Elevated Levels Of Zn Research Articles

Rice cultivation and safety concerns from irrigation with ZnO nanoparticle-contaminated treated municipal wastewater

ABSTRACT The proliferation of metal-based nanoparticles in treated municipal wastewater (TWW) has raised environmental and health concerns. This study examined the health risks and effects of ZnO nanoparticles (NPs) in TWW on rice growth, yield, and nutrition. Continuous fertigation was used to irrigate rice plants with TWW containing 0, 2, and 5 mg L−1 of either ZnO NPs or ZnSO4. Results indicated that TWW with higher ZnO NP concentrations significantly reduced plant height and root mass but increased shoot biomass and rice yield. ZnO NPs or ZnSO4 exposure increased Zn accumulation in rice roots, shoots, and grains while reducing Cd levels by 30%. However, elevated Zn levels also increased toxic metal accumulation, such as As and Mo. The estimated daily intake values for As, Zn, and Mo increased by over 100, 29–47, and 14–18%, respectively, raising cumulative health risks from trace element exposure, with hazard index (HI) values exceeding the safe threshold (HI > 1). Despite no acute toxicity in rice plants, the continuous use of ZnO NP-contaminated TWW presents significant long-term environmental and health risks. This highlights the urgent need for stringent monitoring and management of TWW quality to safeguard the sustainability of agricultural wastewater reuse.

Environmental Factors Influencing Metal Concentrations in Scomber coliasAlong the Canary Islands.

A total of 140 specimens of Scomber colias were collected from the Canary archipelago waters during the first semester of 2021, with 20 samples from each of the seven main islands. After analyzing the concentrations of metals (Al, Zn, Cd, Pb, Fe, and Cu) with ICP-OES, significant variations were observed among islands, with specimens from Tenerife and Gran Canaria containing higher levels of Al, Cd, and Pb, while those from Lanzarote and Fuerteventura had elevated levels of Zn, Fe, and Cu. These differences are probably related to greater anthropogenic activity around Tenerife and Gran Canaria coasts, leading to higher pollution levels, and the influence of Saharan dust and African upwelling on Lanzarote and Fuerteventura, enriching the waters with nutrients. Specific management strategies to mitigate marine pollution and continuous monitoring are crucial to safeguard marine ecosystems and to ensure food security.

Optimizing tea waste as a sustainable substrate for oyster mushroom (Pleurotus ostreatus) cultivation: a comprehensive study on biological efficiency and nutritional aspect

IntroductionIn Bangladesh, rice straw (RS) and sawdust (SD) substrates have traditionally been used in the production of oyster mushrooms (Pleurotus ostreatus). However, the rising costs of these substrates have led many to look for alternatives.ObjectivesThe present study thus focuses on the potential of waste tea leaves (WTL) for mushroom farming.MethodsWe prepared various substrate mixtures by combining WTL with SD and RS, subsequently evaluating mushroom yield and various quality parameters such as amino acid concentration, mineral content, and biological efficiency.Results and discussionOur investigation revealed that WTL alone is not a suitable substrate for mushroom (Pleurotus ostreatus) growth. However, when combined with SD at a 50% ratio, it significantly boosts mushroom yield and biological efficiency (BE). Conversely, a reduction in yield was noted when WTL was mixed with RS in all tested treatments, although BE surpassed 50%. In summary, incorporating WTL into both substrates proves economically viable from the BE standpoint. According to PCA analysis, the minerals and amino acid content varied based on the different substrate formulations involving WTL blending with both SD and RS at different ratios. Remarkably, mushroom fruiting bodies exhibited lower levels of Na and Fe despite these elements being present in higher concentrations in the growing substrates, suggesting the inability of P. ostreatus to bioaccumulate Na and Fe. Conversely, we observed higher bioaccumulation of Zn and P, even exceeding substrate levels. Importantly, our findings showed that mushrooms cultivated on WTL-based formulations consistently contained elevated Zn levels irrespective of substrate types, indicating that WTL enriched Zn in mushrooms. Additionally, the Fe level increased specifically in RS + WTL-based formulations. All essential and non-essential amino acids were detected, with the highest concentration of histidine, isoleucine, and methionine found in the WTL + SD formulation. Non-essential amino acids (NEAA) like alanine and glutamic acid were more prominent in formulations combining WTL with RS. This study represents the first documented exploration of the impact of WTL on the accumulation of intracellular metabolites including minerals and amino acids, in P. ostreatus.

