Freshwater Mussel Anodonta Cygnea Research Articles

Fabrication of a new reactor design to apply freshwater mussel Anodonta cygnea for biological removal of water pollution

Population growth increases wastewater production, enhances environmental concerns, and increases wastewater treatment costs. This study aimed to use Anodonta cygnea (freshwater mussels) exposed to some water pollution in a closed cycle to treat wastewater by consuming harmful or undesirable pollutants in water. The results demonstrated that mussels eliminated all microalgae, reduced organic pollutant concentration (chemical oxygen demand removal rate 40% faster than lacked mussels tank), and removed some water hardening minerals such as Calcium (Ca) (more than 77%) and Nickel (Ni) as heavy metal (more than 78%), confirming that freshwater mussels could be helpful in the wastewater treatment cycle. The method can be used as the practical implementation of setting up a semi-natural system for the decentralized wastewater purification relying on the recruitment of mussels. The method also suggests a favorable and eco-friendly treatment mechanism to remove chemical oxygen demand, chemical elements, biological pollutions, and microorganisms.

Changes in the Gill Lipid Composition of Freshwater Mussel Anodonta cygnea under the Influence of Copper in Various Concentrations

Changes in the composition of reserve and membrane lipids in the gills of freshwater mussel Anodonta cygnea L., 1758 in response to the effect of copper at different concentrations (5, 50, 100, and 250 μg/L) are studied. Modifications in the content of phospholipids and their fatty acids depended on the duration of the copper effect: the unsaturation of phospholipids fatty acids increased on the 1st day of copper exposure and decreased on the 3rd day. By the end of the experiment (on the seventh day), changes in the lipid composition were determined by the copper concentration: relatively low concentrations (5 and 50 μg/L) caused a decrease in the unsaturation of fatty acids in phospholipids, while the high copper concentration (250 μg/L), on the contrary, contributed to its increase. It is shown that the transformation of the structural organization of membrane lipids and their fatty acids in A. cygnea under the effect of copper at different concentrations is based on internal reserves (triacylglycerols) and the additional synthesis of unsaturated fatty acids.

COPPER EFFECT ON COMPONENTS OF THE ANTIOXIDANT SYSTEM OF THE DIGESTIVE GLAND IN THE FRESHWATER MUSSEL ANODONTA CYGNEA

The effects of copper accumulation and its impact on the functioning of some components of the antioxidant system (AOS) – CAT, GST, GSH – in the digestive gland of the freshwater mussel Anodonta cygnea were studied in an aquarium experiment. After a 12‑day acclimation, the mussels were divided among aquariums with Cu²⁺ concentrations of 0, 5, 50, 100, and 250 μg/L. Hepatopancreas tissue samples were taken for analysis after 1, 3, and 7 days. Copper ions content, GST and CAT activity, as well as GSH concentration were determined in the tissue. The accumulation process was shown to be doseand time-dependent. The metal accumulated in this concentration was not lethal. The rate of the metal accumulation in the studied organ increased along with the concentration of copper ions in the water. The activity of AOS enzymes in the swan mussel is modified as an adaptation in response to elevated copper concentrations to neutralize the products of oxidative reactions. Changes in the activity of AOS enzymes (CAT and GST) were observed mainly on the seventh day of the experiment at the highest copper concentrations tested. GST proved to be the most stable enzyme. The GSH level in the digestive gland changed 1 day after the start of the experiment, corroborating this tripeptide is involved in the first wave of protection against xenobiotics. Copper ions have a cumulative effect. The changes in enzyme activity observed on day 7 at Cu²⁺ concentration of 250 μg/L suggest that a longer exposure to copper, even in low concentrations, can be detrimental.

