Copper Tolerance and Accumulation on Pelargonium graveolens L’Hér. Grown in Hydroponic Culture

Heavy metal contamination is a major health issue concerning the commercial production of medicinal and aromatic plants (MAPs) that are used for the extraction of bioactive molecules. Copper (Cu) is an anthropogenic contaminant that, at toxic levels, can accumulate in plant tissues, affecting plant growth and development. On the other hand, plant response to metal-induced stress may involve the synthesis and accumulation of beneficial secondary metabolites. In this study, hydroponically grown Pelargonium graveolens plants were exposed to different Cu concentrations in a nutrient solution (4, 25, 50, 100 μM) to evaluate the effects Cu toxicity on plant growth, mineral uptake and distribution in plants, some stress indicators, and the accumulation of bioactive secondary metabolites in leaf tissues. P. graveolens resulted in moderately tolerant Cu toxicity. At Cu concentrations up to 100 μM, biomass production was preserved and was accompanied by an increase in phenolics and antioxidant capacity. The metal contaminant was accumulated mainly in the roots. The leaf tissues of Cu-treated P. graveolens may be safely used for the extraction of bioactive molecules.

Protective Effects of Taurine Against Inflammation and Apoptosis in Cadmium-Induced Hepatotoxicity

Cadmium (Cd), a heavy metal contaminant,which seriously threatens human and animal health. Taurine (Tau) has been used to against hepatotoxicity caused by different environmental toxins. However, it has not been elucidated whether Tau exerts its protective function against Cd-induced hepatotoxicity. The aim of this study was thus to evaluate the ameliorative function of Tau on Cd-induced liver toxicity in mice. The histopathologic and ultrastructure changes, as well as alterations in indexes related to liver function, antioxidant biomarkers, inflammatory and apoptosis were evaluated. The results showed that Tau alleviated the vacuolar degeneration, nuclear condensation, mitochondria swelling and cristae lysis of hepatocytes induced by Cd. In addition, Tau treatment significantly restored the ALT, AST levels in serum, and inflammatory factor TNF-α and IL-1β in liver tissue. Furthermore, Tau treatment decreased the Bax/Bcl-2 ratio and cleaved caspase-3 protein expression levels. Taken together, these observations demonstrate that Tau has important hepatic protective function against the inflammation and apoptosis induced by Cd.

Genotypic screening of wheat and their physiological responses under lead toxicity

Lead (Pb) is the second most harmful heavy metal contaminant in the environment and toxic for plant growth and development. Therefore, the identification and selection of plant genotypes tolerant to Pb stress are of great significance. In this study, twenty-six wheat lines (Triticum aestivum) were screened for Pb tolerance based on their morpho-physiological variations at the seedling stage with a rapid hydroponic technique using lead nitrate (Pb(NO3)2) at two concentrations (500 ?M and 1 mM) along with control. Wheat genotypes showed distinct variations in plant height, plant biomass and chlorophyll concentration in response to different concentrations of Pb. Considering all parameters, Akbar was found most tolerant (T) with minimum RS (2.97) to Pb stress, followed by BARI Gom-31 (3.45), Barkat (3.54) and Sufi (3.65), while BARI Gom-26 (10.14) was most sensitive (S) followed by Khude Gom (9.69), BARI Gom-30 (8.79), LalGom (8.76) and BARI Gom-32 respectively. More scores were seen in the remaining genotypes and were graded as moderately tolerant/resistant (MT) to Pb stress. Results showed that the resistant line had less damage to root and shoot characteristics along with chlorophyll score, thereby providing a hint about the Pb tolerance capacity of wheat genotypes at the seedling stage. Furthermore, findings indicate that Pb susceptibility in wheat is predominantly associated with a decrease in the Pb components of the root and shoot. We suggest Akbar as an elite genotype to cultivate or use in downstream studies on the basis of our findings to ensure an improved crop production relative to other varieties evaluated. These findings provide the necessary background for Pb cleansing and Pb-free wheat development for environment and health safety.

Laminated graphene oxide membrane for recovery of mercury-containing wastewater by pervaporation

Mercury (Hg) is a toxic heavy metal contaminant and has very harmful effects for human health. In this work, Hg-containing wastewater with Hg concentration of 6.36 ppb and 9.4 ppb were recovered with polyethylenimine (PEI) cross-linked graphene oxide (GO) layered membrane (c-GO-PEI) by pervaporation. The influence of ionic type, the concentration of Hg and the feed temperature were investigated. The c-GO-PEI exhibited not only high rejection for salts (> 99.97%), Hg (77.5–100%) and non-purgeable organic carbon (NPOC) (67.3–90.8%) but also high flux (30.30 kg·m−2·h−1) to treat with the wastewater. In addition, the flux could be largely recovered after simple washing, indicating the excellent antifouling property of the membrane.