Elevated levels of Zn, Cu and Co are associated with an increased risk of endometriosis: Results from a case[sbnd]control study

BackgroundEndometriosis is a common gynecological disease that affects approximately 5 %∼10 % of reproductive-aged women. Zinc (Zn), selenium (Se), copper (Cu), cobalt (Co) and molybdenum (Mo) are essential trace elements and are very important for human health. However, studies on the relationship between mixtures of essential trace elements and the risk of endometriosis are limited and inconsistent. In particular, studies confirming the association via different sample types are limited. ObjectiveThis study aimed to investigate the associations between Zn, Se, Cu, Co and Mo concentrations in blood and follicular fluid (FF) and endometriosis risk in a Chinese population. MethodsA total of 609 subjects undergoing in vitro fertilization (IVF) were recruited; 836 samples were analyzed, including 451 blood samples (234 controls and 217 cases) and 385 FF samples (203 controls and 182 cases). In addition, 227 subjects provided both blood and FF samples. Zn, Se, Cu, Co and Mo concentrations in blood and FF were quantified via inductively coupled plasma−mass spectrometry (ICP−MS). The associations between the levels of Zn, Se, Cu, Co and Mo and the risk of endometriosis were assessed using single-element models (logistic regression models), and the combined effect of the trace elements on endometriosis risk was assessed using multielement models (Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression). ResultsBased on the single-element models, significant associations of Zn concentrations in blood (high-level vs. low-level group: aOR = 14.17, 95 % CI: 7.31, 27.50) and FF (first tertile vs. second tertile group: aOR = 0.34, 95 % CI: 0.16, 0.71; third tertile vs. second tertile group: aOR = 2.32, 95 % CI: 1.38, 3.91, respectively) and Co concentrations in blood (first tertile vs. second tertile group, aOR = 0.24, 95 % CI: 0.12, 0.48) and FF (third tertile vs. second tertile group: aOR = 3.87, 95 % CI: 2.19, 6.84) with endometriosis risk were found after adjustment for all confounders. In FF, Cu and Mo levels were significantly greater among the cases than among the controls, with a positive association with endometriosis risk (Cu (first tertile vs. second tertile group: aOR = 0.39, 95 % CI: 0.19, 0.81; third tertile vs. second tertile group: aOR = 2.73, 95 % CI: 1.61, 4.66, respectively) and Mo (high-level vs. low-level group: aOR = 14.93, 95 % CI: 7.16, 31.12)). However, similar associations between blood Cu and Mo levels and endometriosis risk were not found. In addition, the levels of these five essential trace element mixtures in blood and in FF were significantly and positively associated with endometriosis risk according to the BKMR analyses; the levels of Zn and Cu in blood and the levels of Mo in FF were significantly related to the risk of endometriosis, and the posterior inclusion probabilities (PIPs) were 1.00, 0.99 and 1.00 for Zn and Cu levels in blood and Mo levels in FF, respectively. Furthermore, Zn and Mo were the highest weighted elements in blood and FF, respectively, according to WQS analyses. ConclusionThe risk of endometriosis was associated with elevated levels of several essential trace elements (Zn, Cu and Co). Elevated levels of these elements may be involved in the pathomechanism of endometriosis. However, further studies with larger sample sizes will be necessary to confirm these associations.

Changes in physiological responses and MTP (metal tolerance protein) transcripts in soybean (Glycine max) exposed to differential iron availability

