人参寡糖素对三七悬浮培养细胞生长的效应

从人参培养细胞的细胞壁中分离纯化到不同分子量的单体人参寡糖素。试验结果表明命名为人参寡糖素Ⅶ和人参寡糖素Ⅷ的两种寡糖素对三七悬浮培养细胞的生长具有明显的促进作用,其增长率分别为１９．３４％和１０．５８％,人参寡糖素Ⅶ的适宜浓度为５—１０ｍｇ／ｌ。在高浓度下（大于２５ｍｇ／ｌ）稍抑制培养细胞生长。在细胞培养２２天（指数生长期）后．加入１０ｍｇ／ｌ的人参寡糖素Ⅶ．然后再培养２天。其生长速率即提高,加入人参寡糖素Ⅷ后．缩短了三七细胞悬浮培养生长的延缓期．提前进入对数生长期和指数生长期,并在对数生长期和指数生长期作用最明显,因而最终收获时培养细胞的产率增加。     

单纯疱疹病毒通用及Ⅱ型特异性DNA探针的制备及应用研究

单纯疱疹病毒（ＨＳＶ）Ⅰ型及Ⅱ型之间有很多共同抗原,能引起血清学交叉反应,鉴别诊断比较困难。本实验利用重组ＤＮＡ技术,将部分ＨＳＶ－２ＤＮＡ的ＰｓｔＩ片段克隆到载体质粒ＰＳＫ中,并筛选出两个重组质粒（Ｐ和Ｐ）只与ＨＳＶ－２反应,与ＨＳＶ－１不反应,这两个重组质粒中所含的ＨＳＶ－２ＤＮＡ片段大小分别是３．１和４．３ｋｂ,另外,还筛选了一个重组质粒（ＰＨＳＶ２－１,含５．８ｋｂＨＳＶ－２ＤＮＡ片段）与ＨＳＶ－１和ＨＳＶ－２均反应。将４．３ｋｂ的片段用光生物素标记后作为探针检测了１５９份人阴道拭子,其中２３份样品呈阳性反应,其余均为阴性,从２３份阳性样品中挑选１２价涂片用间接荧光抗体法检测也都呈阳性反应,随机挑选的几份杂交反应阴性样品在间接荧光试验中也是阴性。本实验制备的ＨＳＶ通用及ＨＳＶ－２型特异性探针将比常规的血清学方法诊断和鉴别ＨＳＶ－１和ＨＳＶ－２感染更为可靠。     

外源水杨酸对NaCl胁迫下白榆幼苗光合作用及离子分配的影响

以1年生白榆幼苗为研究对象,设置0、0.5、1.0和2.0 mmol·L^-1水杨酸(SA)与0、50、100和150 mmol·L^-1 NaCl处理组合,考察盐胁迫下白榆幼苗生物量、光合色素含量、光合作用参数及根叶离子含量、分配、运输的情况,探讨外源SA对NaCl胁迫下白榆幼苗耐盐生理特征的影响。结果表明:(1)NaCl胁迫显著抑制了白榆幼苗的生长、光合色素含量及光合能力,并破坏了白榆体内离子平衡。(2)喷施外源SA使盐胁迫下白榆幼苗的干重和根冠比均不同程度升高,0.5和2.0 mmol·L^-1 SA不同程度提高了50和100 mmol·L^-1 NaCl处理组幼苗叶片光合色素含量。(3)0.5 mmol·L^-1 SA显著提升了50 mmol·L^-1 NaCl处理组白榆幼苗的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr),1.0和2.0 mmol·L^-1 SA对150 mmol·L^-1 NaCl处理组幼苗净光合速率改善效果较好,外源SA对100 mmol·L^-1 NaCl处理组幼苗的光合作用参数无显著影响。(4)NaCl胁迫下,外源SA处理的白榆幼苗叶和根Na^+含量及Na^+/K^+、Na^+/Ca^2+和Na^+/Mg^2+显著降低,离子选择运输系数SK,Na、SCa,Na和SMg,Na升高,从而促进了幼苗K^+、Ca^2+和Mg^2+由根向叶片的转运;隶属函数分析发现对白榆幼苗叶和根中离子含量改善效果最好的SA浓度分别为1.0和2.0 mmol·L^-1。因此,适宜浓度的外源水杨酸能够有效改善NaCl胁迫下白榆幼苗的光合能力,有效调节白榆幼苗体内离子状态,从而增强白榆对NaCl胁迫的抗性。     

