Floral-dip法大豆GmDREB转录因子转拟南芥研究

DREB（dehydration responsive element binding）转录因子通过调控下游多个抗逆相关基因的表达,能有效提高植物的抗逆性。将构建的植物高效表达载体GmDREB：：pCAMBIA1304,借助优化的floral-dip法,转入模式植物拟南芥,并经潮霉素Hygromycine（40-50mg·L^-1）抗性筛选得到22棵抗性植株。对抗性植株再进行PCR和GUS检测获得19颗阳性苗,阳性率为86．3％。对T1代种子进行抗性分离比例统计,有4个株系的分离比例接近3：1,符合孟德尔遗传定律,说明外源基因GmDREB在这些株系的染色体中可能是单拷贝插入。继续对上述4个株系的后代进行抗性筛选．现已得到2个纯合的转基因株系。导入的报告基因GUS组织染色检测表明,转入大豆DREB基因在拟南芥的根系和子叶中均有大量表达,并在叶脉中表达。     

Analysis of synonymous codon usage patterns in the genus Rhizobium

The codon usage patterns of rhizobia have received increasing attention. However, little information is available regarding the conserved features of the codon usage patterns in a typical rhizobial genus. The codon usage patterns of six completely sequenced strains belonging to the genus Rhizobium were analysed as model rhizobia in the present study. The relative neutrality plot showed that selection pressure played a role in codon usage in the genus Rhizobium. Spearman’s rank correlation analysis combined with correspondence analysis (COA) showed that the codon adaptation index and the effective number of codons (ENC) had strong correlation with the first axis of the COA, which indicated the important role of gene expression level and the ENC in the codon usage patterns in this genus. The relative synonymous codon usage of Cys codons had the strongest correlation with the second axis of the COA. Accordingly, the usage of Cys codons was another important factor that shaped the codon usage patterns in Rhizobium genomes and was a conserved feature of the genus. Moreover, the comparison of codon usage between highly and lowly expressed genes showed that 20 unique preferred codons were shared among Rhizobium genomes, revealing another conserved feature of the genus. This is the first report of the codon usage patterns in the genus Rhizobium.     

Factors restraining parasitism of the invasive vine Mikania micrantha by the holoparasitic plant Cuscuta campestris

Mikania micrantha (Asteraceae) is one of the 10 most invasive weeds in the world and has caused tremendous economic and environmental losses in southern China. The dodder Cuscuta campestris (Convolvulaceae) is a native holoparasite that can parasitize and suppress M. micrantha, and thus is recommended as an effective control agent. However, the natural growth of dodder lags behind that of M. micrantha and fails to exert direct year-round suppression. To verify the effective parasitic distance, we placed a dodder seedling at a designated distance from the stem of M. micrantha and monitored coiling, haustorium formation, and survival. To verify suitable host stems for the parasite, we grew M. micrantha for more than 6 months to form stems of different sizes, taped dodder seedlings to the stems, and monitored. We used various temperatures to determine the effect on dodder seed germination and M. micrantha sprouting. The results showed that a dodder–host distance of 4 cm decreased the probability of successful parasitism to 0; dodder seedlings cannot parasitize M. micrantha stem diameters ≥0.3 cm; and the temperatures for the highest dodder seed germination and M. micrantha sprouting are 26 and 30 °C, respectively. We conclude that the lack of suitable M. micrantha parts within the dodder’s effective parasitism distance is the major cause of restricted dodder parasitism and that the lower temperature for the highest dodder germination compared to that for the highest M. micrantha sprouting may decrease the possibility of parasitism. To acquire aggressive parasitism, dodder should be manually assisted by dispersing its vegetative form.     

Enzymatic synthesis of antithrombin III-binding heparan sulfate pentasaccharide

Heparan sulfate (HS) proteoglycans are crucial to numerous biological processes and pathological conditions, but to date only a few HS structures have been synthesized and characterized with regard to structure-function relationships. Because HS proteoglycans are highly diverse in structure, there are substantial limitations on their synthesis by classical chemical means, and thus new methods to rapidly assemble bioactive HS structures are needed. Here we report the biosynthesis of bioactive HS oligosaccharides using an engineered set of cloned enzymes that mimics the Golgi apparatus in vitro. We rapidly and efficiently assembled the antithrombin III-binding pentasaccharide in just 6 steps, in contrast to the approximately 60 steps needed for its chemical synthesis, with an overall yield at least twofold greater and a completion time at least 100 times faster than for the chemical process.     

Post-immobilization of modified macromolecular reagents using assembled penicillin acylase for microenvironmental regulation of nanopores and enhancement of enzyme stability

Penicillin acylase (PA) is known to regulate the microenvironment of nanospores. In this study, nanopores containing chemically-modified macromolecules co-assembled with immobilized PA were constructed. We also investigated the various types of functionalized mesocellular siliceous foams (MCFs) commonly used for the immobilization of PA by measuring the catalytic performance and stability of each PA preparation. Amino-MCF activated by p-benzoquinone was chosen as the optimum support for PA immobilization. Successful modification of macromolecules was verified by FT-IR and ultraviolet (UV) spectroscopy. The specific activity of PA co-assembled with dextran 10 k was 99.1 U/mg, which was 1.5-fold that of pristine immobilized PA, while the optimum pH was shifted to neutral. Compared to pristine immobilized and free PA, the optimum temperatures for the modified PA were 5 and 10°C higher, respectively. The residual activity of the ficoll derivative of PA after treatment at 50°C for 6 h was 70%, and this was later increased to 214.5% compared to that of pristine immobilized PA. The dextran 10 k derivative of PA exhibited 90.2% residual activity after 25 times of continuous use. The results show that chemically-modified macromolecules co-assembled with PA in amino-MCF provided a suitable microenvironment for enzyme stability.     