Members of MTP (metal tolerance protein) family are potential metal ion transporters, but little is known about how their responses and expression are altered in response to the deficiency and excess of Fe in soybean. In this study, root and shoot length and biomass in addition to leaf chlorophyll score, PSII efficiency and photosynthetic performance index were adversely affected by Fe-deficiency and excess Fe. Fe and S concentrations in the root and shoot, as well as the increased root FCR activity, consistently decreased and increased, respectively, accompanied by elevated Zn levels under Fe deficiency and Fe toxicity. This implies that Fe-uptake of plants subjected to differential Fe availability are likely determined by S and Zn nutritional status. In qPCR analysis, GmMTP5, GmMTP7, GmMTP8, and GmMTP10 genes showed downregulation under Fe shortage, whereas GmMTP6 and GmMTP11 were significantly upregulated due to Fe-toxicity. Further, GmMTP1, GmMTP3, GmMTP6, GmMTP7, and GmMTP10 were significantly induced in response to Fe toxicity, indicating their potential role in metal tolerance. Bioinformatics analysis showed that soybean MTP genes possessed a close relationship with certain Arabidopsis genes (i.e. ZAT, MTPB1) involved in solute transport and metal sequestration. Furthermore, top five motifs of soybean MTP protein correspond to the cation efflux family exhibited strong amino acid and evolutionary similarities with Arabidopsisthaliana. These findings shed light on Fe homeostasis mechanisms in soybean and could be used to regulate Fe uptake through breeding or transgenic manipulations of MTP genes.

Links between elevated zinc levels, diet and muscle melanisation in sand flathead (Platycephalus bassensis) from polluted estuaries

Muscle melanisation in sand flathead is defined as the presence of abnormal black spots in the fish's flesh and the phenomenon has been associated with Zn pollution in the environment. In this study, Zn levels in the fish muscle and crabs were analysed to investigate the role of Zn in causing muscle melanisation and the fish's uptake of Zn via its diet, crabs. An improved technique for extracting melanised fish muscle from fillets with black spots was developed. It enabled Zn levels in melanised muscle to be more accurately determined when compared to previous study and showed Zn levels were 2.1–3.5 times higher in melanised regions of muscle than non-melanised regions of muscle from fish with melanisation and fish unaffected by melanisation. This indicated elevated levels of Zn were localised in the melanised muscle. Muscle melanisation was potentially caused by Zn ions binding to the active site of tyrosinase, an enzyme involved in melanin production, likely facilitated by the presence of higher Zn than Cu in the polluted estuaries. A digestion reagent mixture suitable for microwave assisted acid digestion and analysis of Zn in the whole crab was developed using a mixture of HNO3 and H2O2. Zn levels in the whole crab were 1.5 times higher in 50% of the crab species studied from a polluted estuary compared to the same species from an unpolluted estuary. As sand flathead primarily feed on crabs, the fish's diet was a likely source of elevated Zn for the fish. Overall, this study has described new techniques useful for the study of melanised fish and heavy metal levels in the whole crab. The findings from this study also provided insights that will inform and guide the direction of future research on muscle melanisation in sand flathead.

Toxicokinetics of zinc oxide nanoparticles and food grade bulk-sized zinc oxide in rats after oral dosages

The increasing application of zinc oxide nanoparticles (ZnO NPs) in consumer products has raised concerns about the potential health risks in human. It is crucial to understand the toxicokinetic information of ZnO NPs, especially the differences between NPs and non-nano form material. This study investigated the toxicokinetic profile of ZnO NPs and food grade bulk-sized ZnO in rats after single or repeated oral dosages. For single oral administration of ZnO suspensions at 350 mg/kgbw, the Zn content in blood and tissues showed no elevation, the majority of ZnO particles were eliminated via feces within 48 h. For repeated oral exposure to ZnO suspensions at 350 mg/kgbw or ZnSO4 solution at 700 mg/kgbw for 90 days, elevated Zn levels were observed in liver, kidney, and bone in all three treatment groups, the Zn level recovered to normal level in liver and kidney, but not in bone, after a recovery period. ZnO NPs and bulk-sized ZnO showed similarity in toxicokinetics in rats, regardless of exposure duration or gender. ZnO particles shared a similar biodistribution profile with ZnSO4, and were likely to be absorbed mostly in ionic forms.

Investigating zinc toxicity responses in marine Prochlorococcus and Synechococcus.

