蛋白质：生物界中又一类信息的储存者和传递者 ——对 prion 生物学相关知识的重新解读

蛋白质在相当一段时间内一直被认为只是 DNA 或 RNA 等遗传物质的表达形式,其单独不具有储存和传递生物信息的功能,而储存和传递生物信息却是遗传物质的两个基本属性 . 随着近年来 prion 生物学的出现和研究的逐步深入,人们已经认识到蛋白质单独就具有储存和传递生物信息的功能,从这个意义上讲,蛋白质也是一类遗传物质 . 所以很有必要站在这个角度对 prion 生物学的相关知识进行重新的梳理和再认识,通过对哺乳动物 prion 生物学和真菌 prion 生物学各自发展历程的简要回顾和最新研究成果的介绍,以及它们之间相同点和不同点的比较,总结出蛋白质储存和传递生物信息的一般规律并指出其表现形式的多样性 .     

Use of dynamic mechanical analysis (DMA) to determine critical transition temperatures in frozen biomaterials intended for lyophilization

Dynamic mechanical analysis is widely used to determine glass transitions in solid state materials. However, here we demonstrate the application of DMA for the determination of glass transitions (Tg’) in the frozen liquid state by means of a steel sample pocket. The use of the pocket allows frozen material to be analysed and glass transition events demonstrated. In addition, it allows weak glass transitions to be detected clearly in some complex formulations where they can be obscured by eutectic and other strong thermal events when other methods such as DSC or DTA are used. Classical excipients (trehalose, lactose, dextran) were analysed and shown to give reproducible Tg’ values, though with values slightly higher than those obtained by DSC. Finally, several complex real biological materials, typical of those encountered when freeze drying biological and biopharmaceutical materials, were analysed and the potential value of DMA demonstrated to determine the relevant glass transition temperatures for use in cryobiology and freeze drying.     

抗微生物作用的纳米材料研究新进展

通过对国内外抗微生物作用的纳米材料研究进行综述,总结几种最常应用的抗微生物作用的纳米材料的应用范围、作用原理及优缺点,为纳米材料的选用提供参考。目前抗微生物作用的纳米材料主要有金属元素型纳米材料、金属氧化物型纳米材料、非金属无机化合物型纳米材料、有机化合物型纳米材料和天然纳米材料等;纳米材料的抗微生物机制主要有催化反应与接触反应学说两种;有些纳米材料按现有制作方法和使用方法,具有一定的生物毒性。因此,今后应重视如何降低纳米材料的生物毒性以及进一步开发应用天然纳米材料的研究。     

Biological variability in biomechanical engineering research: Significance and meta-analysis of current modeling practices

Biological systems are characterized by high levels of variability, which can affect the results of biomechanical analyses. As a review of this topic, we first surveyed levels of variation in materials relevant to biomechanics, and compared these values to standard engineered materials. As expected, we found significantly higher levels of variation in biological materials. A meta-analysis was then performed based on thorough reviews of 60 research studies from the field of biomechanics to assess the methods and manner in which biological variation is currently handled in our field. The results of our meta-analysis revealed interesting trends in modeling practices, and suggest a need for more biomechanical studies that fully incorporate biological variation in biomechanical models and analyses. Finally, we provide some case study example of how biological variability may provide valuable insights or lead to surprising results. The purpose of this study is to promote the advancement of biomechanics research by encouraging broader treatment of biological variability in biomechanical modeling.     

Biobanking

Biobanks, more formally known as biological resource centers (BRCs), form an “unsung” yet critical component of the infrastructures for scientific research, industry and conservation, without which much of the current scientific activity involving microbial cultures and cell-lines would be effectively impossible. BRCs are de facto depositories of “biological standards” holding taxonomic and other reference strains on which much of the associated published science and industrial standards are built and upon which some significant international commercial and ethical issues rely. The establishment and maintenance of BRCs is a knowledge- and skill-rich activity that in particular requires careful attention to the implementation of reliable preservation technologies and appropriate quality assurance to ensure that recovered cultures and other biological materials perform in the same way as the originally isolated culture or material. There are many types of BRC, which vary both in the kinds of material they hold and in their functional role. All BRCs are expected to provide materials and information of an appropriate quality for their intended use and work to standards relevant to those applications. There are important industrial, biomedical, and conservation issues that can only be addressed through effective and efficient operation of BRCs in the long term. This requires a high degree of expertise in the maintenance and management of collections of biological materials at ultra-low temperatures, or as freeze-dried material, to secure their long-term integrity and relevance for future research, development, and conservation.     

