Polyamines play an important role in plant response to abiotic stress. S-adenosyl-1-methionine decarboxylase (SAMDC) is one of the key regulatory enzymes in the biosynthesis of polyamines. In order to better understan...Polyamines play an important role in plant response to abiotic stress. S-adenosyl-1-methionine decarboxylase (SAMDC) is one of the key regulatory enzymes in the biosynthesis of polyamines. In order to better understand the effect of regulation of polyamine biosynthesis on the shelf life improvement of litchi fruit, SAMDC cDNA isolated from Datura stramonium cloned in pBI121 was introduced into litchi genome by means of Agrobacterium tumefaciens through zygote disc transformation. Transgene and its expression are confirmed by Southern and Northern blot analyses, respectively. Transgenic plants expressing Datura SAMDC produced 1.7- to 2.4-fold higher levels of spermidine and spermine than wildtype plants under normal environmental condition, which indicated that the transgenic litchi presented an enhanced polyamines synthesis compared to wildtype plants. Our results demonstrated clearly that increasing polyamine biosynthesis in plants may be a means of creating improved fruit shelf life germplasm.展开更多
Objective：To generate recombinant adenovirus that could simultaneously express ornithine decarboxylase（ODC） and S-adenosylmethionine decarboxylase（AdoMetDC） antisenses specifically in prostate cancer cells,and ev...Objective：To generate recombinant adenovirus that could simultaneously express ornithine decarboxylase（ODC） and S-adenosylmethionine decarboxylase（AdoMetDC） antisenses specifically in prostate cancer cells,and evaluate its inhibitory effect on prostate cancer in vivo.Methods：Fragments of ODC and AdoMetDC genes were generated by PCR,cloned into the pPGL-PSES,and then recombined with pAdEasy-1 vectors in AdEasy-1 cells.Ad-PSES-ODC-AdoMetDCas virus was produced in HEK293 cells.Following transfection with Ad-PSES-ODC-AdoMetDCas,the levels of ODC or AdoMetDC were determined by RT-PCR and western blot assays.The effect of Ad-PSES-ODC-AdoMetDCas treatment on tumor formation and growth was evaluated in xenograft models of prostate cancers in vivo.Results：The plasmid pAdEasy-PSES-ODC-AdoMetDCas was successfully constructed and the recombinant Ad-PSES-ODC-AdoMetDCas adenovirus was produced.Transfection with Ad-PSES-ODC-AdoMetDCas adenovirus significantly inhibited the expression of ODC and AdoMetDC genes specifically in prostate DU145 cells,but not H1299,HT29 and HepG2 cancer cells,and disrupted the ability of DU145 cells to form solid prostate cancer in vivo.Intratumoral treatment with Ad-PSES-ODC-AdoMetDCas adenovirus significantly inhibited the growth of engrafted prostate tumors in vivo.Conclusion：The recombinant Ad-PSES-ODC-AdoMetDCas adenovirus specifically reduces the expression of both ODC and AdoMetDC genes in prostate cells and may be used for treatment of prostate cancers at the clinic.展开更多
To study gene control mechanisms in Xenopus embryos, we analyzed polyamines, cloned SAMDC (S-adenosylmethionine decarboxylase), a key enzyme of polyamine metabolism, and microinjected its mRNA into Xenopus fertilized ...To study gene control mechanisms in Xenopus embryos, we analyzed polyamines, cloned SAMDC (S-adenosylmethionine decarboxylase), a key enzyme of polyamine metabolism, and microinjected its mRNA into Xenopus fertilized eggs. The microinjection induced a large increase in SAMDC activity, exhaustion of the substrate SAM (S-adenosylmethionine), and execution of apoptosis at the stage called midblastula transition (MBT). By tracing GFP (green fluorescence protein)-marked apoptotic cells, we reached a conclusion that the apoptosis provides pre-blastula embryos with a fail-safe mechanism of early development. We analyzed caspase mRNAs and found that caspase-9 and -3 mRNAs are maternal mRNA and activation of caspase-9 is one of the key steps for the execution of the apoptosis. We also found that over- expression of caspase-8, and in addition p53, a tumor suppressor protein, also induces apoptosis at MBT, just like the overexpression of SAMDC and caspase-9 does. The apoptosis induced by p53 was suppressed by Xdm-2, a negative regulator of p53, and by a peptide inhibitor and a dominant-negative type mutant of caspase-9, but not by those of caspase-8. By contrast, apoptosis induced by SAMDC was suppressed by peptide inhibitors and dominant-negative mutants of both caspase-9 and caspase-8, but not by Xdm-2. Unlike caspase-9 mRNA, caspase-8 mRNA was not a maternal mRNA, but newly expressed during cleavage stage (pre-MBT stage) only in embryos overexpressed with SAMDC. In SAMDC-induced apoptotic embryos activities to process procaspase-8 and procaspase-9 appeared, whereas in p53-induced apoptotic embryos only activity to process procaspase-9 appeared. Thus, Xenopus embryos have at least two pathways to execute the maternal program of apoptosis: One induced by SAMDC overexpression through activation of caspase-9 and do novo expression of caspase-8 gene, and the other induced by p53 overexpression through activation of caspase-9 but not caspase-8. In Xenopus embryos, it has long been believed that zygotic genes are silent until MBT, but results obtained with caspase-8 may provide a novel example of gene expression before MBT.展开更多