Marine plastic pollution is a growing concern worldwide and has the potential to impact marine life via leaching of chemicals, with zinc (Zn), a common plastic additive, observed at particularly high levels in plastic leachates in previous studies. At this time, however, little is known regarding how elevated Zn affects key groups of marine primary producers. Marine cyanobacterial genera Prochlorococcus and Synechococcus are considered to be some of the most abundant oxygenic phototrophs on earth, and together contribute significantly to oceanic primary productivity. Here we set out to investigate how two Prochlorococcus (MIT9312 and NATL2A) and two Synechococcus (CC9311 and WH8102) strains, representative of diverse ecological niches, respond to exposure to high Zn concentrations. The two genera showed differences in the timing and degree of growth and physiological responses to elevated Zn levels, with Prochlorococcus strains showing declines in their growth rate and photophysiology following exposure to 27 µg l−1 Zn, while Synechococcus CC9311 and WH8102 growth rates declined significantly on exposure to 52 and 152 µg l−1 Zn, respectively. Differences were also observed in each strain’s capacity to maintain cell wall integrity on exposure to different levels of Zn. Our results indicate that excess Zn has the potential to pose a challenge to some marine picocyanobacteria and highlights the need to better understand how different marine Prochlorococcus and Synechococcus strains may respond to increasing concentrations of Zn in some marine regions.

Impact of microbial multi-metal and broad spectrum antibiotic tolerance in urban SW (Adi Ganga, Kolkata) on adjacent groundwater: A future threat

One hundred and sixty six bacterial strains were isolated from a highly polluted location of Adi Ganga surface water (SW, n = 144), groundwater (GW, n = 22) system for their multi metal and antibiotic resistance study. A BOD(5) of 45 mg/L and ORP of −368 mV with faecal coliform contamination (>1800/100 ml) was noted for SW along with elevated levels of Zn (228 μg/L) and Mn (396 μg/L). However, no faecal coliform could be detected in GW sample. Multi-metal tolerance was observed to be a common property among the strains isolated. Resistance to seven or more heavy metals was prevalent among 70% of the SW bacterial population. Remaining 30% comprised isolates from both SW and GW resistant to 2–6 metals. Bacterial resistance to metals was highest for Pb followed by Cr, Mo, Ni, Hg, Cd, As, Cu, Co, Zn. Muti antibiotic resistance profiling indicated very high resistance towards ampicillin, chloramphenicol, aerosporin and streptomycin whereas the population was considerably sensitive to ciprofloxacin and gentamycin. High MAR index of 0.8 (SW) and 0.3 (GW) is a threat to the health of mankind and a possible indication of origin of multidrug resistant bacterial infections. Correlation in heavy metal and antibiotic resistance suggested their natural co-selection. Acquisition of such genetic elements by disease causing pathogenic microbes might confer resistance to a broad spectrum of antibiotics. Contamination of GW with such multi-metal and antibiotic resistant strains may spread the resistance property to human microflora.

Using zebrafish as a model to assess the individual and combined effects of sub-lethal waterborne and dietary zinc exposure during development

The present research used zebrafish (5–28 days post-fertilization; dpf) as a model organism to investigate the effects of chronic exposure to environmentally relevant sub-lethal concentrations of waterborne (261 μg/L) and dietary zinc (Zn) (1500 mg Zn/kg dw), either independently or simultaneously, during development. The results showed that whole body contents of Zn were increased in all Zn treatment groups, with the highest accumulation of Zn observed in larvae simultaneously exposed to elevated waterborne and dietary Zn. In addition, exposure to elevated levels of Zn, either through the water or the diet, led to a decrease in whole body calcium (Ca) contents at 28 dpf. The findings also suggested that exposure to elevated levels of Zn resulted in a significant reduction in whole body manganese (Mn) contents. More importantly, the magnitude of decrease in Mn contents by Zn exposure was markedly higher than that in Ca and appeared to mirror the increases in whole body Zn accumulation. These results indicate that Mn regulation is more sensitive than Ca to disruption by Zn exposure in developing fish. Further examination of the Zrt-Irt-Like Protein (ZIP) family of transporters using droplet digital PCR technologies revealed that several zip transporters exhibited temporal and exposure route-specific changes following Zn exposure. In particular, the level of zip4 was influenced by Zn exposure regardless of the exposure routes, while changes in zip7 and zip8 levels were predominantly driven by waterborne exposure. Overall, our findings demonstrated that zebrafish during the developmental periods are sensitive to elevated levels of Zn seen in the environment, particularly following co-exposures to waterborne and dietary Zn. Future toxicological assessment of elevated Zn exposure should consider both the exposure routes and the life stages of fish.

