Effect of the sequences upstream from the ribosome-binding site on the yield of protein from the cloned gene for phage MS2 coat protein

The translational efficiency of the coat protein gene of phage MS2 has been examined in vivo with respect to neighbouring sequences. The cloned MS2 DNA has been gradually shortened starting at the 5' or 3' terminus, and its effect on coat protein synthesis monitored. Removal of the 3'-terminal sequences had little influence. In contrast, the gradual removal of the 5'-terminal region profoundly reduces translation. Long before the ribosomal binding site (RBS) of the coat protein (CP) gene is reached, the yield of CP has dropped by one order of magnitude. Functional half-lives of the various messengers were found not to be significantly different. Available evidence indicates that the secondary structure of the RBS in native and shortened MS2 RNA is identical. We infer that important determinants for ribosome recognition lie 5' to the RBS region of the MS2 RNA coat gene.     

Protein-lipid interactions and differential scanning calorimetric studies of bacteriorhodopsin reconstituted lipid-water systems

Bacteriorhodopsin has been reconstituted at various molar concentrations into liposomes of dimyristoyl- and also of dipalmitoylphosphatidylcholine. Differential scanning calorimetry indicates that as the protein concentration within the lipid bilayer increases, the cooperativity of the lipid phase transition is reduced, i.e. the transition is broadened, while the midpoint transition temperature remains virtually unchanged. Freeze-fracture electron microscopy of our preparation shows, in agreement with previous data from other laboratories, that extensive protein aggregation occurs when the liposome is cooled below the T_c transition temperature of the lipid. Laser flash photolysis measurements of protein rotation of the bacteriorhodopsin show, especially in the case of protein-rich recombinants, that protein aggregates exist even above T_c. The perturbation caused by the presence of bacteriorhodopsin in the lipid bilayer is similar to that produced by other intrinsic proteins. The difficulty of correlating the observed calorimetric enthalpy data with a simple concept of a ‘boundary lipid layer’ based upon consideration of a single isolated protein is discussed in view of the occurrence of protein aggregates both above and below T_c. It is concluded that the reduction of enthalpy is related to the number of lipids which solvate the protein aggregates within the protein-lipid patches and are thereby removed from the cooperative melting and enthalpy of the remaining regions of pure lipid.     

两种方法检测接种流行性出血热沙鼠肾细胞灭活疫苗后人体的中和抗体

本文应用空斑减少中和试验(PRNT)和细胞病变中和试验(cPENT)两种方法对出血热沙鼠肾细胞灭活疫苗扩大人体免疫后的血清进行中和抗体水平检测。根据两种方法对总计74人份的免疫后血清检测比较结果,两种方法检测的抗体阳转率和抗体水平(GMT)。CPENT法均高于PRNT法,经统计学处理均有显著性差异。不同免疫组的中和抗体水平比较结果,注射三针的阳转率(n=10,100％)高于两针组(n=10,20—30％);接种加氢氧化铝佐剂疫苗(n=13)较接种不加佐剂的两种疫苗(n=26)的抗体水平高,阳转率为92％—100％GMT为22—69;皮下途径(n=15)和肌肉途径(n=13)注射无明显差别,阳转率分别为87—93％和92—100％,GMT分别为29—46和22—61。以上结果进一步肯定沙鼠肾细胞疫苗的人体免疫性     

新生儿乙型肝炎血源疫苗的免疫策略和成本效益分析

比较了6种新生儿血源乙型肝炎疫苗的免疫方案,其中一种只免疫HBsAg阳性母亲的婴儿效果最差,群体有效率仅17.79％,成本效益比值亦低。其它5种方案都是对全部新生儿进行免疫,效果均好。这5种方案是10μg与3μg两种剂量的不同组合,其中用10μgg3JI疫者成本效益比值最高,有效率为78.61％。HBsAg阳性母亲新生儿按30μg×3,而阴性母亲婴儿首剂用30μg,第2、3剂各10μg,有效率高达87.47％,但成本效益比值最低。应根据我国经济发展的水平与群众的承受能力,对各地区选用不同的新生儿免疫方案。     

