SARS病毒核蛋白基因的克隆及其表达研究

从一例输入性传染性非典型性肺炎病人血清中提取病毒RNA,通过RT—PCR方法扩增出SARS病毒核蛋白基因片段,克隆入质粒载体pUCm—T后,进行核苷酸序列的测定及分析,与已公布的SARS病毒基因序列进行比较,证实为SARS冠状病毒核蛋白基因。为了解该病毒核蛋白的抗原特性,将核蛋白基因插入表达载体,构建重组质粒pET28a—SN,转导大肠杆菌BL21(DE3)后,加IPTG诱导表达。产物经SDS—PAGE电泳分析,表达出相对分子量约为50kDa的蛋白,占整个菌体的45％左右。Westem—blot分析表明,表达产物仅与SARS阳性病人血清起反应,而与正常血清不起反应。间接ELISA免疫检测,抗原滴度达1：12500。表明表达的核蛋白为SARS特异性抗原,这为SARS病毒的诊断试剂的研制提供了方便而安全的抗原来源。     

Modeling the Effects of Harvest Alternatives on Mitigating Oak Decline in a Central Hardwood Forest Landscape

Oak decline is a process induced by complex interactions of predisposing factors, inciting factors, and contributing factors operating at tree, stand, and landscape scales. It has greatly altered species composition and stand structure in affected areas. Thinning, clearcutting, and group selection are widely adopted harvest alternatives for reducing forest vulnerability to oak decline by removing susceptible species and declining trees. However, the long-term, landscape-scale effects of these different harvest alternatives are not well studied because of the limited availability of experimental data. In this study, we applied a forest landscape model in combination with field studies to evaluate the effects of the three harvest alternatives on mitigating oak decline in a Central Hardwood Forest landscape. Results showed that the potential oak decline in high risk sites decreased strongly in the next five decades irrespective of harvest alternatives. This is because oak decline is a natural process and forest succession (e.g., high tree mortality resulting from intense competition) would eventually lead to the decrease in oak decline in this area. However, forest harvesting did play a role in mitigating oak decline and the effectiveness varied among the three harvest alternatives. The group selection and clearcutting alternatives were most effective in mitigating oak decline in the short and medium terms, respectively. The long-term effects of the three harvest alternatives on mitigating oak decline became less discernible as the role of succession increased. The thinning alternative had the highest biomass retention over time, followed by the group selection and clearcutting alternatives. The group selection alternative that balanced treatment effects and retaining biomass was the most viable alternative for managing oak decline. Insights from this study may be useful in developing effective and informed forest harvesting plans for managing oak decline.     

石香薷（唇形科）的胚胎学研究

石香薷(Mosla chinensis Buch.-Ham.ex Maxim.)花药壁发育属双子叶型。花药具4个小孢子囊;腺质绒毡层,细胞具2～4核,有3至数个核仁;初生造孢细胞直接行小孢子母细胞的功能,在小孢子囊中成单列。花粉母细胞减数分裂后胞质分裂为同时型;小孢子四分体呈四面体形,也有左右对称形,成熟花粉具2细胞。胚珠倒生,单珠被,薄珠心,大孢子四分体线形排列,功能性大孢子位于合点端,少数为合点端第二个细胞。胚囊发育属蓼型,珠孔区近卵圆形,比合点区稍短,合点区较狭窄。胚胎发生属柳叶菜型。细胞型胚乳,珠孔吸器为单孢3核,合点吸器为单孢2核。种子无胚乳,种皮由珠被发育。石香薷雌雄配子体的发育、胚胎发生及胚乳形成,与紫苏属的Perilla ocimoides几乎完全一致。不同点仅在于石香薷在2-细胞花粉时,药室内壁细胞切向伸长,壁尚未发生纤维状加厚(P.ocimoides药室内壁细胞径向伸长,胞壁纤维状加厚),珠孔吸器为单孢3核(P.ocimoides为单孢4核)。胚胎学显示石荠苎属与紫苏属有密切的亲缘关系。     

