Sensitivity Enhancement for Surface Plasmon Resonance Imaging Biosensor by Utilizing Gold�CSilver Bimetallic Film Configuration

Gold–silver bimetallic film configuration is brought forward to realize surface plasmon resonance imaging (SPRI) biosensor with the virtues of both high sensitivity and chemical stability. The theoretical calculation is adopted to optimize the thicknesses of the metal films, and bimetallic film configuration with high refractive index sensitivity and a good linearity between reflectivity and refractive index is presented. Then, the property of the detection system is discussed. The results show that in comparison to most commercial SPRI biosensors which use single gold films, the sensitivity and molecule detection ability of the gold–silver bimetallic film configuration can be improved to a great extent. For the substrate of BAK3 glass used in this paper, the sensitivity enhancement reaches as high as 80%, which makes it a much better choice for SPRI biosensing applications.     

Air pollution could drive global dissemination of antibiotic resistance genes

Antibiotic-resistant pathogens pose a significant threat to human health. Several dispersal mechanisms have been described, but transport of both microbes and antibiotic resistance genes (ARGs) via atmospheric particles has received little attention as a pathway for global dissemination. These atmospheric particles can return to the Earth’s surface via rain or snowfall, and thus promote long-distance spread of ARGs. However, the diversity and abundance of ARGs in fresh snow has not been studied and their potential correlation with particulate air pollution is not well explored. Here, we characterized ARGs in 44 samples of fresh snow from major cities in China, three in North America, and one in Europe, spanning a gradient from pristine to heavily anthropogenically influenced ecosystems. High-throughput qPCR analysis of ARGs and mobile genetic elements (MGEs) provided strong indications that dissemination of ARGs in fresh snow could be exacerbated by air pollution, severely increasing the health risks of both air pollution and ARGs. We showed that snowfall did effectively spread ARGs from point sources over the Earth surface. Together our findings urge for better pollution control to reduce the risk of global dissemination of antibiotic resistance genes.Subject terms: Environmental sciences, Air microbiology     

Hydrogen Sulfide Improves the Vase Life and Quality of Cut Roses and Chrysanthemums

Recent studies indicate that hydrogen sulfide (H₂S) plays various physiological roles in plants. However, whether H₂S participates in the postharvest senescence in cut flowers remains unknown. In this study, the regulatory roles of H₂S during the senescence of cut roses (Rosa hybrida L.) and chrysanthemums (Dendranthema morifolium Ramat.) were investigated. The results showed that compared with the control (distilled water), the 50 μM sodium hydrosulfide (NaHS) treatment, a H₂S donor, extended the vase life of cut roses to 9.3 days and their flower diameter also showed an increment of 22.7% after 4 days treatment. Treatments with 30 μM NaHS significantly prolonged the vase life of cut chrysanthemums to 8.87 days and the flower diameter was 13.21% longer than the control on day 6. Additionally, results also indicated that a 30 or 50 μM NaHS treatment effectively decreased the rate of fresh weight changes and O²⁻ production and H₂O₂ content, increased the levels of soluble sugar, soluble protein, anthocyanin and carotenoid, and enhanced the activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase and ascorbate peroxidase) of cut roses and chrysanthemums in comparison with the control, implying that H₂S might be involved in regulating the osmotic balance, antioxidant system and the degradation of nutrient and pigments. Altogether, H₂S at proper doses might play an important role in improving the longevity and quality of cut roses and chrysanthemums by maintaining water balance, reducing the degradation of pigments and nutrient and enhancing antioxidant capacity.