title: Gene cloning, expression and activity analysis of manganese superoxide dismutase from two strains of Gracilaria lemaneiformis (Gracilariaceae, Rhodophyta) under heat stress.
abstract: Manganese superoxide dismutase (Mn-SOD) plays a crucial role in antioxidant responses to environmental stress. To determine whether Mn-SOD affects heat resistance of Gracilaria lemaneiformis, we cloned Mn-SOD cDNA sequences of two strains of this red alga, wild type and cultivar 981. Both cDNA sequences contained an ORF of 675 bp encoding 224 amino acid residues. The cDNA sequences and the deduced amino acid sequences of the two strains shared relatively high identity (more than 99%). No intron existed in genomic DNA of Mn-SOD in G. lemaneiformis. Southern blotting indicated that there were multiple copies, possibly four, of Mn-SOD in both strains. Both in the wild type and cultivar 981, SOD mRNA transcription and SOD activity increased under high temperature stress, while cultivar 981 was more heat resistant based on its SOD activity. This research suggests that there may be a direct relationship between SOD activity and the heat resistance of G. lemaneiformis.
authors.affiliation: Key Laboratory of Marine Genetics and Breeding, Ministry of Education, Ocean University of China, Qingdao 266003, China. xnzang@ouc.edu.cn
authors.forename: Ning
authors.initials: N
authors.lastname: Lu
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Zang
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Zhang
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Feng
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D004789:Enzyme Activation; D044724:Gracilaria / Q000201:enzymology*; D006358:Hot Temperature; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017385:Sequence Homology; D013482:Superoxide Dismutase / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D013482:Superoxide Dismutase