Glyphosate does not show higher phytotoxicity than cadmium: Cross talk and metabolic changes in common herb

Interaction of nickel with oxidative and antioxidative molecules in Cichorioideae species

The uptake of nickel (Ni) by Asteraceae/Cichorioideae species Cichorium intybus, Leontodon hispidus and Hieracium aurantiacum exposed to Ni (0.3 or 30 μM) over 14 days and subsequent changes of metabolites were compared in order to identify their phytoaccumulation potential. Hieracium contained the most Ni (194 and 1558 μg Ni/g DW at 30 μM Ni in shoots and roots) but had unchanged amount of antioxidants (vitamin C and thiols) in the shoots and an elevated amount in the roots, which may be the reason for the absence of visible damage. On the contrary, Leontodon reacted by a decrease in antioxidants to an excess of Ni, which can be related to enhanced oxidative stress (an increase in ROS and a decrease in nitric oxide detected by fluorescence microscopy). All roots were anatomically in the secondary state and Ni-induced cell wall thickening (i.e. lignin/suberin deposition) was most visible in Hieracium roots, which also contained 2-times more Ni than the other species. Among essential elements, mainly Fe accumulation was affected by Ni excess. The content of soluble phenols increased while organic acids (malic and citric) decreased sometimes extensively (up to 90%) in individual species. PCA analyses showed that especially ascorbic acid, thiols and phenols affect the separation in the shoots especially with regard to applied concentration of Ni, while these metabolites in the roots clearly separated the species (Cichorium from the others). The data show the highest tolerance to Ni in Hieracium, but the highest phytoaccumulation of Ni was found in Cichorium (626 μg Ni/plant or 122 μg Ni/shoot at a dose of 30 μM Ni).

Effect of Ginkgo biloba extract on pharmacology and pharmacokinetics of atorvastatin in rats with hyperlipidaemia

Ginkgo biloba extract (GBE) is a common dietary supplement used by people with dyslipidaemia worldwide to reduce the risk of cardiovascular disease. Many studies have found that GBE itself has a variety of pharmacological activities. However, the role of GBE as an adjunct to conventional therapy with chemical drugs remains controversial. Therefore, this study explored the additional benefits of GBE in the treatment of hyperlipidaemia with statins in terms of both pharmacodynamics and pharmacokinetics. A hyperlipidaemia model was established by feeding rats a high-fat diet for a long time. The animals were treated with atorvastatin only, GBE only, or a combination of atorvastatin and GBE. The results showed that statins combined with GBE could significantly improve the blood lipid parameters, reduce the liver fat content, and reduce the size of adipocytes in abdominal fat. The effect was superior to statin therapy alone. In addition, the combination has shown additional liver protection against possible pathological liver injury or statin-induced liver injury. A lipidomic study showed that GBE could regulate the abnormal lipid metabolism of the liver in hyperlipemia. When statins are combined with GBE, this callback effect introduced by GBE on endogenous metabolism has important implications for resistance to disease progression and statin resistance. Finally, in the presence of GBE, there was a significant increase in plasma statin exposure. These results all confirmed that GBE has incremental benefits as a dietary supplement of statin therapy for dyslipidaemia.

Calcium-enriched biochar modulates cadmium uptake depending on external cadmium dose

The impact of calcium-enriched biochar (BC, containing Ca, Al, Fe and P as dominant elements in the range of 6.9-1.3% with alkaline pH) obtained from sewage sludge (0.1 or 0.5% in the final soil) on cadmium-induced toxicity (final dose of 1.5 mg Cd/kg in control and 4.5 or 16.5 mg Cd/kg soil in low and high Cd treatment) was tested in medicinal plant Matricaria chamomilla. Low Cd dose had typically less negative impact than high Cd dose at the level of minerals and metabolites and the effect of BC doses often differed. Contrary to expectations, 0.5% BC with a high Cd dose increased Cd accumulation in plants about 2-fold. This was reflected in higher signals of reactive oxygen species, but especially the high dose of BC increased the amount of antioxidants (ascorbic acid and non-protein thiols), minerals and amino acids in shoots and/or roots and usually mitigated the negative effect of Cd. Surprisingly, the relationship between BC and soluble phenols was negative at high BC + high Cd dose, whereas the effect of Cd and BC on organic acids (mainly tartaric acid) differed in shoots and roots. Interestingly, BC alone applied to the control soil (1.5 mg total Cd/kg) reduced the amount of Cd in the plants by about 30%. PCA analyses confirmed that metabolic changes clearly distinguished the high Cd + high BC treatment from the corresponding Cd/BC treatments in both shoots and roots. Thus, it is clear that the effect of biochar depends not only on its dose but also on the amount of Cd in the soil, suggesting the use of Ca-rich biochar both for phytoremediation and safer food production.

