在大肠杆菌中人腺病毒5型及昆虫核多角体病毒晚期启动子表达CAT基因

本文证明,含有人5型腺病毒及苜蓿丫纹夜蛾核型多角体病毒(AutograPha californica Nuclear Polyhedrosis Virus, AcNPV)启动子的DNA片段,可在大肠杆菌中起始氯霉素乙酰基转移酶(Chloramphenicol Acetyltransferase,CAT)基因的转录和表达,使转化宿主菌表现为氯霉素抗性型。这说明,除痘苗病毒启动子外,其它人类病毒及昆虫病毒的启动子也能有效地在大肠杆菌中工作。     

Changes in lipid content and composition during the development of N-nitrosodiethylamine induced hepatocarcinoma

Alterations in lipid content and composition in the N-nitrosodiethylamine-induced hepatocarcinoma were investigated. Rats were administrated with N-nitrosodiethylamine in the drinking water for 12 weeks followed by normal tap water for another 6 weeks. The cholesterol content in the liver was increased shortly after the administration of N-nitrosodiethylamine and remained elevated after the removal of the nitrosoamine from the water. The phosphatidylethanolamine level was elevated during N-nitrosodiethylamine administration with a concomitant reduction in phosphatidylcholine level. Lysophosphatidylcholine and sphingomyelin levels were increased during the last four weeks of the study. The level of phosphatidylinositol was substantially reduced after eight weeks of N-nitrosodiethylamine treatment, and remained low during the post-treatment period. We postulate that changes in lysophosphatidylcholine and sphingomyelin may be a compensatory mechanism for maintaining the asymmetrical distribution of choline-containing lipids in the outer leaflet of the membrane. The elevated level of cholesterol may be a useful indicator for the early detection of N-nitrosodiethylamine-induced hepatocarcinoma.     

湖北宜昌震旦系-寒武系界线地层Micrhystridium regulare化石的发现及其地层意义

该文记述了国际前寒武系-寒武系界线层型候选剖面所在地,湖北宜昌震旦系-寒武系界线地层中发现的小刺球藻类化石Micrhystridium regulare,regulare,讨论了它们的产出层位及其归属,并对小刺球藻类化石在时间上、空间上的分布作了简要的归纳,最后提出了小刺球藻类化石在震旦系-寒武系界线地层的划分和大区域地层对比中重要的潜在作用。     

原位椭圆偏振术研究牛血清清蛋白在固/液界面的吸附

用原位椭圆偏振术系统研究了硅片表面因素及缓冲液环境因素对牛血清清蛋白在固/液界面吸附的影响。在生理条件下,疏水表面与亲水表面相比BSA吸附量较大。随着硅片表面电荷密度增加,BSA吸附量增加。BSA吸附量当体溶液pH值等于BSA等电点时达到最大。而随着体溶液离子强度增加,BSA吸附量亦上升。实验结果提示:除了熵驱动作用之外,硅片表面与BSA分子及BSA分子之间的静电作用在BSA吸附中起着十分重要的作用。     

Mechanisms of heat protection by cycloheximide or puromycin: Involvement of polyamines?

1. 1.|When Chinese hamster ovary cells are treated with cycloheximide (10 μg/ml) or puromycin (100 μg/ml) for 2 h before and during heating at 43°C for 3 h, there is protection from hyperthermic killing; i.e. the plating efficiency increases 2000-fold from 3.7 × 10⁻⁵ to (6–9) × 10⁻².

2. 2.|The total intracellular levels of spermidine and spermine are not altered by the hyperthermic or drug treatments.

3. 3.|The small 30% decrease in intracellular putrescine observed after heating is not altered by drug treatment.

4. 4.|Heat protection by treatment with cycloheximide or puromycin cannot be attributed to changes in levels of total intracellular polyamines.

Potent and selective activity of a new carbocyclic nucleoside analog (carbovir: NSC 614846) against human immunodeficiency virus in vitro

Carbocyclic 2',3'-didehydro-2',3'-dideoxyguanosine (Carbovir: NSC 614846), a novel nucleoside analog, emerged as a potent and selective anti-HIV agent from a large screening program conducted by the National Cancer Institute and its contractors. Its hydrolytic stability and its ability to inhibit the infectivity and replication of HIV in T-cells at concentrations of approximately 200- to 400-fold below toxic concentrations make carbovir a top-priority candidate for development as a potential antiretroviral agent in the treatment of AIDS patients.     

Human liver alkaline phosphatase, purification and partial sequencing: homology with the placental isozyme

Human liver alkaline phosphatase (AP) has been purified to homogeneity. The enzyme has a molecular weight of 150,000 in its native state and consists of two identical subunits of Mr 75,000. After treatment with endoglycosidase F the molecular weight is reduced to 50,000 indicating a high degree of glycosylation. The amino-terminal sequence up to 22 residues was found to be Leu-Val-Pro-Glu-Lys-Glu-Lys-Asp-Pro-Lys-Tyr-(Ala)-Arg-Asp-Gln-Ala-Gln-?- Thr-Leu-Lys-Tyr. The amino-terminal portions of human and bovine liver AP are identical. The amino termini of the human liver and human placental AP isozymes have appreciable homology. Conformationally the amino termini are very similar.     

Selective destruction by formaldehyde fixation of an H-2Kb serological determinant involving lysine 89 without loss of T-cell reactivity

In preparation for functional analyses, a study of the binding of H-2K^b-specific monoclonal antibodies (mAb) to formaldehyde (FOR)-fixed H-2^b spleen or tumor cells revealed that three of nine mAb tested had lost reactivity with the FOR-fixed cells, whereas the reactivity of the other mAb generally did not diminish. Comparison of the reactivity of these mAb on untreated H-2K ^bm mutant cells and on FOR-treated H-2K^b cells suggests that for three mAb the total loss of reactivity on the latter could be a consequence of the alteration by FOR of lysine 89, which is substituted by alanine in mutant bm3. H-2KP^b-specific alloreactive polyclonal or monoclonal CTL, all of which had retained reactivity with bm3 target cells, had also retained reactivity with FOR-fixed H-2^b cells as indicated by cold target inhibition studies. The H-2K^b-specific CTL were probably reactive with conformational determinants of H-2K^b, which are dependent on the integrity of both the 1 and the 2 domains of the H-2K^b molecule. Results are compatible with FOR treatment selectively affecting a serological determinant in the 1 domain without affecting conformational-type CTL determinants.Abbreviations used in this paper CTL cytotoxic T lymphocyte - FOR formaldehyde - PBS phosphatebuffered saline - FCS fetal calf serum - mAb monoclonal antibody - TNBS trinitrobenzene sulfonate