The size and conformation of Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) DNA in infected cells and virions.

The genome of a novel human herpesvirus has been detected in specimens of Kaposi's sarcoma (KS) and in several AIDS-related lymphoproliferative disorders. Here we examine the size and genomic conformation of the DNA of this virus (known as KS-associated herpesvirus or human herpesvirus 8) in latently and lytically infected cells and in virions. Pulsed-field gel electrophoresis of viral DNA shows that the viral genome is similar in size to those of other gammaherpesviruses (160 to 170 kb). As with Epstein-Barr virus, KS-associated herpesvirus DNA is stably maintained in latently infected B cells as episomal monomer circles and induction from latency is associated with the selective accumulation of linear genomic forms.     

棕色固氮菌缺失nifZ基因的突变种固氮酶MoFe蛋白的纯化和性质

采用 52℃下加热 6 min,后经 DEAE- 52、Sephacryls S- 2 0 0和 Q- Sepharose等柱层析方法 ,分离纯化了棕色固氮菌 (Azotobacter vinelandii)缺失 nif Z基因突变种固氮酶 Mo Fe(Δnif Z Mo Fe)蛋白 ,其纯度达到电泳纯。Δnif Z Mo Fe蛋白的固氮活性为 2 83nmol C2 H2 还原 / (min·mg蛋白 ) ,远低于野生种 Mo Fe蛋白。Δnif Z Mo Fe蛋白对氧更敏感 ;热稳定性略低于野生种。Δnif Z Mo Fe蛋白的可见光吸收光谱与野生种 Mo Fe蛋白极为相似。其圆二色谱和磁圆二色谱在 450～ 550 nm与野生种 Mo Fe蛋白显著不同 ,表明其 P- cluster及其周围环境与野生种 Mo Fe蛋白有所差异。这亦可能是造成缺失 nif Z突变种 Mo Fe蛋白固氮活性低的原因。     

鲇鱼成鱼和幼鱼中含色素的巨噬细胞集结的诱导发生

通过腹腔注射不同剂量的牛血清白蛋白（ＢＳＡ）或墨汁以刺激巨噬细胞活动,研究了鲇鱼成鱼和幼鱼头肾、肾、脾和肝中含色素的巨噬细胞集结（ＰＭＡ）的发生。鲇鱼淋巴样组织中存在巨噬细胞的不均一性,可分网状／纤维状巨噬细胞,梭状巨噬细胞,圆形红色巨噬细胞,圆形黄红色巨噬细胞和含色素的巨噬细胞。注射ＢＳＡ或墨汁后,头肾、肾,脾和肝中ＰＭＡ和圆形巨噬细胞的数量最终均有不同程度的增加。通过诱导发生实验,表明含色素的     

黑曲霉糖化酶高产和低产菌株糖化酶基因调控区的克隆及其分析比较

以PCR合成的糖化酶高产菌株黑曲霉(Asp. Niger)T21糖化酶基因5’近端非编码区588bp(EcoRI-BamHI)的序列为探针,从T21染色体DNA中克隆到近2.0kb的糖化酶基因5’端非编码区序列,并以此序列为探针从糖化酶低产菌株黑曲霉3.795(T21的诱变出发株)的染色体DNA中克隆到1.5kb的糖化酶基因5’端非编码区序列。该二序列的分析测定结果表明,其结构特征与文献报道的黑曲霉糖化酶基因5’端非编码区的基本一致,被称为“核心启动子”(Core promoter)的TATAAAT框及GCAAT框,分别在翻译起始点的-109bp及-178bp处。此外,在曲霉amdS,amyB基因中已发现有调控功能的CCAAT序列存在于-449bp和-799bp处。高产和低产菌株糖化酶基因5’端非编码区序列的分析比较结果表明,有9个部位的碱基发生了变化。此实验结果为进一步研究黑曲霉糖化酶基因在转录水平上的调控规律打下了基础。     

水解淀粉的酿酒酵母菌的构建

把黑曲霉糖化酶cDNA,酵母磷酸甘油激酶基因启动子区和终止区以及酵母Ty因子的δ序列构建成整合型的糖化酶表达分泌质粒pKG 1。该质粒转化酿酒酵母Y33得到整合型转化子。转化子分泌糖化酶活力在3.0μ/ml以上,在以5％可溶性淀粉为碳源的培养基中静止培养7d,淀粉利用率达86％,生成酒精的浓度与以5％葡萄糖为碳源时相等。     

Interaction between inclusions embedded in membranes.

