title: Influences of calcium deficiency and cerium on the conversion efficiency of light energy of spinach.
abstract: Chloroplast absorbs light energy and transforms it into electron energy, and then converts it into active chemical energy and stable chemical energy. In the present paper, we investigated the effects of Ce(3+), which has the most significant catalytic effects and similar characteristics with Ca(2+), on light energy conversion of spinach chloroplasts under Ca(2+)-deficient stress. The results illuminated that the Hill reaction activity, electron flow both photosystems and photophosphorylation rate of spinach chloroplasts reduced significantly under Ca(2+)-deficient condition, and activities of Mg(2+)-ATPase and Ca(2+)-ATPase on the thylakoid membrane were severely inhibited. Meanwhile, the activity of Rubisco, which is the key enzyme of photosynthetic carbon assimilation, was also prohibited. However, Ce(3+) decreased the inhibition of calcium deprivation the electron transport rate, the oxygen evolution rate, the cyclic and noncyclic photophosphorylation, the activities of Mg(2+)-ATPase, Ca(2+)-ATPase and Rubisco of spinach chloroplasts. All above implied that Ca(2+)-depletion could disturb light energy conversion of chloroplasts strongly, which could be reversed by Ce(3+).
authors.affiliation: Medical College of Soochow University, Suzhou 215123, P.R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Huang
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Liu
authors.forename: Chunxiang
authors.initials: C
authors.lastname: Qu
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Fashui
authors.initials: F
authors.lastname: Hong
mesh_terms: D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002118:Calcium / Q000172:deficiency* / Q000494:pharmacology*; D002563:Cerium / Q000494:pharmacology*; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D004579:Electron Transport; D008027:Light; D010100:Oxygen / Q000378:metabolism; D010785:Photophosphorylation / Q000187:drug effects*; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D018724:Spinacia oleracea / Q000187:drug effects* / Q000378:metabolism
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D002563:Cerium; D017301:Ca(2+) Mg(2+)-ATPase; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen; D002118:Calcium