纳米材料的食品暴露及其毒性研究进展

纳米材料作为一类新兴化学品广泛用于食品加工、作物栽培和包装运输等领域,来改善营养成分、生物活性和包装材料性能,经摄食进入人体后能分布于血液、消化道和组织细胞中,广泛参与多种生理代谢过程.当前,纳米材料在食品中的暴露途径、分类、存在状态和毒性机制引起了广泛关注,但尚未形成完整、广泛接受的科学研究体系.结合近几年文献,本文分析了食品中纳米颗粒的暴露途径,探讨了当前食品中纳米颗粒分析检测技术的优缺点,阐述了生物化学转化、生物过程环境及分布状态对纳米毒性的诱导机制,在结尾归纳相关研究不足并对今后研究的趋势进行了展望.     

纳米金颗粒进入梨形四膜虫体内的方式及其分布

以梨形四膜虫为模式动物,研究水体中的纳米金颗粒进入生物体的方式、分布及其生物学效应.实验中所采用的纳米金颗粒平均粒径为13 nm,分散均匀.透射电镜结果表明,纳米金颗粒可以通过口沟（进食）和细胞膜（内吞）两种方式进入梨形四膜虫体内;纳米金颗粒进入梨形四膜虫体内后,主要分布在食物泡中,另外细胞质和细胞核（大核）中也含有少量的纳米金颗粒.同时,研究表明在实验所用的浓度范围内,纳米金颗粒对梨形四膜虫无明显毒性.     

氰戊菊酯生理毒物代谢动力学模型的建立

利用生理毒物代谢动力学(PBTK)对小鼠静脉注射农药氰戊菊酯后,氰戊菊酯在体内分布转化代谢过程进行模拟,为评价农药暴露风险提供依据。小鼠静脉注射氰戊菊酯的PBTK模型构建分为5个房室:肝脏、肺、肾脏、充分灌注室和不充分灌注室,各房室内氰戊菊酯的浓度变化率由质量守恒微分方程表示。根据欧拉数值计算方法,对小鼠静脉注射氰戊菊酯后的毒物代谢动力学数据进行模拟。结果模拟预测了小鼠静脉注射0.5 mg·kg-1、2.5 mg·kg-1、10 mg·kg-1氰戊菊酯后血液、肝脏和肺中氰戊菊酯浓度变化曲线。为验证该模型的准确性,对小鼠静脉注射0.77 mg·kg-1氰戊菊酯后血液、肝脏和肺中氰戊菊酯的浓度值变化模拟值与前人的实验测量值进行比较,结果显示模拟值与实验值之间不存在显著性差异。因此利用该方法可以估测小鼠静脉注射氰戊菊酯的毒物代谢动力学数据,为评估农药暴露体内剂量数据提供了便利途径。     

玉米对纳米TiO2的吸收和累积

研究了玉米对不同浓度及粒径纳米TiO2的吸收和累积,并应用同步辐射微束X射线荧光分析(μ-XRF)在微观尺度表征了玉米根中纳米TiO2的分布.结果表明,纳米TiO2主要累积在玉米根部,且在根部的累积量随暴露浓度的增加而增加;茎叶中TiO2累积很少,其在玉米体内的传输因子小于0.01.根中纳米TiO2的累积与其在溶液中的...     

碳基纳米铜复合材料对普通小球藻胁迫作用的研究

随着科技的飞速发展,纳米类材料在电化学、药物运输、生物传感器等领域中得到了广泛的应用,这导致了其通过各种途径进入水、土壤、大气等环境介质中,对生态环境安全造成潜在威胁。以水体中环境浓度的碳基纳米铜复合材料为受试浓度范围,以环境适应性和污染物耐受性均较强的普通小球藻(Chlorella vulgaris)为对象,研究了水体中不同浓度碳基纳米铜复合材料对普通小球藻的细胞胁迫作用,使用分光光度法检测了0,0.05,0.5,5,50 mg·L^-1碳基纳米铜暴露条件下普通小球藻叶绿素a含量的变化。运用非靶向代谢组学(气相-质谱联用)检测法探究了不同浓度碳基纳米铜胁迫条件下第8天普通小球藻细胞内代谢物相对丰度变化、代谢通路及相关代谢组学特性的变化。结果表明,在培养周期的第8天,藻细胞叶绿素a含量随碳基纳米铜浓度的升高而降低,当碳基纳米铜达到50 mg·L^-1时,将严重抑制藻细胞叶绿素a的产生。代谢组学检测结果表明,当碳基纳米铜复合材料的浓度达到50 mg·L^-1时,藻细胞中与叶绿素合成密切相关的碳固定过程、氨基酸代谢过程均受到了严重抑制。这表明,高浓度碳基纳米铜会扰乱普通小球藻的细胞代谢并产生明显胁迫作用。文章旨在评估水体中碳基纳米铜复合材料对水体初级生产者普通小球藻的胁迫作用,以期为水体污染修复与藻细胞生态毒理学的研究提供一定的数据支持与参考。     

