Circulating nucleic acids and evolution

INTRODUCTION: J.B. Lamarck in 1809 was the first to present a theory of evolution. He proposed it was due to the adaptation of species to environmental changes, this adaptation being acquired by the offspring. In 1868, Darwin suggested that cells excrete gemmules, which circulate through the body and reach the gonads where they are transmitted to the next generation. His main argument came from graft hybrids. AREAS COVERED: In the fifties and sixties, Russian geneticists, rejecting neo-Darwinism, said that acquired characteristics were the basis of evolution. The main experiments on which they based their theory were the transmission of hereditary characteristics by a special technique of grafting between two varieties of plants. We repeated this kind of experiment and also succeeded in obtaining hereditary modifications of the pupil plants that acquired some characteristics of the mentor variety. Rather than adopting the views of the Russian scientists, we suggested that DNA was circulating between the mentor and pupil plants. Hirata's group have shown recently, by using molecular techniques such as cloning, RFLP PCR and sequencing some genes of their graft hybrids of pepper plants, that transfer of informative molecules from the mentor to the pupil plant does exist. Nucleic acids are actively released by cells; they circulate in the body. They can transform oncogenically or trigger antibody response but the only genetic transformation showing that DNA can go from the soma to the germen comes from graft hybrids. EXPERT OPINION: This suggests that circulating nucleic acids, in this case DNA, like Darwin's gemmules, play a role in the mechanism of evolution.     

A study of the antigenicity of T3 and T4 coli-dysentery bacteriophages during the vegetative stage of development

The development of viral neutralizing antibodies in animals injected with T₃ or T₄ phage is considerably inhibited by the presence of bacterial antigens. A new procedure has been described to liberate phage from infected E. coli B bacteria by inducing lysis with penicillin. By immunological means it has been shown that T₄-infected cultures of E. coli B, in which phage development has been inhibited with proflavine, contain the viral neutralizing antigen after lysis. In contrast, it has not been possible to demonstrate by immunological means the appearance of viral neutralizing antigen in E. coli B infected with T₃ prior to the appearance of intracellular phage.     

The detection of temperature induced structural changes in T4B and T7 bacteriophages by means of high precision acoustic velocity measurements

High precision measurements of the velocity of 7-7.5 MHz ultrasonic waves in suspensions of both T4B and T7 bacteriophages as a function of temperature revealed the presence of a distinct transition in the physiological range of 35-45 degrees C. Data from acoustic measurements, sedimentation analysis and electron microscopy enabled us to identify this transition as being caused by the protein component of the phage and not the DNA. This transition does not depend on the position of the long tail fibers and may be part of some normal physiological process within the bacteriophage which presumably enhances its recognition and attachment to its host cell.     

Adjuvancy of streptococcal nucleic acids.

A study was performed to find out whether or not RNA and DNA isolated from Group A streptococcal cytoplasm does possess adjuvant activity. The findings obtained indicate that the adjuvancy of streptococcal RNA is very similar to that of poly I:C. The adjuvant activity of poly I:C is characterized by its capacity to increase the number of pre-existing hemolysin-producing spleen cells and by its ability to increase the development of 19S and 7S producers early in the 12-day-period of primary immune response. The adjuvancy of streptococcal DNA was considerably less pronounced than that of RNA. Neither poly I:C nor streptococcal RNA and DNA were found to be capable of increasing the process of priming for the secondary immune response.     

人巨细胞病毒核酸标准物质研制与应用

人巨细胞病毒(human cytomegalovirus,HCMV)是威胁人类健康的最重要病原之一.随着分子生物学技术的发展,HCMV核酸水平的检测逐渐得到了广泛的认可,这也就需要研制HCMV核酸标准物质来保证检验数据的真实可靠.本文简要介绍了国内外目前存在的HCMV核酸标准物质的研制情况,并对这些标准物质在应用中遇到的问题进行了阐述,旨在为人巨细胞病毒核酸检测诊断试剂的标准化,以及为其质量控制提供参考.     