Evaluation of the phycoremediation potential of microalgae for captan removal: Comprehensive analysis on toxicity, detoxification and antioxidants modulation

Captan is one of the most widely used organochlorine fungicides, its frequent application contaminates both terrestrial and aquatic ecosystems and negatively affects their key ecological processes. This study demonstrated the toxicity and efficient removal of captan by two different taxonomic species; the green microalga Scenedesmus obliquus and cyanobacterium Nostoc muscorum. After a week of exposure to mild (15 mg/L) and severe (30 mg/L) captan doses, the intracellular captan uptake, degradation and metabolic regulation of captan detoxification were studied. Compared to N. muscorum, S. obliquus accumulated more captan, but efficiently degraded it into two safe eco-friendly by-products; phthalic acid and 1,2,3,6-tetrahydro phthalimide. S. obliquus showed less decrease in cell growth, photosynthesis activity and related parameters including Chla content and activity of PEPC and RuBisCo enzymes. Captan at the severe dose induced oxidative damage particularly in N. muscorum, as expressed by the high levels of H₂O₂, MDA, NADPH oxidase and protein peroxidation. Both species invested glutathione-s-transferase enzyme in captan detoxification however, induction of antioxidant defence system e.g. ascorbate and glutathione cycle was more pronounced in S. obliquus which could explain its tolerance ability. This study provided a better understanding of the environmental risks of captan and introduced S. obliquus as a promising captan phycoremediator.

Cadmium uncouples mitochondrial oxidative phosphorylation and induces oxidative cellular stress in soybean roots

Cadmium (Cd) inhibits soybean root growth, but its exact mode of action is still not completely understood. We evaluated the effects of Cd on growth, mitochondrial respiration, lipid peroxidation, total phenols, glutathione, and activities of lipoxygenase (LOX), superoxide dismutase (SOD), and catalase (CAT) in soybean roots. In primary roots, Cd stimulated KCN-insensitive respiration and KCN-SHAM-insensitive respiration, indicating the involvement of the alternative oxidase (AOX) pathway, while it decreased KCN-sensitive respiration, suggesting an inhibition of the cytochrome oxidase pathway (COX). In isolated mitochondria, Cd uncoupled the oxidative phosphorylation since it decreased state III respiration (coupled respiration) and ADP/O and respiratory control ratios, while it increased state IV respiration (depletion of exogenously added ADP). The uncoupling effect increased extramitochondrial LOX activity, lipid peroxidation, and oxidized and reduced glutathione, which induced an antioxidant response with enhanced SOD and CAT activities. In brief, our findings reveal that Cd acts as an uncoupler of the mitochondrial oxidative phosphorylation in soybean roots, disturbing cellular respiration and inducing oxidative cellular stress.

Azospirillum brasilense Az39 restricts cadmium entrance into wheat plants and mitigates cadmium stress

In this work, we tested if inoculation with the plant growth-promoting rhizobacteria Azospirillum brasilense strain Az39 alleviates Cd²⁺ stress in wheat seedlings grown under controlled conditions. Growth, total N, N-related metabolites/enzymes, and oxidative stress parameters were measured. Additionally, the usefulness of a real-time PCR protocol to screen the preferred colonization site of the introduced microorganism was evaluated. Inoculated plants demonstrated mitigation of cadmium-induced adverse effects on plant growth and less reactive oxygen species accumulation in their roots by the end of the experiment, 28 days after sowing. Cd addition resulted in lower NO₃^- content in the leaves and higher NO₃^- content in the roots, and a significant rise in NH₄⁺ concentration in both organs in uninoculated plants; in inoculated plants, NH₄⁺ content in the roots did not vary. A. brasilense Az39 enhanced NO levels in wheat root tips, and more adventitious roots and root hairs were observed in inoculated plants. Despite having a more developed root system, inoculated plants showed lower Cd levels in their roots compared to non-inoculated plants. Inoculation with this PGPR favored ion homeostasis in the roots of metal-exposed plants, decreasing Cd/Fe ratio. We corroborated A. brasilense Az39 preference for wheat exorhizosphere using a real-time PCR-based method targeting the nifA gene.

