Ligation of highly modified bacteriophage DNA

After digestion by TaqI or nicking by DNAase I, five highly modified bacteriophage DNAs were tested as substrates for T4 DNA ligase. The DNAs used were from phages T4, XP12, PBS1, SP82, and SP15, which contain as a major base either glucosylated 5-hydroxymethylcytosine, 5-methylcytosine, uracil, 5-hydroxymethyluracil, or phosphoglucuronated, glucosylated 5-(4′,5′-dihydroxypentyl)uracil, respectively. The relative ability of cohesive-ended TaqI fragments of these DNAs and of normal, λ DNA to be ligated was as follows: $\text{λ}\text{DNA}\text{=}\text{XP}\text{12}\text{DNA}\text{>}\text{SP}\text{82}\text{DNA}\text{?}\text{nonglucosylated}\text{T}\text{4}\text{DNA}\text{>}\text{T}\text{4}\text{DNA}\text{=}\text{PBS}\text{1}\text{DNA}\text{?}\text{SP}\text{15}\text{DNA}$. TaqI-T4 DNA fragments were also inefficiently ligated by Escherichia coli DNA ligase. However, annealing-independent ligation of DNAase I-nicked T4, PBS1, and λ DNAs was equally efficient. We conclude that the poor ligation of TaqI fragments of T4 and PBS1 DNAs was due to the hydroxymethylation (and glucosylation) of cytosine residues at T4's cohesive ends and the substitution of uracil residues for thymine residues adjacent to PBS1's cohesive ends destabilizing the annealing of the restriction fragments. Only SP15 DNA with its negatively charged, modified base was unable to serve as a substrate for T4 DNA ligase in an annealing-independent reaction; therefore, its modification directly interfered with enzyme binding or catalysis.     

Thymus-independent immunogenicity in vitro of the divalent antigen DNP-polyethylene oxide

Chemically simple and physically well-defined dinitrophenyl derivatives of polyethylene oxide (DNP-PEO) can be prepared in a wide range of forms and sizes. These materials were used to investigate the molecular basis of immunogenicity and the binding of the antigens to membrane-bound receptors. Both di- and multivalent DNP-PEO activate normal murine B lymphocytes to yield primary anti-DNP antibody response in vitro. The immunogenicity is dependent on the carrier chain length but independent of T cells. Responses comparable to those induced by DNP-conjugated polymerized flagellin are induced by divalent linear materials of medium molecular weights of about 60,000. A highly multivalent material is moderately immunogenic, but at much lower antigen doses than divalent materials. The carrier PEO does not affect B-cell responses to DNP-PEO or T-cell response to succinyl concanavalin A. Moreover, it shows no polyclonal mitogenicity at concentrations as high as 1 mg/ml. Studies of antigen binding to cell surface DNP receptors show that the strongly immunogenic materials of medium molecular weights have an appreciable tendency to bind bivalently and thus potentially to crosslink receptors. The binding of smaller, less immunogenic antigen appears predominantly monovalent.     

The mode of action of cytotoxic and antitumor 1-nitroacridines. I. The 1-nitroacridines do not exert their cytotoxic effects by physicochemical binding with DNA

The mode of action of cytotoxic and antitumor 1-nitroacridines and their isomeric derivatives was studied by comparing their effects in cell-free systems and towards cultured tumor HeLa cells, assuming that the nitroacridines considered exert cytotoxic effects by physicochemical binding with the DNA. All the nitroacridines impaired biosyntheses of DNA, RNA and protein in cultured HeLa cells and a causal relationship between nitroacridine inhibition of macromolecular biosyntheses and lethal effects of the agents appears likely. In cell-free systems, the nitroacridines bound with two independent sites on the DNA, forming complexes with enhanced resistance to DNA strand separation upon melting and inhibited the DNA polymerase reaction by altering activity of template and/or of enzyme. The 1-nitroacridines were poorly effective in cell-free systems and were the most potent inhibitors toward the growth of HeLa cells among the derivatives studied. It is concluded that the primary events responsible for cytotoxic effects of antitumor 1-nitroacridines and of their isomeric derivatives are different. The metabolic activation of 1-nitroacridines to more reactive intermediates which will attach to and alter the structure and/or function of DNA of sensitive cells is suggested.     