The effect of zinc on human trophoblast proliferation and oxidative stress

Adequate Zinc (Zn) intake is required to prevent multiple teratogenic effects however deviations from adequate Zn intake, including high maternal Zn status, have been linked to increased incidence of pregnancy complications, including those associated with inadequate placentation. Using placental trophoblast HTR8/SVneo cells and first trimester human placental explants (n = 12), we assessed the effects of varying Zn concentrations on trophoblast proliferation, viability, apoptosis and oxidative stress. Compared to physiologically normal Zn levels (20 µM), HTR-8/SVneo cell proliferation index was significantly lower in the presence of physiologically elevated (40 µM; P = .020) and supra-physiological (80 µM; P = .007) Zn. The latter was also associated with reduced proliferation (P = .004) and viability (P < .0001) in cultured placental explants, but not apoptosis. Reactive oxygen species production in HTR8/SVneo cultures was significantly higher in the presence of 80 µM Zn compared to all physiologically relevant levels. Oxidative stress, induced by an oxidizing agent menadione, was further exacerbated by high (80 µM) Zn. Zn did not affect lipid peroxidation in either HTR8/SVneo cells or placental explants or antioxidant defense mechanisms that included glutathione reductase and superoxide dismutase. Further study should focus on elucidating mechanisms behind impaired trophoblast proliferation and increased oxidative stress as a result of elevated Zn levels.

Title: Excess Zn-induced changes in physiological parameters and expression levels of TaZips in two wheat genotypes

Zinc (Zn) is an important higher plant micronutrient; however, high amounts of Zn in soil may negatively affect plant growth. In this study, two wheat (Triticum aestivum L.) genotypes [Aikang58 (AK) and Zhengmai0856 (ZM)] were grown in nutrient solutions containing various Zn concentrations and were characterized using physiological and molecular approaches. Compared to sufficient Zn supply (0.25 mg L−1), excess Zn (2.5 mg L−1) significantly decreased the biomass and root morphological features (root length, volume, and surface area) of AK, whereas only a slight decrease was observed in ZM. ZM maintained higher Zn concentration and translocation factor, and lower net photosynthetic rate than AK under excess Zn supply. Excess Zn decreased Cu, Fe, and Mn concentrations in roots of both wheat genotypes, whereas Mn concentrations in shoots increased. In addition, the expression of TaZIPs indicated that TaZIP5, −6, and −13 in roots are primarily involved in Zn uptake when the medium has elevated Zn levels. The translocation of more Zn from the roots to shoots facilitates in maintaining the efficiency of photosynthesis by using lower amounts of photosynthetic pigments, and TaZIP genes involved in cell ion homeostasis contributes to greater Zn tolerance in ZM than AK.

An Evaluation of Kernel Zinc in Hybrids of Elite Quality Protein Maize (QPM) and Non-QPM Inbred Lines Adapted to the Tropics Based on a Mating Design

Genetic improvement of maize with elevated levels of zinc (Zn) can reduce Zn deficiency among populations who rely on maize as a staple. Inbred lines of quality protein maize (QPM) and non-QPM with elevated Zn levels in the kernel have been identified. However, information about the optimal strategy to utilize the germplasm in breeding for high-Zn concentration is lacking. As a preliminary step, this study was conducted to ascertain the potential of QPM, non-QPM, or a combination of QPM and non-QPM hybrids for attaining desirable Zn concentration. Twenty elite inbreds, 10 QPM and 10 non-QPM, were crossed according to a modified mating design to generate hybrids, which were evaluated in four environments in Mexico during 2015 and 2016 in order to evaluate their merits as parents of hybrids. The highest mean values of Zn were observed when high-Zn QPM lines were crossed with high-Zn non-QPM lines. Hybrids with high Zn and grain yield were identified. General combining ability (GCA) effects for Zn concentration were more preponderant than specific combining ability (SCA) effects, suggesting the importance of additive gene action for the inheritance of Zn.

Insights into the tolerance and phytoremediation potential of Coronopus didymus L. (Sm) grown under zinc stress.

