title: Polyamine effects on protein disulfide isomerase expression and implications for hypersalinity stress in the marine alga Ulva lactuca Linnaeus(1).
abstract: Full-length protein disulfide isomerase (UfPDI) cDNA was cloned from the intertidal macroalga Ulva lactuca Linnaeus. Modulation of UfPDI expression by stresses and polyamines (PA) was studied. UfPDI transcription and enzyme activity were increased by hypersalinity (90) or high light illumination (1,200 μmol photons · m(-2)  · s(-1) ), decreased by the addition of 100 μM CuSO4 . An exposure to a salinity of 90 decreased PA contents. Treating with PA biosynthetic inhibitors, D-arginine (D-Arg) or α-methyl ornithine (α-MO), led to a further decrease and also inhibited UfPDI expression and recovery of the growth rate. These results suggest that PAs are required to activate UfPDI expression with hypersalinity, even PA contents are decreased at a salinity of 90. The induction of UfPDI expression by hypersalinity of 90 and tolerance to hypersalinity could be enhanced if internal PA contents rise. Sung et al. (2011b) showed that PA contents could be increased by pretreating with putrescine (Put, 1 mM), spermidine (Spd, 1 mM), or spermine (Spm, 1 mM) at a salinity of 30. Therefore, PA pretreatment effect on UfPDI expression was examined. Pretreatment with Spd and Spm, but not with Put, enhanced UfPDI expression after transferred to a salinity of 90 and restored the growth rate. In conclusion, induction of UfPDI expression by Spd or Spm before exposure to hypersaline conditions and continuous up-regulation after hypersalinity exposure are required for the acquisition of hypersalinity tolerance in the intertidal green macroalga U. lactuca.
authors.affiliation: Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Lu-Chuan
authors.initials: LC
authors.lastname: Li
authors.affiliation: Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Yuan-Ting
authors.initials: YT
authors.lastname: Hsu
authors.affiliation: Institute of Marine Biology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.|Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.|The Asia-Pacific Ocean Research Center, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Hsueh-Ling
authors.initials: HL
authors.lastname: Chang
authors.affiliation: Institute of Marine Biology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Tzure-Meng
authors.initials: TM
authors.lastname: Wu
authors.affiliation: Institute of Marine Biology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Ming-Shiuan
authors.initials: MS
authors.lastname: Sung
authors.affiliation: Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Chung-Lung
authors.initials: CL
authors.lastname: Cho
authors.affiliation: Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.|Institute of Marine Biology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.|Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Tse-Min
authors.initials: TM
authors.lastname: Lee
keywords: Ulva lactuca; acclimation; hypersalinity stress; polyamine; protein disulfide isomerase