Immunologic and clinical improvement of progressive coccidioidomycosis following administration of transfer factor

Three patients with progressive coccidioidomycosis were given preparations of transfer factor (TF). Adverse reactions to TF were minimal. Following TF administration two of these patients had prolonged clinical remissions in their coccidioidal disease. Cellular immune responses were sequentially evaluated by coccidioidininduced delayed-type skin tests, lymphocyte blast transformation and macrophage inhibition factor production (MIF). These three patients each exhibited different cellular immune patterns before and after TF administration. Two patients converted their coccidioidin skin tests, and one converted lymphocyte transformation response to coccidioidin. Also, TF apparently favorably affected the MIF response in all three patients.     

Bioluminescence in oceanology

For analytical purposes bioluminescence can be used in three main ways: 1. luminescence measurement of bioluminescent system components isolated in vitro; 2. determination of luminous organisms' reaction to the in vivo test-action; 3. measurement of bioluminescence in marine ecological systems. The majority of the reports of this Symposium are dealing with the first two topics. The aim of our presentation is to draw attention to the third one. The possibilities of bioluminescent analysis are wider than its traditional scheme of applications in the laboratory, when the emitting system is withdrawn from a native source and is placed in a cuvette of the light measuring device. The reverse scheme is also possible, i.e. the device can be introduced into light emitting system such as a marine biocenosis–the community of the sea inhabitants–where we obtain a highly sensitive and rapid means of gaining the information on the vital activity of marine ecosystems, i.e. their spatial structure, rhythms, man's influence upon them, etc. The present communication will consider the possibilities of this form of bioluminescent analysis.     

蚕豆叶片发育与衰老过程中超氧物歧化酶活性与丙二醛含量变化

蚕豆植株叶片随茎节自上而下表现出明显的发育与衰老顺序,可作为衰老特征的是叶绿素和蛋白质含量明显下降。蚕豆叶中SOD活性主要定位于12 000× g离心后所得的上清液和叶绿体组分。衰老叶片的SOD总活性和叶绿体组分的相对活性都有所下降,SOD同工酶谱也发生了改变。O_2~ 产生速率随叶龄增大而稍上升;而MDA含量在叶片外观表现枯黄衰老征兆前就急剧上升。可能因为衰老叶片过氧化氢酶活性大幅度下降与SOD之间的不平衡,致使O_2~ 代谢中间产物累积而引起膜的损伤.     

注射依赖cAMP的蛋白激酶催化亚基加速胚胎内细胞间连接通讯的发育(英文)

本研究以爪蟾胚胎内胚层细胞间连接通讯发育的时程为指标,观察了cAMP和依赖cAMP的蛋白激酶催化亚基对这一发育的影响。将依赖cAMP的蛋白激酶催化亚基注射入爪蟾胚胎四细胞期的每一个细胞可使该胚胎内胚层细胞间连接通讯的发育明显加快,提示在正常状态下这一发育的进程是受细胞内依赖cAMP的磷酸化水平的制约。但用双丁酰cAMP和磷酸二酯酶抑制剂对胚胎进行培育,或将cAMP和磷酸二酯酶抑制剂注射入胚胎细胞,对这一发育并无影响,可能是由于这些胚胎细胞内依赖cAMP的蛋白激酶的实际有效含量较低而cAMP含量较高所致。注射这种蛋白激酶催化亚基所诱导的胚胎细胞间连接通讯在注射后约8.5小时出现。这一时间比前人在哺乳动物细胞培养中用cAMP或必需的信使RNA诱导出细胞间连接通讯所需要的时间(2—4小时)长得多,提示在胚胎中依赖cAMP的磷酸化对细胞间连接通讯发育的作用是从RNA转录的水平上开始的。     

绕茧蜂属寄生于云杉四眼小蠹成虫的—新种记述并附本属世界种检索表(膜翅目:茧蜂科)

绕茧蜂属Ropalophorus Curtis,1837是茧蜂科中的一个小属,迄今世界上仅记载有2种。一种为R.clavicornis(Wesmael),1835,分布于欧州及日本,寄生于云杉八齿小蠹Ips typographus及I.amitinus成虫体内;另一种为R.wisconsinensis Shenefelt,1960,仅分布于美国,由于该种是用诱捕器捕到的,因此,其奇主不详,但有可能为I.pini(Shenefelt,1960)。