Controlling release from the lipidic cubic phase. Amino acids, peptides, proteins and nucleic acids.

Drugs are optimally effective in the therapeutic concentration range. A challenge in the delivery area is to design a system that will allow the therapeutic range to be accessed and to be maintained for defined periods. The lipidic cubic phases have been used as delivery matrices with such properties. For water-soluble drugs, release from the cubic phase is controlled by transport through aqueous channels that permeate the phase. Channel size can be tuned over wide limits by adjusting temperature and lipid identity. Thus, the possibility exists to regulate the rate of drug release from the cubic phase. With a view to exploiting these features for small molecule, proteinaceous and nucleic acid drugs, we have taken a systematic approach toward understanding how cubic phase transport is controlled by phase identity and microstructure and by the physical and chemical properties of the drug itself. Measurements were made using tryptophan, rubipy, DNA and six proteins as drug surrogates and with three hosting lipids. Remarkably, transport was observed with apo-ferritin whose size far exceeds that of the aqueous channel suggesting a molecular breathing or peristalsis type of facilitated release. Exquisite control over release was achieved by adjusting electrostatic interaction strength and by His-tag displacement.     

The effect of nucleic acids and of carbohydrates on the formation of streptolysin

1. Ribonucleic acid of yeast causes the formation of a potent hemolysin in broth cultures of Streptococcus pyogenes. 2. The hemolysin whose formation is induced by yeast ribonucleic acid appears to be identical with streptolysin S. 3. Desoxyribonucleic acid, products of acid or alkaline hydrolysis of ribonucleic acid, or many other substances tested, fail to produce a similar effect. 4. Digestion by ribonuclease increases markedly the streptolysin-inducing activity of certain preparations of ribonucleic acid. 5. A fraction (AF) of yeast nucleic acid has been isolated which possesses approximately 100 times the streptolysin-inducing capacity of the starting material. Some of the properties which distinguish AF, a polynucleotide, from ordinary yeast nucleic acid are described. AF is associated with the ribonuclease-resistant fraction of yeast nucleic acid. 6. Ribonucleic acid prepared from streptococci, wheat germ, and mammalian liver, and subsequently treated with ribonuclease, is about as active in causing streptolysin formation as ribonuclease-treated yeast nucleic acid. 7. Ribonucleic acid of tobacco mosaic virus, tested under comparable conditions, was found to be inactive. 8. Ribonucleic acid prepared from streptococci, wheat germ, and tobacco mosaic virus resembles yeast nucleic acid in possessing a ribonuclease-resistant fraction. 9. In addition to AF, a factor (or factors), present in meat infusion and in peptone, was found to be required for the formation of streptolysin. 10. The factor can be partially replaced by any one of several carbohydrates, the most active being maltose, glucosamine, and trehalose, in that order. 11. When appropriate concentrations of AF, maltose, and glucose are used, the nucleic acid-induced streptolysin can be produced in a medium whose chemical composition is essentially defined.     

Circulating nucleic acids in plasma and serum: past, present and future

Circulating nucleic acids have been detected in plasma/serum from cancer patients with a variety of tumor types. Polymerase chain reaction techniques provide a ubiquitous and facile approach for the identification of these tumor-associated genetic alterations from a minimal amount of tissue and body fluids. Increased levels of free DNA and RNA during malignancy, as well as in various medical conditions and infectious states, offers potential clinical utility for disease screening, diagnosis, prognosis, assessing occult disease progression, identifying potential therapeutic targets and monitoring treatment response. Additionally, elevated fetal DNA and RNA circulate in maternal blood and may serve as a diagnostic aide for assessing chromosomal abnormalities, fetal sexing and monitoring complications associated with pregnancy. Issues persist regarding the characteristics, etiology and potential pathological consequences of circulating cell-free DNA and RNA. Regardless, disease surveillance using nucleic acid-based assays for the evaluation of plasma/serum and body fluids provides a non-invasive and highly practical method for assessing patients.     

