Carcinogen activation by human liver enzymes in the Ames mutagenicity test.

Liver post-mitochondrial supernatants derived from 10 individuals were used as the source of metabolic activation for carcinogens in the Ames quantitative mutagenicity test using Salmonella typhimurium TA 100. The liver samples were obtained from brain-dead donors and autopsy cases. The ability of human enzymes to activate aromatic amines ranged from the undetectable to highly active for 2-acetylaminofluorene. None of the samples exhibited any ability to activate benzidine. A generally low activity was observed in the capability of human enzymes to activate the polynuclear aromatic hydrocarbons, 3-methylcholanthrene and benzo(a)pyrene. Most samples were positive for activating 4-nitrobiphenyl. However, the highest mutagenic activity in the presence of human enzymes was consistently observed for aflatoxin B1 and sterigmatocystin. These results indicated that (a) human enzyme systems, like rodent systems, are more effective in inducing mutagenic activity from mycotoxins than aromatic amines and polynuclear aromatic hydrocarbons, and (b) samples derived from different individuals exhibited considerable variation in the ability to activate carcinogens belonging to a same class of compound.     

走马胎的组织培养与快速繁殖

以走马胎(Ardisia gigantifolia)幼嫩茎段为外植体, 通过腋芽增殖的方式进行组织培养和快速繁殖研究。结果表明, 培养基MS+1.0 mg·L ^-1 6-BA+0.2 mg·L ^-1NAA和MS+0.5 mg·L ^-1 ZT均可用于腋芽的诱导和前期继代培养, 诱导率分别为89.3%和85.7%; 芽增殖最佳培养基为MS+0.5 mg·L ^-16-BA+0.1 mg·L ^-1ZT+0.1 mg·L ^-1NAA, 增殖系数为4.3倍; 根诱导最佳培养基为1/2MS+1.5 mg·L ^-1 IAA+1.0 mg·L ^-1 NAA, 生根率达92.3%, 且根系发达, 植株健壮; 生根苗在混合基质园土:泥炭:珍珠岩=3:1:1 (v/v/v )中移栽成活率为82%。该研究建立了走马胎种苗的组织培养快速繁殖技术体系, 且可应用于规模化生产。     

蛇胆饮料对动物（小鼠）促生长及耐力对比实验研究

本文对蛇胆饮料的促生长及耐受力进行实验研究,结果表明喝蛇胆饮料的动物小鼠有明显的促生长发育功能,并有增强耐受力抗疲劳的功能.     

双拷贝人α型心钠素基因的组建及大肠杆菌分泌型克隆与表达

将单拷贝人α心钠素基因3′端用Ban Ⅱ酶解除去包括终止密码在内的36个碱基对,代之以人工合成的含Glu-Lys-Phe-Glu连接片段与另一单拷贝人α心钠素基因的5′端串连成编码60肽的双拷贝心钠素基因,克隆于大肠杆菌分泌型表达载体pIN-Ⅲ-OmpA_2质粒中,表达生成60肽的双拷贝人α型心钠素衍生物,在信号肽的作用下分泌至胞膜间质并自动切割为60肽的外源基因产物。分子量约8K的表达产物用分子筛或超滤膜分离后再经HPLC纯化,表达产物具有明显的心钠素放免活性和舒张血管活性。     

杭州湾六市土地生态环境的数量评价及其在国土规划上的意义

在系统调查分析和特尔斐测定的基础上,选取人口密度、耕地人口负荷量、土地工业经济密度、居民点、厂矿用地、>25°土地面积、单位森林蓄积占用土地、耕地非旱涝保收面积7项指标,应用分值权重累加、系统聚类分析和模糊综合评价3种方法对杭州湾6市土地生态环境作综合分析评价,结果可应用于国土规划实践,对探讨土地生态环境评价的理论与方法有参考价值。     

基因定点诱变删除及天然α型心钠素的分泌型表达

用基因定点诱变技术,删除了pO_1α ANF表达质粒中的33对碱基,使人α型心钠素结构基因直接与大肠杆菌分泌型表达质粒pIN-Ⅲ-OmPA中的信号肽酶切位点编码区相连,构成天然人α型心钠素的表达质粒pANF,在IPTG诱导下表达28肽的天然人α型心钠素。纯化后的表达产物具有天然心钠素的放免活性和很强的舒张血管的生物活性。     