Cd and Ni modulate fatty acid composition and oxidative status in the freshwater mussel Anodonta cygnea

To determine the different effects of metal ions with various chemical properties on freshwater bivalve molluscs, the effect of Cd and Ni on Anodonta cygnea was examined. Aside from highlighting some indicators of oxidative damage (i.e. lipid peroxidation product content) and antioxidant defence (i.e. the content of reduced glutathione and the activity of catalase and glutathione-S-transferase), we also analysed the composition of the phospholipid fatty acids in the gills of the mussels. The mussels were exposed to 10, 50 and 100 μg/L of Cd and Ni (the control was no metal exposure) for 1 and 3 days, respectively. Then, the biochemical parameters of the mussel gills, such as the fatty acid composition, the conjugated dienes, thiobarbituric acid reactive species products and reduced glutathione contents and the glutathione-S-transferase and catalase activities were analysed. The one-day effect of Cd induced a decrease in the linoleic acid content and an increase in the lipid peroxidation products and glutathione-S-transferase activity. The one-day Ni exposure caused an increase in the arachidonic acid content without any elevation of the activity of the studied antioxidant enzymes. On day 3, the presence of Cd caused an increase in the linoleic and arachidonic acid content and catalase activity, whereas no changes in the fatty acid composition and antioxidant enzyme activity were noted in the presence of Ni. Different metabolic changes occur with the studied metals (Cd and Ni) in freshwater A. cygnea. Therefore, various mechanisms are involved in their defensive metabolic responses.

Changes in lipid composition and lipid peroxidation products content in the freshwater mussel Anodonta cygnea L. under cadmium effect

In order to identify specific biomarkers to cadmium-induced oxidative stress in freshwater organisms, changes in the composition of membrane and storage lipids and their fatty acids in the gills and digestive glands of freshwater mussels, Anodonta cygnea (Linnaeus, 1758), exposed to cadmium ions at 10, 50 and 100 µg/L were studied. Cadmium-induced oxidative stress was estimated by the content of lipid peroxidation products such as conjugated dienes and trienes, malondialdehyde, and Schiff bases. Accumulation of lipid peroxidation products in the gills and digestive glands reflected the intensity of lipid peroxidation, depending on the concentration and duration of cadmium exposure. Changes in the fatty acid composition of phospholipids and triacylglycerols reflected their compensatory role in the response of the mussels to the action of cadmium at various concentrations. Some indices of lipid composition (phosphatidylserine and triacylglycerol content) similarly altered under cadmium effect in both marine and freshwater mussels. The assessment of oxidative stress biomarkers and the main targets for these oxidative processes including lipids and their fatty acid composition makes it possible to identify protective biochemical mechanisms providing the high resistance of mussels to environmental pollution.

Hermaphroditic freshwater mussel Anodonta cygnea does not have supranumerary open reading frames in the mitogenome

The complete mitogenome of Anodonta cygnea is 15,613 bp long. This compact, circular molecule contains the set of 37 genes, typical for invertebrate mitogenomes, in the same order and orientation as in maternally inherited genomes of other bivalves from the same subfamily. There are only two unassigned regions longer than 200 bp (266 bp and 274 bp) and no indication of any supranumerary open reading frames.

Morphological and chemical characterization of mineral concretions in the freshwater bivalve Anodonta cygnea (Unionidae).

The freshwater mussel Anodonta cygnea is commonly used as a model organism for biomineralization studies, its peculiar morphofunctional properties also make it an excellent environmental biomonitor. The first detailed on the calcareous concretions from gill and mantle tissue, as well as fluids of the freshwater bivalve A. cygnea, supported by histological, scanning, spectrometry, and spectroscopy analyses. Through these analyses, the morphology, structure, and chemical characterization of these biomineral concretions were accomplished. The concretions represent a high percentage of the dry weight of these organisms. In gill tissue, it can reach up to 50% of dry weight prior to reproductive maturity. Analysis of elemental composition of the tissue concretions showed the presence of calcium and phosphate, as main components, associated with other residual elements like iron, manganese, magnesium, and zinc. Concretions are arranged in concentric alternated layers of organic and inorganic matrix. The shape and size of the concretions vary substantially, from very small, less than 1 μm diameter with very regular round structure, found mainly in the mantle tissue, to more than 50 μm length with irregular globular clusters, found predominantly in the gills. The microstructural organization is of a hydroxyapatite polymorphism in the mantle, in contrast to the gills, which exhibit irregular structure and carbonated hydroxyapatite polymorphism. These differences are supported by higher contents of dinitrogen pentoxide, magnesium, and iron in the mantle concretions, but higher contents of manganese and zinc in the gills. Furthermore, the results indicate that the mineral concretion formation in A. cygnea is a hemocytes reaction to particle or toxic invasions. A second relevant role, concerns the close involvement of these microspherules on the adult and larval shell calcification.