Polystyrene Nanoplastics as Carriers of Metals. Interactions of Polystyrene Nanoparticles with Silver Nanoparticles and Silver Nitrate, and Their Effects on Human Intestinal Caco-2 Cells

Environmental plastic wastes are continuously degraded to their micro and nanoforms. Since in the environment they coexist with other pollutants, it has been suggested that they could act as vectors transporting different toxic trace elements, such as metals. To confirm this, we have assessed the potential interactions between nanopolystyrene, as a model of nanoplastic debris, and silver compounds (silver nanoparticles and silver nitrate), as models of metal contaminant. Using TEM-EDX methodological approaches, we have been able to demonstrate metal sorption by nanopolystyrene. Furthermore, using Caco-2 cells and confocal microscopy, we have observed the co-localization of nanopolystyrene/nanosilver in different cellular compartments, including the cell nucleus. Although the internalization of these complexes showed no exacerbated cytotoxic effects, compared to the effects of each compound alone, the silver/nanopolystyrene complexes modulate the cell’s uptake of silver and slightly modify some harmful cellular effects of silver, such as the ability to induce genotoxic and oxidative DNA damage.

Recent Advancements in Bioremediation of Metal Contaminants

Biofilms are an accumulation of single or various populations of microorganisms that are present on the surfaces through membrane-bound substances due to the gene expression, which differs from free-floating expression and leads to expressed genes regulating biofilm formation and development. In this regard, recent advances in microbial-based heavy metals have propelled bioremediation as a prospective alternative to conventional techniques. Adsorption and biodegradation of organic contaminants and the immobilization, mobilization, and/or transformation of metals are the main remediation processes that can be mediated by the action of several microorganisms surviving in hostile environments with high concentrations of pollutants. The chapter discussed the formation and regulation of biofilms to degrade the metal contaminant, the importance of gene transfer, and applications of biofilm-mediated bioremediation processes.

Impact of Climate Change on Metal and Suspended Sediment Concentrations in Urban Waters

In order to study the impact of climate change on metal contaminant transport in urban waters and its relevance for water quality, we have analyzed variations in metal- and suspended sediment concentrations (SSC) in three urban rivers and one small creek in the Gothenburg region during various hydrological events such as spring flood, dry period, and wet period. To interpret river loads of metals and SSC we have furthermore followed meteorological trends since 1961 and additionally calculated future trends for the Gothenburg region, located on the west coast of Sweden. During periods of a short-term increase in precipitation we found an increased particle bound metal transport in urban watercourses of the Göta Älv River. In addition, a correlation between studied parameters indicates that surface runoff from brownfields most likely is the main source to the increased transport of pollutants in river systems rather than re-suspension of polluted river sediment.

Development of predicitve models to distinguish metals from non-metal toxicants, and individual metal from one another

Background Evaluating the toxicity of chemical mixture and their possible mechanism of action is still a challenge for humans and other organisms. Microarray classifier analysis has shown promise in the toxicogenomic area by identifying biomarkers to predict unknown samples. Our study focuses on identifying gene markers with better sensitivity and specificity, building predictive models to distinguish metals from non-metal toxicants, and individual metal from one another, and furthermore helping understand underlying toxic mechanisms. Results Based on an independent dataset test, using only 15 gene markers, we were able to distinguish metals from non-metal toxicants with 100% accuracy. Of these, 6 and 9 genes were commonly down- and up-regulated respectively by most of the metals. 8 out of 15 genes belong to membrane protein coding genes. Function well annotated genes in the list include ADORA2B, ARNT, S100G, and DIO3. Also, a 10-gene marker list was identified that can discriminate an individual metal from one another with 100% accuracy. We could find a specific gene marker for each metal in the 10-gene marker list. Function well annotated genes in this list include GSTM2, HSD11B, AREG, and C8B. Conclusions Our findings suggest that using a microarray classifier analysis, not only can we create diagnostic classifiers for predicting an exact metal contaminant from a large scale of contaminant pool with high prediction accuracy, but we can also identify valuable biomarkers to help understand the common and underlying toxic mechanisms induced by metals.

Biosensor Design for Detection of Mercury in Contaminated Soil Using Rhamnolipid Biosurfactant and Luminescent Bacteria

In this study, a biosensor is designed to remove mercury as a toxic metal contaminant from the soil. The rhamnolipid biosurfactant was used to extract the mercury sorbed to soil to the aqueous phase. An immobilized bioluminescent bacterium (Escherichia coli MC106) with pmerRBPmerlux plasmid is assisted for mercury detection. A significant decrease in luminescence level was observed in a biosensor system containing contaminated soil sample extract. The concentrations of extracting mercury are well correlated with the mercury toxicity data obtained from experimental biosensor systems according to the RBL value. The optimum aeration rate of 20 ml/min was obtained for the biosensor systems. The advantage of such a biosensor is the in situ quantification of mercury as a heavy metal contaminant in soils. Therefore, this system could be proposed as a good biosensor-based alternative for future detection of heavy toxic metals in soils.