Zinc (Zn) is a vital micronutrient for plants, but its abundance can be calamitous. In this study, a screenhouse experiment was conducted over a 6-week period to assess the effect of soil enrichment with Zn regimes (100, 250 and 500mgkg-1) on growth, Zn accumulation, photosynthetic pigment concentration, oxidative stress markers and activities of antioxidant enzymes in Coronopus didymus. Results revealed that Zn concentration in C.didymus roots and shoots reached up to 1848mgkg-1 DW and 1845mgkg-1 DW at 500mgkg-1 Zn regime, respectively. The plant growth (root-shoot length and biomass) increased, while leaf pigment concentration and soluble protein content in C.didymus tissues decreased progressively with the increased Zn regimes in the soil. At 500mgkg-1 Zn regime, hydrogen peroxide and malondialdehyde level increased ∼219% and 111% in roots, while ∼170% and 105% in shoots, with respect to the control. Likewise, superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase and glutathione reductase activities increased significantly with elevated Zn levels. Contrarily, compared to the control, CAT activity declined gradually and reached a minimum of ∼45% in roots and 12% in shoots under highest Zn regime. The results suggested that C.didymus displayed high Zn accumulation and emerged as a tolerant plant species towards Zn stress. Elevated Zn regimes provoked reactive oxygen species generation in C.didymus tissues which was effectively neutralised and scavenged by the antioxidant enzymes, thus marked its efficacy to be potentially employed in phytoremediation and reclamation of Zn-contaminated soils.

Geographic distribution of heavy metals and identification of their sources in soils near large, open-pit coal mines using positive matrix factorization

Mining activities are considered the most important factor causing heavy metal accumulation in surface soil and it is important to understand the spatial distribution and source of heavy metals in typical steppes. In this study, the contents, spatial distribution, and sources of heavy metals were determined using geostatistical analyses, multivariate statistical analyses, and a positive matrix factorization (PMF) model using 152 soil samples collected from a grassland near the Sheng-Li coal base. The results shows that the mean concentration of heavy metals is low and does not threaten the quality of the local soil. However, the concentrations of eight heavy metals (Cu 15.04 mg kg-1, Zn 49.30 mg kg-1, Cd 0.11 mg kg-1, Pb 20.00 mg kg-1, Se 0.12 mg kg-1, Ge 1.45 mg kg-1, As 9.06 mg kg-1, and Sn 2.52 mg kg-1) are higher than their mean background values in soil in Inner Mongolia. High coefficients of variation for the heavy metals, especially Ge (1.03), and As (0.56), indicate that the concentrations of the elements are affected by the presence of the open-pit mines. Multivariate statistical and geo-statistical analyses show that Ge and As are highly correlated (R2 = 0.67, P < 0.01), suggesting that they have the same source. Using geostatistical and PMF models, we identified five potential pollution sources in the study area: 1) Industrial pollution (21.2 %), which includes smelting activity and open-pit coal mines, as suggested by elevated levels of Zn, Cd, Ge, and Cu; 2) Germanium mining (7.6 %), as indicated by higher levels of Ge and As; 3) Natural sources (37.2 %), as indicated by higher levels of Mn and Ni; 4) Coal mining activity (8.5 %), as indicated by higher levels of Sn and Cr; 5) Coal conveyor belts and high vehicular traffic, as indicated by elevated levels of Pb and Se. Taken together, the results of this study indicate that the coal base has a significant effect on the heavy metal concentration in the grassland. Therefore, the identification of the spatial distribution of heavy metals in the area may be key to controlling the pollution in the grassland. The results of this study can help to reduce pollution sources, cut down on pollution transport. So that zonal pollution control and ecological protection in the typical steppe region is achieved.

