chlorophyll-a and nickel-chloride

Plants, in their life cycle, are usually exposed to various kinds of non-biological stresses including heavy metals. One of these heavy metals is nickel which affects many physiological processes of plants. Studies have shown that the changes in planting conditions can affect the qualitative and quantitative features of Catharanthus roseus; therefore, creating stressful conditions (e.g. NiCl2) can be an effective way to investigate the changes. In this research, we investigated the effect of 0, 2.5, 5, 10, 25 and 50 mM concentrations of NiCl2 on the degree of catalase enzyme activity, amount of proline aggregation and photosynthetic parameters on seeds of pink variety of C. roseus. The results indicated that the degree of catalase enzyme activity and the amount of proline aggregation increased in plants which were exposed to NiCl2 treatments, especially in high concentrations, while the total protein decreased. The stress of Ni also affected photosynthetic parameters, and decreased the amount of pigments, as well as the efficiency of photosystem II.

Topics: Catalase; Catharanthus; Chlorophyll; Chlorophyll A; Metals, Heavy; Nickel; Photosystem II Protein Complex; Plant Proteins; Proline; Stress, Physiological

An experiment was designed to assess the capacity of Salvinia minima Baker to uptake and accumulate nickel in its tissues and to evaluate whether or not this uptake can affect its physiology. Our results suggest that S. minima plants are able to take up high amounts of nickel in its tissues, particularly in roots. In fact, our results support the idea that S. minima might be considered a hyper-accumulator of nickel, as it is able to accumulate 16.3 mg g(-1) (whole plant DW basis). Our results also showed a two-steps uptake pattern of nickel, with a fast uptake of nickel at the first 6 to 12h of being expose to the metal, followed by a slow take up phase until the end of the experiment at 144 h. S. minima thus, may be considered as a fern useful in the phytoremediation of residual water bodies contaminated with this metal. Also from our results, S. minima can tolerate fair concentrations of the metal; however, at concentrations higher than 80 μM Ni (1.5 mg g(-1) internal nickel concentration), its physiological performance can be affected. For instance, the integrity of cell membranes was affected as the metal concentration and exposure time increased. The accumulation of high concentrations of internal nickel did also affect photosynthesis, the efficiency of PSII, and the concentration of photosynthetic pigments, although at a lower extent.

Topics: Biodegradation, Environmental; Chlorophyll; Dose-Response Relationship, Drug; Ferns; Light; Metals; Nickel; Photosynthesis; Plant Roots; Water Pollutants, Chemical

The toxic effect of Ni(2+) on photosynthetic electron transport was studied in a photosystem II submembrane fraction. It was shown that Ni(2+) strongly inhibits oxygen evolution in the millimolar range of concentration. The inhibition was insensitive to NaCl but significantly decreased in the presence of CaCl(2). Maximal chlorophyll fluorescence, together with variable fluorescence, maximal quantum yield of photosystem II, and flash-induced fluorescence decays were all significantly declined by Ni(2+). Further, the extrinsic polypeptides of 16 and 24 kDa associated with the oxygen-evolving complex of photosystem II were depleted following Ni(2+) treatment. It was deduced that interaction of Ni(2+) with these polypeptides caused a conformational change that induced their release together with Ca(2+) from the oxygen-evolving complex of photosystem II with consequent inhibition of the electron transport activity.

Topics: Calcium Chloride; Cell Membrane; Chlorophyll; Electron Transport; Electrons; Kinetics; Manganese; Metals; Microscopy, Fluorescence; Models, Chemical; Nickel; Oxygen; Peptides; Photosynthesis; Photosystem II Protein Complex; Time Factors

Topics: Cell Count; Cell Division; Chlorella; Chlorophyll; Hydrogen-Ion Concentration; Nephelometry and Turbidimetry; Nickel; Reproducibility of Results; Spectrophotometry, Ultraviolet; Water Pollutants, Chemical