Expression of antimicrobial peptides thanatin(S) in transgenic Arabidopsis enhanced resistance to phytopathogenic fungi and bacteria

Thanatin(S) is an analog of thanatin, an insect antimicrobial peptide possessing strong and broad spectrum of antimicrobial activity. In order to investigate if the thanatin could be used in engineering transgenic plants for increased resistance against phytopathogens, the synthetic thanatin(S) was introduced into Arabidopsis thaliana plants. To increase the expression level of thanatin(S) in plants, the coding sequence was optimized by plant-preference codon. To avoid cellular protease degradation, signal peptide of rice Cht1 was fused to N terminal of thanatin(S) for secreting the expressed thanatin(S) into intercellular spaces. To evaluate the application value of thanatin(S) in plant disease control, the synthesized coding sequence of Cht1 signal peptide (Cht1SP)-thanatin(S) was ligated to plant gateway destination binary vectors pGWB11 (with FLAG tag). Meanwhile, in order to observe the subcellular localization of Cht1SP-thanatin(S)-GFP and thanatin(S)-GFP, the sequences of Cht1SP-thanatin(S) and thanatin(S) were respectively linked to pGWB5 (with GFP tag). The constructs were transformed into Arabidopsis ecotype Col-0 and mutant pad4-1 via Agrobacterium-mediated transformation. The transformants with Cht1SP-thanatin(S)-FLAG fusion gene were analyzed by genomic PCR, real-time PCR, and western blots and the transgenic Arabidopsis plants introduced respectively Cht1SP-thanatin(S)-GFP and thanatin(S)-GFP were observed by confocal microscopy. Transgenic plants expressing Cht1SP-thanatin(S)-FLAG fusion protein showed antifungal activity against Botrytis cinerea and powdery mildew, as well as antibacterial activity against Pseudomonas syringae pv. tomato. And the results from confocal observation showed that the GFP signal from Cht1SP-thanatin(S)-GFP transgenic Arabidopsis plants occurred mainly in intercellular space, while that from thanatin(S)-GFP transgenic plants was mainly detected in the cytoplasm and that from empty vector transgenic plants was distributed uniformly throughout the cell, demonstrating that Cht1 signal peptide functioned. In addition, thanatin(S) and thanatin(S)-FLAG chemically synthesized have both in vitro antimicrobial activities against P. syringae pv. tomato and B. cinerea. So, thanatin(S) is an ideal candidate AMPs for the construction of transgenic crops endowed with a broad-spectrum resistance to phytopathogens and the strategy is feasible to link a signal peptide to the target gene.     

Association study between of Tie2/Angiopoietin-2 and VEGF/KDR pathway gene polymorphisms and vascular malformations

Vascular malformations (VMs) are common congenital and neonatal dysmorphogenesis. VMs mostly occur sporadically with a few exceptions of inheritability. Tie2/angiopoietins-2 (Ang-2) and VEGF/KDR pathways are known to be involved in normal and pathogenic angiogenesis. Our study was aimed to test the contribution of these pathway gene variants to VMs. A total of 8 variants were found among 103 VM patients and 142 healthy controls. These variants comprised rs638203, rs639225, rs80338908 and rs80338909 in Tie2 gene, rs1870377 and rs2305949 in KDR gene, rs79337921 and rs34590960 in ANTXR1 gene. Our results indicated that rs638203 (p = 0.029) and rs639225 (p = 0.018) in Tie2 gene were associated with VM. A further bioinformatics analysis suggested the rs638203-G and rs639225-G might cause an abnormal splicing of Tie2 gene into to a defective protein. Our results identified two novel Tie2 gene polymorphisms with genetic susceptibility to VMs, although future functional validation of the two polymorphisms is warranted in the future.     

