生物传感器在环境污染监测中的应用研究

简要介绍了生物传感器的基本组成、工作原理、分类及特点、重点论述了生物传感器在环境污染监测方面应用的研究进展。     

中国莲子草属药用种植物花粉形态的研究

作者搜集了在中国分布的莲子草属(Alternanthera)4种药用植物的花粉,运用光学显微镜和扫描电镜对其花粉形态进行了详细的观察和比较,为该属植物积累了孢粉学资料,并为莲子草类药材的鉴别提供了科学依据。     

Nucleocytoplasmic trafficking is essential for BAK1‐ and BKK1‐mediated cell‐death control

BRI1‐ASSOCIATED KINASE 1 (BAK1) was initially identified as a co‐receptor of the brassinosteroid (BR) receptor BRI1. Genetic analyses also revealed that BAK1 and its closest homolog BAK1‐LIKE 1 (BKK1) regulate a BR‐independent cell‐death control pathway. The double null mutant bak1 bkk1 displays a salicylic acid‐ and light‐dependent cell‐death phenotype even without pathogen invasion. Molecular mechanisms of the spontaneous cell death mediated by BAK1 and BKK1 remain unknown. Here we report our identification of a suppressor of bak1 bkk1 (sbb1–1). Genetic analyses indicated that cell‐death symptoms in a weak double mutant, bak1–3 bkk1–1, were completely suppressed by the loss‐of‐function mutation in SBB1, which encodes a nucleoporin (NUP) 85‐like protein. Genetic analyses also demonstrated that individually knocking out three other nucleoporin genes from the SBB1‐located sub‐complex was also able to rescue the cell‐death phenotype of bak1–3 bkk1–1. In addition, a DEAD‐box RNA helicase, DRH1, was identified in the same protein complex as SBB1 via a proteomic approach. The drh1 mutation also rescues the cell‐death symptoms of bak1–3 bkk1–1. Further analyses indicated that export of poly(A)⁺ RNA was greatly blocked in the nup and drh1 mutants, resulting in accumulation of significant levels of mRNAs in the nuclei. Over‐expression of a bacterial NahG gene to inactivate salicylic acid also rescues the cell‐death phenotype of bak1–3 bkk1–1. Mutants suppressing cell‐death symptoms always showed greatly reduced salicylic acid contents. These results suggest that nucleocytoplasmic trafficking, especially of molecules directly or indirectly involved in endogenous salicylic acid accumulation, is critical in BAK1‐ and BKK1‐mediated cell‐death control.     

城市污水处理系统的菌群分析和除氮基因工程出发菌的选择

目的:对脱氮污水处理工艺的活性污泥的菌群组成进行分析,以期获得适合于脱氮基因工程改良的出发菌.方法:首先采用平板稀释法对活性污泥进行菌落计数,并对分离到的菌落进行详细的生化鉴定,对其中的优势菌-假单胞菌进行脱氮能力测定,并分析其对常作为筛选标志的抗生素的药物敏感性.结果:发现在采用该工艺的活性污泥中,优势菌为假单胞菌、肠杆菌、莫拉菌和不动杆菌,分别占总菌数的23%、16%、16%和12%.根据菌群分析的结果,从中选择了两株耐药性弱、脱氮能力强的菌作为基因改良的出发菌.结论:本研究阐明了活性污泥的菌群构成,获得了两株适合基因工程改良的菌株,为日后脱氮基因工程菌的构建奠定基础.     

Dnmt1 overexpression causes genomic hypermethylation, loss of imprinting, and embryonic lethality

Biallelic expression of Igf2 is frequently seen in cancers because Igf2 functions as a survival factor. In many tumors the activation of Igf2 expression has been correlated with de novo methylation of the imprinted region. We have compared the intrinsic susceptibilities of the imprinted region of Igf2 and H19, other imprinted genes, bulk genomic DNA, and repetitive retroviral sequences to Dnmt1 overexpression. At low Dnmt1 methyltransferase levels repetitive retroviral elements were methylated and silenced. The nonmethylated imprinted region of Igf2 and H19 was resistant to methylation at low Dnmt1 levels but became fully methylated when Dnmt1 was overexpressed from a bacterial artificial chromosome transgene. Methylation caused the activation of the silent Igf2 allele in wild-type and Dnmt1 knockout cells, leading to biallelic Igf2 expression. In contrast, the imprinted genes Igf2r, Peg3, Snrpn, and Grf1 were completely resistant to de novo methylation, even when Dnmt1 was overexpressed. Therefore, the intrinsic difference between the imprinted region of Igf2 and H19 and of other imprinted genes to postzygotic de novo methylation may be the molecular basis for the frequently observed de novo methylation and upregulation of Igf2 in neoplastic cells and tumors. Injection of Dnmt1-overexpressing embryonic stem cells in diploid or tetraploid blastocysts resulted in lethality of the embryo, which resembled embryonic lethality caused by Dnmt1 deficiency.     

生物合成聚3-羟基丙酸酯的研究进展

聚3-羟基丙酸酯(P3HP)作为聚羟基脂肪酸酯家族(PHAs)中的新型热塑性塑料,具有生物降解性和生物相容性等优点。目前,未见野生微生物可以合成P3HP的报道,生产途径主要为化学法和生物法。其中,通过化学法或添加3-HP单体及其结构类似物作为前体的P3HP合成效率低、成本高且不具环保性;而通过构建和改造工程菌的生物代谢途径,能够利用廉价、可再生的碳源,已经逐渐成为研究热点。文中综述了国内外P3HP生物合成研究进展,并对甘油途径、丙二酸单酰辅酶A(Malonyl-Co A)途径和β-丙氨酸途径等合成方法进行了优缺点分析,为生物合成P3HP的深入研究奠定理论基础。