Selective feeding by Anodonta cygnea (Linnaeus, 1771): The effects of seasonal changes and nutritional demands

Many animal species, during their life cycles, can select specific food elements that meet the special and unique metabolic needs of crucial stages such as growth, gonad maturation or larvae production and brooding. The objective of this study was to analyze the seasonal phytoplankton composition in the stomach contents of the freshwater mussel Anodonta cygnea in order to determine whether it was capable of selecting food seasonally and which were its preferences. Specimens and water samples were collected monthly from Barrinha de Mira lagoon in the northwest of Portugal during one year. From the microalgae composition found in the water and stomach content samples, Chlorophyta presented a clear predominance, followed by Cryptophyta and Bacillariophyta in water samples, and Bacillariophyta and Cyanobacteria in stomach contents. Although mussels ingested algae in a pattern very similar to its abundance in the natural habitat, in some periods specific groups were preferred even if they were present in very low concentrations in the environment. Thus, these animals are capable of selecting food by its specific characteristics and this selectivity may be associated with its physiological cycle, mainly with the reproductive cycle. Namely, the large relative abundance (ratio stomach/environment) peak of blue green algae that co-occur with gamete development covering two other smaller peaks: one of Bacillariophyta that co-occurs with gametogenesis restart and the other of Chlorophyta at the end. In addition, a significant peak of Cryptophyta co-occurs with growth and glochidia brooding periods.

Accumulation and depuration of cyanobacterial paralytic shellfish toxins by the freshwater mussel Anodonta cygnea

The increasing frequency by which the production of paralytic shellfish toxins (PST) by freshwater bloom-forming cyanobacteria is being noticed world-wide raises the possibility of PST bioaccumulation by freshwater mussels. This study evaluates PST accumulation and depuration by the freshwater mussel Anodonta cygnea exposed over a 14-day period to high densities (mean=1.4×10 9 cells l −1, S.D.=0.29×10 9 cells l −1) of the toxic cyanobacterium Aphanizomenon issatschenkoi (corresponding to a mean toxin concentration of 25.5 nmol PST l −1, S.D.=9.9 nmol PST l −1). Mussels were subsequently detoxified either by starvation or by feeding on the non-toxic green-algae Ankistodesmus falcatus. Filter feeding activity and toxin uptake by the mussels were followed by cell counting and toxin analysis in water samples taken before and after each daily water renewal. The accumulation and depuration of PST as well as the anatomical distribution of toxins were monitored throughout the experiment by HPLC analysis of mussel extracts. Mussels fed the toxic cyanobacterium removed on average 65.3% of cells and 40.36% of total PST daily provided. Daily rates of cell clearance (% of initial) were negatively correlated with the amounts of PST daily provided (but not with the amount of cells). This suggests a negative effect of toxins on the feeding behaviour of mussels. Small amounts of toxins could be detected in the mussels after the second day of exposure, reaching a maximum of 26 μg PST 100 g −1 by day 7. The viscera contained the greatest proportion of toxins (78%) at the start of the toxification. However, increasing amounts of PST were found in the remaining tissues (gills, mantle and foot) over time. Toxins detected in the mussel extracts were the same provided in the dietary A. issatschenkoi. Nevertheless, mussels showed a higher proportion of saxitoxin and decarbomoylsaxitoxin and a lower proportion of gonyautoxin-5 than the fed cyanobacterium. Similar depuration efficiencies were observed among starved individuals (6.9% day −1) and those fed with A. falcatus (8.2% day −1) indicating that both treatments had comparable effects on toxin metabolism. Mussels showed a typical S shaped depuration kinetics curve consisting of a first short period of slow toxin decay followed by a rapid loss and a subsequent slower release of toxins. Trace to undetectable levels of PST were found in mussels after the 14-day depurating period. Although freshwater mussels are not widely consumed by humans, their capacity to accumulate PST points to the risk of PST propagation through the food chain of freshwater ecosystems via filter-feeding mussels.