DdrB stimulates single-stranded DNA annealing and facilitates RecA-independent DNA repair in Deinococcus radiodurans

The bacterium Deinococcus radiodurans can survive extremely high exposure to ionizing radiation. The repair mechanisms involved in this extraordinary ability are still being investigated. ddrB is one gene that is highly up-regulated after irradiation, and it has been proposed to be involved in RecA-independent repair in D. radiodurans. Here we cloned, expressed and characterized ddrB in order to define its roles in the radioresistance of D. radiodurans. DdrB preferentially binds to single-stranded DNA. Moreover, it interacts directly with single-stranded binding protein of D. radiodurans DrSSB, and stimulates single-stranded DNA annealing even in the presence of DrSSB. The post-irradiation DNA repair kinetics of a ddrB/recA double mutant were compared to ddrB and recA single mutants by pulsed-field gel electrophoresis (PFGE). DNA fragment rejoining in the ddrB/recA double mutant is severely compromised, suggesting that DdrB-mediated single-stranded annealing plays a critical role in the RecA-independent DNA repair of D. radiodurans.     

Spectroscopic investigation on the interaction of J-aggregate with human serum albumin

The interactions of three cyanine dyes, which exhibit different meso substituent in polymethine chain, with human serum albumin (HSA) have been investigated by the means of absorption, fluorescence and circular dichroism (CD) spectra. In phosphate buffer solution (PBS), the mentioned dyes exist not as isolated monomers but rather in the formation of J-aggregation. In the presence of HSA, the absorption and fluorescence emission spectra indicated that the J-aggregation was decomposed to monomer because of the strong affinity between dye molecules and HSA. Besides the association of cyanine dyes with HSA, binding to HSA gave rise to the J-aggregation CD signals. The meso substituent in the polymethine plays an important role in the interaction of HSA and the J-aggregation. Spectral studies showed that the dye bound with HSA in a 1:1 formation. The apparent constant (K(a)) value was roughly identified by analysis of the corresponding fluorescence data at various HSA concentrations. The higher affinity of the molecule with meso phenyl towards HSA with respect to molecules with meso ethyl or methyl can be attributed to the arrangement of molecules in J-aggregation and the hydrophobic force between the molecules and HSA.     

Cytochrome P450 epoxygenase CYP2J2 attenuates nephropathy in streptozotocin-induced diabetic mice

Cytochrome P450 (CYP) epoxygenases metabolize arachidonic acid into epoxyeicosatrienoic acids (EETs), which play important and diverse roles in the cardiovascular system. The anti-inflammatory, anti-apoptotic, pro-angiogenic, and anti-hypertensive properties of EETs in the cardiovascular system suggest a beneficial role for EETs in diabetic nephropathy. This study investigated the effects of endothelial specific overexpression of CYP2J2 epoxygenase on diabetic nephropathy in streptozotocin-induced diabetic mice. Endothelial CYP2J2 overexpression attenuated renal damage as measured by urinary microalbumin and glomerulosclerosis. These effects were associated with inhibition of TGF-β/Smad signaling in the kidney. Indeed, overexpression of CYP2J2 prevented TGF-β1-induced renal tubular epithelial-mesenchymal transition in vitro. These findings highlight the beneficial roles of the CYP epoxygenase-EET system in the pathogenesis of diabetic nephropathy.