Chromatography of Biological Materials on Polyethylene Glycol Treated Controlled-Pore Glass

Controlled-pore glass (CPG) columns will withstand high pressures without damage or loss of flow rates and their pore size and bed dimensions are independent of the eluent. Utilization of untreated CPG has been previously limited for permeation chromatography of various biological materials due to surface adsorption. Treatment of CPG with 1% polyethylene glycol (20, 000) solution prior to column preparation minimizes the adsorption phenomenon. High speed chromatography of proteins and enzymes was performed on treated CPG of various pore diameters. With some exceptions the proteins and enzymes eluted with greater than 92% recovery of the starting material and/or biological activity. Surface-treated CPG represents a useful tool for the characterization of many biological materials.     

纳米技术与生物学实验的微型化

纳米技术是近年来发展迅速的新技术,有着几乎无限的潜力。一方面生物分子的尺度是纳米与亚纳米级的,纳米技术可以从生物科学学到许多生物分子作用的奥秘;另一方面,纳米技术为生物学的研究提供新材料、新方法,使生物学研究可以多快好省地进行。本文简单介绍几种利用纳米技术开展生物学研究的思路与方法。     

Verapamil as a co-mutagen in the Salmonella/mammalian microsome mutagenicity test

Verapamil is a calcium-channel blocking agent, commonly used for chronic treatment of heart conditions. We have previously demonstrated that verapamil acts as a co-mutagen in a bacterial mutagenicity test for some experimental anilinoacridine antitumour drugs. Within the anilinoacridines series there are several compounds which are apparently non-mutagenic (or very weak mutagens) in the absence of verapamil, but strong mutagens in its presence. We have now tested a wider range of materials for verapamil enhancement of mutagenicity, to include some of those to which persons on verapamil therapy might be exposed through life-style or occupation. Some verapamil enhancement of mutagenicity was seen with most mutagenic compounds including anticancer drugs, antiparasitic agents, one biological stain and one hair dye. A number of tricyclic antidepressants and biological stains were tested and found to be non-mutagenic. If these results extrapolate to mammalian cells, long-term verapamil therapy could potentially increase the effects of certain environmental mutagens.     

User-friendly cell patterning methods using a polydimethylsiloxane mold with microchannels

Techniques for partitioning cell adhesion are useful tools in biological and medical experiments. However, conventional cell patterning methods require special apparatus, special materials or high-level skills. Therefore, we have developed a new cell patterning methodology which can be easily carried out in biological laboratories. Non-cell adhesive material including hydrogel or gas patterns to restrict cell adhesion on a culture dish or glass substrates can be constructed by exploiting a polydimethylsiloxane (PDMS) mold with microchannels. The PDMS molds suck non-adhesive materials into microchannels from the inlet of the microchannels and the materials are immobilized onto the substrates with a desired pattern. High resolution under a few micrometers and long-term stability can be realized. This method has been used for analysis of stem cells, muscle cells, neuron development and other cells in collaboration with many biological researchers. Several examples to use this technique are introduced in this review.     

An overview of the biophysical applications of atomic force microscopy

The potentialities of the atomic force microscopy (AFM) make it a tool of undeniable value for the study of biologically relevant samples. AFM is progressively becoming a usual benchtop technique. In average, more than one paper is published every day on AFM biological applications. This figure overcomes materials science applications, showing that 17 years after its invention, AFM has completely crossed the limits of its traditional areas of application. Its potential to image the structure of biomolecules or bio-surfaces with molecular or even sub-molecular resolution, study samples under physiological conditions (which allows to follow in situ the real time dynamics of some biological events), measure local chemical, physical and mechanical properties of a sample and manipulate single molecules should be emphasized.     

