A low-maintenance,primary cell culture model for the assessment of carbon nanotube toxicity

Carbon nanotubes (CNTs) have gained substantial interest as a material for biomedical devices with reliable properties suitable for electrically conducting biomedical devices. While CNTs combine ideal properties for a number of tissue-interfacing applications, their biocompatibility and safety have been the source of considerable conjecture. This study outlines a method for evaluating biocompatibility, using a low-cost, short-term assessment model of CNT with primary cells, which are more representative of an in vivo situation than cell lines. It was demonstrated that carboxylate-modified, multi-walled CNTs exhibit cytotoxic behavior in as little as 6 hr of exposure to primary fibroblasts. The resultant cell death was concentration dependent, demonstrating the efficacy of acute assessment of cytocompatibility. Although cell viability remained relatively high (being above 85% for all CNT concentrations up to 500 μg/ml), these results reflect similar relationships found for longer term exposures. This method has reliable potential for high-throughput assessment and quality control of CNTs in biomedical applications using a primary cell model.     

全球变暖环境下基于金属媒介的气候敏感性研究：对一种典型两栖动物的早期和潜在影响

尽管有很多复杂的模型预测了未来温度对变温动物的影响,广泛分布的亚致命性污染物对变温动物的热应激反应产生的影响却少有模型提及。由不断上升的温度所带来更高的代谢率可以让变温动物获利地加快代谢与发育,但在长期亚致命性污染物的存在下,因清除或解毒而导致的对生存资源的额外需求很可能使得生物难以跟上温度上升的步伐,即毒物诱导的气候敏感性假说。在以自然湖水为背景的室外生物鉴定中,我们调查了一种模式变温动物在6个不同浓度的镉、铜和铅混合物以及3个热动态下(环境温度,高于环境温度1.5摄氏度以及高于环境温度2.5摄氏度)的日周期性温度变化。金属浓度在大约10倍生物可利用性慢性标准单位 (BCCU,慢性标准浓度的生物可利用性比例总和)之下时,升温对于寇普氏树蛙(Hyla chrysoscelis)没有显著作用。在高于10倍BCCU以及高于环境温度1.5摄氏度的处理条件下,生长受到促进。相反地,在28倍BCCU以及升温2.5摄氏度的条件下,不仅生长情况收到抑制,变态后20 d未成年树蛙的身体状况指标相比于背景环境(环境温度下的湖水)中的未成年树蛙也要低34%。这些发现认为毒物诱导的气候敏感性是通过对青少年阶段的生物产生长期潜在的影响而实现的。在22世纪,即使在最保守的全球变暖预测模型下,亚致命性污染物依然会加剧变温动物所遭受的来自升温的影响。
精选自Tyler A. Hallman, Marjorie L. Brooks. Metals-mediated climate susceptibility in a warming world: larval and latent effects on a model amphibian. Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1872–1882, July 2016. DOI: 10.1002/etc.3337
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3337/full
     

Repeatability of physiological traits in juvenile Pacific abalone, Haliotis discus hannai

Several studies on individual physiological traits assume that past records may predict future performance. Marine mollusks, as other animals, show a wide range of between- and within-individual variation of physiological traits. However, in this group, almost nothing is known about the relative influence of genetic factors on that variation. Repeatability (R) is a measure of the consistency of the variation of a trait, which includes its genetic variance and represents the maximum potential value of its heritability (h ²). Traits that show high inter-individual variation and high repeatability levels could potentially evolve through selection (natural or artificial). We estimated the repeatability [using intra-class (τ) and Pearson-moment (r) correlation coefficients] of several physiological traits related to energy acquisition and allocation in juvenile Pacific abalone Haliotis discus hannai, maintained under controlled environment growing systems. In order to estimate the range of the R values and the effect of the time elapsed between measurements on these estimates, we measured these traits monthly during 6 months for each individual. Among the physiological traits, those related to energy allocation like oxygen consumption (standard metabolic rate, SMR) and ammonium excretion rates, and oxygen/nitrogen ratio (O/N), showed intermediate levels of repeatability (0.48, 0.55 and 0.39, respectively), when this was estimated by τ coefficient. However, the r estimation showed that SMR and O/N repeatability were significant and high (0.6–0.7 and 0.5–0.7, respectively) during the first 5 consecutive measurements, decreasing strongly (0.3 and 0.2, respectively) during the last measurement. For ammonia excretion, although repeatability (r) decreased from 0.8 to 0.5 during the 6 consecutive measurements, they remain significant during the experimental period. Therefore, our results indicate that for H. discus hannai juveniles, physiological traits like SMR, ammonia excretion and O/N are significantly repeatable (i.e. good predictors of future measurements) during a period of 4–5 months. These significant repeatability values suggest an important genetic control upon the phenotypic variation of these physiological traits, and could potentially respond to natural or artificial selection, and be used in genetic improvement programs. By contrast, those traits related to energy acquisition (i.e. ingestion, absorption and assimilation) and physiological efficiencies (i.e. net growth and scope for growth) showed very low levels of repeatability (0–0.07). This indicates that the phenotypic variation of these traits would be more influenced by environment rather than by genetic factors.     