We calculate the membrane-induced interaction between inclusions, in terms of the membrane stretching and bending moduli and the spontaneous curvature. We find that the membrane-induced interaction between inclusions varies nonmonotonically as a function of the inclusion spacing. The location of the energy minimum depends on the spontaneous curvature and the membrane perturbation decay length, where the latter is set by the membrane moduli. The membrane perturbation energy increases with the inclusion radius. The Ornstein-Zernike theory, with the Percus-Yevick closure, is used to calculate the radial distribution function of inclusions. We find that when the spontaneous curvature is zero, the interaction between inclusions due to the membrane deformation is qualitatively similar to the hard-core interaction. However, in the case of finite spontaneous curvature, the effective interaction is dramatically modified.     

A novel centrifugal impeller bioreactor. II. Oxygen transfer and power consumption

The effects of the impeller configuration, aeration rate, and agitation speed on oxygen transfer coefficient K(L)a were studied in a newly designed centrifugal impeller bioreactor (5-L). The oxygen transfer rates in the novel bioreactor were also compared with those in a cell-lift bioreactor with comparable dimensions. The cell-lift impeller produced much higher surface oxygen transfer rates than the centrifugal one at an agitation speed over 200 rpm. This result was in good agreement with our observation that the cell-lift impeller produced much higher unfavorable turbulence. In addition, the experiments using granulated agar particles as pseudo plant cells indicated that the K(L)a value decreased steadily with an increase in agar particle concentration, and the centrifugal impeller still demonstrated a larger K(L)a than the cell lift up to a high pseudo cell concentration of 19.5 g dry weight (DW)/L (under 150 rpm and 0.20 vvm) or 22.3 g DW/L (under 200 rpm and 0.20 vvm). Furthermore, the correlation between power number and impeller Reynolds number for both the centrifugal and the cell-lift impellers was successfully obtained, which could be used for predicting the power input required by each impeller. From the results obtained, the centrifugal impeller bioreactor is expected to have great potential in its application to shear-sensitive biological systems.     

Antitumor effects of human recombinant interleukin-1α and etoposide against human tumor cells: mechanism for synergismin vitro and activityin vivo

Recombinant human interleukin 1α (rh IL-1α) and etoposide (VP-16) synergize for direct growth inhibition of several human tumor cell linesin vitro. Our previous studies demonstrated that VP-16 increased the number of membrane-associated IL-1 receptors (IL-1Rs) and also enhanced the internalization of receptor-bound rh IL-1α. The purposes of this study were to test our hypothess that these events were critical to the synergy between rhIL-1α and VP-16, to determine whether rhIL-1α and VP-16 synergize to increase superoxide (SO) anion radical productionin vitro since SO anion has been implicated in the toxic effects of IL-1, and to investigate the antitumor efficacy of the combinaton against tumors in vivo. A375/C6 melanoma cells and OVCAR-3 ovarian carcinoma cells were tested with IL-1 receptor antagonist (IL-1ra) before exposure to rhIL-1α, VP-16 and rhIL-1α plus VP-16. The synergistic or antagonistic effects were assessed by MTT assay. SO production was measured by reduction of cytochrome C. Athymic female mice bearing the A375/C6 melanoma were treated by rhIL-1α, VP-16, and rhIL-1α+VP-16. The antitumor effects were evaluated by quantitating tumor growth and survival time. Pretreatment with the IL-1ra abrogated the synergistic effects of rhIL-1α and VP-16. The production of SO radical by A375/C6 cells was increased 2.5 fold by the combination of rhIL-1α and VP-16, and the addition of exogenous SOD blocked the synergy between rhIL-1α and VP-16. However, when A375/S0D15 cells which over-expressed manganese superoxide dismutase (MnSOD) after MnSOD cDNA transfecton were exposed to rhIL-1α and VP-16, in vitro antagonism was observed. In vivo studies demonstrated that the combination of rhIL-1α and VP-16 delayed tumor growth better than either agent alone, although long-term survival was not improved because of substantial toxicity. Our results suggest that the synergistic antitumor effects of IL-1α and VP-16 may be due to IL-1R modulation and increased internalization of IL-1-IL-1R complex by VP-16 treatment, as well as to a subsequent increase in SO anion radical production from the tumor cells exposed to both drugs. Thus, the combnation of IL-1α and VP-16 might prove useful for the treatment of malignant diseasein vivo, if the increased toxicity can be reduced or managed. The US Government’s right to retain a non-exclusive royalty-free license on and to any copyright is acknowledged.