RESUMO
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 wild-type 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 CO(2) assimilation and protected the plants from high temperature stress, which indicated that the transgenic tomato presented an enhanced tolerance to high temperature stress (38 degrees C) 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.
Assuntos
Temperatura Alta , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Poliaminas/metabolismo , Solanum lycopersicum/metabolismo , Solanum lycopersicum/fisiologia , Adenosilmetionina Descarboxilase/genética , Adenosilmetionina Descarboxilase/fisiologia , Agrobacterium tumefaciens/genética , Northern Blotting , Southern Blotting , Solanum lycopersicum/genética , Plantas Geneticamente Modificadas/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/fisiologiaRESUMO
S-adenosylmethionine decarboxylase activity (SAMDC) is a key enzyme involved in biosynthesis of the polyamines, viz. spermidine and spermine. In the present study, SAMDC gene analogues from 14 species of 6 genera in Cruciferae were obtained by PCR strategy using specific primers designed from conserved regions of SAMDC gene reported in the GenBank. The phylogenetic relationships of these species belonging to the family Cruciferae were investigated through comparison of the genes. Homologous sequences of SAMDC comparison indicated that the similarities among the genes at nucleotide and amino acid levels were over 87% and 90%, respectively. The differences in genes at nucleotide and amino acid levels between species ranged from 0.2 % to 10.1 % and 0.3% to 6.6%, respectively, while those between genera except Raphanus were 4.9 % to 13.6 % and 3.1 % to 10.3%, respectively. The differences of sequences of nucleotides and amino acids among genera were higher than those among species, and the differences of nucleotides sequences were higher than those of amino acids. The phylogenetic tree was thus constructed based on the alignment nucleotides sequences from Nei's genetic distances. The neighbor-joining (NJ) and minimum-evolution (ME) trees showed that Brassica was closely related to Raphanus, followed by Barbarea, Roripl Scop and Arabidopsis Heynh, but was remotely related to Capsella Medic. This research elucidated the relationship among crucifer species at nucleotide level, which could proved some help for the utilization of plant germplasms.
Assuntos
Adenosilmetionina Descarboxilase/genética , Brassicaceae/genética , Evolução Molecular , Proteínas de Plantas/genética , Sequência de Bases , Brassicaceae/classificação , Brassicaceae/enzimologia , Clonagem Molecular , Dados de Sequência Molecular , Filogenia , Homologia de Sequência do Ácido NucleicoRESUMO
Depletion of splenic and hepatic macrophages has potentials to alleviate hemorrhage in patients who suffered from immune thrombocytopenic purpura (ITP). This investigation was aimed to assess whether nanotechnology can play a role in this clinical setting by absorbing bisphosphonate clodronate (CLOD) to type A gelatin nanospheres (GNS) to form CLOD-GNS. First, the stability of CLOD-GNS was assessed in vitro and up to 6 mg CLOD can be adsorbed in 1 mg GNS. The ability of CLOD-GNS to target the spleen and the liver was then evaluated by biodistribution assay and 99mTc-CLOD-GNS scintigraphy in rats. It showed that up to 70.6% of CLOD-GNS could be accumulated in the liver and spleen. The survival of the macrophages in vitro and the phagocytic ability of hepatic and splenic macrophage in vivo were reduced and later demonstrated by 99mTc-phytic colloid scintigraphy. In rats with induced ITP, administration of CLOD-GNS successfully prevented peripheral platelet levels from decreasing. Our preliminary data demonstrate that CLOD-GNS can effectively target reticuloendothelial system and its potentials in the treatment of ITP warrants further study.
