Tradescantia Bioassays as Monitoring Systems for Environmental Mutagenesis: A Review

Since the early studies on the genetic effects of chemical and physical agents, species and clones of Tradescantia have been used as experimental subjects, by virtue of a series of favorable genetic characteristics. Bearing just six pairs (2n = 12) of large, easily observable chromosomes, cells from almost every part of the plant, from the root tips to the developing pollen tube, yield excellent material for cytogenetic studies.

As a consequence of the intensive use of Tradescantia in genetic studies, a series of genetic characteristics have been found that offer opportunities for the detection of agents affecting the stability of the genome. At least five such characteristics have been selected as endpoints for the establishment of assays to evaluate mutagenesis. Three of these, root-tip mitosis, pollen-tube, and microspore mitosis are essentially chromosome aberration assays, wherein one observes and evaluates the visible damage in the chromosomes. A fourth, the stamen-hair mutation assay (Trad-SHM), is a point mutation mitotic assay based on the expression of a recessive gene for flower color in heterozygous plants. The fifth assay is a cytogenetic test based on the formation of micronuclei (Trad-MCN) that result from chromosome breakage in the meiotic pollen mother cells.

This article examines the characteristics and fundamentals of the Trad-MCN and the Trad-SHM assays and reviews the results obtained to date with these systems in the assessment of environmental mutagenesis.     

Quantifying Synergy: A Systematic Review of Mixture Toxicity Studies within Environmental Toxicology

Cocktail effects and synergistic interactions of chemicals in mixtures are an area of great concern to both the public and regulatory authorities. The main concern is whether some chemicals can enhance the effect of other chemicals, so that they jointly exert a larger effect than predicted. This phenomenon is called synergy. Here we present a review of the scientific literature on three main groups of environmentally relevant chemical toxicants: pesticides, metal ions and antifouling compounds. The aim of the review is to determine 1) the frequency of synergy, 2) the extent of synergy, 3) whether any particular groups or classes of chemicals tend to induce synergy, and 4) which physiological mechanisms might be responsible for this synergy. Synergy is here defined as mixtures with minimum two-fold difference between observed and predicted effect concentrations using Concentration Addition (CA) as a reference model and including both lethal and sub-lethal endpoints. The results showed that synergy occurred in 7%, 3% and 26% of the 194, 21 and 136 binary pesticide, metal and antifoulants mixtures included in the data compilation on frequency. The difference between observed and predicted effect concentrations was rarely more than 10-fold. For pesticides, synergistic mixtures included cholinesterase inhibitors or azole fungicides in 95% of 69 described cases. Both groups of pesticides are known to interfere with metabolic degradation of other xenobiotics. For the four synergistic metal and 47 synergistic antifoulant mixtures the pattern in terms of chemical groups inducing synergy was less clear. Hypotheses in terms of mechanisms governing these interactions are discussed. It was concluded that true synergistic interactions between chemicals are rare and often occur at high concentrations. Addressing the cumulative rather than synergistic effect of co-occurring chemicals, using standard models as CA, is therefore regarded as the most important step in the risk assessment of chemical cocktails.     

环境条件对植物稳定碳同位素组成的影响

植物稳定碳同位素技术是近年兴起的一项快速、可靠的技术。利用稳定碳同位素技术可以揭示碳同化的过程的许多方面的信息。1 3C和1 2 C同位素效应 ,使它们在进行碳循环时发生稳定碳同位素的分馏。植物光合作用过程中CO2 经气孔扩散分差和RUBPCase及PEPCase羧化分馏是造成植物稳定碳同位素比率 (R =1 3C/ 1 2 C)不同于源CO2 中碳同位素比率的主要原因。遗传因素和环境因子同时决定植物碳同位素组成。植物稳定碳同位素技术同时还是古气候重建和预测未来环境变化的理论基础。本文综述了光照、温度、水分、二氧化碳、矿质营养、盐分和大气污染物等环境因素对植物稳定碳同位素组成影响方面的研究进展。     

A Review on Mechanisms of Plant Tolerance and Role of Transgenic Plants in Environmental Clean-up