纳米颗粒帮助评估水生生物毒性

<正>2014年4月24日来源:《生态毒理学与环境安全》一个美国研究小组开发了一种对水生生物给送试验化学物质的方法,以用于评估经口暴露的影响。马里兰大学的科学家将一种试验化学物质封包在生物高聚物纳米颗粒内,然后,通过pH变化触发在试验生物体的消化系统内将该化学物质释放出来。目前,由于化学物质给送的困难性,很少在水生生物系统中评估经口暴露。化学物质常常会溶解到水中,     

纳米二氧化铈对蛋白核小球藻和大型溞的毒性及其在大型溞体内的形态转化

随着纳米技术的飞速发展,纳米材料的应用日益广泛。同时,这类具有独特物理化学特性的微小颗粒对环境和健康的影响引起了人们的关注。本工作参考国际经济合作与发展组织(OECD)化学品生态毒理测试方法,以蛋白核小球藻(Chlorella pyrenoidosa)和大型溞(Daphnia magna)为受试生物,研究了CeO_2纳米颗粒暴露对小球藻生长、叶绿素含量和细胞内活性氧水平以及大型溞运动能力的影响,分析了大型溞体内铈的形态。随着暴露浓度的升高和时间延长,CeO_2纳米颗粒逐渐抑制小球藻的生长,导致叶绿素水平的降低和活性氧水平升高。暴露96 h后,CeO_2纳米颗粒对小球藻生长的EC50为30.4 mg·L-1,而对大型溞活动抑制的24 h、48 h-EC50分别为430.2 mg·L-1和142.7 mg·L-1。根据中华人民共和国环境保护行业标准中的毒性分级标准,CeO_2纳米颗粒对小球藻属于中毒性物质,对大型溞属于低毒性物质。CeO_2纳米颗粒在大型溞体内主要以Ce(IV)的形式存在,约有3%转化为Ce(III)。对CeO_2纳米颗粒的水生态效应给予足够重视并深入研究其毒性作用机制。     

基于分子信标探针的荧光定量PCR方法检测转基因食品

选择了内源基因大豆植物凝集素(lectin)、玉米转化酶(invertase)和外源基因花椰菜花叶病毒35S(CaMV35S)启动子的分子信标探针,确定了探针浓度和镁离子浓度等反应条件,分别对转基因大豆和转基因玉米系列标准品进行内源基因和外源基因的荧光PCR扩增,在PCR反应过程中分别以两种荧光通道信号分别追踪同一样品DNA内源基因和外源基因的扩增动力学变化,并依此绘制了循环阈值与转基因食品百分比含量之间的标准曲线,建立了转基因大豆和转基因玉米的分子信标探针-荧光定量PCR检测方法,该方法具有特异性强、敏感性高的特点,实现了对转基因食品的定量分析.图7表1参11     

代谢组学在量子点毒性研究中的应用进展及前景

量子点是由Ⅱ～Ⅵ或Ⅲ～Ⅴ族元素组成的半导体纳米微晶体。因其独特的光电学特性,例如荧光强度高和稳定性好,被广泛应用于生命科学领域,用于荧光探针、药学研究、医学成像和生物芯片等。但是,由于应用较广的量子点成分通常含有重金属,研究者普遍认为量子点具有一定的毒性,因而通过毒理学研究来评价量子点的生物安全性对于量子点的生物学应用至关重要。代谢组学是利用分析化学方法来研究一个代谢组中小分子代谢相关物质的含量,以及内外因素导致其变化规律的学科。目前,越来越多的研究者将代谢组学应用于量子点毒性研究中,利用其生物标志物的特异性,为量子点毒性研究提供了新的思路和技术。应用代谢组学不但提高了纳米毒理学研究的完善度,更可以准确地研究某些以前在量子点低剂量暴露后无法发现的生化反应。本文重点阐述了代谢组学在量子点毒性研究中的应用进展及发展前景,为以后相关的研究方向和研究内容提供有价值的参考。     

