Biological Responses to Cadmium Stress in Liverwort Conocephalum conicum (Marchantiales)

Oxidative damage (production and localization of reactive oxygen species) and related response mechanisms (activity of antioxidant enzymes), and induction of Heat Shock Protein 70 expression, have been studied in the toxi-tolerant liverwort Conocephalum conicum (Marchantiales) in response to cadmium stress using two concentrations (36 and 360 µM CdCl₂). Cadmium dose-dependent production of reactive oxygen species (ROS) and related activity of antioxidant enzymes was observed. The expression level of heat shock protein (Hsp)70, instead, was higher at 36 µM CdCl₂ in comparison with the value obtained after exposure to 360 µM CdCl₂, suggesting a possible inhibition of the expression of this stress gene at higher cadmium exposure doses. Biological responses were related to cadmium bioaccumulation. Since C. conicum was able to respond to cadmium stress by modifying biological parameters, we discuss the data considering the possibility of using these biological changes as biomarkers of cadmium pollution.

Mytilus galloprovincialis (Lamarck, 1819) spermatozoa: hsp70 expression and protamine-like protein property studies

In this work, we describe results of the reproductive health monitoring studies in Mytilus galloprovincialis following spermatozoa hsp70 expression and protamine-like protein properties. Mussels control (ctr) were released within cages for 30 days in three different marine sites near Naples (Campania, Italy): Bagnoli south (BAs) and Bagnoli north (BAn), both close to a disposal metallurgical factory and in Capo Miseno (CM). Studies of hsp70 gene expression carried out, by RT-qPCR, in mussel spermatozoa have shown varied expression levels, particularly 5, 13, and 15-fold more than ctr in CM, BAs, and BAn, respectively, indicating highest involvement of stress proteins in spermatozoa of mussels in Bagnoli. In order to evaluate the possible risk on Mytilus galloprovincialis sustainability loss, electrophoretic analyses were performed on protamine-like proteins (PL) of collected spermatozoa. The results showed that CM PL were apparently unaltered with respect to ctr PL, while BAs and BAn PL appeared in part in the form of peptides and in part as bands with low mobility. Further, CM and BAs PL showed, by electrophoretic mobility shift assay, a decrease in DNA binding ability and a change in their DNA binding mode. The results of this investigation show the usefulness of the study of alterations of spermatozoa hsp70 expression and protamine-like protein properties for eco-toxicological evaluation using Mytilus galloprovincialis as a bioindicator.

Mercury in the gold mining district of San Martin de Loba, South of Bolivar (Colombia)

Gold mining is responsible for most Hg pollution in developing countries. The aims of this study were to assess the levels of total Hg (T-Hg) in human hair, fish, water, macrophyte, and sediment samples in the gold mining district of San Martin de Loba, Colombia, as well as to determine fish consumption-based risks for T-Hg ingestion. T-Hg levels were measured by electrothermal atomization and atomic absorption spectroscopy. The overall mean T-Hg level in hair for humans in the mining district of San Martin de Loba was 2.12 μg/g, whereas for the reference site, Chimichagua, Cesar, it was 0.58 μg/g. Mean T-Hg levels were not different when considered within localities belonging to the mining district but differed when the comparison included Chimichagua. T-Hg levels in examined locations were weakly but significantly associated with age and height, as well as with fish consumption, except in San Martin de Loba. High T-Hg concentrations in fish were detected in Pseudoplatystoma magdaleniatum, Caquetaia kraussii, Ageneiosus pardalis, Cyrtocharax magdalenae, and Triportheus magdalenae, whereas the lowest appeared in Prochilodus magdalenae and Hemiancistrus wilsoni. In terms of Hg exposure due to fish consumption, only these last two species offer some guarantee of low risk for Hg-related health problems. Water, floating macrophytes, and sediments from effluents near mining sites also had high Hg values. In mines of San Martin de Loba and Hatillo de Loba, for instance, the geoaccumulation index (I(geo)) for sediments reached values greater than 6, indicating extreme pollution. In short, these data support the presence of a high Hg-polluted environment in this mining district, with direct risk for deleterious effects on the health of the mining communities.

Mercury and selenium intake by seafood from the Ionian Sea: A risk evaluation

The subject of the present study is the evaluation of the concentrations of mercury (Hg) and selenium (Se) in fish and shellfish from the Gulf of Catania (Ionian Sea) and the assessment of related risk-based consumption limits per single contaminant in adults and children. In contrast to the potential harm from Hg, Se is an essential element that is normally found in high levels in seafood. If the amount of Hg is high enough, it could bind Se and irreversibly inhibit selenium-dependent enzymes. Thus, adequate levels of Se need to be available to replace the amount of Se lost to Hg sequestration, thereby maintaining normal selenoprotein synthesis. Hg analysis was conducted using a flow injection analysis system coupled with an atomic adsorption spectrometer, and Se analysis was conducted using an inductively coupled plasma mass spectrometry (ICP-MS). Of the trace elements investigated, only Hg has a limit set by the European Community for human consumption, and this was never exceeded. Nevertheless, based on Target Hazard Quotient (THQ) over 1, and on the Estimated Daily Intake per meal (EDIm) higher than the Provisional Tolerable Intake (PTI) suggested by the Joint FAO/WHO Expert Committee on Food Additive (JECFA), Hg oral exposure derived from consumption of the benthonic fish and of the bigger pelagic fish species analyzed, could follow the occurrence of systemic effects. Se was found always in molar excess respect to Hg in all pelagic fish and in the shellfish, nearly equimolar in the benthonic fish. Determining the evidence that foods, such as pelagic fish, with high molar excess of Se, could contribute to replace the amount of Se bound to Hg and thereby maintaining normal selenoprotein synthesis, is useful for a better understanding of the seafood safety.