Nanomaterials in biological environment: a review of computer modelling studies

Nanotechnology is set to impact a vast range of fields, including computer science, materials technology, engineering/manufacturing and medicine. As nanotechnology grows so does exposure to nanostructured materials, thus investigation of the effects of nanomaterials on biological systems is paramount. Computational techniques can allow investigation of these systems at the nanoscale, providing insight into otherwise unexaminable properties, related to both the intentional and unintentional effects of nanomaterials. Herein, we review the current literature involving computational modelling of nanoparticles and biological systems. This literature has highlighted the common modes in which nanostructured materials interact with biological molecules such as membranes, peptides/proteins and DNA. Hydrophobic interactions are the most favoured, with π-stacking of the aromatic side-chains common when binding to a carbonaceous nanoparticle or surface. van der Waals forces are found to dominate in the insertion process of DNA molecules into carbon nanotubes. Generally, nanoparticles have been observed to disrupt the tertiary structure of proteins due to the curvature and atomic arrangement of the particle surface. Many hydrophobic nanoparticles are found to be able to transverse a lipid membrane, with some nanoparticles even causing mechanical damage to the membrane, thus potentially leading to cytotoxic effects. Current computational techniques have revealed how some nanoparticles interact with biological systems. However, further research is required to determine both useful applications and possible cytotoxic effects that nanoparticles may have on DNA, protein and membrane structure and function within biosystems.     

菊科几种入侵和非入侵植物种子需光发芽特性差异

对入侵菊科植物(假苍耳、薇甘菊、紫茎泽兰、飞机草)以及非入侵菊科植物(扫帚梅、天人菊、金鸡菊、麦秆菊、翠菊、黑心菊)对比研究发现,入侵组种子往往是需光发芽,即有光条件下平均高出无光条件发芽率40%(P0.01),而非入侵组的需光发芽特性不明显,即有光和无光条件下种子发芽率差异不显著(P0.05)。以入侵植物假苍耳为例对其种子需光发芽的特性研究发现:红光有利于提高种子的萌发率(萌发率为62%),而蓝光起到相反的作用(萌发率37%);当以全光的25%照射种子时,最能够促进种子的萌发(萌发率59%),更高的光强抑制种子萌发(100%光强时,发芽率为21%)。适宜浓度水杨酸SA处理(0.01mmol/L)可以起到与光照类似的效果而促进种子萌发(提高30%发芽率),而PEG和低温处理对其不存在显著影响,说明这种需光发芽的机理可能与SA处理影响种子萌发存在一定的联系。研究证实了入侵和非入侵菊科植物之间确实存在需光发芽的差异,其生理生化差异及是否有利于入侵植物的快速入侵需深入研究。     

Biomolecule imprinting: Developments in mimicking dynamic natural recognition systems

The principle of molecular imprinting has repeatedly been proven a successful and effective means of creating sites of specific recognition within polymers. After almost three decades of development, we finally have some evidence of large molecule imprinting. In this review, the authors aim to bring the molecular imprinting community up-to-date. We describe here some of the new and innovative work that endeavours to take molecular imprinting away from its chromatographic, synthetic past and make use of this technique in new, exciting and developing fields, such as drug delivery, biotechnology, biosensors, protein/drug recognition and in the development of novel materials. The main discussion analyses a variety of different two-dimensional and three-dimensional approaches recently developed for the recognition of larger molecules or biomolecules, such as proteins, viruses and cells, and how the traditional imprinting methods have been adapted to suit the mass transfer requirements of these biological templates. We also review a relatively new technique that has emerged from the imprinting approach, which aims to develop novel materials from the imprints of biological materials.     

In vivo electron paramagnetic resonance oximetry with particulate materials

Electron paramagnetic resonance (EPR) methods can be used to study tissue pO(2) (PtO(2)) in anesthetized or awake animals (EPR oximetry). The method takes advantage of the fact that some paramagnetic materials have an EPR linewidth that is sensitive to the pO(2) in which the material is located. This article provides an overview of the method of EPR oximetry using implanted particulate materials as the sensors of pO(2). Characteristics of these materials are described to help the reader understand the factors involved in choosing the optimum particulate material. Examples of biological studies are included that show how EPR oximetry may be used on both awake and anesthetized animals.     