Evaluation of glutathione S-transferase genetic variants affecting type 2 diabetes susceptibility: A meta-analysis

Genetic polymorphisms of glutathione S-transferases (GSTs) and type 2 diabetes mellitus (T2DM) risk have been widely studied, however, the results were somewhat conflicting. To evaluate the association of GSTs (GSTM1, GSTT1 and GSTP1) gene polymorphisms with T2DM, a meta-analysis was performed before October, 2012. ORs were pooled according to random-effects model. There were a total of 1354/1666 (n = 9) cases/controls (studies) for GSTM1, 1271/1470 (n = 8) for GSTT1, and 1205/1250 (n = 7) for GSTM1. There were significant associations between GSTM1 polymorphism, GSTT1 polymorphism and T2DM in the contrast of present genotype vs. null genotype, with pooled OR = 1.99 (95%CI = 1.46–2.71) and OR = 1.61 (95%CI = 1.19–2.17), respectively. Yet no significant association of GSTP1 polymorphism and T2DM was showed. When stratified by ethnicity, the significant associations were also existed in Asians for GSTM1 and GSTT1, but not GSTP1. No publication bias but some extent of heterogeneity was observed. Finally, the accumulated evidence proved the obvious associations of GSTM1 and GSTT1 polymorphisms with an increased risk of T2DM.     

Analysis of genetic variability and relationships among Mentha L. using the limonene synthase gene, LS

The genus Mentha comprises a group of aromatic plants with worldwide distribution. Because of frequent interspecific hybridization, the genetic relationships within the genus are not clearly understood. Limonene synthase, which catalyses the first committed step in the essential oil monoterpene biosynthetic pathway, is considered to be a possible rate limiting enzyme. With the homology-based cloning method, primers were designed according to cDNA sequence to amplify full-length DNA sequences in 13 Mentha samples from five species, using Perilla as an outgroup. Analyses of gene structure, length variation, GC-content, Ts/Tv ratio and evolutionary diversity were carried out. Consensus phylogenetic trees were obtained using maximum likelihood, neighbor-joining, and maximum parsimony, respectively, based on the full-length genomic DNA sequences, complete ORF coding sequences and predicted amino acid sequences. The results presented here based on the sequence of MhLS provide the first credibly supported genetic relationships for Mentha, which enables a basis for further mint taxonomy, cultivation and breeding.     

Myeloperoxidase G-463A polymorphism and susceptibility to coronary artery disease: A meta-analysis

Published data on the association between the myeloperoxidase (MPO) G-463A polymorphism and coronary artery disease (CAD) are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis on this topic was performed. PubMed, EMBASE and Chinese national knowledge infrastructure were searched for studies regarding the association between the MPO G-463A polymorphism and CAD. A logistic regression analysis was used to estimate the genetic effect and the possible genetic model of action. Summary odds ratios (ORs) with their corresponding 95% confidence intervals (CIs) were calculated. There was strong evidence for an association between the MPO G-463A polymorphism and CAD. The genetic model of action was most likely to be co-dominant. Overall, the data showed that AA and GA genotypes were significantly associated with reduced risk of CAD (AA vs. GG: OR = 0.37, 95% CI = 0.17–0.78; GA vs. GG: OR = 0.73, 95% CI = 0.57–0.92). In subgroup analyses by study population and sources of controls, statistically significant results were observed in the Chinese population (AA vs. GG: OR = 0.21, 95% CI = 0.10–0.43; GA vs. GG: OR = 0.57, 95% CI =0.44–0.74) and in hospital-based control studies (AA vs. GG: OR = 0.20, 95% CI = 0.10–0.39; GA vs. GG: OR = 0.61, 95% CI = 0.48–0.77). This meta-analysis suggests that the MPO G-463A variant genotypes may be associated with decreased risk of CAD. However, given the limited number of studies and the potential biases, the influence of this polymorphism on CAD risk needs further investigation.     