铜及氧化铜纳米颗粒对浮萍、藻类的毒性效应及机理研究进展

由于大量的生产和使用,铜及氧化铜纳米颗粒不可避免地被排放到环境当中。水生植物属于生态系统的初级生产者,纳米颗粒对其造成的损伤及在其体内的积累很可能会通过食物链或食物网进行传递,从而威胁生态系统乃至人类健康。因此,本文就现有研究中铜及氧化铜纳米颗粒对2类重要水生植物(即浮萍、藻类)的毒性效应及致毒机理进行了总结。通过分析发现纳米颗粒的浓度、粒径以及暴露体系的pH值、溶解性有机质、温度和紫外线等环境因素均能影响铜及氧化铜纳米颗粒的毒性效应。据此提出今后相关研究中需更加关注水生植物对铜、氧化铜纳米颗粒及Cu~(2+)的吸收及积累情况,以及区分纳米颗粒本身及Cu~(2+)的毒性贡献的重要性,这有助于深入了解铜及氧化铜纳米颗粒对浮萍、藻类的致毒机理。     

Achieving Open Access to Conservation Science

Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación     

Representation of the world's biophysical conditions by the global protected area network

Protected areas (PAs) are often implemented without consideration of already existing PAs, which is likely to cause an overrepresentation of certain biophysical conditions. We assessed the representativeness of the current PA network with regard to the world's biophysical conditions to highlight which conditions are underprotected and where these conditions are located. We overlaid terrestrial and marine PAs with information on biophysical conditions (e.g., temperature, precipitation, and elevation) and then quantified the percentage of area covered by the PA network. For 1 variable at a time in the terrestrial realm, high temperature, low precipitation, and medium and very high elevation were underrepresented. For the marine realm, low and medium sea surface temperature (SST), medium and high sea surface salinity (SSS), and the deep sea were underrepresented. Overall, protection was evenly distributed for elevation across the terrestrial realm and SST across the marine realm. For 2 variables at a time, cold and very dry terrestrial environments had mostly low protection, which was also the case for low SST and low and medium SSS across most depths for marine environments. Low protection occurred mostly in the Sahara and the Arabian Peninsula for the terrestrial realm and along the Tropic of Capricorn and toward the poles for the marine realm. Although biodiversity measures are of prime importance for the design of PA networks, highlighting biophysical gaps in current PAs adds a frequently overlooked perspective. These gaps may weaken the potential of PAs to conserve biodiversity. Thus, our results may provide useful insights for researchers, practitioners, and policy makers to establish a more comprehensive global PA network.     

Quantitative composition of the defensive secretion ofBledius species (Coleoptera: Staphylinidae: Oxytelinae) is adapted to naturally occurring predators

Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in either-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.     

Democracy versus development: New urban debates

The politics of development includes subtexts of choice, as underpinned by community consensus (or lack of it), against the larger backdrop of a liberal democracy, with its intricate power structures that influence the choice of concepts and often lead to complicity rather than consent. A dilemma exists between the understanding of field-level practitioners and that of academics, whose understandings of progress differ. Progress can (and often does) imply long-term change across generations whereas development is often more a matter of crisis management and delivering tangible results to end-users. This makes it a bone of contention across political systems, irrespective of local or global dynamics. Development can emerge as a tool to be wielded for power and further political mileage at the expense of progress. Progress cannot be studied as a counterpoint to development as the sense of history is often missing in development interventions. Development tends to be piecemeal as its very logic often stems from the rationale of power. This is not to suggest, however, that development is only about politics; it is definitely more than the politics of everyday life and involves all of civil society that requires its critical and immediate attention. In this sense, it has become a priority for politicians with an underlying agenda designed to out-manouevre dissent and all statements of protest.     