Epstein-Barr病毒基因组编码的BARF-1和EC-LF4蛋白质与免疫球蛋白结构同源

将EB病毒蛋白质BARF-1和EC-LF4与NBRF蛋白质库的序列进行局部同源性检索以及与已知的Ig V或C功能区相关分子进行对准比较,检查了同源性积分的统计学意义,并进行了二级结构预测和疏水性分析,确定了BARF-1的第13-124位和第126-221位残基片段分别与V和C样功能区类似,EC-LF4的第20-135位残基片段与V样功能区相似,BARF-1是非膜蛋白,EC-LF4是膜整合蛋白,其胞外部分近膜侧有一个类似于Ig绞链区的序列。因此,BARF-1与Ig轻链结构相似,EC-LF4与CD8抗原的第一条链相似。根据Ig超族分子的一般功能(即介导细胞粘附和细胞识别),推测EC-LF4可能作为一种粘附分子与淋巴细胞表面的Ig相关分子结合而促进EB病毒对淋巴细胞的感染。BARF-1因已知与病毒复制有关,与Ig超族的一般功能无关。EC-LF4和BARF-1的Ig样功能区可能来源于EB病毒对宿主细胞Ig基因的整合。     

Identification of a membrane-associated 1-0-alkyl-2-arachidonoyl-sn-glycero-3-phosphocholine hydrolyzing phospholipase A2 in guinea pig 1 epidermis. Implications in the cutaneous biosynthesis of platelet-activating factor.

A membrane-associated 1-0-alkyl-2-arachidonoyl-GPC hydrolyzing phospholipase A2 was identified in guinea pig epidermis. It is regio-specific (associated with the particulate microsomal fraction) and specific for the hydrolysis of 1-0-alkyl-2-arachidonoyl-sn-glycero-3-phosphocholine. It is sensitive to low calcium concentrations suggesting that it may be activated by increasing intracellular calcium. Since ether-linked phospholipids are known to exist in the epidermis, further understanding of the properties of this 1-0-alkyl-arachidonoyl-hydrolyzing PLA2 may allow us to control the generation of 1-0-alkyl-2-lyso-sn-glycero-3-phosphocholine, a key substrate for the generation of the platelet-activating factor in the tissue.     

The transmembrane domain of N-glucosaminyltransferase I contains a Golgi retention signal.

The enzyme N-acetylglucosaminyltransferase I (NT, EC 2.4.1.101) is a resident type II transmembrane protein of the Golgi apparatus. To delineate the portion of its primary sequence that is responsible for the Golgi retention of this protein, we constructed chimeras containing different N-terminal portions of NT joined to a reporter sequence, the ectodomain of a type II surface membrane protein. These chimeric proteins were found to be retained in the Golgi apparatus as assessed by cell surface biotinylation and immunofluorescence. We found that the transmembrane domain of NT is sufficient to confer Golgi retention of the fusion proteins and propose that it contains the Golgi retention signal of the parent molecule.     

A comparison of the rates of reaction and function of UVRB in UVRABC- and UVRAB-mediated anthramycin-N2-guanine-DNA repair.

The repair of anthramycin-DNA adducts by the UVR proteins in Escherichia coli follows two pathways: the adducts may be incised by the combined actions of UVRA, UVRB, and UVRC, or alternatively, the anthramycin may be removed by UVRA and UVRB in the absence of UVRC and with no DNA strand incision. To assess the competition between these two competing pathways, the rate of UVRABC-mediated excision repair of anthramycin-N2-guanine DNA adducts and the rate of UVRAB-mediated removal of the adduct were measured with single end-labeled DNAs under identical reaction conditions. UVR protein concentrations of 15 nM UVRA, 100 nM UVRB, and 10 nM UVRC protein were chosen to mimic in vivo concentrations. With these UVR protein concentrations and anthramycin-DNA concentrations of 1-2 nM the incision reaction and the release reactions are described by first-order kinetics. The rate of the UVRABC reaction, measured as the increase in incised fragments, was six to seven times faster than the rate of the UVRAB reaction, measured as the decrease in incised fragments. The UVRABC incision rate on anthramycin-modified linear DNA was four to five times the incision rate measured on the same DNA irradiated with ultraviolet light. We also investigated the role of the ATPase function of UVRB in UVRAB-mediated anthramycin removal. We found that a UVRB analogue with alanine at arginine 51, which retains near wild type ATPase activity, supported removal of anthramycin in the presence of UVRA, whereas a UVRB analogue with alanine at lysine 45, which abolishes the ATPase activity, did not. UVRB*, a specific proteolytic cleavage product of UVRB which retains the ATPase activity, did support removal of anthramycin in the presence of UVRA.