Amparo Torreblanca

Quantification of cadmium-induced metallothionein in crustaceans by the silver-saturation method

Metallothionein (MT) has been proposed as a specific biochemical probe for metal exposure of aquatic organisms. It is recognized that its usefulness as a monitoring tool depends on the full understanding of its function and on the possibility of measuring its concentration in tissues. Therefore the study of MT in crustaceans is interesting from two different points of view: the need to understand mechanisms associated with the toxicology of metals, and the potential use of this protein for monitoring metal-contamined environments. Several methods have been developed for quantitative measurements of MT in biological samples. Immunochemical and electrochemical procedures are reliable techniques but they require sophisticated equipment and highly trained staff. In the present work, modifications to the silver-saturation method have been developed for the quantitative determination of MT in crustacean tissues, estimating silver concentrations by flame in an atomic absorption spectrophotometer. Cadmium and MT were measured both in Artemia and Procambarus clarkii after sublethal exposure to cadmium. An increase in MT content was recorded in crustacean tissues after 12 h of cadmium exposure. A high responsiveness was found in MT induction by cadmium in the two crustaceans and there was a clear relationship between cadmium concentration in water and MT levels in tissues. The silver-saturation assay may be a rapid assay technnique for biomonitoring purposes.

Effects of temperature on the acute toxicity of heavy metals (Cr, Cd, and Hg) to the freshwater crayfish,Procambarus clarkii (Girard)

Chromium, an essential trace element for humans and animals is involved in normal carbohydrate metabolism; however, it is toxic at high concentrations. There is no evidence that cadmium and mercury are biologically essential but their toxicity for organisms is well known. Both cause toxic effects at low concentrations to most organisms, especially in combination with other environmental variables such as temperature. Lake Albufera and the surrounding rice field waters are subjected to very heavy loads of sewage and toxic industrial residues (including heavy metals) from the many urban and waste waters in this area. In 1978, the American red crayfish Procambarus clarkii appeared in lake Albufera and in the surrounding rice fields. Without adequate sanitary control, the crayfish is presently being fished commercially for human consumption. The purpose of the present study is to evaluate the degree of toxicity of various heavy metals (chromium, cadmium and mercury) to freshwater crayfish Procambarus clarkii at various temperatures.

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.

Effect of cadmium exposure on zinc levels in the brine shrimp Artemia parthenogenetica

Zinc and cadmium have been reported as metabolic antagonists, such that high zinc intake afford animals some protection against the potentially toxic effects of cadmium exposure. There is considerable evidence to support a role of metallothioneins (MTs) in regulating or controlling the intracellular availability of essential metals and the non-essential metal. The effect of 24-h cadmium pre-exposure (10 mg Cd/l) on zinc concentrations in the brine shrimp Artemia parthenogenetica exposed to zinc (5 mg Zn/l) was studied. The zinc content of shrimps was not altered by cadmium. The homeostatic mechanism for zinc regulation appears not to be disturbed by cadmium exposure in shrimps kept in naturally occurring zinc concentrations. When zinc was added to the water after cadmium exposure, the zinc concentrations attained by cadmium treated animals were lower than that of the non-exposed to cadmium. No effect of zinc exposure on cadmium elimination was observed. In order to investigate the potential role of metallothionein in this effect, metallothionein levels were measured and protein bound zinc and cadmium were studied. A clear relationship between cadmium/zinc interactions with metallothionein content or metal bound to this protein was not evident.

Cadmium induced metallothionein in hepatopancreas of Procambarus clarkii : quantification by a silver-saturation method

Abstract 1. Cadmium induced metallothionein (MT) in crayfish hepatopancreas was measured by silver-saturation method. 2. An increase in MT content was recorded in crayfish hepatopancreas after 12 hr of exposure to 10 mg Cd/l. 3. There was found to be a linear relationship between MT concentrations in hepatopancreas and cadmium concentration in the water. 4. MT levels in hepatopancreas of 20 mg Cd/l exposed crayfish were 7-fold higher than those in control animals.

Cadmium accumulation in the crayfish,Procambarus clarkii, using graphite furnace atomic absorption spectroscopy

Lake Albufera and the surrounding rice-field waters are being subject to very heavy loads of sewage and toxic industrial residues (including heavy metals and pesticides) from the many urban and wastewaters in this area. The American red crayfish Procambarus clarkii is native to the Louisiana marshes (USA). In 1978, the crayfish appeared in Lake Albufera near Valencia (Spain), and presently, without adequate sanitary controls, the crayfish is being fished commercially for human consumption. In view of this interest, it is important to have accurate information on concentrations of cadmium in natural waters and cadmium levels of tissues of freshwaters animals used as human food, as well as the accumulation rates of this metal in this animal. In the present study, the authors investigated the accumulation of cadmium in several tissues of the red crayfish, P clarkii (Girard) from Lake Albufera following cadmium exposure. Determinations of cadmium were made by flameless atomic absorption spectroscopy and the standard additions method. Digestion of samples was made by wet ashing in open flasks with concentrated HNO/sub 3/ at 80-90/sup 0/C.

