Metallothionein in the freshwater gastropod Melanopsis dufouri chronically exposed to cadmium: a methodological approach.

Previous studies have demonstrated that the use of differential pulse polarography (DPP) for metallothionein (MT) determination in marine gastropod tissues, particularly the digestive gland, requires taking into account the presence of heat-stable high molecular weight compounds that exhibit polarographic signal. In the present paper, similar compounds were identified in tissues from the freshwater snail Melanopsis dufouri which also interfere with MT determination by DPP and, due to their silver binding capacity, also interfere in the silver assay for MT quantification. Ultrafiltration seems to be effective in removing these high molecular weight compounds from heat-denatured homogenate supernatant allowing direct MT quantification by DPP. A fully validated procedure for metallothionein determination in M. dufouri is described. In spite of a considerable accumulation of cadmium in the visceral complex of M. dufouri following exposure to 100 microg CdL(-1) for 8 weeks (up to 37 microgg(-1)) only a small increase in MT concentration was found.

Carbamazepine exposure in the sea anemones Anemonia sulcata and Actinia equina: Metabolite identification and physiological responses.

Pharmaceuticals and other emerging contaminants (EC) have been increasingly detected and measured in coastal waters and large effort has been devoted to knowing the effects these substances have in coastal ecosystems. Anthozoa class is underrepresented in ecotoxicology studies despite some of their species being endangered. Anemonia sulcata and Actinia equina are species widely distributed in the Mediterranean Sea. The objectives of this work have been to evaluate the ability of these species to accumulate carbamazepine (CBZ) from water, to determine the effects of this pharmaceutical on some physiological and biochemical endpoints and to characterize the degradation routes followed by this compound in Anthozoa tissues (biotransformation) and water. Sea anemones were exposed to 1 µg L-1 and 100 µg L-1 of CBZ in artificial sea water in a semi-static system for 8 days. At several times small portions of the tentacles and whole organisms were taken. Ion transport (measured as NKATPase activity), energetic metabolism (measured as glucose and lactate levels) and nitrogen excretion (measured as ammonia concentration in tissues) were determined. CBZ-exposed individuals of A. sulcata and A. equina were analyzed by ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) on a quadrupole-time-of-flight (QqTOF). The structures of nine metabolites have been tentatively identified using HRMS and HRMS/MS data with the aid of the free available Medline database. The current work constitutes the first study on the identification of Cnidarian metabolites of CBZ in species of the Anthozoa class.

The combined use of chemical and biochemical markers to assess water quality along the Ebro River.

Carp (Cyprinus carpio) and barbel (Barbus graellsii) were collected from five sites along the Ebro River. The study was designed to assess levels of persistent organic pollutants and metals bioaccumulated by fish, and some biochemical responses (cytochrome P450 system, phase II activities, and metallothioneins) against those pollutants. The highest levels of PCBs and DDTs were detected in carp from industrialised areas, which also showed high levels of mercury and cadmium in the liver, and high levels of nonylphenol in bile. Significant alterations in some biochemical markers were observed and associated to combined exposure to pollutants. The activity 7-ethoxyresorufin O-deethylase ranged from 69 pmol/min/mg protein in carp from the reference site to 415 pmol/min/mg protein in those from polluted sites. Carp from the Ebro Delta, an agricultural area, had depressed acetylcholinesterase in muscle tissue. Metallothionein concentrations were positively correlated with copper residues, but no significant differences among sampling points were observed.

Comparing the acute response to cadmium toxicity of nauplii from different populations of Artemia.

The lethal responses to cadmium of instar II nauplii from eight populations of Artemia belonging to the species Artemia franciscana, Artemia salina, Artemia persimilis, and Artemia parthenogenetica have been compared. Generalized linear models were used to fit mortality. The model indicates that there is a relationship between species, type of population, and mortality rate. The two populations of A. franciscana were the most sensitive to cadmium toxicity (median lethal concentration, LC50, of 93.3-142 mg/L), while the population of A. persimilis was the most resistant (LC50 of 284 mg/L). Differences in the phenotypic variability in each population were assessed through the slope of the mortality curve, with A. persimilis exhibiting the highest diversity. This study suggests that habitat peculiarities and historical origin of the populations may have a significant influence on their response to cadmium toxicity.

Long-term effect of temperature on bioaccumulation of dietary metals and metallothionein induction in Sparus aurata.

Previous studies have demonstrated that the commercial feed of aquacultured fish contains trace amounts of toxic and essential metals which can accumulate in tissues and finally be ingested by consumers. Recently rising temperatures, associated to the global warming phenomenon, have been reported as a factor to be taken into consideration in ecotoxicology, since temperature-dependent alterations in bioavailability, toxicokinetics and biotransformation rates can be expected. Sparus aurata were kept at 22°C, 27°C and 30°C for 3 months in order to determine the temperature effect on metallothionein induction and metal bioaccumulation from a non-experimentally contaminated commercial feed. A significant temperature-dependent accumulation of cadmium (Cd), copper (Cu), mercury (Hg), zinc (Zn), lead (Pb) and iron (Fe) was found in liver, together with that of manganese (Mn), Fe and Zn in muscle. Hg presented the highest bioaccumulation factor, and essential metal homeostasis was disturbed in both tissues at warm temperatures. An enhancement of hepatic metallothionein induction was found in fish exposed to the highest temperature.

Developmental and reproductive effects of low cadmium concentration on Artemia parthenogenetica.

Hatching, reproductive, and lifespan characteristics of an Artemia parthenogenetica population from La Mata (Alicante, Spain) exposed to cadmium were studied. No effects on percentage of cyst hatched nor time of hatching were observed on cysts exposed from 0.01 to 5 mg Cd/L. Cohorts of Artemia were chronically exposed to cadmium in life-table experiments to test whether ecologically relevant impacts may occur after several generations of exposure to a very low concentration of cadmium. Chronic toxicity tests were performed using neonates of a third generation of shrimps exposed to 0.08 mg Cd/L (1/1000 of the LOEC for 24 h acute toxicity test). No significant reduction in the intrinsic rate of natural increase (rm) was found as a result of cadmium exposure, although the age-specific fecundities of the cadmium exposed shrimps were lower than those of the controls. A significant decrease in the prereproductive period and a reduction in the percentage of fertile females was also found as a consequence of the metal exposure.