Bryophytes collected from the IV Region of Chile, were treated with CdCl 2 to stimulate the synthesis of phytochelants. After cadmium treatment, total peptides were extracted from the plants and were analyzed using HPLC to search for the presence of phytochelatin molecules.Chromatography results showed the absence of phytochelatin-like molecules in bryophytes. However, glutathione and a molecule suspected to be γ-glutamilcistein were detected. The latter compound is knowed to be involved in the metabolic pathway of the gluthatione and phytochelatin synthesis.The results indicated the absence of detectable phytochelatins in bryophytes containing heavy metal as contaminants. The increase in glutathione during the experimental period may have been due to a response to oxidative stress. Thus this work suggests an important role of the glutathione in the detoxification mechanisms of bryophytes.Key words: Bryophytes, glutathione, chromatography, oxidative stress.
INTRODUCTONContamination is currently one of the most studied phenomena. Elevated concentrations of heavy metals, of natural or anthropogenic origin, are one of the most difficult contaminants to study 1 . However there are organisms, like a large variety of plants, which are resistant to high levels of heavy metals 2,3 . Research in these organisms resistant to heavy metals have found the presence of compounds synthesized at intra-cellular level, which are capable of immobilizing these elements. Because of their ability to store metals, these organisms have been considered as an alternative to be used as bio-monitors or biological extractors at contaminated sites 4,5,6,7 .The phytochelatins and the glutathione compose a class of compounds generated by plants in response to heavy metals. These phylochelatins are a family of peptides that have been identified in plants and some microorganisms. Phytochelatins have a primary structure of (γ-glutamil-cysteine) n glycine, with n=2-11 8,9,10 . They are synthesized from glutathione, which is a tripeptide formed by glutamic acid, cysteine and glycine (γ-glutamil-cisteinilglycine). Glutathione also plays an important role in the response of plants to environmental stress, oxidative stress and that produced by xenobiotic compounds such as heavy metals 4,6,11 . Phytochelatins have been described in different types of organisms such as plants, nematodes, algae and yeasts 3,12 . Some studies have demonstrated that bryophytes (mosses) do not form phylochelatins, but only their precursor glutathione 5,11 .Considering that bryophytes have been described as organisms which are particularly reactive to contaminants and thus may have an important role as bio-indicators of environmental contamination 5,13,14,15,16,17 , this contribution examined the presence of phytochelants in endemic Chilean mosses challenged with a heavy metal, cadmium, by means of high-pressure liquid chromatography (HPLC).
EXPERIMENTAL Collection and maintenance of mossesMosses were collected from the area of Alcohuas in the IV Region of Chile (Figu...