The G to A polymorphism at -597 of the interleukin-6 gene is extremely rare in southern Han Chinese

Interleukin-6 (IL-6) is a cytokine involved in different physiologic and pathophysiologic processes including essential hypertension (EH). Associations of the IL-6 promoter region polymorphisms with circulating level of IL-6 have been reported in various studies. We detected the IL-6-597G/A polymorphism in 246 EH patients and 194 healthy controls from Jiangsu area (south of China). Individuals all carried the GG wild genotype, no GA or AA genotypes were found. Our results suggest that IL-6-597G/A polymorphism is extremely rare and unlikely to be contributing significantly to disease susceptibility in southern Han Chinese.     

Structural and functional studies of LRP6 ectodomain reveal a platform for Wnt signaling

LDL-receptor-related protein 6 (LRP6), alongside Frizzled receptors, transduces Wnt signaling across the plasma membrane. The LRP6 ectodomain comprises four tandem β-propeller-EGF-like domain (PE) pairs that harbor binding sites for Wnt morphogens and their antagonists including Dickkopf 1 (Dkk1). To understand how these multiple interactions are integrated, we combined crystallographic analysis of the third and fourth PE pairs with electron microscopy (EM) to determine the complete ectodomain structure. An extensive inter-pair interface, conserved for the first-to-second and third-to-fourth PE interactions, contributes to a compact platform-like architecture, which is disrupted by mutations implicated in developmental diseases. EM reconstruction of the LRP6 platform bound to chaperone Mesd exemplifies a binding mode spanning PE pairs. Cellular and binding assays identify overlapping Wnt3a- and Dkk1-binding surfaces on the third PE pair, consistent with steric competition, but also suggest a model in which the platform structure supports an interplay of ligands through multiple interaction sites.     

AhCYCB1基因的克隆和在ABA抑制花生侧根发生过程中的表达

根据水稻、拟南芥和玉米等植株的CYCB基因序列设计引物,以花生根系成熟区总RNA逆转录得到的cDNA为模板,用PCR扩增克隆花生CYCB1基因片段,命名为AhCYCB1（GenBank登录号为GQ868755）。该基因编码的蛋白具有CYCB1蛋白序列的特征区,与拟南芥的AtCYCB1蛋白聚类关系最近。半定量RT-PCR分析表明,ABA处理后,侧根起始部位的AhCY-CB1基因表达水平降低,ABA合成抑制剂萘普生（naproxen）处理使AhCYCB1基因表达水平明显上调。推测ABA抑制侧根发生与其降低侧根发生部位由G2期进入M期的细胞数目有关。     

The possible structural models for polyglutamine aggregation: a molecular dynamics simulations study

Huntington's disease is a neurodegenerative disorder caused by a polyglutamine (polyQ) expansion near the N-terminus of huntingtin. Previous studies have suggested that polyQ aggregation occurs only when the number of glutamine (Q) residues is more than 36-40, the disease threshold. However, the structural characteristics of polyQ nucleation in the very early stage of aggregation still remain elusive. In this study, we designed 18 simulation trials to determine the possible structural models for polyQ nucleation and aggregation with various shapes and sizes of initial β-helical structures, such as left-handed circular, right-handed rectangular, and left- and right-handed triangular. Our results show that the stability of these models significantly increases with increasing the number of rungs, while it is rather insensitive to the number of Qs in each rung. In particular, the 3-rung β-helical models are stable when they adopt the left-handed triangular and right-handed rectangular conformations due to the fact that they preserve high β-turn and β-sheet contents, respectively, during the simulation courses. Thus, we suggested that these two stable β-helical structures with at least 3 rungs might serve as the possible nucleation seeds for polyQ depending on how the structural elements of β-turn and β-sheet are sampled and preserved during the very early stage of aggregation.     

Genetic diversity of Ralstonia solanacearum strains from China assessed by PCR-based fingerprints to unravel host plant- and site-dependent distribution patterns

Bacterial wilt caused by Ralstonia solanacearum is a serious threat to crop production in China. A collection of 319 R. solanacearum strains isolated from 14 different diseased host plants collected in 15 Chinese provinces was investigated by BOX fingerprints in order to test the influence of the site and the host plant on their genetic diversity. Phylotype, fliC-RFLP patterns and biovar were determined for all strains and the sequevar for 39 representative strains. The majority of strains belonged to the Asian phylotype I, shared identical fliC-RFLP patterns and were assigned to four biovars (bv3:123; bv4:162; bv5:3; and bv6:11). Twenty strains were phylotype II, assigned to biovar 2, and had distinct fliC-RFLP patterns. BOX-PCR fingerprints generated from the genomic DNA of each strain revealed a high diversity of the phylotype I strains, where 28 types of BOX fingerprints could be distinguished. While many BOX clusters comprised isolates from different provinces and several host plants, some groups contained isolates that were plant or site specific. All phylotype II isolates originating from 10 provinces belonged to sequevar 1 and displayed identical BOX patterns as the potato brown rot strains from various regions of the world.     