This article deals with the advances and implication of phytoremediation technologies with emphasis on remediation of toxic heavy metals from contaminated soil. Most of the conventional remedial technologies are expensive and inhibit the soil fertility and cause negative impacts on various ecosystem services. However, phytoremediation is a cost effective and ecofriendly approach, which does not adversely affect soil properties and ecosystem services. In recent years, major progresses have been made in understanding the physiological mechanisms of metal uptake and transport in hyper accumulators. However, the molecular mechanisms of metal uptake, translocation, accumulation and detoxification in plants and their further implication in transgenic development for efficient phytoremediation are not well understood. In view of above, present review article brings together existing bits of information to create a new direction for future research, critical gap in knowledge and a new perspective on remediation of toxic pollutants.     

Spatial Distribution of Podoconiosis in Relation to Environmental Factors in Ethiopia: A Historical Review

Background

An up-to-date and reliable map of podoconiosis is needed to design geographically targeted and cost-effective intervention in Ethiopia. Identifying the ecological correlates of the distribution of podoconiosis is the first step for distribution and risk maps. The objective of this study was to investigate the spatial distribution and ecological correlates of podoconiosis using historical and contemporary survey data.

Methods

Data on the observed prevalence of podoconiosis were abstracted from published and unpublished literature into a standardized database, according to strict inclusion and exclusion criteria. In total, 10 studies conducted between 1969 and 2012 were included, and data were available for 401,674 individuals older than 15 years of age from 229 locations. A range of high resolution environmental factors were investigated to determine their association with podoconiosis prevalence, using logistic regression.

Results

The prevalence of podoconiosis in Ethiopia was estimated at 3.4% (95% CI 3.3%–3.4%) with marked regional variation. We identified significant associations between mean annual Land Surface Temperature (LST), mean annual precipitation, topography of the land and fine soil texture and high prevalence of podoconiosis. The derived maps indicate both widespread occurrence of podoconiosis and a marked variability in prevalence of podoconiosis, with prevalence typically highest at altitudes >1500 m above sea level (masl), with >1500 mm annual rainfall and mean annual LST of 19–21°C. No (or very little) podoconiosis occurred at altitudes <1225 masl, with annual rainfall <900 mm, and mean annual LST of >24°C.

Conclusion

Podoconiosis remains a public health problem in Ethiopia over considerable areas of the country, but exhibits marked geographical variation associated in part with key environmental factors. This is work in progress and the results presented here will be refined in future work.     

A Nitrite Microsensor for Profiling Environmental Biofilms

A highly selective liquid membrane nitrite microsensor based on the hydrophobic ion-carrier aquocyanocobalt(III)-hepta(2-phenylethyl)-cobrynate is described. The sensor has a tip diameter of 10 to 15 (mu)m. The response is log-linear in freshwater down to 1 (mu)M NO(inf2)(sup-) and in seawater to 10 (mu)M NO(inf2)(sup-). A method is described for preparation of relatively large polyvinyl chloride (PVC)-gelled liquid membrane microsensors with a tip diameter of 5 to 15 (mu)m, having a hydrophilic coating on the tip. The coating and increased tip diameter resulted in more sturdy sensors, with a lower detection limit and a more stable signal than uncoated nitrite sensors with a tip diameter of 1 to 3 (mu)m. The coating protects the sensor membrane from detrimental direct contact with biomass and can be used for all PVC-gelled liquid membrane sensors meant for profiling microbial mats, biofilms, and sediments. Thanks to these improvements, liquid membrane sensors can now be used in complex environmental samples and in situ, e.g., in operating bioreactors. Examples of measurements in denitrifying, nitrifying, and nitrifying/denitrifying biofilms from wastewater treatment plants are shown. In all of these biofilms high nitrite concentrations were found in narrow zones of less than 1 mm.     