乙型肝炎血源疫苗不同免疫剂量阻断新生儿母婴传播的效果观察

用乙型肝炎血源疫苗,按0、1、6程序,分5种不同剂量免疫HBsAg和HBeAg均阳性(双阳性)母亲和仅HBsAg阳性母亲的新生儿,井于首针后8～12个月采血,用放射免疫(RIA)法检测他们的HBsAg和抗-HBs、抗-HBc,以比较不同剂量乙肝疫苗阻断母婴传播的效果。结果,10μg×3组对双阳性和仅HBsAg阳性母亲的新生儿的保护率,分别是42.9％和53.5％;20μ×3组为67.4％和69.7％;30μg、10μg、10μg组为75.6％和79.8％,30.20、20μg(含30、30、10μg)组为80.2％和81.5％;30μg×3组为82.3％和83.7％。随疫苗剂量增加保护率逐渐增加,抗-HBs阳转率也是如此。     

HBsAg阴性母亲的新生儿接种不同剂量乙型肝炎血源疫苗的效果

HBsAg阴位母亲的新生儿,按0,1、6月程序分别接种10-10-10μg(1组)、20-10-10μg(2组)和30-10-10μg(3组)乙型肝炎血源疫苗。第一针后一年,检查抗-HBs阳转率,分别为87.60％,90.64％和88.97％,无统计学显著差异。3针10μg组免疫后l～4年抗-HBs阳性率分别为88.31％、81.08％、80.10％和78.39％,虽稍下降,但无统计学显著差异。3个剂量组HBsAg阳性率分别为0.71％,0.49％和0.74％,说明HBsAg阴性母亲的新生儿,用国产血源HBsAg疫苗免疫以10μ×3效果较理想。     

Estimations of number of active loci,dominance and heritability in polygenic inheritance of gregarious behavior inMuscidifurax raptorellus [Hymenoptera: Pteromalidae]

Estimates of the minimum number of genetic loci governing expressions of gregarious oviposition inMuscidifurax raptorellus Kogan & Legner were enabled by the verification of recombinant males, which were secured from virgin hybrid females, formed by crossing cohorts from solitary and gregarious populations. Examinations of parasitization behavior in female progeny that had F₁ male fathers indicated the presence of hybrids among the males. Estimates of gene number, made on the basis of variances in P₁, F₁, F₂ and backcross progeny, and by observing behavior in second and third order backcrosses, ranged from two to 19, with most between two and five. However, backcrossing data suggested that at least eight loci were actively segregating for this characteristic. Semi-dominance of the solitary trait (D=0.63 to 0.84), and unequal gene effects probably caused these gene estimated to be lower than the actual number. Estimates of the coefficient of heritability, in the broad sense based on parental and F₁ and F₂ variances indicated that variability of gregarious behavior in the experimental environment was influenced >60% by genotypic factors, offspring-parent regression analyses gave estimates >38%.      

Effects of glucose on the production of recombinant protein C in mammalian cell culture

Effects of glucose on a cultured Chinese hamster ovary cell line producing recombinant human protein C were investigated. After the recombinant cells reached confluency, they were maintained in the medium containing 10% serum and different levels of glucose in either batch or daily-exchange mode. High concentrations of glucose to the cultures yielded higher cell densities. Daily exchanges of media produced higher cell densities than the corresponding batch culture. Total protein C production per cell decreased with time in batch culture, in accordance with the declined glucose metabolism. Supplementation of the media with high levels of glucose diminished both the expression and gamma-carboxylation activities of the recombinant cells. Production of protein C persisted in daily-exchange culture, resulting in a constant production rate of protein C. In this case again, glucose reduced the specific productivity of recombinant protein C. An apparent glucose inhibition constant was determined to be 0.11 mg/mL by Dixon plots. The ability to gamma-carboxylate recombinant protein C was also impaired at the highest level of glucose. From these results, a strategy to maximize recombinant protein C productivity is discussed.