Accumulation and depuration of cyanobacterial paralytic shellfish toxins by the freshwater mussel Anodonta cygnea

The increasing frequency by which the production of paralytic shellfish toxins (PST) by freshwater bloom-forming cyanobacteria is being noticed world-wide raises the possibility of PST bioaccumulation by freshwater mussels. This study evaluates PST accumulation and depuration by the freshwater mussel Anodonta cygnea exposed over a 14-day period to high densities (mean=1.4×10 9 cells l −1 , S.D.=0.29×10 9 cells l −1 ) of the toxic cyanobacterium Aphanizomenon issatschenkoi (corresponding to a mean toxin concentration of 25.5 nmol PST l −1 , S.D.=9.9 nmol PST l −1 ). Mussels were subsequently detoxified either by starvation or by feeding on the non-toxic green-algae Ankistodesmus falcatus . Filter feeding activity and toxin uptake by the mussels were followed by cell counting and toxin analysis in water samples taken before and after each daily water renewal. The accumulation and depuration of PST as well as the anatomical distribution of toxins were monitored throughout the experiment by HPLC analysis of mussel extracts. Mussels fed the toxic cyanobacterium removed on average 65.3% of cells and 40.36% of total PST daily provided. Daily rates of cell clearance (% of initial) were negatively correlated with the amounts of PST daily provided (but not with the amount of cells). This suggests a negative effect of toxins on the feeding behaviour of mussels. Small amounts of toxins could be detected in the mussels after the second day of exposure, reaching a maximum of 26 μg PST 100 g −1 by day 7. The viscera contained the greatest proportion of toxins (78%) at the start of the toxification. However, increasing amounts of PST were found in the remaining tissues (gills, mantle and foot) over time. Toxins detected in the mussel extracts were the same provided in the dietary A. issatschenkoi . Nevertheless, mussels showed a higher proportion of saxitoxin and decarbomoylsaxitoxin and a lower proportion of gonyautoxin-5 than the fed cyanobacterium. Similar depuration efficiencies were observed among starved individuals (6.9% day −1 ) and those fed with A. falcatus (8.2% day −1 ) indicating that both treatments had comparable effects on toxin metabolism. Mussels showed a typical S shaped depuration kinetics curve consisting of a first short period of slow toxin decay followed by a rapid loss and a subsequent slower release of toxins. Trace to undetectable levels of PST were found in mussels after the 14-day depurating period. Although freshwater mussels are not widely consumed by humans, their capacity to accumulate PST points to the risk of PST propagation through the food chain of freshwater ecosystems via filter-feeding mussels.

Accumulation and depuration of the cyanobacterial toxin cylindrospermopsin in the freshwater mussel Anodonta cygnea

