant enzyme, and then inhibited the cellular growth and development.(4) The unusual behavior of Ce(?) in plant cells was observed from the experimental results of EMARG and XPS. After the horseradish was treated with Ce(?) in high concentration, some of Ce(?)-contained nanospheres, which were self-assembled intracellularly, were discharged from horseradish leaves during the physiological activities and migrated to stern and root, it finally moved into soil. The other Ce(?)-contained nanospheres were embedded in mesophyll cells. The intracellular Ce(?) was partly oxidated into Ce(?) after the horseradish was treated with Ce(?) in either low or high concentration and it exists in the cells as the mix valence state of Ce(?) and Ce(?).