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

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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

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