Cylindrospermopsin (CYN) is a toxic alkaloid produced by several genera of freshwater cyanobacteria. This compound has been implicated in outbreaks of human sickness and the death of domestic and wild animals. Given that several of the cyanobacterial genera known to produce CYN are common components of the phytoplankton of freshwaters including aquaculture facilities, we studied the accumulation of CYN in the freshwater mussel (swan mussel) Anodonta cygnea. Anodonta were exposed to CYN-producing cultures of the cyanobacterium Cylindrospermopsis raciborskii for 16 days and were found to accumulate the toxin to concentrations up to 2.52 μg g tissue dry weight −1. There was considerable variation in the concentrations of CYN detected in different parts of the body. At the end of a 2-week accumulation period the distribution of CYN in the body of Anodonta was as follows: haemolymph (68.1%), viscera (23.3%), foot and gonad (7.7%) and mantle (0.9%). No CYN was detected in the gills or adductor muscle of any animals. Following a 2-week depuration period, approximately 50% of the toxin remained in the tissues. Based on the recently derived guideline value for CYN in human drinking water (1 μg l −1) and the concentrations of this compound in animal tissues reported here, there is a clear need for the increased monitoring of this compound in organisms grown for human and animal consumption.

The role of abiotic factors and pesticide levels on enzymatic activity in the freshwater mussel Anodonta cygnea at three different exposure sites

Natural variation in abiotic factors, such as temperature and pH, probably influence the activity of enzymes used as potential biomarkers in bivalve mollusks to assess environmental contamination in the field. Changes in levels of an enzymatic biomarker may thus merely reflect natural variation in the annual physiological cycle of a species rather than exposure to contaminants. To investigate this issue, we documented the relationship between pesticide levels in water and three different enzymatic biomarkers over 1 year in enclosed populations of the freshwater unionid mussel Anodonta cygnea at three different sites of exposure. We considered the natural variation in temperature, pH and dissolved oxygen over the year and across the different sites as a potential correlate of enzymatic activity to disentangle the relative contribution of abiotic factors and pesticide levels. Pesticide levels varied among the three sites and over the course of the year. Catalase (CAT) and acetylcholinesterase activity (AChE) varied as a function of abiotic factors but showed no relation to pesticide levels. Glutathione S-transferase (GST) activity was also related to abiotic factors but also decreased with increases in total pesticide levels. The lack of activity induction or inhibition by pesticides and the natural variation in abiotic factors among sites and across time limits the use of CAT and AChE to assess environmental contamination in this species.

Effect of sub-lethal concentrations of aluminium on the filtration activity of the freshwater mussel Anodonta cygnea L. at neutral pH.

Significant amounts of aluminium (Al) are commonly present in rivers and lakes, largely in particulate form in neutral waters. Freshwater bivalves, as filter feeders are therefore exposed to both particulate and dissolved metal and are potentially vulnerable to Al. The effect of Al on filtering behaviour of the freshwater mussel Anodonta cygnea L. was investigated during short (1 hour) and long-term (15 days) exposure to environmentally relevant concentrations (250 and 500 microg l(-1)) at neutral pH. Water flow through the outflow siphon was monitored as an indicator of pumping capacity. Short-term (1 hour) exposure to 500 microg l(-1) added Al produced an irreversible decrease in the duration of filtering periods, presumably as an avoidance response to the toxicant. One-hour exposure 250 microg l(-1) Al had no detectable effect. When mussels were exposed to 250 or 500 microg l(-1) added Al for 15 days, siphon activity measured in days 11-15 of exposure was inhibited by 50% and 65%, respectively, compared to pre-exposure levels. Recovery occurred following transfer of mussels to uncontaminated water. Interaction between Al and freshwater bivalves at neutral pH may affect both the performance of the mussels and the chemical speciation of the metal in the natural environment.

Vitellogenin levels in mussel hemolymph—a suitable biomarker for the exposure to estrogens?

Increased vitellogenin (vtg) levels in the blood of male fish are frequently used as an indicator of estrogenic exposure. Similar responses are expected for mussels, where the concentration of vtg-like proteins has been reported to depend on estrogens. To verify the role of hemolymph during vitellogenesis of mussels, the saltwater mussel Mytilus edulis and the freshwater mussel Anodonta cygnea were exposed to 17β-estradiol (E 2) and wastewater treatment plant effluents, known for their estrogenic potential. Gel electrophoresis did not reveal any significant induction (or repression) of plasma proteins compared to control plasma. Our results do not support the hypothesis that mussel hemolymph is a carrier of estrogen-dependent major egg-yolk precursors (vtg-like proteins). However, additional information on a 35±2-kDa hemolymph protein, previously reported to bind heavy metals, was obtained by high-resolution two-dimensional electrophoresis. It was resolved in a cluster of single proteins with properties that match the characteristics of a previously reported histidine-rich glycoprotein.

