Characterization and expression of DNA sequences encoding putative type II metallothioneins in the seagrass Posidonia oceanica Delile.

Abstract Posidonia oceanica is a marine phanerogam, largely widespread in the Mediterranean sea, representing an important food substrate for many marine organisms. A progressive reduction ofP. oceanica meadows has been reported, due to anthropogenic coastal activity. Studying mechanisms by which this species responds to environmental stresses, three DNA sequences putatively encoding metallothioneins (MTs) have been isolated, by PCR. Two sequences, Pomt2a (accession no. AJ249603) andPomt2b (accession no. AJ249602), show high similarities with genes encoding type-II MTs and are interrupted by two and one intron, respectively. The third sequence, Pomt2c(accession no. AJ249604), is supposed to be a pseudogene, originated by retrotranscription of the Pomt2b mRNA. These sequences belong to a multigene family with at least five members. Northern hybridizations indicated that MT transcripts accumulation is constitutive and seasonally regulated. MT encoding RNAs increase after rhyzome harvesting and (at a lesser extent) after 15 d of cultivation in an aquarium. As for animal MTs, transcripts accumulation is observed also after exposure to trace metals such as copper and cadmium. In the case of copper, the effect depends on concentration. Finally, taking into consideration the great interest in studying the biogeochemical cycle of mercury in the Mediterranean basin and sinceP. oceanica is commonly considered a bioindicator of this metal, the effect of mercury treatments on the accumulation of MT transcripts has been analyzed: in only a few experiments a small increase in the level of transcripts was recorded, suggesting that MTs are not key elements in the mercury accumulation by this species.</jats:p

Erratum to: Expression and characterization of two new alkane-inducible cytochrome P450s from Trichoderma harzianum

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Mercury Emissions Into the Atmosphere From A Chlor-alkali Complex Measured With the Lidar Technique

Data are reported on atmospheric mercury flux measured by a lidar system at a chlor-alkali plant located in central Italy. Two mercury sources were identified over the electrolytic cell rooms. A flux value of 36 g h-1 was determined during the daytime while at night the value increase to 56 g h-1. The mercury emitted into the atmosphere was found to be 4 g per 1000 kg of chlorine produced. Atmospheric mercury concentrations were supplemented with some determinations made with the point monitor technique

Atmospheric mercury mapping in a cinnabar mining area

7sinoneA mobile differential absorption lidar system was used in conjunction with point monitors to study the spatial and temporal distribution of atomic mercury in the atmosphere around an abandoned mercury mine at Abbadia S. Salvatore, Italy. The use of the remote sensing technique allows a fast coverage of large areas both horizontally and vertically with a good temporal resolution. Concentrations exceeding 1000 ng/m3 were measured close to the distillation plant and considerably elevated values also were evident above deposits of roasted cinnabar. Vertical gradients of the mercury concentration in air were established. These showed a very pronounced decrease a few centimeters above the ground.noneEdner, H.; Ragnarson, P.; Svanberg, S.; Wallinder, E.; Ferrara, R.; Maserti, B.E.; Bargagli, R.Edner, H.; Ragnarson, P.; Svanberg, S.; Wallinder, E.; Ferrara, R.; Maserti, B. E.; Bargagli, R

Vertical Profiles of Atmospheric Mercury Concentration

Vertical profiles of atmospheric mercury concentration determined with a lidar and point monitor systems in the mineralized region of Mt. Amiata (Italy) are reported. Measurements were performed over a large flat area, without arboreal and herbaceous vegetation, constituting a roasted cinnabar deposit which still contains about two parts per thousand of mercury. The determinations carried out with the two techniques yielded comparable results for the working conditions used. Data demonstrate the presence of a vertical gradient of atmospheric mercury concentration, which is particularly large in the layers of air nearest the soil. The highest values (45-1000 ng m-3) were measured a few centimeters from the soil, while background values (2-3 ng m-3) were reached at heights of 10-20 m. The vertical gradient proved to be strongly dependent on ambient temperature

Mercury degassing rate from mineralized areas in the Mediterranean basin

Knowledge of the natural emissions of mercury in the Mediterranean basin, which has large cinnabar anomalies, has particular weight as these deposits could be an important source of atmospheric mercury. Data on the degassing rate of mercury from soils sampled both in mineralized areas (Mt. Amiata, Italy and Almaden, Spain) and rural areas are reported. Measurements were carried out 'in situ' using a transparent flux chamber and collecting the gaseous mercury on gold collectors. The highest values were observed in Almaden over the roasted cinnabar banks (up to 100 mu g/m(2)h) from past and present mining activity. In Italian rural areas the values of the volatilization rate of mercury are on the order of few ng/m(2)h. The degassing rate was observed to be strongly dependent on the ambient temperature and not only seasonal but also daily variations were measured in all the studied areas

Atmospheric mercury concentrations and fluxes in the Almaden District (Spain)

Atmospheric mercury levels around the world's largest mining and refining complex (Almaden, Spain) were determined during two field campaigns (September 1993 and February 1994) using both point monitors and lidar techniques. High mercury concentrations (0.1-5 mu g m(-3)) were measured over the village of Almaden in the prevailing wind direction. In the month of September the total mercury flux into the atmosphere was estimated to range from 600 to 1200 g h(-1). An attempt was made to measure the contribution from individual mercury sources. (C) 1998 Elsevier Science Ltd. All rights reserved