Determination of lead in treated crayfish Procambarus clarkii: accumulation in different tissues

The continual loading of trace metals into our environment represents a water pollution problem due to their toxic effects on aquatic biota. In addition, metal ions can be incorporated into food chains and concentrated by aquatic organisms to a level that affects their physiological state. There are several investigations on the toxic effects and bioaccumulation of lead in fishes, molluscs, and crustaceans. Lake Albufera (Valencia, Spain) and the surrounding rice-field waters are subjected to large loads of sewage and toxic industrial residues (including heavy metals) from many urban wastewaters in the area. In 1978, the American red crayfish Procambarus clarkii (Girard) appeared in Lake Albufera. The crayfish have reached a high density producing ecological and agricultural economic problems in rice crops. The crayfish is being fished commercially for human consumption without adequate protection to human health. The purpose of the present study was to investigate the accumulation of lead in tissues of the crayfish P. clarkii following short term lead exposure at several sublethal concentrations. The gills, midgut glands, antennal glands and muscle were analyzed by atomic absorption spectrophotometry.

Cadmium toxicity, accumulation and metallothionein induction in echinogammarus echinosetosus

Abstract The responses of Echinogammarus echinosetosus to experimental cadmium exposure were analyzed. The LC50–96 hr for cadmium in this crustacean was 0.48 mg/L. Cadmium content reached a maximun of 18 μg/g after 48 hr of treatment to 200 μg Cd/L resulting in a calculated concentration factor of approximately 70. An increase in MT content was recorded in E. echinosetosus after 24 hr of cadmium exposure (100 μg/L). The high sensitivity this species shows to cadmium in comparison with other crustaceans may be due to a very low effectiveness in MT induction by cadmium (9 μg/g) and a moderate concentration factor which results in a low molar MT/Cd ratio (2×10‐3) in the cytosolic fraction.

Gill ATPase activity in Procambarus clarkii as an indicator of heavy metal pollution.

Lake Albufera and the surrounding rice field waters are subjected to very heavy loads of sewage and toxic industrial residues, including heavy metals, from the many urban and waste waters of this area. The American red crayfish, Procambarus clarkii have a high resistance to toxic effects of heavy metals. The sublethal effects of heavy metals on gills of fish and aquatic invertebrates have been extensively studied. Some metabolic disturbances and histologic damages have been reported, as well as osmoregulation alterations. However, little work has been done about the effect of heavy metals on Na,K and Mg-ATPases of freshwater invertebrate gills. Na,K-ATPase is the prime mediator of ion transport across cellular membranes and plays a central role in whole body ion regulation in marine and estuarine animals. Na,K-ATPase has been reviewed and assessed as a potentially useful indicator of pollution stress in aquatic animals. The purpose of this study is look for the relation, if any, between crayfish gill ATP-ase activity changes and metal exposure in laboratory. This find would allow the authors to assay this potential indicator in the field.

EFFECTS OF LOW MERCURY CONCENTRATION EXPOSURE ON HATCHING, GROWTH AND SURVIVAL IN THE ARTEMIA STRAIN LA MATA PARTHENOGENETIC DIPLOID

The effects of exposure to low levels of mercury in the developmental events occurring from hatching to adult life in the Artemia strain La Mata parthenogenetic diploid were studied. Mercury (5, 25, 50, 250 and 500 nM) added at the beginning of incubation had no effect on hatching and emergence. We studied mercury effects on the growth of viviparous nauplii obtained from mothers that had been acclimatised to 25 nM of mercury for all their lives. Measurements of the length of Artemia individuals were carried out using video recordings in order to reduce the stress experienced by the test animals. The mean body length of the mercury-treated group (25 nM) was higher than that of the control animals for all times studied. For testing whether the larger size of the mercury-exposed shrimps was due to a greater size at birth or to an increased growth rate, or both, a mathematical model was used. This model showed that both initial size (size at birth) and growth rate were higher in the mercury-exposed subpopulation than in the control subpopulation. However, at this mercury concentration, lifespan is reduced in the metal-treated group in comparison with the controls. These effects may be related to the phenomenon of hormesis and to an increased reproductive allocation.