Biological properties and ultrastructure of brucellae during L-transformation and reversion]

There was shown a difference in the biological properties and the ultrastructure of two strains of brucellae, spheroplasts obtained from them under the action of penicillin, L-form and revertants obtained from the L-form. Spheroplasts formation was characterized by a change of brucellae into R-form and some virulence reduction. The cells had an outer and a cytoplasmic membranes, and usually lost their capacity to binary division. L-forms were obtained during the 9th and the 35th passage on a medium with penicillin; their formation was accompanied by the change in serological properties of the culture and significant reduction of the virulence; the cells were characterized by a marked polymorphism and the capacity to budding; they had 2 membranes on the cell surface and an intensively developed system of intracytoplasmic membranes. The revertants formed on the medium without penicillin during the 16th-30th passage or spontaneously on the medium with penicillin. They differed from the initial strains of brucella culture by a marked increase in penicillin-resistance, by the changes in serological properties, and also by polymorphism of cells, capable, however, of binary division.     

Reversion of nonculturable forms of <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> under the influence of exometabolites of <Emphasis Type="Italic">Aranicola</Emphasis> spp.

It was established that the exometabolites of Aranicola spp., isolated from beef, promoted the reversion of nonculturable forms of Listeria monocytogenes, isolated from the same product, into the proliferative state, influencing the expression of their biological properties, which was expressed by a change in the morphology and enzymatic properties of the colony, and also by an increase the hemolytic activity and a decrease in adhesiveness. It was noted that all changes in the biological properties of L. monocytogenes were phenotypic. Passage in trypticase-soy broth with further seeding of Listeria on yeast agar after the third passage led to a gradual change in the biological properties, until their complete recovery after the fifth passage on the sixth day of the study.     

The Use of Streptococcus faecalis as an Indicator of the Hygienic Condition of Meat Preserves and the Possibility of Interference by Aerococcus viridans

Summary: Few arguments may be put forward in favour of the use of Escherichia coli as an indicator of the hygienic condition of preserved meat products. In products of this type E. coli occurs only rarely. The proposal, which is supported by logical considerations and practical experience, to replace this organism by Streptococcus faecalis as an indicator of possible faecal contamination is strongly upheld by the authors. However, it is necessary to stress that the ubiquitous micro-organism, Aerococcus viridans , occurs frequently in preserved meat products and, as it strongly resembles Strep. faecalis , may cause difficulties in the hygienic evaluation of such foods. The morphological and biological characteristics found suitable for differentiating these two organisms are described. Results supporting the view that Aerococcus, Pediococcus and Gaffkya be considered as distinct genera are also given.     

Cell structure and the pathogenicity of Brucella at different stages of L transformation]

On the basis of changes in the biological properties and morphology of Br. abortus culture under the action of penicillin 3 stages of L-transformation in Brucella were determined. The prevalence of first bacilliform and then typical L-cells and rapid reversion hampering the determination of virulence were characteristic of the initial stage (passages 1-4). Typical L-cells with the wrinkled surface, deep depressions and holes as well as a decrease in virulence and slight pathomorphological changes in the organs of the infected animals were characteristics of the intermediate stage (passages 5-10). Typical L-cells and amorphous masses, a further decrease in virulence, pathomorphological changes of toxic character (only after the injection of L-culture in large doses) were characteristic of the late stage (from passage 11 and further on). At all stages of L-transformation Brucella cultures showed a high reproductive capacity, binary division, the formation of elementary bodies by budding both inside and on the surface of L-cells.     

Different Permeability of Potassium Salts across the Blood-Brain Barrier Follows the Hofmeister Series

The passage of ions across biological membranes is regulated by passive and active mechanisms. Passive ion diffusion into organs depends on the ion-pairing properties of salts present in the serum. Potassium ions could affect brain activity by crossing the blood-brain barrier (BBB) and its accumulation in the extracellular cerebral space could precipitate seizures. In the present study, we analyze passive diffusion of a series of potassium salts in the in vitro isolated guinea pig brain preparation. Different potassium counter-anions confer ion-pairing and lipophilicity properties that modulate membrane diffusion of the salt. Extracellular recordings in different cortical areas demonstrated the presence of epileptiform activities that strongly relate to anion identity, following the qualitative order of the Hofmeister series. Indeed, highly lipophilic salts that easily cross the BBB enhanced extracellular potassium concentration measured by ion-selective electrodes and were the most effective pro-epileptic species. This study constitutes a novel contribution for the understanding of the potential epileptogenicity of potassium salts and, more generally, of the role of counter-anions in the passive passage of salts through biological membranes.     

眼部浅绿色气球菌感染4例报道

目的 提高对眼部气球菌感染的认识.方法 报告4例眼部气球菌感染病例并复习文献,对其发病因素、临床症状、诊断、及治疗和预后进行分析.结果 4例眼部感染气球菌患者为中年或老年人,基础疾病为青光眼、糖尿病(2例)及甲状腺功能亢进症,均经病原菌的分离鉴定后确诊为浅绿色气球菌感染,且对左氧氟沙星、万古霉素等常用药敏感,4例患者中除1例青光眼患者用药效果不理想外,其余均经1～2周的治疗后痊愈.结论 对眼部感染患者,应加强浅绿色气球菌的分离与鉴定.     

