Search

Addressing global Zinc (Zn) deficiency in food and feed requires innovation in Zn fertilizer. Recently, Zn oxide nanoparticles (ZnONPs) have piqued interest for potential use as a novel nano-Zn fertilizer. However, little is known about potential factors influencing ZnONPs partitioning in different plant tissues, and changes in root system architecture (RSA) and soil characteristics. Herein, we tested the effects of particle size (38, 59, and > 500 nm) and concentration (0-500 mg/kg) of ZnONPs on Zn bioaccumulation in multiple tissues in soil-grown soybean (Glycine max) grown for 120 days, including changes in RSA (root biomass, length, area, volume, and density) and soil characteristics (pH and electrical conductance [EC]). Our results showed significant effects of Zn compound types, Zn concentrations and their interaction on RSA, and Zn uptake by root, stem, leaf, and seed, in soybean. Concentration-response curves for root structures with varied sized ZnONPs and Zn 2+ ions were deemed nonlinear, whereas for Zn distribution between different tissues the concentration-response curves were linear. Interestingly, ZnONPs and Zn 2+ ions up to 200 mg/kg showed beneficial effects on root growth and development, but toxic response was observed at higher concentrations for both compounds. Root dry weight, length, volume, and area with 200 mg/kg ZnONPs-38 nm were higher by 48%, 56%, 33% and 44%, respectively, compared to control, and were higher by 15%, 23%, 15% and 19%, respectively, compared to 200 mg/kg ZnCl 2 . In general, soybean responses to the smallest size ZnONPs-38 nm were higher for all parameters evaluated compared to the larger-sized ZnONPs (59 and > 500 nm) and Zn 2+ ions. Zn bioaccumulation varied among tissues in the order: root > seed > leaf > stem. A minor but steady decrease in soil pH and EC occurred among different concentrations for both ZnONPs and Zn 2+ ions. Improved RSA can facilitate water and nutrient uptake in soybean, promoting growth and yield, especially considering arid and semi-arid climates where water is a limiting factor. Further, improving seed and shoot Zn levels, as demonstrated herein using ZnONPs, is paramount to addressing Zn deficiency in food and feed. Future studies assessing potential impacts on soil microbes, soil health and food safety upon ZnONPs application is critical for risk assessment of the novel nanofertilizer., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2022. Published by Elsevier B.V.)

Bioanalytical equivalents (BEQs) of mixtures and environmental samples are widely used to reflect the potential threat of pollutants in the environment and can be obtained by bioassays or using chemical analysis combined with relative potencies (REPs). In this study, the relationships between bioassay-detected BEQs (Bio-BEQs) and chemically analyzed BEQs (Chem-BEQs) were studied. BEQs and REPs are correlated with effect level and the concentration-response curves of the reference standard and sample. Thus, effect level (e.g., EC 10 , EC 25 and EC 50 ) should be addressed for the BEQ values obtained from bioassays or chemical analyses. The previous prerequisites for REPs application (i.e., curves that are parallel and have the same maximum response) are redundant, and the use of REPs for the calculation of BEQs or in risk assessment should instead be based on the same effect level. For a complex mixture with many components, all active components can be regarded as dilutions of a standard compound for inducing a specific effect. Relative toxicity estimates based on EC 50 ignore the contribution of weak-active components with maximum response below EC 50 of the reference standard, especially in complex mixtures or environmental samples. REPs based on an effect level EC 10 that can be clearly discriminated from background response are recommended for BEQ calculation. As an example, the aryl hydrocarbon receptor (AhR)-mediated activity of US EPA priority polycyclic aromatic hydrocarbons (PAHs) in RTL-W1 cells was used to assess the reliability of REPs for mixture toxicity prediction based on the effect level EC 10 ., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Chemical and physical analyses are commonly used as screening methods for the environmental water. However, these methods can only look for the targeted substance but may miss unexpected toxicants. Furthermore, the synergistic effects of mixture cannot be detected. In order to set up the assay criteria for determining various biological activities at a cellular level that could potentially lead to toxicity of environmental water samples, a novel test based on cellular response by using Real-Time Cellular Analyzer (RTCA) is proposed in this study. First, the water sample is diluted to a series of strengths (80%, 60%, 40%, 30%, 20% and 10%) to get the multi-concentration cellular response profile. Then, the area under the cellular response profile (AUCRP) is calculated. Comparing to the normal cell growth of negative control, a new biological activity index named Percentage of Effect (PoE) has been presented which reflects the cumulative inhibitory activity of cell growth over the log-phase. Finally, a synthetical index PoE50 is proposed to evaluate the intensity of biological activities in water samples. The biological experiment demonstrates the effectiveness of the proposed method., (Copyright © 2015 Elsevier Inc. All rights reserved.)