Display rate by male fairy-wrens (Malurus cyaneus) during the fertile period of females has little influence on extra-pair mate choice

Empirical and theoretical studies have only recently begun to examine how females use complex multi-component displays when selecting mates. Superb fairy-wrens are well suited to the study of female choice because females have control over extra-group paternity and cuckold their mates at high rates, while males possess a variety of sexually selected traits. Available evidence suggests that females base their extra-group mate choice on the timing of male moult into breeding plumage or the onset of display. However, males continue to perform elaborate displays throughout the season, and direct most displays to females during their fertile period. We therefore conducted focal observations on fertile females to quantify the frequency of male display and used microsatellite genotyping to compare the role of display rate during the breeding season and the timing of male moult on female mate choice. We show that the addition of data on male display rate does not improve our ability to predict which males obtain extra-group paternity. The timing of male moult into breeding plumage remains the only predictor of male extra-group reproductive success. Nevertheless, we found that males displayed more to females that were unable to select extra-group mates on the basis of the timing of moult or the onset of display. This raises the possibility that there are circumstances when females use display rate to discriminate between potential extra-group sires. Overall this study supports the theoretical prediction that females are more likely to base their mate choice on reliable indicators of male quality such as fixed morphological traits and displays of endurance, in this case an early moult into breeding plumage and the performance of an elaborate display during the winter, than a flexible behavioural trait such as display rate during the breeding season. Received: 26 January 2000 / Revised: 1 August 2000 / Accepted: 26 August 2000     

Comparison of recidivism rates for a teenage trauma prevention program after the addition of high-fidelity patient simulation

Objectives: We evaluated the benefits of adding high-fidelity simulation to a teenage trauma prevention program to decrease recidivism rates and encourage teens to discuss actionable steps toward safe driving.

Methods: A simulated pediatric trauma scenario was integrated into an established trauma prevention program. Participants were recruited because they were court-ordered to attend this program after misdemeanor convictions for moving violations. The teenage participants viewed this simulation from the emergency medical services (EMS) handoff to complete trauma care. Participants completed a postsimulation knowledge assessment and care evaluation, which included narrative data about the experience. Qualitative analysis of color-coded responses identified common themes and experiences in participants' answers. Court records were reviewed 6 years after course completion to determine short- and long-term recidivism rates, which were then compared to our program's historical rate.

Results: One hundred twenty-four students aged 16–20 years participated over a 2-year study period. Narrative responses included general reflection, impressions, and thoughts about what they might change as a result of the course. Participants reported that they would decrease speed (30%), wear seat belts (15%), decrease cell phone use (11%), and increase caution (28%). The recidivism rate was 55% within 6 years. At 6 months it was 8.4%, at 1 year it was 20%, and it increased approximately 5–8% per year after the first year. Compared with our programs, for historical 6-month and 2-year recidivism rates, no significant difference was seen with or without simulation.

Conclusions: Adding simulation is well received by participants and leads to positive reflections regarding changes in risk-taking behaviors but resulted in no changes to the high recidivism rates This may be due to the often ineffectiveness of fear appeals.     

Comparison of DNA extraction methodologies used for assessing fungal diversity via ITS sequencing

Traditional methods of assessing fungal exposure have been confounded by a number of limiting variables. The recent utilization of molecular methods such as internal transcribed spacer (ITS) sequencing of ribosomal RNA genes has provided improved insight into the diversity of fungal bioaerosols in indoor, outdoor and occupational environments. However, ITS analyses may also be confounded by a number of methodological limitations. In this study, we have optimized this technology for use in occupational or environmental studies. Three commonly used DNA extraction methodologies (UltraClean Soil kit, High Pure PCR Template kit, and EluQuik/DNeasy kit) were compared in terms of sensitivity and susceptibility to PCR inhibitors in dust for three common fungal bioaerosols, Aspergillus versicolor, Rhizopus microsporus and Wallemia sebi. Environmental dust samples were then studied using each extraction methodology and results were compared to viable culture data. The extraction methods differed in terms of their ability to efficiently extract DNA from particular species of fungi (e.g. Aspergillus versicolor). In addition, the ability to remove PCR inhibitors from dust samples was most effective using the soil DNA extraction kit. The species composition varied greatly between ITS clone libraries generated with the different DNA extraction kits. However, compared to viable culture data, ITS clone libraries included additional fungal species that are incapable of growth on solid culture medium. Collectively, our data indicated that DNA extraction methodologies used in ITS sequencing studies of occupational or environmental dust samples can greatly influence the fungal species that are detected.     

