孕期应激对子代大鼠骨髓淋巴干细胞发育的影响

孕期应激对子代产生的影响是多方面的,这种影响是复杂的。研究表明,出生前的应激经历可导致出生后子代长期的免疫功能改变。这些改变追其根源与骨髓淋巴干细胞的改变有关。本文综述了大鼠孕期经历应激的子代骨髓淋巴干细胞所受的影响及免疫系统的相关改变,并根据现有的研究提出假说,为进一步研究孕期应激导致子代免疫系统改变的机理研究提供新的思路。     

Generation and Analysis of ESTs from the Grass Carp,Ctenopharyngodon idellus

Grass carp, Ctenopharyngodon idellus (Valenciennes, 1844), is an economically important species widely cultured in the world, but its genome research resources are largely lacking. The objectives of this study were to construct normalized cDNA libraries for efficient EST analysis, to generate ESTs from these libraries, and to identify EST-related molecular markers such as microsatellites and single nucleotide polymorphisms (SNPs) for genetic analysis of this species. A total of 6,269 ESTs were generated representing 4,815 unique sequences, from which 105 putative microsatellites and 5,228 SNPs were identified. These genome resources provide the material basis for future genetic and functional analyses in this species.     

马传染性贫血病毒基因非编码区LTR嵌合克隆的构建

在已有全长感染性克隆pLGFD3-8和pD70344的基础上,根据马传贫弱毒疫苗致弱过程中不同代次毒株LTR序列的分析,在LTR U3区选取特定的酶切位点对EIAV非编码区LTR基因进行了部分替换.将替换的全基因克隆转染驴胎皮肤细胞(FDD)并以驴白细胞(DL)传代,用逆转录酶活性检测、RT-PCR方法及Real-time RT-PCR验证其感染性.结果发现,其衍生病毒感染上述两种细胞均出现明显的细胞病变;细胞培养上清可检测到RT酶活性和RT-PCR阳性.电镜下可见大量典型的EIAV颗粒.pLGFD9-12嵌合克隆衍生病毒与其父本克隆衍生病毒pLGFD3-8具有相似的复制水平,pLGFD9-12嵌合克隆衍生病毒在DL细胞上复制水平略高于FDD细胞.此结果为进一步深入研究LTR对马传染性贫血病毒复制水平和毒力的影响奠定了基础.     

PNAS-4 expression and its relationship to p53 in colorectal cancer

PNAS-4 is a novel pro-apoptotic protein activated during the early response to DNA damage; however, the molecular mechanisms and pathways regulating PNAS-4 expression in tumors are not well understood. We hypothesized that PNAS-4 is a p53 down-stream target gene and designed this study. We searched online for putative p53-binding sites in the entire PNAS-4 gene and did not find any corresponding information. In HCT116 colon cancer cells, after being transfected with small interfering RNA to silence p53, the expressions of PNAS-4 and other known p53 target gene (Apaf1, Bax, Fas and Dr5) were determined by real-time PCR. We found that PNAS-4 was up-regulated while Apaf1, Bax, Fas and Dr5 were down-regulated. We then examined the expression of PNAS-4 and p53 mutation in colorectal cancer patients. PNAS-4 expressed both in colorectal cancers and normal tissues, but compared with paired control, PNAS-4 was up-regulated in cancers (P = 0.018). PNAS-4 overexpression ratios were correlated to the p53 mutant status (P = 0.001). The mean PNAS-4 expression levels of p53 mutant homozygote group and heterozygote group were higher than that of p53 wild type group (P = 0.013). The expression ratios of PNAS-4 (every sample in relative to its paired normal mucosa) were different between negative lymph node metastasis (66% up-regulated, 34% down-regulated) and positive metastasis (42% up-regulated, 58% down-regulated). Taken together, these findings suggested that PNAS-4 was not a p53 target, but overexpression of PNAS-4 was correlated to p53 inactivity in colorectal cancer.     