Knockout of G protein β5 impairs brain development and causes multiple neurologic abnormalities in mice

Gβ5 is a divergent member of the signal-transducing G protein β subunit family encoded by GNB5 and expressed principally in brain and neuronal tissue. Among heterotrimeric Gβ isoforms, Gβ5 is unique in its ability to heterodimerize with members of the R7 subfamily of the regulator of G protein signaling proteins that contain G protein-γ like domains. Previous studies employing Gnb5 knockout (KO) mice have shown that Gβ5 is an essential stabilizer of such regulator of G protein signaling proteins and regulates the deactivation of retinal phototransduction and the proper functioning of retinal bipolar cells. However, little is known of the function of Gβ5 in the brain outside the visual system. We show here that mice lacking Gβ5 have a markedly abnormal neurologic phenotype that includes impaired development, tiptoe-walking, motor learning and coordination deficiencies, and hyperactivity. We further show that Gβ5-deficient mice have abnormalities of neuronal development in cerebellum and hippocampus. We find that the expression of both mRNA and protein from multiple neuronal genes is dysregulated in Gnb5 KO mice. Taken together with previous observations from Gnb5 KO mice, our findings suggest a model in which Gβ5 regulates dendritic arborization and/or synapse formation during development, in part by effects on gene expression.     

甘蔗黄叶病毒CP蛋白基因ihpRNA表达载体构建及烟草转化

为提高甘蔗抗病性,本研究根据甘蔗黄叶病毒海南分离物ScYLV-CHN-HN1全基因组序列(GenBank no. HQ342888),利用病毒CP蛋白介导的RNAi技术,针对病毒外壳蛋白CP,设计两对含有酶切位点的特异性引物,CPsf1/CPsr1和CPasf1/CPasr1,以构建好的pMD19-T/CP质粒为模板,pRNAi1017为中间载体,分别合成构建干扰载体的正反向片段pRNAi-CP-F-R,将CP正反向片段分别插入表达载体pCAMBIA2300的相应位置,构建含有发卡结构的RNAi载体p2300-CP-F-R,经过PstⅠ酶切鉴定,证明载体构建成功。通过农杆菌介导的方法,以干扰表达载体p2300-CP-F-R转化烟草,经过PCR检测,得到12株阳性转基因植株,Southern blot杂交和半定量RT-PCR对其检测,证明干扰片段已经整合烟草基因组中并进行了转录,该结果为RNAi介导抗病毒甘蔗育种研究奠定基础。     

Effects of the expression of foreign insect-resistant genes in cotton plants on Bemisia tabaci

以转基因棉花和对应的常规棉花亲本为材料,探讨外源基因导入对棉花烟粉虱Bemisia tabaci(Gennadius)种群的影响.结果表明,在转基因棉花GK12、33B、SGK上,烟粉虱从卵发育到成虫羽化的历期分别为15.56、15.35和15.25d,较对应的常规棉亲本SM3(19.38d)、33(20.81d)、SY321(18.76d)分别短24.55％、26.23％、18.71％;GK12和33B棉花上烟粉虱的存活率(69.16％)分别较对应的常规棉亲本SM3(54.76％)和33(64.91％)高26.29％和12.81％,而SGK(63.21％)上烟粉虱的存活率与对应的常规棉亲本SY321(62.61％)之间差异不显著;烟粉虱在GK12(84.00)和33B(77.25)上的产卵量分别较SM3(62.25)、33(70.00)高34.93％和10.35％,但SGK和SY321之间差异不显著;在转基因棉花GK12、33B、SGK上,烟粉虱的雌雄性比分别比对应的常规棉亲本高26.71％、46.23％和19.17％.结果表明,外源基因导入后,有助于烟粉虱的发育,提高了烟粉虱的产卵量和雌雄性比,从而促进了烟粉虱种群的上升.