Changes in water level,land use,and hydrological budget in a semi-permanent playa lake,Southwest Spain

Medina playa lake, a Ramsar site in western Andalusia, is a brackish lowland lake of 120 ha with an average depth of 1 m. Water flows into Medina from its 1,748-ha watershed, but the hydrology of the lake has not previously been studied. This paper describes the application of a water budget model on a monthly scale over a 6-year period, based on a conceptual hydrological model, and considers different future scenarios after calibration to improve the understanding of the lake’s hydrological functioning. Climatic variables from a nearby weather station and observational data (water-level evolution) were used to develop the model. Comparison of measured and predicted values demonstrated that each model component provided a reasonable output with a realistic interaction among the components. The model was then used to explore the potential consequences of land-use changes. Irrigation of olive groves would significantly reduce both the hydroperiod (becoming dry 15% of the time) and the average depth of the lake (water level <0.5 m 40% of the time). On the other hand, removal of an artificial overflow would double the average flooded surface area during high-water periods. The simulated water balance demonstrates that the catchment outputs are dominated by lake evaporation and surface outflow from the lake system to a creek. Discrepancies between predicted and observed water levels identify key areas of uncertainty for future empirical research. The study provides an improved basis for future hydrological management of the catchment and demonstrates the wider utility of this methodology in simulating this kind of system. This methodology provides a realistic appraisal of potential land-use management practices on a catchment-wide scale and allows predictions of the consequences of climate change.     

Tidal salt marsh sediment in California, USA: part 3. Current and historic toxicity potential of contaminants and their bioaccumulation

To assess potential health risks to benthic organisms from exposure to toxic contaminants, sediment chemistry data from five salt marshes along the coast of California were compared with threshold effects levels (TELs) and probable effects levels (PELs). As an integrated estimate of toxicity potential of multiple contaminants, mean PEL quotients (mPELQs) were used to categorize sampling stations into three groups: high (>0.5), medium (0.1–0.5) and low (<0.1). In all sediments from Stege Marsh located in San Francisco Bay, at least one contaminant exceeded PELs by up to 18-fold and mPELQs were higher than 0.7. Mean PELQs in two core sediments from eastern Stege Marsh ranged from 0.7 to 2.1, indicating that benthic organisms in Stege Marsh may have been adversely affected for several decades. To investigate bioavailability and bioaccumulation of contaminants in sediments, longjaw mudsuckers (Gillichthys mirabilis) were transplanted to six Stege Marsh stations for 60 days. Body burdens of organic contaminants clearly showed that they were readily available for benthic organisms. Measured concentrations of organic contaminants in mudsuckers were similar to estimated levels computed using a theoretical bioaccumulation potential model. Levels of PCBs and arsenic in mudsuckers were higher than screening values set as guidelines for the protection of humans and levels of PCBs and DDTs were higher than criteria for wildlife. The results of this study indicate that the levels of contaminants in Stege Marsh sediments may not fully support the well-being of benthic organisms and also may provoke adverse effects on fish-eating animals and humans through trophic transfer.     

Movement of bromacil in a Hawaii soil under pineapple cultivation - a field study

Recent discovery of low concentrations of bromacil in drinking water prompted the State of Hawaii to examine the leaching behavior of bromacil in pineapple fields. This study is a follow up to earlier work on bromacil concentrations in soil profiles in a pineapple field in central Oahu, Hawaii. Soil samples were collected for bromacil analysis at different times prior to and after application from a pineapple field that was previously surveyed by other research workers. The leaching pattern of bromacil was further investigated at two different application rates (2.25 and 1.8 kg ha(-1)). The concentration of bromacil in the topsoil about 100 days after bromacil application (1.8 kg ha(-1)) was substantially higher in 2002 compared to 1999. The distribution profiles were generally consistent with the one presented in the previous study. Residual bromacil was present in the entire sampled zone (3m deep) about 18 months after the previous bromacil application. Over a period of 9 months, there was substantial dissipation of bromacil residue present in the topsoil. The residual concentration of bromacil in the area that received the reduced application rate (1.8 kg ha(-1)) were lower than those receiving the current application rate (2.25 kg ha(-1)) and the depth of penetration of the bromacil front was shallower at the reduced application rate. Because of the common practice of placing plastic mulch around the base of the pineapple plants to retain volatile nematicides, the applied bromacil was found to be concentrated in the areas between the plastic mulch, transported by runoff from the plastic. The study results encourage the use of less than the label led rate of application of bromacil for pineapple fields.