Parturition in Anodonta cygnea induced by selective serotonin reuptake inhibitors (SSRIs)

The selective serotonin reuptake inhibitors (SSRIs) fluoxetine (Nodep) and fluvoxamine (Dumyrox) are drugs commonly prescribed for the treatment of depression in humans. They act to increase serotonin (5-hydroxytryptamine) neurotransmission by inhibiting reuptake transport proteins at synapses. A similar effect of SSRIs seems to occur naturally in one group of invertebrates, the molluscs. In this study the action of these drugs at different concentrations and under different conditions was tested in the freshwater mussel Anodonta cygnea. Fluoxetine was more potent than fluvoxamine, inducing an intense release of larvae (parturition) at a concentration of 1 × 10–6 M in the presence of light. The non-SSRI antidepressants trazodone (Triticum), mianserine (Tolvon), and L-5-hydroxytryptophan (Cincofarm), which are known to have different serotoninergic mechanisms, had a strong, no, and a weak effect, respectively, on larval parturiton in A. cygnea. These effects suggest that serotonin could be a normal and relevant mediator of larval parturition in A. cygnea. Other parallel visible signs due to incubation with SSRIs were an increase in the volume of the foot and gills through water uptake and stimulation of valve movements. These results indicate that incubation with SSRIs is potentially important in culturing the larvae of freshwater bivalves, since it facilitates control of the intensity and timing of larval parturition.

Mechanism for maintaining oxygen consumption under varying oxygenation levels in the freshwater clamCorbicula fluminea

The basic adaptation mechanisms that allow the Asian freshwater clam Corbicula fluminea to maintain its oxygen (O2) consumption constant under resting conditions when the partial pressure of O2([Formula: see text]) in the water varies from 4 to 40 kPa were studied at plankton concentrations which were high enough that ventilation was not affected. Steady-state values for O2consumption, [Formula: see text], and O2concentration in the arterial and venous blood, [Formula: see text] in the expired water, and ventilatory and circulatory blood flow were determined after 24-h periods of exposure to selected water [Formula: see text] values. The key adaptation after 1 day of acclimation was the maintenance of O2consumption, which was achieved exclusively by ventilatory adjustment, with no change in the oxygenation status of the internal milieu. Specifically, arterial [Formula: see text] remained constant at 3 kPa and venous [Formula: see text] at 2 kPa. Arterial and venous blood O2concentrations and blood-flow rate also remained constant. The data are discussed in terms of feeding versus respiratory control of ventilation in filter-feeders in an environmental context. The agreement between the homeostasis strategy described here and previous results reported for the freshwater mussel Anodonta cygnea, crustaceans, and teleosts is emphasised.

Organic compounds in the extrapalial fluid and haemolymph of Anodontacygnea (L.) with emphasis on the seasonal biomineralization process