电化学发光免疫法检测TSH、T3、T4、FT3、FT4相关性观察

目的观察电化学发光免疫检测血清TSH、T3、T4、FT3、FT4之间相关性。方法对134例临床标本同时进行TSH、T3、T4、FT、3、FT4电化学发光免疫法检测,并对此五项指标间相关性进行统计学分析。结果TSH／T3、TSH／T4、TSH／FT3、TSH／FT4、T3／FT4、FT3／T4之间具有直线相关关系,相关系数分别为:0.362,0.324,0.404,0.335,0.907,0.819,0.808,0.839,0.839,0.955。结论T3／T4、FT3／FT4之间相关系数大,r2>0.8,具有一定的医学意义。     

Molecular beacons: colorful analysis of nucleic acids

The completion of the Humane Genome Project has resulted in an exponential rise in the demand for molecular diagnostic assays. To meet this demand, several innovative technologies have become available for performing homogeneous genetic analyses. For this type of assay, special detector probes are necessary. In 1996, Tyagi and Kramer described fluorogenic hairpin-shaped detector probes, called 'molecular beacons', which are extraordinarily specific. Since they characterize alleles by the generation of fluorescent signals, they are perfectly suited for homogeneous genetic analysis. Molecular beacons assays are simple, fast, inexpensive, sensitive, utilize a high-throughput format, enable the testing of many samples simultaneously and allow the detection of a series of different agents in the same assay tube. This review is designed to give the reader a greater understanding of the exciting applications of molecular beacons in DNA, RNA and protein studies.     

Diagnostic potential of circulating nucleic acids for oncology

Approximately a decade ago, the PCR-based detection of extracellular, tumor-derived circulating nucleic acids in the plasma and serum of cancer patients was introduced as a noninvasive tool for cancer detection. Although the test criteria, sensitivity and specificity, compare favorably with conventional diagnostic measures, until now the methodical ponderousness of circulating nucleic acids in plasma and serum analysis prevented it from becoming a clinical routine application. However, with rapid technical improvement towards automated high-throughput platforms, it is expected that the next 5 years will see circulating nucleic acids in plasma and serum analysis integrated into the initial diagnosis and follow-up monitoring of cancer patients. The hope is that the use of circulating nucleic acids in plasma and serum as a molecular tumor marker and potential profiling tool will finally translate into a longer survival and better quality of life for cancer patients.     

4种SARS-Cov-2核酸检测试剂盒测定结果分析

目的 比对4种严重急性呼吸综合征冠状病毒2(SARS-CoV-2)核酸检测试剂盒测定结果,为实验室选择试剂盒和评估试剂盒性能提供参考.方法 收集318例咽拭子标本,提取核酸后,分别用4种SARS-CoV-2核酸检测试剂盒进行检测.结果 4种试剂盒检测结果比对的Kappa值分别为0.741(试剂盒A与B比较)、0.653...     

The role of L3T4 in recognition of Ia by a cytotoxic, H-2Dd-specific T cell hybridoma

The expression of T4/T8 surface markers on human T cells and of L3T4/Lyt-2 on murine T cells has lead to the association of these surface markers with recognition of either class II or class I major histocompatibility complex (MHC) antigens. It has been suggested that these T cell surface antigens interact with MHC antigens. We have examined the role of L3T4 in the recognition of Dd by the T cell hybridoma, 3DT52.5. This T cell hybridoma was found to be specific for the N/Cl domain of Dd. The recognition of a class I antigen by an Lyt-2-, L3T4+ T cell hybridoma allowed the separate evaluation of interactions between L3T4/Ia and the T cell antigen receptor, Dd. Recognition by this hybridoma resulted in the production of interleukin 2 (IL-2) and cytolytic activity. Antibody blocking experiments have demonstrated that L3T4 was involved in triggering the effector function of 3DT52.5 only on Ia+ stimulator or target cells. We have demonstrated that an L3T4+, Dd-specific T cell hybridoma, 3DT52.5, uses the L3T4 molecule to directly interact with nonpolymorphic Ia determinants.