Glutathione S-Transferase(GST)Identified from Giant Kelp Macrocystis pyrifera Increases the Copper Tolerance of Synechococcus elongatus PCC 7942

The glutathione S-transferases gene family plays an important regulatory role in growth and development,and responses to environmental change.In this study,six complete GST genes(Mp GST1,Mp GST2,Mp GST3,MpGST4,Mp GST5,and Mp GST6)were cloned from the gametophytes of brown alga Macrocystis pyrifera.Subsequent bioinformatics analysis showed that these six genes encoded proteins with 202,216,288,201,205,and 201 aa,respectively.Moreover,Mp GST3 differs from the other GST genes.Phylogenetic analysis suggested that MpGST3 belongs to the Ure2p type GST.Domain analysis suggested that the other GSTs from M.pyrifera belong to the soluble GST family and form an independent branch with the GSTs found in the other macroalgae,suggesting that a new GST type was formed during macroalgal evolution.GST genes were upregulated in M.pyrifera when 2.5 mg L^(-1)Cu ions were added to the medium.Six GST genes were integrated into the genome of Synechococcus elongatus PCC 7942,and their functions were verified by measuring light absorbance,photosynthetic pigment content,and photosynthetic parameters of the transformed strains under 0.3 mg L^(-1)Cu ion stress.The results showed much higher levels of various parameters in the transformed strains than in the wild strain.The transformed strains(with the MpGST genes)showed significantly enhanced resistance to Cu ion stress,while the wild strain almost died.The results of this study lay a theoretical foundation for further research on the Cu ion stress resistance function of GSTs in M.pyrifera.

Inhibitory activities of microalgal extracts against Epstein-Barr virus DNA release from lymphoblastoid cells

This study aimed to assess the inhibitory activities of methanol extracts from the microalgae Ankistrodesmus convolutus,Synechococcus elongatus,and Spirulina platensis against Epstein-Barr virus(EBV) in three Burkitt's lymphoma(BL) cell lines,namely Akata,B95-8,and P3HR-1.The antiviral activity was assessed by quantifying the cell-free EBV DNA using real-time polymerase chain reaction(PCR) technique.The methanol extracts from Ankistrodesmus convolutus and Synechococcus elongatus displayed low cytotoxicity and potent effect in re-ducing cell-free EBV DNA(EC50<0.01 μg/ml) with a high therapeutic index(>28 000).After fractionation by column chromatography,the fraction from Synechococcus elongatus(SEF1) reduced the cell-free EBV DNA most effectively(EC50=2.9 μg/ml,therapeutic index>69).Upon further fractionation by high performance liquid chromatography(HPLC),the sub-fraction SEF1'a was most active in reducing the cell-free EBV DNA(EC50=1.38 μg/ml,therapeutic index>14.5).This study suggests that microalgae could be a potential source of antiviral compounds that can be used against EBV.