Polyamines play an important role in plant response to abiotic stress. S-adenosyl-l-methionine decarboxylase （SAMDC） is one of the key regulatory enzymes in the biosynthesis of polyamines. In order to better underst...Polyamines play an important role in plant response to abiotic stress. S-adenosyl-l-methionine decarboxylase （SAMDC） is one of the key regulatory enzymes in the biosynthesis of polyamines. In order to better understand the effect of regulation of polyamine biosynthesis on the tolerance of high-temperature stress in tomato, SAMDC cDNA isolated from Saccharomyces cerevisiae was introduced into tomato genome by means of Agrobacterium tumefaciens through leaf disc transformation. Transgene and expression was confirmed by Southern and Northern blot analyses, respectively. Transgenic plants expressing yeast SAMDC produced 1.7- to 2.4-fold higher levels of spermidine and spermine than wildtype plants under high temperature stress, and enhanced antioxidant enzyme activity and the protection of membrane lipid peroxidation was also observed. This subsequently improved the efficiency of CO2 assimilation and protected the plants from high temperature stress, which indicated that the transgenic tomato presented an enhanced tolerance to high temperature stress （38℃） compared with wild-type plants. Our results demonstrated clearly that increasing polyamine biosynthesis in plants may be a means of creating high temperature-tolerant germplasm.展开更多
文摘Polyamines play an important role in plant response to abiotic stress. S-adenosyl-1-methionine decarboxylase (SAMDC) is one of the key regulatory enzymes in the biosynthesis of polyamines. In order to better understand the effect of regulation of polyamine biosynthesis on the shelf life improvement of litchi fruit, SAMDC cDNA isolated from Datura stramonium cloned in pBI121 was introduced into litchi genome by means of Agrobacterium tumefaciens through zygote disc transformation. Transgene and its expression are confirmed by Southern and Northern blot analyses, respectively. Transgenic plants expressing Datura SAMDC produced 1.7- to 2.4-fold higher levels of spermidine and spermine than wildtype plants under normal environmental condition, which indicated that the transgenic litchi presented an enhanced polyamines synthesis compared to wildtype plants. Our results demonstrated clearly that increasing polyamine biosynthesis in plants may be a means of creating improved fruit shelf life germplasm.
基金supported by the National Natural Science Foundation of China(No.30900730)the grants from the Natural Science Foundation of Shangdong Province(No.Q2007D01)
文摘Objective：To generate recombinant adenovirus that could simultaneously express ornithine decarboxylase（ODC） and S-adenosylmethionine decarboxylase（AdoMetDC） antisenses specifically in prostate cancer cells,and evaluate its inhibitory effect on prostate cancer in vivo.Methods：Fragments of ODC and AdoMetDC genes were generated by PCR,cloned into the pPGL-PSES,and then recombined with pAdEasy-1 vectors in AdEasy-1 cells.Ad-PSES-ODC-AdoMetDCas virus was produced in HEK293 cells.Following transfection with Ad-PSES-ODC-AdoMetDCas,the levels of ODC or AdoMetDC were determined by RT-PCR and western blot assays.The effect of Ad-PSES-ODC-AdoMetDCas treatment on tumor formation and growth was evaluated in xenograft models of prostate cancers in vivo.Results：The plasmid pAdEasy-PSES-ODC-AdoMetDCas was successfully constructed and the recombinant Ad-PSES-ODC-AdoMetDCas adenovirus was produced.Transfection with Ad-PSES-ODC-AdoMetDCas adenovirus significantly inhibited the expression of ODC and AdoMetDC genes specifically in prostate DU145 cells,but not H1299,HT29 and HepG2 cancer cells,and disrupted the ability of DU145 cells to form solid prostate cancer in vivo.Intratumoral treatment with Ad-PSES-ODC-AdoMetDCas adenovirus significantly inhibited the growth of engrafted prostate tumors in vivo.Conclusion：The recombinant Ad-PSES-ODC-AdoMetDCas adenovirus specifically reduces the expression of both ODC and AdoMetDC genes in prostate cells and may be used for treatment of prostate cancers at the clinic.