Bivalve mollusks, such as the freshwater mussel Anodonta cygnea, show seasonal changes in calcification. This cycle of calcification must either be a cause or a consequence for seasonal fluctuations in the organic composition of the animal’s fluids, haemolymph and extrapallial fluid, the liquid media for biomineralization. We monitored the fluids of A. cygnea, throughout a 1-year cycle, for the presence of organic constituents, known to be important for biomineralization, such as proteins, glycosaminoglycans (GAGs) and hexosamines. Proteins were subjected to further study, namely through the total amino acid determination and fraction separation by agarose gel electrophoresis. GAG levels were fairly constant throughout the year, with a maximum concentration in July and a minimum in January, a feature also detected for glucosamine, although with higher fluctuations. Proteins showed highly increased concentrations during June and July, both in total amounts and individual fractions. All fractions showed similar trends throughout the year, with lowest general levels in October, the starting month of a period when some fractions were not detectable at all. All fractions ended this low period in May, when a sometimes-important increase could be detected. As to the total amino acid composition of the fluids, the general trend followed that of proteins, except for ornithine (Orn), a non-proteic amino acid. The overall fluctuations detected in the biological fluids of A. cygnea suggest that the main variation related to the calcification cycle must be quantitative, since no different compounds appear in specific periods, to achieve also specific results.

Effect of reduced oxygen tension on the heart rate and the kinetic properties of glycolytic key enzymes PFK, PK and glycogen phosphorylase from the freshwater mussel Anodonta cygnea (L.)

The effect of reduced oxygen tension (pO 2) on the cardiac activity of the freshwater mussel Anodonta cygnea and the kinetic properties of glycolytic enzymes phosphofructokinase (PFK) and pyruvate kinase (PK) from the ventricle of A. cygnea were examined. The percentage of the active a form of glycogen phosphorylase was also measured under the same conditions. The results showed that A. cygnea responds to declining oxygen tension with bradycardia, but only at very low values of pO 2. In contrast, during the first stages of the reduction of water pO 2 a conversion of PK to a less active form was observed. In vitro experiments of phosphorylation and dephosphorylation revealed that inhibition of PK during anaerobiosis may be due to enzyme phosphorylation. Similarity to PK, the reduction of pO 2 converted PFK to a less active form and reduced the percentage of the active a form of glycogen phosphorylase. The data suggest that reversible modification of glycolytic enzymes PK and PFK and the reduction of the active a form of glycogen phosphorylase contribute to the depression of metabolic rate in the ventricle of A. cygnea under anoxic conditions.

Low sensitivity of ciliary activity in the gills of Anodonta cygnea to some ecotoxicals

1. The effects of some ecotoxical model substances on the activity of frontal gill cilia of freshwater mussel Anodonta cygnea were studied in 1 and 24 hr experiments with the particle transport method. The effects were compared with the results of standard Daphnia magna ec 50 tests with the same substances. 2. Variations of pH between 4.8 and 8.1 affected the ciliary activity by less than 30%. 3. Ciliary activity was less sensitive to heavy metal salts, sodium lauryl sulphate and to two pulp industry waste model substances than D. magna. 4. Compared to D. magna, the ciliary activity was more sensitive to formalin and 2,4-dinitrophenol, and as sensitive to ethanol. 5. Ciliary activity in bivalve gills is a well regulated and/or a relative insensitive function, but it may be used as a rapid screening test for some cell ecotoxicals.

Monovalent cation activated ouabain-insensitive ATPase in the gills of freshwater mussel Anodonta cygnea

Abstract 1. 1. The ouabain-insensitive Na + -ATPase of gill microsomes of the freshwater mussel Anodonta cygnea is activated similarly also by K + , Li + , Tl + , Rb + , Cs + and NH 4 + . 2. 2. Na + -ATPase also hydrolyses UTP and ADP, but with lower activity. 3. 3. The Na + -ATPase activity is maximal at pH 6.5. 4. 4. Na + -ATPase activity is inhibited by furosemide, but by ethacrynic acid and vanadate only at high concentrations. 5. 5. The temperature dependence of Na + -ATPase activity of Anodonta gill microsomes is linear between 5 and 50°C without the discontinuities usually observed in the function of this enzyme from other sources. 6. 6. Cd 2+ , but not Ca 2+ , may substitute Mg 2+ as the necessary cofactor. 7. 7. No significant ouabain-sensitive (Na + + K + )-ATPase activity has been detected in Anodonta gill microsomes, but this and the relative unspecificity of Na + -ATPase do not at present allow for evolutionary conclusions.