Subacute Sclerosing Panencephalitis Measles Virus: Study of Biological Markers

Comparative studies between two measles virus strains isolated from patients with subacute sclerosing panencephalitis (SSPE) and a prototype low tissue culture passage Edmonston measles virus are described. Differences were noted in several properties. The findings described in this report suggest that strains of measles virus associated with SSPE have different biological properties and apparently cannot be distinguished from laboratory and field strains of the virus.     

The Tumorgenicity of Glioblastoma Cell Line U87MG Decreased During Serial In Vitro Passage

Established cancer cell lines are routinely used to study cancer. Several factors such as serial passage may affect the reproducibility of experiments with cancer cell lines, but few researches focused on these changes. In the present study, different morphology and decreased tumorigenicity were observed in late passage U87MG cells. In vitro experiments further revealed that late passage U87MG cells possessed lower invasion properties than early passage, whereas no significant differences of proliferation and migration were found between early and late passage U87MG cells. In particular, we confirmed that late passage U87MG cells exhibited more epithelial phenotype with decreased PI3K/Akt pathway and TGF-β pathway expressions at protein level. In summary, our results focused on the changes of U87MG cells during serial in vitro passage, suggested that passage-induced changes may lead to notable changes of biological characteristics and several molecular transitions in cancer cell lines, indicating the necessity to shorten experiment-span and accomplish experiments with the same or similar passage cancer cell strains.     

Primary mechanisms of the biological effect of electromagnetic fields

Based on the model of a bulk knitted structure, a possible mechanism of action of an external electromagnetic field on biological systems was proposed. The electromagnetic field affects biological processes through changes in the rates of biochemical reactions in response to changes in the conformational properties of water in the electromagnetic field.     

猪源绿色气球菌的分离鉴定与药敏特性研究

目的鉴定研究2006年和2008年本实验室分别从广东清远和广西北流两个猪场发病小猪的膝关节积液中分离到2株呈四联状或成对排列,在山羊血琼脂平板上能形成明显的α-溶血圈的G+球菌。方法采用小白鼠致病性试验、细菌常规生理生化鉴定、药敏试验、耐药基因检测及16S rRNA序列分析等方法对上述分离的2株细菌进行鉴定及药敏特性研究。结果确定这2株G+球菌为正常情况下非致病性绿色气球菌(登录号分别为:GQ161096;GQ161097)。系统发育分析表明,两分离株与绿色气球菌15MS(登录号:EU075039.1)同源性分别高达99.4%和98.7%。药敏试验及耐药基因检测发现,这2株绿色气球菌除了对新霉素、氟哌酸、恩诺沙星、菌必治和环丙沙星等5种药物呈高敏外,对先锋V等13种抗菌素均不敏感。耐药基因检测结果表明,GXBL-1可检出6个耐药基因,GDQY-1则可检出多达10个耐药基因。结论从这2株分离株耐药谱检测结果可以看出,正常菌株同样携带多重耐药基因,存在着通过质粒转座子和整合子将耐药基因转移给敏感菌,导致耐药性传播的可能,应引起足够重视。     

Making the right connections: biological networks in the light of evolution

Our understanding of how evolution acts on biological networks remains patchy, as is our knowledge of how that action is best identified, modelled and understood. Starting with network structure and the evolution of protein–protein interaction networks, we briefly survey the ways in which network evolution is being addressed in the fields of systems biology, development and ecology. The approaches highlighted demonstrate a movement away from a focus on network topology towards a more integrated view, placing biological properties centre‐stage. We argue that there remains great potential in a closer synergy between evolutionary biology and biological network analysis, although that may require the development of novel approaches and even different analogies for biological networks themselves.     

DNA mimics on the base of pyrrolidine and hydroxyproline

In order to improve physicochemical and biological properties of natural oligonucleotides in particular increasing their affinity for nucleic acids, the selectivity of action and biological sustainability, several types of DNA mimics were designed. The survey collected data on the synthesis and properties of the DNA mimics - peptide-nucleic acids analogues, which are derivatives of pyrrolidine and hydroxyproline. We examine some physicochemical and biological properties of negatively charged mimics of this type, containing phosphonate residues, and possessing a high affinity for DNA and RNA, selective binding with nucleic acids and stability in various biological systems. Examples of the use of these mimics as tools for molecular biological research, particularly in functional genomics are given. The prospects for their use in diagnostics and medicine are discussed.     

Ion passage pathways and thermodynamics of the amphotericin B membrane channel

Amphotericin B is a polyene macrolide antibiotic used to treat systemic fungal infections. Amphotericin B's chemotherapeutic action requires the formation of transmembrane channels, which are known to transmit monovalent ions. We have investigated the ion passage pathways through the pore of a realistic model structure of the channel and computed the associated thermodynamic properties. Our calculations combined the free energy computations using the Poisson equation with a continuum solvent model and the molecular simulations in which solvent molecules were present explicitly. It was found that there are no substantial structural barriers to a single sodium or chloride ion passage. Thermodynamic free energy calculations showed that the path along which the ions prefer to move is off center from the channel's central axis. In accordance with experiments, Monte Carlo molecular simulations established that sodium ions can pass through the pore. When it encounters a chloride anion in the channel, the sodium cation prefers to form a solvent-bridged pair configuration with the anion.     