Modelling Environmental Responses of Plant Associations: A Review of Some Critical Concepts in Vegetation Study

The definition of vegetation types at different hierarchical levels, both to study the vegetation processes and for practical cartographic representation, is still considered a critical issue in many circles of plant ecologists. The problems are mainly related to the misleading idea that classification of the vegetation system, as developed by European phytosociologists during the last century within the discipline called syntaxonomy, would imply the assumption of the organismic concept of the plant community. After a short discussion on the role of Braun-Blanquet approach in plant ecology and in landscape ecology, the methods to detect multispecies responses along environmental gradients are briefly reviewed. In the main part of this article, we intend to stress that concepts considered critical, such as plant association and its ecological niche, are just operational tools that have nothing to do with the individualistic or organismic interpretation of plant communities in vegetation studies. Important to our views on vegetation, we believe that plant associations as well as the higher syntaxa can be regarded as fuzzy sets in an operational context for describing vegetation along ecological gradients in synthetic ways and can further the understanding of vegetation variation.     

Environmental Estrogen-Like Chemicals and Hydroxyl Radicals Induced by MPTP in the Striatum: A Review

Oxygen free radical formation has been implicated in lesions caused by the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and iron. Although MPTP produces a parkinsonian syndrome after its conversion to 1-methyl-4-phenylpyridine (MPP⁺) by type B monoamine oxidase (MAO) in the brain, the etiology of this disease remains obscure. This review focuses on the role of an environmental neurotoxin chemically related to MPP⁺-induced free radical generation in the pathogenesis of Parkinson's disease. Environmental-like chemicals, such as para-nonylphenol or bisphenol A, significantly stimulated hydroxyl radical (OH) formation in the striatum. Allopurinol, a xanthine oxidase inhibitor, prevents para-nonylphenol and MPP⁺-induced OH generation. Tamoxifen, a synthetic nonsteroidal antiestrogen, suppressed the OH generation via dopamine efflux induced by MPP⁺. These results confirm that free radical production might make a major contribution at certain stages in the progression of the injury. Such findings may be useful in elucidating the actual mechanism of free radical formation in the pathogenesis of neurodegenerative brain disorders, including Parkinson's disease and traumatic brain injuries.     

原核启动子识别研究进展

原核启动子识别是研究原核基因转录调控的重要环节。该文以大肠杆菌为例,首先介绍原核启动子的基本特征,再对已有的各种识别方法进行具体分析,最后探讨可能的改进方向。     

Review of Potential Environmental and Health Risks of the Nanomaterial Graphene

Several future applications have been suggested for the nanomaterial graphene, and its production is increasing dramatically. This study is a review of risk-related information on graphene with the purpose of outlining potential environmental and health risks and guide future risk-related research. Available information is presented regarding emissions, environmental fate, and toxicity of graphene. The results from this study indicate that graphene could exert a considerable toxicity and that considerable emission of graphene from electronic devices and composites are possible in the future. It is also suggested that graphene is both persistent and hydrophobic. Although these results indicate that graphene may cause adverse environmental and health effects, the results foremost show that there are many risk-related knowledge gaps to be filled and that the emissions of graphene, the fate of graphene in the environment, and the toxicity of graphene should be further studied.     

A Proposed Framework for Investigation of Cause for Environmental Effects Monitoring

Environmental Effects Monitoring (EEM) programs in Canada have been developed for the pulp and paper and metal mining industries, and require a cyclical evaluation of the receiving environment to determine whether effects exist when the facilities are in compliance with existing regulations. Identifying the cause of environmental effects is a specific, identified stage in this monitoring program, but as yet there has not been a synthesis of what is meant by “identification of cause”. We propose a multitiered guidance framework for the identification of the cause of environmental effects after they have been detected, confirmed, and their extent and magnitude documented. As part of point source confirmation, the framework includes levels to define whether there is an effect, whether it is related to the effluent discharge facility, and whether response patterns in the receiver are characteristic of a particular stressor type. The next tier involves investigating individual process wastes within the facility to determine the components that are contributing to effects caused by exposure to the final effluent. The last three tiers of the framework relate to characterizing the chemical classes involved in the effect and, ultimately, to identifying the specific chemicals associated with the responses. Although there is increasing knowledge of specific causes of environmental effects gained as one progresses through the levels of investigation, there is a concomitant increase in effort and costs required. Stakeholder input is critical in determining the depth of the investigation as well as how to proceed once the environmental effects information is available.     

