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Yang L.-E.,Nanjing University | Yang L.-E.,Jiangsu Institute of Oceanology and Marine Fisheries | Huang X.-Q.,Nanjing University | Lu Q.-Q.,Jiangsu Institute of Oceanology and Marine Fisheries | And 2 more authors.
Journal of Applied Phycology | Year: 2015

Carotenoid metabolism in red algae is not well understood. Geranylgeranyl diphosphate (GGPP), synthesized by GGPP synthase (GGPS), is a precursor for the biosynthesis of many biologically important metabolites, including carotenoids and chlorophylls. GGPSs have been functionally characterized in many organisms, but not in species of the primitive red algal order Bangiales. Here, we cloned and characterized the gene encoding GGPS (PuGGPS) in Pyropia umbilicalis (Bangiales). PuGGPS encodes a protein of 345 amino acids with an N-terminal transit peptide. The catalytic activity of PuGGPS for the production of GGPP was verified by a color complementation assay in Escherichia coli and subsequent high-performance liquid chromatography analysis. Homology modeling of PuGGPS showed that its tertiary structure resembles that of other known GGPSs and that this structure allows for the precise docking of the enzymatic product of PuGGPS, GGPP. When leafy thalli of P. umbilicalis were treated with norflurazon, an inhibitor of the key carotenoid metabolism enzyme phytoene desaturase, the expression of PuGGPS increased by twofold compared with that of the control in the first 2 h, suggesting a prompt response to metabolic perturbation. Prolonged norflurazon treatment failed to increase PuGGPS expression. Sequence analysis showed that PuGGPS shares seven conserved motifs with other previously identified GGPSs from different organisms, including two aspartate-rich GGPS signature motifs. Phylogenetic analysis also indicated that PuGGPS is a member of the type II GGPSs found in eubacteria and plants. © 2015 Springer Science+Business Media Dordrecht Source

He L.,CAS Qingdao Institute of Oceanology | He L.,University of Chinese Academy of Sciences | Zhu J.,Changshu Institute of Technology | Lu Q.,Jiangsu Institute of Oceanology and Marine Fisheries | And 4 more authors.
Journal of Phycology | Year: 2013

Pyropia yezoensis (Ueda) M. S. Hwang et H. G. Choi (previously called Porphyra yezoensis) is an economically important alga. The blades generated from conchospores are genetic chimeras, which are not suitable for genetic similarity analysis. In this study, two types of blades from a single filament of P. yezoensis sporophyte filament were obtained. One type, ConB, consisted of 40 blades that had germinated from conchospores. The other type, ArcB, consisted of 88 blades that had germinated from archeospores released from ConB. Both of them were analyzed by amplified fragment length polymorphism. The low genetic similarity levels for both conchospore-germinated and archeospore-germinated blades demonstrated that the conchcelis we used was cross-fertilized. Furthermore, a higher polymorphic loci ratio (98.6%) was detected in ArcB than in ConB (80.7%), and the average genetic similarity of ArcB (average 0.61) was lower than that of ConB (average 0.71). These differences indicated that genetic analysis using ArcB gives more accurate results. © 2013 Phycological Society of America. Source

Zhang T.,Changshu Institute of Technology | Li J.,Changshu Institute of Technology | Li J.,Nanjing Agricultural University | Ma F.,Changshu Institute of Technology | And 4 more authors.
Journal of Applied Phycology | Year: 2014

The photosynthetic characteristics of thalli of cultured Pyropia yezoensis strains collected in January, February, and March in seaweed cultivation area of South China Yellow Sea were studied. Results showed that the maximum quantum efficiency (Fv/Fm) of all P. yezoensis thallus collected at different times was 0.65. The actual quantum efficiency (ΔF/Fm′) of samples in January was the lowest of all samples, while the ΔF/Fm′ of samples in March was significantly higher than those in January and February. The increase of temperature and photosynthetic pigments ratios of phycoerythrin and chlorophyll a (PE/Chla) and phycocyanin and chlorophyll a (PC/Chla) from January to March may be the important reasons for the increase in light use efficiency of thallus; although the thallus in March was significantly thicker than in January which may have reduced the light energy absorbed by photosynthetic pigments, the increase of relative high energy use efficiency also helped to maintain the photosynthetic oxygen evolution rate in March. The thicker thallus also reduced photodamage, and the thallus area was increased obviously in March, so the growth rate of thallus in March was over 35 % higher than that in February. Our research indicates that the photosynthetic characteristics of P. yezoensis strains thalli have a close relationship with their growth stage and environmental factors especially temperature, and those photosynthetic characteristics are also reflected in the growth rate of the thalli. © 2013, Springer Science+Business Media Dordrecht. Source

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