Mapping the amino acid properties of constituent nucleoporins onto the yeast nuclear pore complex

Visualization of molecular structures aids in the understanding of structural and functional roles of biological macromolecules. Macromolecular transport between the cell nucleus and cytoplasm is facilitated by the nuclear pore complex (NPC). The ring structure of the NPC is large and contains several distinct proteins (nucleoporins) which function as a selective gate for the passage of certain molecules into and out of the nucleus. In this note we demonstrate the utility of a python code that allows direct mapping of the physiochemical properties of the constituent nucleoporins on the scaffold of the yeast NPC׳s cytoplasmic view. We expect this tool to be useful for researchers to visualize the NPC based on their physiochemical properties and how it alters when specific mutations are introduced in one or more of the nucleoporins. The code developed using Python is available freely from the authors.     

Tipping the scales--specifier proteins in glucosinolate hydrolysis

Glucosinolates are a group of secondary plant metabolites found in the Brassicales order that are beneficial components of our diet, determine the flavor of a number of vegetables and spices and have been implicated in pest management strategies. These properties, most of the biological activities and the pungent odor and taste associated with glucosinolate-containing plants are due to the products formed from glucosinolates by their hydrolytic enzymes, myrosinases, upon tissue disruption. Specifier proteins impact the outcome of glucosinolate hydrolysis without having hydrolytic activity on glucosinolates themselves. In the presence of specifier proteins, glucosinolate hydrolysis results in nitriles, epithionitriles and organic thiocyanates whose biological functions are currently unknown. In contrast, isothiocyanates formed in the absence of specifier proteins have been demonstrated to possess a variety of biological activities and are thought to protect plants from herbivore and pathogen attack. This review discusses the current knowledge on plant and insect specifier proteins with special emphasis on their biochemical properties and possible mechanisms of action.     

The effects of serial passage of a nucleopolyhedrosis virus through an alternate host system

The multiple-embedded velvetbean caterpillar nucleopolyhedrosis virus (VBC-NPV) ofAnticarsia gemmatalis Hübner was shown to be infectious of a variety of noctuid hosts. The mortality data demonstrated the importance of defining the dosage used in host range analysis. Serial passage of the VBC-NPV through the soybean looper,Pseudoplusia includens, was done to select for host range variants of this NPV. After several passages of the VBC-NPV through this insect the virulence of the progeny virus remained unchanged indicating heterogeneity in the host and not the virus population. However, between the 3rd and 5th serial passage throughPseudoplusia a latent NPV identical to a single-embedded NPV previously associated fromA. gemmatalis was activated. The biological and biochemical characteristics of this isolate demonstrated it to be distinct from the original VBC-NPV. A single passage of this activated virus throughA. gemmatalis resulted in the production of viral progeny having characteristics of the original VBC-NPV. Serial passage of this virus preparation throughP. includens resulted in virus progeny having biological properties associated with both the original VBC-NPV and the activated NPV isolate.     

Principles of viable preservation of parasitic Protozoa

Viable preservation is fundamentally different from serial passage as a way of maintaining Protozoa in the laboratory. In serial passage there is continuous selection of a reproducing population so that biological characteristics deviate from those representative of the original population towards those of a population adapted to the special conditions of the passage. Viable preservation arrests reproduction and so, this selection. Viably preserved material, therefore, deserves to be defined by a special term, ‘stabilate’, a stabilate being defined as a population of organisms viably preserved on a unique occasion. Materials maintained by serial passage are appropriately called ‘strains’.     

B-lymphocyte regulation of the immune system. III. Preparation and characterization of rabbit antibodies that inhibit the biological activity of the lymphokine, B-cell-derived enhancing factor (BEF)

Antibodies that inhibit the biological activity of B-cell-derived enhancing factor (BEF) were produced in a rabbit immunized with BEF obtained from a non-immunoglobulin-producing B-cell line. Immunoglobulin G (IgG) fractions purified from the preimmune or the immune rabbit serum were compared by testing for their capacity to inhibit regulatory activities of BEF. It was found that the enhancing activity exerted by BEF on the in vitro antibody response to sheep red blood cells was inhibited when anti-BEF IgG was incorporated in the cultures. Moreover, anti-BEF IgG abolished the inhibitory activity exerted by BEF on the expression of Fc receptor by lymphoid cells. Comparable concentrations of preimmune IgG were ineffective in inhibiting BEF activity. The passage of supernatant fluid containing BEF activity through an anti-BEF IgG-coupled Sepharose column yielded an 84-fold purified product that exhibit BEF immunoregulatory properties. These results will accelerate further studies aimed at better characterization of the BEF molecule(s).