根系分泌物生态学研究

在植物生长过程中 ,由根系的不同部位分泌或溢泌一些无机离子及有机化合物 ,这些物质统称为根系分泌物。植物在其生长过程中不断地分泌无机离子及有机化合物 ,这是植物长期适应外界环境而形成的一种适应机制。早在 2 0世纪 5 0年代就有人对植物根系分泌物进行了研究 ,Ｒｏｖｉｒａ等[4 3] 和Ｖａｎｃｕｒａ等[4 7] 对根土界面根系分泌物进行了系统的研究 ,切尔诺布里维卡[2 6 ] 研究了植物根系分泌物的生物学作用 ,揭示了其在间作中的作用 ,直到 70年代对根系分泌物的研究才出现了蓬勃发展的趋势。近年来的研究表明 ,根系分泌物是保持根际微…     

A Brief Review of Software Tools for Pangenomics

Since the proposal for pangenomic study, there have been a dozen software tools actively in use for pangenomic analysis. By the end of 2014, Panseq and the pan-genomes analysis pipeline(PGAP) ranked as the top two most popular packages according to cumulative citations of peerreviewed scientific publications. The functions of the software packages and tools, albeit variable among them, include categorizing orthologous genes, calculating pangenomic profiles, integrating gene annotations, and constructing phylogenies. As epigenomic elements are being gradually revealed in prokaryotes, it is expected that pangenomic databases and toolkits have to be extended to handle information of detailed functional annotations for genes and non-protein-coding sequences including non-coding RNAs, insertion elements, and conserved structural elements. To develop better bioinformatic tools, user feedback and integration of novel features are both of essence.     

Electroacupuncture for Tinnitus: A Systematic Review

Background

Treatment effects of electroacupuncture for patients with subjective tinnitus has yet to be clarified.

Objectives

To assess the effect of electroacupuncutre for alleviating the symptoms of subjective tinnitus.

Methods

Extensive literature searches were carried out in three English and four Chinese databases (PubMed, EMBASE, Cochrane Library, CNKI, Wanfang Chinese Digital Periodical and Conference Database, VIP, and ChiCTR).The date of the most recent search was 1 June 2014. Randomized controlled trials (RCTs) or quasi-RCTs were included. The titles, abstracts, and keywords of all records were reviewed by two authors independently. The data were collected and extracted by three authors. The risk of bias in the trials was assessed in accordance with the Cochrane Handbook, version 5.1.0. (http://www.handbook.cochrane.org). Eighty-nine studies were retrieved. After discarding 84 articles, five studies with 322 participants were identified. Assessment of the methodological quality of the studies identified weaknesses in all five studies. All studies were judged as having a high risk of selection and performance bias. The attrition bias was high in four studies. Incompleteness bias was low in all studies. Reporting bias was unclear in all studies. Because of the limited number of trials included and the various types of interventions and outcomes, we were unable to conduct pooled analyses.

Conclusions

Due to the poor methodological quality of the primary studies and the small sample sizes, no convincing evidence that electroacupuncture is beneficial for treating tinnitus could be found. There is an urgent need for more high-quality trials with large sample sizes for the investigation of electroacupuncture treatment for tinnitus.     

Risk and Decision-Making: A Workshop for Environmental Professionals

In the early 1990s, U.S. Environmental Protection Agency Region 9 developed a training workshop for environmental professionals. It was successfully taught throughout Region 9 in collaboration with the California Department of Toxic Substances Control. We have updated the workshop's manual to incorporate current practices including: vapor intrusion into indoor air, benchmark dose, cancer guidelines, inhalation guidance, ecological and screening risk assessments, conceptual site models, and data quality objectives. We maintained the popular workshop format, with participants evaluating information and drawing conclusions in an interactive hands-on approach. We kept the case study approach to simulate realistic environmental issues. After a case study introduction, participants plan a sampling strategy. Principles of toxicology are introduced, and participants develop toxicity criteria using hypothetical animal study results. Participants then identify exposure pathways, and calculate exposure and risk and hazard estimates. Finally, participants develop remedial alternatives and practice risk communication through role playing exercises. The workshop has been an effective tool for training new employees and providing continuing education for experienced employees from consulting, military, and regulatory agencies. The format provides a dynamic learning environment, fostering exchanges among professionals with a wide range of skills and backgrounds (project managers, toxicologists, geologists, engineers, public participation experts).