A framework to measure the wildness of managed large vertebrate populations

As landscapes continue to fall under human influence through habitat loss and fragmentation, fencing is increasingly being used to mitigate anthropogenic threats and enhance the commercial value of wildlife. Subsequent intensification of management potentially erodes wildness by disembodying populations from landscape-level processes, thereby disconnecting species from natural selection. Tools are needed to measure the degree to which populations of large vertebrate species in formally protected and privately owned wildlife areas are self-sustaining and free to adapt. We devised a framework to measure such wildness based on 6 attributes relating to the evolutionary and ecological dynamics of vertebrates (space, disease and parasite resistance, exposure to predation, exposure to limitations and fluctuations of food and water supply, and reproduction). For each attribute, we set empirical, species-specific thresholds between 5 wildness states based on quantifiable management interventions. We analysed data from 205 private wildlife properties with management objectives spanning ecotourism to consumptive utilization to test the framework on 6 herbivore species representing a range of conservation statuses and commercial values. Wildness scores among species differed significantly, and the proportion of populations identified as wild ranged from 12% to 84%, which indicates the tool detected site-scale differences both among populations of different species and populations of the same species under different management regimes. By quantifying wildness, this framework provides practitioners with standardized measurement units that link biodiversity with the sustainable use of wildlife. Applications include informing species management plans at local scales; standardizing the inclusion of managed populations in red-list assessments; and providing a platform for certification and regulation of wildlife-based economies. Applying this framework may help embed wildness as a normative value in policy and mitigate the shifting baseline of what it means to truly conserve a species.     

Some polyphagous Homoptera gain protection from their natural enemies by feeding on the toxic plantsSpartium junceum andErythrina corallodendrum (Leguminosae)

Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.     

Sexual Predators,Energy Development,and Conservation in Greater Yellowstone

Abstract: In the United States, as elsewhere, a growing debate pits national energy policy and homeland security against biological conservation. In rural communities the extraction of fossil fuels is often encouraged because of the employment opportunities it offers, although the concomitant itinerant workforce is often associated with increased wildlife poaching. We explored possible positive and negative factors associated with energy extraction in the Greater Yellowstone Ecosystem (GYE), an area known for its national parks, intact biological diversity, and some of the New World's longest terrestrial migrations. Specifically, we asked whether counties with different economies—recreation (ski), agrarian (ranching or farming), and energy extractive (petroleum)—differed in healthcare (gauged by the abundance of hospital beds) and in the frequency of sexual predators. The absolute and relative frequency of registered sex offenders grew approximately two to three times faster in areas reliant on energy extraction. Healthcare among counties did not differ. The strong conflation of community dishevel, as reflected by in‐migrant sexual predators, and ecological decay in Greater Yellowstone is consistent with patterns seen in similar systems from Ecuador to northern Canada, where social and environmental disarray exist around energy boomtowns. In our case, that groups (albeit with different aims) mobilized campaigns to help maintain the quality of rural livelihoods by protecting open space is a positive sign that conservation can matter, especially in the face of rampant and poorly executed energy extraction projects. Our findings further suggest that the public and industry need stronger regulatory action to instill greater vigilance when and where social factors and land conversion impact biological systems.     

Comparison of the insecticidal effects of water extracted and intact aromatic plants onAcanthoscelides obtectus,a bruchid beetle pest of kidney beans

Summary Acanthoscelides obtectus (Say) is one of the most damaging pests of kidney beans,Phaseolus vulgaris L. worldwide. However, aromatic plants from the families Lamiaceae, Lauraceae, Myrtaceae and Poaceae can protect kidney beans by direct or delayed insecticidal effect, through increased adult mortality and inhibition of beetle reproduction (both oviposition and adult emergence). The efficiency of hydrodistillated and intact plants fromThymus vulgaris andT. serpyllum, Mentha piperata, Rosmarinus officinalis, Satureia hortensis, Eucalyptus globulus, Laurus nobilis, Origanum vulgare, andCymbopogon nardus was compared. For both extracts,Origanum vulgare had the best effect. The insecticidal effect was induced by more than the essential oils because no significant difference was noticed between distilled and intact plants extract. Inhibition of reproduction was particularly important. These results suggest that lipidic as well as non lipidic, allelochemicals, such as phenolics, or non-protein amino-acids, or flavonoids may be involved in the toxicity of aromatic plants to this beetle.     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.