水稻Rop基因OsRac5表达特性

Rop在植物生长、发育、免疫及环境信号应答等多种生物学过程中具有重要作用。已有研究显示水稻Rop基因OsRac5可能与育性控制有关,但是该基因的表达特性,以及非生物胁迫和植物生长物质对其表达的影响尚不清楚。本文采用qRT-PCR技术检测了OsRac5在水稻生长发育过程中、非生物胁迫以及植物生长物质处理条件下的表达特性,结果显示OsRac5在水稻生长发育过程中在多种组织广泛表达,尤其在根和雌雄蕊形成期的幼穗中高表达;干旱、高盐和低温等非生物胁迫均能诱导OsRac5表达;ABA、GAs、6-BA等植物生长物质能上调OsRac5基因表达,提示该基因与水稻幼穗发育、抗逆性及细胞生长等过程相关。     

π–π Stacking mediated drug–drug interactions in human CYP2E1

Because of having many low molecular mass substrates, CYP2E1 is of particular interests to the pharmaceutical industry. Many evidences showed that this enzyme can adopt multiple substrates to significantly reduce the oxidation rate of the substrates. The detailed mechanism for this observation is still unclear. In the current study, we employed GPU‐accelerated molecular dynamics simulations to study the multiple‐binding mode of human CYP2E1, with an aim of offering a mechanistic explanation for the unexplained multiple‐substrate binding. Our results showed that Thr303 and Phe478 were key factors for the substrate recognition and multiple‐substrate binding. The former can form a significant hydrogen bond to recognize and position the substrate in the productive binding orientation in the active site. The latter acted as a mediator for the substrate communications via π–π stacking interactions. In the multiple‐binding mode, the aforementioned π–π stacking interactions formed by the aromatic rings of both substrates and Phe478 drove the first substrate far away from the catalytic center, orienting in an additional binding position and going against the substrate metabolism. All these findings could give atomic insights into the detailed mechanism for the multiple‐substrate binding in human CYP2E1, providing useful information for the drug metabolism mechanism and personalized use of clinical drugs. Proteins 2013; © 2012 Wiley Periodicals, Inc.     

Study of PE and iPP orientations on the surface of carbon nanotubes by using molecular dynamic simulations

In this study, the early stage of interfacial crystallisation behaviour of low molecular weight polyethylene (PE) and isotactic polypropylene (iPP) oligomer on the surface of carbon nanotubes (CNTs) with different diameters, chiralities and topography structures was studied using MD simulations. We started to simulate the effect of CNTs chirality and diameter on PE molecular chain orientation, and then the effect of CNTs topography structure on PE and iPP molecular chain orientation was investigated. Finally, some experiments were carried out to prove the simulated results. Our study shows that for CNTs with a diameter comparable with the radius of gyration (R_g) of a polymer chain, an easy orientation of PE chains along CNTs axis is observed for all the systems of the CNTs with different chiralities due to a geometric confinement effect. For CNTs with a much larger diameter, multiple orientation of PE chains is induced on its surface due to the lattice matching between graphite lattice and PE molecular chains. In this case, the chirality of CNTs dominates the orientation of graphite lattice, which determines the orientation of PE chains arrangement on CNTs surface. More importantly, it was found that the groove structure formed by CNT bundles is very useful for the stabilisation of polymer chain, and thus facilitates the orientation of molecular chain along the long axis of CNTs. As a result, a novel nanohybrid shish–kebab (NHSK) structure with CNTs acting as central shish while polymer lamellae as kebab can be successfully obtained for both PE with zigzag conformation and iPP with helical conformation. This simulation result was well supported by the experimental observation. Our study could provide not only a deep understanding of the origin of the polymer chain orientation on CNTs surface but also the guidance for the preparation of polymer/CNTs nanocomposites with novel NHSK structure.     

GSK-3β Polymorphism Discriminates Bipolar Disorder and Schizophrenia: A Systematic Meta-Analysis

Glycogen synthase kinase 3 (GSK-3) is a well-known conserved and ubiquitous protein kinase and playing a pivotal role in neurodevelopment, neurogenesis, learning/memory, and neuronal cell death. Dysfunction of GSK-3 had been seen in multiple neurodegenerative and psychiatric diseases. Bipolar disorder and schizophrenia are two common psychiatric diseases first occur in adolescence or young adulthood. They share similar risk genes as well as clinical symptoms, which make it is difficult to be discriminated from each other. Here, by using meta-analysis we reported that glycogen synthase kinase 3β promoter inactive mutant rs334558 may contribute to the development of schizophrenia not bipolar disorder. This might be used to distinguish these two diseases.