Effects of triacontanol on ascorbate-glutathione cycle in Brassica napus L. exposed to cadmium-induced oxidative stress.

The ability of exogenous triacontanol (TRIA), a plant growth regulator, to reduce Cd toxicity was studied in canola (Brassica napus L.) plants. The following biological parameters were examined in canola seedlings to investigate TRIA-induced tolerance to Cd toxicity: seedling growth, chlorophyll damage and antioxidant response. In particular, TRIA application reduced Cd-induced oxidative damage, as shown by reduction of ROS content, lipoxygenase (LOX) activity and lipid peroxidation level. TRIA pretreatment increased non-enzymatic antioxidant contents (ascorbate, AsA, glutathione and GSH), phytochelatin content (PCs) and activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), monodehydroascorbate reductase (MDHAR), dehydro ascorbate reductase (DHAR), and glutathione reductase (GR), so reducing the oxidative stress. These results clearly indicate the protective ability of TRIA to modulate the redox status through the antioxidant pathway AGC and GSH, so reducing Cd-induced oxidative stress

Interaction of triacontanol and arsenic on the ascorbate-glutathione cycle and their effects on the ultrastructure in Coriandrum sativum L.

Exogenous application of triacontanol (TRIA) has the ability to mitigate the adverse effects of abiotic stresses by modulating a number of physio-biochemical processes in different plants. However, information about how its effects may be mediated under heavy metal stress is scanty. In this study, we evaluated how TRIA exerted its role against the toxicity of sodium arsenate in coriander (Coriandrum sativum L.). The activities of enzymes, including ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione-S-transferase (GST), were measured. In addition, the contents of ascorbate (ASC), dehydroascorbate (DHA), reduced glutathione (GSH) and some elements including both As and the nutrients Ca, Mg, Zn, K, P were determined. Results suggested that As decreased GSH, ASA and DHA contents, a clear indication of oxidative stress, but their amounts were raised by TRIA treatment. Also, As stress decreased plant Ca, Zn, K, Mg and P contents, while TRIA improved their uptake and inhibited As accumulation. As 200 μM treatment inhibited the activities of APX, MDHAR, DHAR, and GR, enzymes of the ascorbate-glutathione cycle (AGC). TRIA supplementation restored and even enhanced the activity of all the AGC enzymes. 10 μM TRIA treatment increased GST gene expression and activity to a greater extent than under only As treatment. TRIA-alone treatments did not change the mentioned parameters. Transmission electron microscopy (TEM) observations showed that TRIA was able to protect cells, and most of all chloroplasts, from As-induced damage. These results clearly indicate the protective role of TRIA in modulating the redox status of the plant system through the antioxidant AGC and GSH enzymes, which could counteract arsenic-induced oxidative stress

Response to metals in the liverwort Lunularia cruciata and in the charophyte Nitella mucronata

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Protamine-like proteins have bactericidal activity. The first evidence in Mytilus galloprovincialis.

The major acid-soluble protein components of the mussel Mytilus galloprovincialis sperm chromatin consist of the protamine-like proteins PL-II, PL-III and PL-IV, an intermediate group of sperm nuclear basic proteins between histones and protamines. The aim of this study was to investigate the bactericidal activity of these proteins since, to date, there are reports on bactericidal activity of protamines and histones, but not on protamine-like proteins. We tested the bactericidal activity of these proteins against Gram-positive bacteria: Enterococcus faecalis and two different strains of Staphylococcus aureus, as well as Gram-negative bacteria: Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhmurium, Enterobacter aerogenes, Enterobacter cloacae, and Escherichia coli. Clinical isolates of the same bacterial species were also used to compare their sensitivity to these proteins. The results show that Mytilus galloprovincialis protamine-like proteins exhibited bactericidal activity against all bacterial strains tested with different minimum bactericidal concentration values, ranging from 15.7 to 250 µg/mL. Furthermore, these proteins were active against some bacterial strains tested that are resistant to conventional antibiotics. These proteins showed very low toxicity as judged by red blood cell lysis and viability MTT assays and seem to act both at the membrane level and within the bacterial cell. We also tested the bactericidal activity of the product obtained from an in vitro model of gastrointestinal digestion of protamine-like proteins on a Gram-positive and a Gram-negative strain, and obtained the same results with respect to undigested protamine-like proteins on the Gram-positive bacterium. These results provide the first evidence of bactericidal activity of protamine-like-proteins

Physiological and ultrastructural effects of acute ozone fumigation in the lichen Xanthoria parietina: the role of parietin and hydration state

The physiological and ultrastructural effects induced by acute exposure to ozone (O3) were investigated in the lichen Xanthoria parietina. Our working hypothesis was that parietin content and hydration of the thalli may play a role in the modulation of the effects of O3 exposure. Four batches of X. parietina samples, dry and wet, with (P+) and without (Pâ\u88\u92) parietin, were fumigated for 1 h with 3 ppm O3. The effects of O3 were assessed immediately after the fumigation and after one week of recovery under controlled conditions. O3 fumigation caused physiological and ultrastructural impairment both to the photobiont and the mycobiont, irrespective if samples were fumigated wet or dry, and P+ or Pâ\u88\u92. However, one week after fumigation, a recovery was observed in P+ samples for the photobiont and in dry samples for the mycobiont. We suggest that the hydration state may play a major role in determining the severity of the damage, while the presence of parietin may promote the recovery. Our results provide physiological and ultrastructural basis to explain the ecological insensitivity of lichens to high environmental levels of ozone occurring during dry Mediterranean summers