Ammonia Oxidizers as Biological Health Indicators of Elevated Zn and Cu in Poultry Litter Amended Soil

Ammonia-oxidixing bacteria (AOB) and archaea (AOA) mediate the first and rate-limiting step of nitrification and are responsive to agricultural management practices. These two attributes make them ideal indicators of biological soil health. We conducted a laboratory incubation study to determine their response to elevated levels of zinc (Zn) and copper (Cu) in poultry litter treated soil at three substrate concentrations: 0 (low), 50 (medium) and 100 (high) mg ammonium ($$ {\mathrm{NH}}_4^{+} $$-N) kg−1 soil. Nitrification potential (NP) was measured to characterize changes in their function in which 1-octyne was used to separate their contributions. Quantitative polymerase chain reaction was used to measure their abundance by targeting amoA. Increasing Zn from 21 to 250 mg kg−1 resulted in large reductions in AOB (78%) and AOA (85%) abundance at the high $$ {\mathrm{NH}}_4^{+} $$ level over 28 days. Likewise, increasing Cu from 20 to 120 mg kg−1 significantly reduced AOB (92%) and AOA (63%) abundance at the high $$ {\mathrm{NH}}_4^{+} $$ level over 28 days. The relative contribution of AOB to NP was significantly higher than that of AOA in both Zn (~60%) and Cu (~70%) treated soils despite the numerical dominance of AOA over AOB. Overall, results indicate that elevated levels of Zn and Cu depressed AOB and AOA abundance and function and that their effect was dependent on availability of $$ {\mathrm{NH}}_4^{+} $$. The results also indicated that AOB are functionally more important than AOA under elevated Zn and Cu concentrations and that management practices to improve N use efficiency should focus on AOB under this condition.

Elemental compositions of particulate matter retained on air condition unit\u2019s filters at Greater Doha, Qatar

Elemental composition of airborne dust samples retained by internal filters of air condition units (ACUs) was determined at 12 locations of Doha city, state of Qatar. Twenty-four elements: Al, Ca, Mg, Fe, Na, K, Ti, Zn, P, Sr, Mn, Ba, Cu, Cr, Ni, Pb, V, Mo, Li, Co, Sb, As, Cd, Be, were analysed by ICP-OES technique after acid digestion of the samples. The analysed components reflect 20.6% of the total sample mass. Similar or lower concentration values have been found for As, Cd, Cr, Cu, Mn, Ni, Pb, V, Zn, Al, and Fe compared to the international context of upper crust concentrations, NIST SRM (urban dust), published local dust information of outdoor, and surface terrestrial deposit (STD) counted for 7.2, 0.7, 91.8, 192.8, 369.7, 68.6, 65.3, 52.1, 824.3, 19,791, 20,508 mg/kg, respectively. The coefficient of correlation (p ≤ 0.05) showed significant association of ACUs dust elemental compositions with the main components of the local earth crust and surface deposits, ranging from the lowest 0.77 (Mg–Fe) to the highest 0.98 (Al–Fe), while Ni and V, typical anthropogenic pollutants, are also strongly correlated (0.86). These strong correlation relationships can be interpreted as the contribution of outdoor particulate to the indoor dust. Dendrogram of metal/Al ratios, based on Euclidean distance calculation and average linkage clustering method, distinguished three typical groups. Studying the enrichment factors of the three groups indicated elevated levels of Zn (131), Pb (49), Cu (32), Cd (8) and Ni (5) found indoors compared to the background composition of STD especially at locations in the industrial zone. The major elemental composition of the samples reflects the typical mineral composition of the local dust, while the trace composition demonstrates the influence of indoor sources. The collected ACU filter dust samples show significant contribution of outdoor mineral particles, non-exhaust traffic emission, industrial sources, as well as the influence of indoor activity such as smoking.

The Deletion of TRPC6 Channels Perturbs Iron and Zinc Homeostasis and Pregnancy Outcome in Mice.