乙型肝炎病毒核心抗原基因序列的启动子活性

将核心抗原基因起始码下游的序列,构建两个ＣＡＴ报告基因表达质粒,即ｐＣＡＴＮ Ｉ和ｐＣＡＴＮⅡ,转染ＨｅｐＧ２与ＣＶ－１细胞后,均可使ＣＡＴ报告基因表达,表现出启动子活性。     

转录因子PU.1的最新研究进展

PU.1是ETS转录因子家族(E26 transformation-specific family)的成员,在机体多种组织发育中发挥重要作用.近年来的研究发现,PU.1不仅在造血谱系的确定和分化中起作用,而且还在机体免疫、脂肪形成、组织纤维化、神经发育中发挥功能.在造血及免疫等系统中,PU.1与多个靶基因形成复杂的调节...     

Highly efficient detection of Cu2+ and B4O72− based on a recyclable asymmetric salamo‐based probe in aqueous medium

An asymmetric salamo‐based probe molecule ( H ₂ L ) was synthesized and characterized structurally. When DMF/H₂O (9:1) was used as the solvent, it was shown probe H ₂ L has high sensitivity to Cu²⁺. Using high‐resolution mass spectrometry and theoretical calculation, it was found that probe H ₂ L could form a more stable complex (1:1) with Cu²⁺, the minimum limit of detection (LOD) of H ₂ L for Cu²⁺ was calculated as 9.95 × 10^?8 M. In addition, probe H ₂ L could also be used to identify B₄O₇^2? under the same detection conditions and the minimum LOD of H ₂ L for B₄O₇^2? was calculated as 4.98 × 10^?7 M. At the same time, density functional theory theoretical calculation further proved the flexibility of probe H ₂ L . Through the action of EDTA, probe H ₂ L had a cyclic ability to recognize Cu²⁺, and showed a better response in the physiological pH range; probe H ₂ L had the characteristics of fast recognition speed and high efficiency. In addition, with probe H ₂ L test paper for Cu²⁺ and B₄O₇^2?, the effect was more obvious. Meanwhile, probe H ₂ L can be used to quantitatively detect Cu²⁺ in water samples.     

抑咽侧体素基因在大猿叶虫生殖滞育准备中的功能分析

[目的]本研究旨在明确大猿叶虫Colaphellus bowringi促咽侧体素(allatotropin,AT)和抑咽侧体素(allatostatin,AST)基因的分子特征,分析其在该虫生殖和滞育过程中的表达差异,并探究其在大猿叶虫生殖滞育准备中的功能.[方法]利用前期建立的大猿叶虫转录组数据库,鉴定大猿叶虫CbA...     

CPU-GPU hybrid accelerating the Zuker algorithm for RNA secondary structure prediction applications

Background

Different Cupriavidus metallidurans strains isolated from metal-contaminated and other anthropogenic environments were genotypically and phenotypically compared with C. metallidurans type strain CH34. The latter is well-studied for its resistance to a wide range of metals, which is carried for a substantial part by its two megaplasmids pMOL28 and pMOL30.

Results

Comparative genomic hybridization (CGH) indicated that the extensive arsenal of determinants involved in metal resistance was well conserved among the different C. metallidurans strains. Contrary, the mobile genetic elements identified in type strain CH34 were not present in all strains but clearly showed a pattern, although, not directly related to a particular biotope nor location (geographical). One group of strains carried almost all mobile genetic elements, while these were much less abundant in the second group. This occurrence was also reflected in their ability to degrade toluene and grow autotrophically on hydrogen gas and carbon dioxide, which are two traits linked to separate genomic islands of the Tn4371-family. In addition, the clear pattern of genomic islands distribution allowed to identify new putative genomic islands on chromosome 1 and 2 of C. metallidurans CH34.

Conclusions

Metal resistance determinants are shared by all C. metallidurans strains and their occurrence is apparently irrespective of the strain's isolation type and place. Cupriavidus metallidurans strains do display substantial differences in the diversity and size of their mobile gene pool, which may be extensive in some (including the type strain) while marginal in others.