Characterization,phylogeny, alternative splicing and expression of <Emphasis Type="Italic">Sox30</Emphasis> gene

Background  

Members of the Sox gene family isolated from both vertebrates and invertebrates have been proved to participate in a wide variety of developmental processes, including sex determination and differentiation. Among these members, Sox30 had been considered to exist only in mammals since its discovery, and its exact function remains unclear.     

芜湖市三种生境夏季鸟类多样性分析

1引言鸟类群落结构在一定程度上是鸟类之间相互关系的综合反映.一些鸟类对城市生态环境的变化反应非常敏感,因而对城市生态平衡和环境质量的变化能起到指示剂的作用[8].目前我国正处在城市化加速发展的时期,许多中等城市正在向大城市发展,城市生态建设面临巨大的压力和挑战.鸟类多样性是城市生物多样性的重要组成部分,对维持城市生态平衡具有重要的意义[13],而城市鸟类多样性研究能为城市的生态建设提供重要的参考依据.国内对城市鸟类群落的研究主要集中在北京、武汉、杭州等少数大城市,而对中小城市的研究不多[5,16～19].王宗英等[11]曾对…     

Involvement of Inducible 6-Phosphofructo-2-kinase in the Anti-diabetic Effect of Peroxisome Proliferator-activated Receptor γ Activation in Mice

PFKFB3 is the gene that codes for the inducible isoform of 6-phosphofructo-2-kinase (iPFK2), a key regulatory enzyme of glycolysis. As one of the targets of peroxisome proliferator-activated receptor γ (PPARγ), PFKFB3/iPFK2 is up-regulated by thiazolidinediones. In the present study, using PFKFB3/iPFK2-disrupted mice, the role of PFKFB3/iPFK2 in the anti-diabetic effect of PPARγ activation was determined. In wild-type littermate mice, PPARγ activation (i.e. treatment with rosiglitazone) restored euglycemia and reversed high fat diet-induced insulin resistance and glucose intolerance. In contrast, PPARγ activation did not reduce high fat diet-induced hyperglycemia and failed to reverse insulin resistance and glucose intolerance in PFKFB3^+/− mice. The lack of anti-diabetic effect in PFKFB3^+/− mice was associated with the inability of PPARγ activation to suppress adipose tissue lipolysis and proinflammatory cytokine production, stimulate visceral fat accumulation, enhance adipose tissue insulin signaling, and appropriately regulate adipokine expression. Similarly, in cultured 3T3-L1 adipocytes, knockdown of PFKFB3/iPFK2 lessened the effect of PPARγ activation on stimulating lipid accumulation. Furthermore, PPARγ activation did not suppress inflammatory signaling in PFKFB3/iPFK2-knockdown adipocytes as it did in control adipocytes. Upon inhibition of excessive fatty acid oxidation in PFKFB3/iPFK2-knockdown adipocytes, PPARγ activation was able to significantly reverse inflammatory signaling and proinflammatory cytokine expression and restore insulin signaling. Together, these data demonstrate that PFKFB3/iPFK2 is critically involved in the anti-diabetic effect of PPARγ activation.     

Tumor necrosis factor-alpha stimulates gastric epithelial cell proliferation

TNF-alpha is a cytokine produced during gastric mucosal injury. We examined whether TNF-alpha could promote mucosal repair by stimulation of epithelial cell proliferation and explored further the underlying mechanisms in a rat gastric mucosal epithelial cell line (RGM-1). TNF-alpha treatment (1-10 ng/ml) for 12 or 24 h significantly increased cell proliferation but did not induce apoptosis in RGM-1 cells. TNF-alpha treatment significantly increased cytosolic phospholipase A(2) and cyclooxygenase-2 (COX-2) protein expression and PGE(2) level but did not affect the protein levels of EGF, basic fibroblast growth factor, and COX-1 in RGM-1 cells. The mRNA of TNF receptor (TNF-R) 2 but not of TNF-R1 was also increased. Dexamethasone dose dependently inhibited the stimulatory effect of TNF-alpha on cell proliferation, which was associated with a significant decrease in cellular COX-2 expression and PGE(2) level. A selective COX-2 inhibitor 3-(3-fluorophenyl)-4-[4-(methylsulfonyl)phenyl]-5,5-dimethyl-(5)H-furan-2-one (DFU) by itself had no effect on basal cell proliferation but significantly reduced the stimulatory effect of TNF-alpha on RMG-1 cells. Combination of dexamethasone and DFU did not produce an additive effect. PGE(2) significantly reversed the depressive action of dexamethasone on cell proliferation. These results suggest that TNF-alpha plays a regulatory role in epithelial cell repair in the gastric mucosa via the TNF-alpha receptor and activation of the arachidonic acid/PG pathway.