Chemical Composition and Biological Activities of Oregano and Lavender Essential Oils

Folk medicine uses wild herbs, especially from the Lamiaceae family, such as oregano and lavender, in the treatment of many diseases. In the present study, we investigated the antibacterial activity of the essential oils of Origanum glandulosum Desf. and Lavandula dentata L. against multidrug- resistant Klebsiella pneumoniae strains. The chemical composition of essential oils and their effect on the ultrastructure of the tested bacteria and on the release of cellular components that absorb at 260 nm were studied. Furthermore, the cytotoxicity and the production of reactive oxygen species in human lymphocytes treated with essential oils were evaluated. Thymol (33.2%) was the major constituent in O. glandulosum, and β-pinene (17.3%) was the major constituent in L. dentata. We observed ultrastructural damage in bacteria and increased release of cellular material. Furthermore, ROS production in human lymphocytes treated with essential oils was lower than in untreated lymphocytes and no cytotoxicity was observed. Therefore, the essential oils of lavender and oregano could be used as a source of natural antibacterial and antioxidant agents with potential pharmacological applications

The phytochelatin synthase from Nitella mucronata (Charophyta) plays a role in the homeostatic control of iron(II)/(III)

Although some charophytes (sister group to land plants) have been shown to synthesize phytochelatins (PCs) in response to cadmium (Cd), the functional characterization of their phytochelatin synthase (PCS) is still completely lacking. To investigate the metal response and the presence of PCS in charophytes, we focused on the species Nitella mucronata. A 40 kDa immunoreactive PCS band was revealed in mono-dimensional western blot by using a polyclonal antibody against Arabidopsis thaliana PCS1. In two-dimensional western blot, the putative PCS showed various spots with acidic isoelectric points, presumably originated by post-translational modifications. Given the PCS constitutive expression in N. mucronata, we tested its possible involvement in the homeostasis of metallic micronutrients, using physiological concentrations of iron (Fe) and zinc (Zn), and verified its role in the detoxification of a non-essential metal, such as Cd. Neither in vivo nor in vitro exposure to Zn resulted in PCS activation and PC significant biosynthesis, while Fe(II)/(III) and Cd were able to activate the PCS in vitro, as well as to induce PC accumulation in vivo. While Cd toxicity was evident from electron microscopy observations, the normal morphology of cells and organelles following Fe treatments was preserved. The overall results support a function of PCS and PCs in managing Fe homeostasis in the carophyte N. mucronata

Does air pollution influence the success of species translocation? Trace elements, ultrastructure and photosynthetic performances in transplants of a threatened forest macrolichen

Species translocation can be considered as a primary conservation strategy with reference to in situ conservation. In the case of lichens, translocations often risk to fail due stress factors associated with unsuitable receptor sites. Considering the bioecological characteristics of lichens, air pollution is among the most limiting stress factors. In this study, the forest macrolichen Lobaria pulmonaria was used as a model to test the hypothesis that the translocation of sensitive lichens is effective only in unpolluted environments. At purpose, 500 fragments or whole thalli were translocated in selected beech forests of Central Europe (the Western Carpathians, Slovakia) where the species disappeared in the past and in oak forests of Southern Europe (Tuscany, Central Italy) where native populations are present. Prior to the translocation (May 2016) and after one year, morphological and ultrastructural features, trace elements as well as chlorophyll a fluorescence emission were analysed. Four years later, the effectiveness of lichen translocation was further evaluated as presence of the transplants and of newly formed individuals. After one year, the translocation ensured an effective survival of the thalli in remote oak and beech forests characterized by a negligible or low contamination by heavy metals. The transplants were considered successful and developed new lobules and rhizines, attaching by themselves to the bark of the host trees, looking overall healthy, without evident signs of alteration also at ultrastructural level. Moreover, in a few cases newly formed individuals were observed after four years. On the other hand, the results highlighted the link between the unsuccess of the translocation and air pollution in other areas of the Western Carpathians and suggested that current air quality still limits the possibility of recolonization in areas where the model species disappeared

Salicylic acid and melatonin alleviate the effects of heat stress on essential oil composition and antioxidant enzyme activity in Mentha × piperita and Mentha arvensis L

The aim of this study was to evaluate changes in the chemical profile of essential oils and antioxidant enzymes activity (catalase CAT, superoxide dismutase SOD, Glutathione S-transferases GST, and Peroxidase POX) in Mentha × piperita L. (Mitcham variety) and Mentha arvensis L. (var. piperascens), in response to heat stress. In addition, we used salicylic acid (SA) and melatonin (M), two brassinosteroids that play an important role in regulating physiological processes, to assess their potential to mitigate heat stress. In both species, the heat stress caused a variation in the composition of the essential oils and in the antioxidant enzymatic activity. Furthermore both Salicylic acid (SA) and melatonin (M) alleviated the effect of heat stress