Basic physiology and biochemistry in environmental/experimental plant studies: How to quantify and interpret metabolites correctly

As a reviewer of ca. 50 manuscripts per year submitted to various journals, I often come across questionable metabolic data (both over- or under-estimated) mainly in the journals from the section of Environmental Sciences of Web of Science. Though the trends of visibly incorrect metabolite values may be informative (changes in response to applied treatments or environmental factors), absolute values must be precise enough to allow inter-specific comparison and eventual subsequent calculations. Technical correctness of quantification and calculation of such data is therefore often questionable. One problem arises when calculating metabolites concentration (often nmol or μmol/g of biomass) and another problem is the impact of altered water content on metabolite level (then trend per gram of fresh or dry biomass will differ). Recent discrepancies I found when searching for the literature prompted me to write this technical note aimed at focusing attention of researchers on these problems. I exclude any conflict of interest when discussing the quoted published studies. I strongly urge interested researchers to verify the correctness of metabolite quantification (extraction, dilution/calculation and alternative methods) and also to study similar literature for comparison in order to prevent the spread of incorrect data in the scientific literature.

Phytotoxic evaluation of neonicotinoid imidacloprid and cadmium alone and in combination on tomato (Solanum lycopersicum L.)

Neonicotinoids and heavy metals pollution exist simultaneously in agro ecosystem. However, little is known about their combined ecotoxicological effects on non-target crop plants. We have selected imidacloprid (IMI) and cadmium (Cd), applied alone and in combination, to evaluate their effect on growth, physiological and biochemical parameters of tomato. Results showed that the single application of contaminants (IMI and/or Cd) adversely affected both the growth and chlorophyll pigment, and Cd alone application was more phytotoxic than IMI. However, their combined action aggravated the inhibitory effect and indicate a synergistic effect, but it exerted antagonistic effects on chlorophyll pigment inhibition compared with IMI and Cd alone treatments. Both chemicals increased hydrogen peroxide level and generated lipid peroxidation, and the co-contamination exacerbates oxidative stress by their synergistic effect. Those results implicate that disturbance of cellular redox status is the plausible mechanism for IMI and Cd induced toxicity. In conclusion, the single or combined IMI and Cd cause negative effects on tomatoes.

Long-term impact of cadmium in protonema cultures of Physcomitrella patens

Antioxidative responses of axenic protonema cultures of the moss Physcomitrella patens exposed to 10 μM Cd over 40 d were studied. Cd treatment suppressed growth by ca. 75% with concomitant browning of some filaments and suppression of chlorophyll autofluorescence but had no impact on tissue water content. Despite this negative growth responses which could be related to enhanced ROS formation (as detected using fluorescence staining reagents for total ROS, hydroperoxides and lipid peroxidation), some metabolites revealed strong elevation by Cd which could contribute to attenuation of long-term Cd stress (elevation of ascorbic, malic and citric acids). Molar ratio of malate to Cd was 12.7 and citrate to Cd 2.5, thus potentially contributing to Cd chelation. Interestingly, GSH/GSSG pool and nitric oxide formation remained unaltered by Cd. Accumulation of Cd reached 82 μg/g DW with bioaccumulation factor of 73. Data indicate that Cd induces elevation of potentially protective metabolites even after prolonged exposure though they do not prevent oxidative stress sufficiently.

Uptake, biotransformation and physiological response of TBBPA in mangrove plants after hydroponics exposure

To better understand the uptake, biotransformation and physiological response to tetrabromobisphenol A (TBBPA) in mangrove plants, a short term 14-day hydroponic assay with two mangrove species, Avicennia marina (A. marina) and Kandelia obovata (K. obovata), was conducted. Results showed that two mangrove species could uptake, translocate and accumulate TBBPA from solution. The hydroxylation and debromination metabolites of TBBPA, including OH-TBBPA, TriBBPA, MonoBBPA, and BPA, were found in both mangroves for the first time. The high-level TBBPA suppressed the growth and increased malondialdehyde (MDA) content of K. obovata, did not pose any negative affect on A. marina. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of K. obovata significantly increased in the 7th day, whereas, SOD and POD activities at high-levels of TBBPA became comparable to the control in the 14th day. Contrastingly, the antioxidant enzymes activities of A. marina were positively stimulated by TBBPA during the 14-day of observation, indicating that A. marina was more tolerant of TBBPA.