Detection and identification of optical activity using polarimetry – applications to biophotonics,biomedicine and biochemistry

Polarized light that is reflected or transmitted through chiral specimens can be used to detect and identify biological and chemical materials including human tissue. The determination of the silent footprints of the chiral properties of the biological materials on scattered polarized light is the basis for these investigations. It is of primary importance to identify which combinations of the elements of the Mueller matrix for reflected or for transmitted light can be used to determine the optical activity of the biochemical materials. The optical activity of chiral materials is characterized by optical rotation and circular dichroism. The explicit analytical dependence of these specific elements of the Mueller matrix, upon the angles of incidence and scatter, upon the wavelength and upon the type of chirality has the potential to provide experimentalists with guidance in determining the optimum use of optical polarimetric scatterometers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Latest Advances on Bacterial Cellulose‐Based Materials for Wound Healing,Delivery Systems,and Tissue Engineering

Bacterial cellulose (BC) is a nanocellulose form produced by some nonpathogenic bacteria. BC presents unique physical, chemical, and biological properties that make it a very versatile material and has found application in several fields, namely in food industry, cosmetics, and biomedicine. This review overviews the latest state‐of‐the‐art usage of BC on three important areas of the biomedical field, namely delivery systems, wound dressing and healing materials, and tissue engineering for regenerative medicine. BC will be reviewed as a promising biopolymer for the design and development of innovative materials for the mentioned applications. Overall, BC is shown to be an effective and versatile carrier for delivery systems, a safe and multicustomizable patch or graft for wound dressing and healing applications, and a material that can be further tuned to better adjust for each tissue engineering application, by using different methods.     

Culture as a stressor: A revised model of biocultural interaction

Contemporary urban societies display in high relief the action of social stratification on human biology. Recent studies of biological responses to urban environments and of socioeconomically disadvantaged people indicate that culture allocates risks disproportionately to some individuals and groups within society through its constituent values and related patterns of behavior. Although risk allocation is present in all societies, it is very clear in urban environments within stratified societies where high exposure to harmful materials is many times more likely for some segments of society. In urban environments, culture may be seen as adding stressors to the environment by concentrating naturally occurring materials to levels that are toxic to humans and through the creation of new toxic materials. In stratified societies the risk of exposure to these new stressors is focused on the socioeconomically disadvantaged. This exposure has consequences that increase the likelihood of more exposure and more socioeconomic disadvantage, thereby increasing social stratification. This suggests that models of biocultural interaction include a feedback relationship in which biological factors influence the sociocultural system in addition to the usual action of the sociocultural system on biological features and responses. This model strongly reinforces the view that stressors can originate from cultural arrangements. Am J Phys Anthropol 102:67–77, 1997 © 1997 Wiley-Liss, Inc.     

Instrumental neutron activation analysis of biological samples

The elemental compositions of 18 biological reference materials have been processed, for 14 stepped combinations of irradiation/decay/counting times, by the INAA Advance Prediction Computer Program. The 18 materials studied include 11 plant materials, 5 animal materials, and 2 other biological materials. Of these 18 materials, 14 are NBS Standard Reference Materials and four are IAEA reference materials. Overall, the results show that a mean of 52% of the input elements can be determined to a relative standard deviation of ±10% or better by reactor flux (thermal plus epithermal) INAA.

     

Microbial Degradation of Forensic Samples of Biological Origin: Potential Threat to Human DNA Typing

Forensic biology is a sub-discipline of biological science with an amalgam of other branches of science used in the criminal justice system. Any nucleated cell/tissue harbouring DNA, either live or dead, can be used as forensic exhibits, a source of investigation through DNA typing. These biological materials of human origin are rich source of proteins, carbohydrates, lipids, trace elements as well as water and, thus, provide a virtuous milieu for the growth of microbes. The obstinate microbial growth augments the degradation process and is amplified with the passage of time and improper storage of the biological materials. Degradation of these biological materials carriages a huge challenge in the downstream processes of forensic DNA typing technique, such as short tandem repeats (STR) DNA typing. Microbial degradation yields improper or no PCR amplification, heterozygous peak imbalance, DNA contamination from non-human sources, degradation of DNA by microbial by-products, etc. Consequently, the most precise STR DNA typing technique is nullified and definite opinion can be hardly given with degraded forensic exhibits. Thus, suitable precautionary measures should be taken for proper storage and processing of the biological exhibits to minimize their decaying process by micro-organisms.