文摘To study gene control mechanisms in Xenopus embryos, we analyzed polyamines, cloned SAMDC (S-adenosylmethionine decarboxylase), a key enzyme of polyamine metabolism, and microinjected its mRNA into Xenopus fertilized eggs. The microinjection induced a large increase in SAMDC activity, exhaustion of the substrate SAM (S-adenosylmethionine), and execution of apoptosis at the stage called midblastula transition (MBT). By tracing GFP (green fluorescence protein)-marked apoptotic cells, we reached a conclusion that the apoptosis provides pre-blastula embryos with a fail-safe mechanism of early development. We analyzed caspase mRNAs and found that caspase-9 and -3 mRNAs are maternal mRNA and activation of caspase-9 is one of the key steps for the execution of the apoptosis. We also found that over- expression of caspase-8, and in addition p53, a tumor suppressor protein, also induces apoptosis at MBT, just like the overexpression of SAMDC and caspase-9 does. The apoptosis induced by p53 was suppressed by Xdm-2, a negative regulator of p53, and by a peptide inhibitor and a dominant-negative type mutant of caspase-9, but not by those of caspase-8. By contrast, apoptosis induced by SAMDC was suppressed by peptide inhibitors and dominant-negative mutants of both caspase-9 and caspase-8, but not by Xdm-2. Unlike caspase-9 mRNA, caspase-8 mRNA was not a maternal mRNA, but newly expressed during cleavage stage (pre-MBT stage) only in embryos overexpressed with SAMDC. In SAMDC-induced apoptotic embryos activities to process procaspase-8 and procaspase-9 appeared, whereas in p53-induced apoptotic embryos only activity to process procaspase-9 appeared. Thus, Xenopus embryos have at least two pathways to execute the maternal program of apoptosis: One induced by SAMDC overexpression through activation of caspase-9 and do novo expression of caspase-8 gene, and the other induced by p53 overexpression through activation of caspase-9 but not caspase-8. In Xenopus embryos, it has long been believed that zygotic genes are silent until MBT, but results obtained with caspase-8 may provide a novel example of gene expression before MBT.
基金Supported by the State Key Basic Research and Development Plan of China (2009CB119000)the National Natural Science Foundation of China(30571268)the Hi-Tech Research and Development Plan of China(G2006AA100108)
文摘Polyamines play an important role in plant response to abiotic stress. S-adenosyl-l-methionine decarboxylase （SAMDC） is one of the key regulatory enzymes in the biosynthesis of polyamines. In order to better understand the effect of regulation of polyamine biosynthesis on the tolerance of high-temperature stress in tomato, SAMDC cDNA isolated from Saccharomyces cerevisiae was introduced into tomato genome by means of Agrobacterium tumefaciens through leaf disc transformation. Transgene and expression was confirmed by Southern and Northern blot analyses, respectively. Transgenic plants expressing yeast SAMDC produced 1.7- to 2.4-fold higher levels of spermidine and spermine than wildtype plants under high temperature stress, and enhanced antioxidant enzyme activity and the protection of membrane lipid peroxidation was also observed. This subsequently improved the efficiency of CO2 assimilation and protected the plants from high temperature stress, which indicated that the transgenic tomato presented an enhanced tolerance to high temperature stress （38℃） compared with wild-type plants. Our results demonstrated clearly that increasing polyamine biosynthesis in plants may be a means of creating high temperature-tolerant germplasm.