Autohydrolysis Pretreatment of Mixed Softwood to Produce Value Prior to Combustion

Autohydrolysis is a hot water pretreatment to extract soluble components from wood that can be used prior to converting the woody residuals into paper, wood products, fuel, or other goods. In this study, mixed softwood chips were autohydrolyzed in hot water at 150, 160, 170, and 180 °C for 1 and 2 h residence times. The objective was to understand the tradeoff between the extraction of fermentable sugar and the residual solid total energy of combustion quantitatively. This process strategy will be referred to as “value prior to combustion”. High-performance liquid chromatography was used to determine chemical compositions (sugars and byproducts such as acetic acid, furfural, and hydroxymethylfurfural) of the extracted liquid and residuals; a bomb calorimeter was used to measure the heating value of original wood and solid residue. As the autohydrolysis temperature increased, material balances of the system indicated higher volatile byproducts loss. More hemicelluloses were solubilized by the hot water extraction process at higher temperatures and longer residence times, and a greater degree of sugar degradation was also observed. The maximum sugar yield was determined to occur at conditions of 170 °C for 2 h, during which 13 g of sugar was recovered from the extract out of 100 g of oven-dried wood. The heating value of the solid residues after extraction was greater than the original wood. The total energy content of the solid residual after extraction ranged from 85 to 98 % of the original energy content of the feed with higher temperatures reducing the total energy content.     

PLZF-RARα融合基因的生物学功能研究

构建了8个PLZF-RARα融合基因突变体.用“滞后”胶实验证实PLZF-RARα与PML-RARα一样,亦能以同二聚体的形式结合到维甲酸反应元件(RARE)上,且PLZF的POZ结构域介导PLZF-RARα同二聚体的形成和稳定.但两者与RARE的结合类型存在差异,在DR5G,PML-RARα的结合强度大于PLZF-RARα;而在DR5T,则是PLZF-RARα强于PML-RARα.进一步工作证实PLZF-RARα能与RXR形成异二聚体,并产生4种复合物.用免疫沉淀法发现PLZF-RARα亦能与PLZF形成异二聚体,而且也是通过POZ结构域介导PLZF-RARα和PLZF异二聚体的形成.同PML-RARα一样,PLZF-RARα对RARE的结合反应亦受维甲酸调控.     

极端酶的研究进展

极端酶具有超常的生物学稳定性,能够在极端温度、pH、压力和离子强度下表现出生物学活性,因此极端酶为生物催化和生物转化提供了良机.新的极端物种的发现、基因组序列的确定及基因工程技术的应用,加快了发现和制备新酶的进程.蛋白质工程和定向进化技术进一步改善酶的活性和特异性,促进了极端酶的工业应用.对极端酶的研究加深了人们对酶稳定性机制的理解,丰富了分子进化理论.     

ArlR反应调节蛋白在表皮葡萄球菌不同生长期表达的检测

表皮葡萄球菌(Staphylococcus epidermidis,SE)是寄居在人体和黏膜表面的条件致病菌,因可在医疗植入材料表面形成生物膜(biofilm)而具有致病性。细菌双组分信号转导系统可调控生物膜形成,但其调控机制在SE中研究甚少。本课题对arlRS双组分信号转导系统的反应蛋白ArlR在细菌不同生长期的表达情况进行初步研究。首先构建ArlR原核表达质粒,用纯化重组ArlR免疫小鼠,获得多克隆抗-ArlR抗体,免疫Dot方法检测结果显示小鼠抗-ArlR血清效价>1∶100000。进一步采用蛋白免疫印迹法检测ArlR在SE1457野生株不同生长期中的表达水平,结果显示,ArlR在2h表达量较低,到4h达高峰,6～10h表达量较4h降低。利用反转录实时荧光定量聚合酶链反应检测arlR基因在不同生长期的转录水平,结果显示相应时间点ArlR蛋白表达水平与arlR基因转录水平一致。本研究结果为后期研究双组分信号转导系统arlRS对SE生物膜形成的影响奠定基础。