Transient receptor potential canonical 6 (TRPC6) protein is a nonselective cation channel permitting the uptake of essential elements such as iron (Fe) and zinc (Zn). TRPC6 is found throughout the body with high expression levels in the placenta. However, its role in this organ is still to be determined. To further advance our understanding of the physiological relevance of TRPC6, we have studied the placental histology, pregnancy outcome and the Fe and Zn status of organs (placenta, brain, kidney, liver and lung) collected from TRPC6 deficient (TRPC6-/-) mice and sex and age-matched C57Bl6/J and B6129SF2/J mice. Metal content was quantified by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Quantitative reverse transcriptase PCR (qRT-PCR) and Western Blottings (WB) were performed to analyze the expression of placental markers and TRPC6. Our data show that TRPC6-/- mice displayed reduced litter sizes, structural changes of the placenta, along with altered mRNA levels of CD31 and Gcm1, two markers of placental development. Furthermore, immunoblots revealed elevated amounts of TRPC6 proteins in placentas from women diagnosed with preeclampsia, a common gestational disease. When compared to C57Bl6/J and B6129SF2/J, TRPC6-/- mice had elevated Zn levels in placenta, liver and kidney during embryonic development and postnatally, but not at adulthood. High amounts of Fe were found in the adult brain and liver of TRPC6-/- mice. The lung was however not affected by the deletion of TRPC6, indicating that this mouse strain developed organ and age-dependent perturbations in their Zn and Fe status. This work indicates that TRPC6 exerts critical pathophysiological functions in placenta, and provides further evidence for a role of this channel in the homeostasis of cations like Zn and Fe.

The aminoglycoside resistance-promoting AmgRS envelope stress-responsive two-component system in Pseudomonas aeruginosa is zinc-activated and protects cells from zinc-promoted membrane damage.

Exposure of wild-type (WT) Pseudomonas aeruginosa PAO1 to ZnCl2 (Zn) yielded a concentration-dependent increase in depolarization of the cytoplasmic membrane (CM), an indication that this metal is membrane-damaging. Consistent with this, Zn activated the AmgRS envelope stress-responsive two-component system (TCS) that was previously shown to be activated by and to protect P. aeruginosa from the membrane-damaging effects of aminoglycoside (AG) antibiotics. A mutant lacking amgR showed enhanced Zn-promoted CM perturbation and was Zn-sensitive, an indication that the TCS protected cells from the CM-damaging effects of this metal. In agreement with this, a mutant carrying an AmgRS-activating amgS mutation was less susceptible to Zn-promoted CM perturbation and more tolerant of elevated levels of Zn than WT. AG activation of AmgRS is known to drive expression of the AG resistance-promoting mexXY multidrug efflux operon, and while Zn similarly induced mexXY expression this was independent of AmgRS and reliant on a second TCS implicated in mexXY regulation, ParRS. MexXY did not, however, contribute to Zn resistance or protection from Zn-promoted CM damage. Despite its activation of AmgRS and induction of mexXY, Zn had a minimal impact on the AG resistance of WT P. aeruginosa although, given that Zn-tolerant AmgRS-activated amgS mutant strains are AG resistant, there is still the prospect of this metal promoting AG resistance development in this organism.

Influences of zinc oxide nanoparticles on Allium cepa root cells and the primary cause of phytotoxicity.

Zinc oxide nanoparticles (ZnO-NPs) are widely used in consumer products, which have raised concerns about their impact on the human health and environment. In this study, Allium cepa were treated with 5 and 50 μg/mL ZnO-NPs solutions for 12, 24, and 36 h, respectively. The cytotoxic and genotoxic effects of ZnO-NPs in root meristems of Allium cepa cells were characterized by cell membrane integrity, metabolic activity, reactive oxygen species (ROS) accumulation, DNA damage, chromosome aberration, and cell cycle progression. Substantially elevated Zn levels were observed in the cytoplasmic and nuclear fractions, and the accumulation of zinc in the nuclear fraction (up to 9764 μg/g) was one magnitude greater than that in the cytoplasm (up to 541 μg/g). The complexation of Zn2+ with diethylene triamine pentacetic acid (DTPA) was performed to explicate the respective contribution of insoluble particles or Zn2+ to ZnO-NPs toxicity. We found that the inhibition of root growth accounted for 24.2% or 36.1% when the plants were exposed to Zn2+ that released from 5 or 50 μg/mL of ZnO-NPs for 36 h, respectively, whereas the exposure to 5 or 50 μg/mL of insoluble particles resulted in 75.8% or 63.9% of inhibition, respectively. These findings demonstrated that adverse effects exerted not just by Zn2+ released from ZnO-NPs, but also directly from the nanoparticles. These findings contribute to a better understanding of ZnO-NPs cytotoxicity and genotoxicity in plant cells and provide valuable information for further research on the phytotoxic mechanisms of ZnO-NPs.