Daphnia Magna Bioassay Research Articles

Evaluation of a high throughput toxicity biosensor and comparison with a Daphnia magna bioassay

A high throughput toxicity biosensor has been designed and constructed using recombinant Escherichia coli cells, containing stress specific promoters ( recA, fabA, or katG) or constitutive promoters ( lac) fused to luciferase genes originating from Vibrio fisheri. These genetically engineered cells were immobilized in 96 well plates. By optimizing cell immobilization conditions and the strains’ response specificity to toxic chemicals, bioluminescent outputs decreased or increased dose-dependently upon adding test chemicals. However, to date the toxicity data obtained using this biosensor have not been compared with the results of other toxicity tests. Phenolics were chosen to evaluate the correlation between the LD50 and the EC50 (GC2) or EC120 (DPD2540) of Daphnia magna and E. coli, respectively. Toxicity data obtained from constitutive strains by bioluminescent level decrements were compared with the results from D. magna as a standard. LD50 values were used as parameters of D. magna toxicity and EC50 of EC120 values were used for the immobilized biosensor. In the DPD2540 test, phenolics, membrane damaging toxic chemicals, for testing immobilized stress specific bacterial strains trigger dose-dependant bioluminescence increase within specific concentration. Although the stress specific responsiveness from the strains could not be compared with D. magna's LD50 values, these responses offer additional information, such as upon the mode of toxic action in the sample, in addition to the cellular toxicity results as indicated by the EC50. This novel high throughput toxicity biosensor can be implemented to investigate the toxicity of any other soluble materials, and can be used as a standardization tool for the evaluation of toxicity.

The use of a Daphnia magna bioassay for rapid screening of acute intoxications with insecticides in dogs and cats.

Sudden death due to acute insecticide intoxications occurs frequently in dogs and cats. The absence of characteristic lesions at autopsy often renders post-mortem diagnosis dependent on the analysis of samples taken from the carcase at autopsy. In the present study, a bioassay utilizing Daphnia magna was proposed and tested as a rapid screening method for acute intoxications in dogs and cats. The bioassay was shown to be highly sensitive for detecting carbamate and organophosphate insecticides in the stomach contents. Generally. the mean survival time of the waterfleas in the control group was 5.17 h (SD = 1.24) and in the intoxicated group 1.32 h (SD = 1.49). during a 6 h observation period. If a cut-off is set at 4 h, this Daphnia bioassay gave 5.5% false negative results and 18.2% false positive results. using the results of toxicological analyses as a gold standard.

Acute toxicity and aqueous solubility of some condensed thiophenes and their microbial metabolites

AbstractPetroleum or creosote contamination of surface waters, soils, or groundwaters introduces countless aromatic compounds to these environments. Among these are condensed thiophenes that were shown to be oxidized to sulfoxides, sulfones, and 2,3‐diones by microbial cultures. In this study, the acute toxicities of 12 compounds (benzothiophene, benzothiophene sulfone, ben‐zothiophene‐2,3‐dione, 3‐, and 5‐methylbenzothiophenes, 3‐, and 5‐methylbenzothiophene sulfones, 5‐, and 7‐methylbenzothio‐phene‐2,3‐diones, dibenzothiophene, dibenzothiophene sulfoxide, and dibenzothiophene sulfone) were determined by the Microtox® and Daphnia magna bioassays. To aid in determining the toxicities, the solubilities of many of these compounds were determined, which showed that the oxidized compounds were much more water soluble than the parent thiophenes. In nearly every case, the oxidized compounds were less toxic than their parent thiophenes. The Microtox method was more sensitive than the D. magna bioassay, but in general, there was a good correlation between toxicities measured by the two tests. Samples were removed from batch cultures of a Pseudomonas strain capable of oxidizing the thiophenes, and these samples were subjected to Microtox bioassays. These experiments showed that the toxicities of the culture supernatants decreased with incubation time.

ACUTE TOXICITY AND AQUEOUS SOLUBILITY OF SOME CONDENSED THIOPHENES AND THEIR MICROBIAL METABOLITES

Petroleum or creosote contamination of surface waters, soils, or groundwaters introduces countless aromatic compounds to these environments. Among these are condensed thiophenes that were shown to be oxidized to sulfoxides, sulfones, and 2,3-diones by microbial cultures. In this study, the acute toxicities of 12 compounds (benzothiophene, benzothiophene sulfone, ben-zothiophene-2,3-dione, 3-, and 5-methylbenzothiophenes, 3-, and 5-methylbenzothiophene sulfones, 5-, and 7-methylbenzothio-phene-2,3-diones, dibenzothiophene, dibenzothiophene sulfoxide, and dibenzothiophene sulfone) were determined by the Microtox® and Daphnia magna bioassays. To aid in determining the toxicities, the solubilities of many of these compounds were determined, which showed that the oxidized compounds were much more water soluble than the parent thiophenes. In nearly every case, the oxidized compounds were less toxic than their parent thiophenes. The Microtox method was more sensitive than the D. magna bioassay, but in general, there was a good correlation between toxicities measured by the two tests. Samples were removed from batch cultures of a Pseudomonas strain capable of oxidizing the thiophenes, and these samples were subjected to Microtox bioassays. These experiments showed that the toxicities of the culture supernatants decreased with incubation time.

Transfer of heavy metals from sediment to fish, and their biliary excretion

Uptake and biliary excretion of metals were studied in rainbow trout, Oncorhynchus mykiss, exposed through spiked sediment to a mixture of seven heavy metals. Metal concentrations and toxicity of bile and blood plasma were used as indicators of exposure. Among the seven metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) only three (Cu, Hg, and Pb) were concentrated in the bile (bile-plasma ratio >1). Bile-plasma ratios in the rainbow trout were similar to those found in rats for Cu and Hg. Daphnia magna bioassays were used to determine toxicity of bile and blood plasma in the same trout. Toxicity of bile and blood plasma increased after treatment with acid. An analysis of variance (ANOVA) showed that toxicity of bile and blood plasma to D. magna in metal-exposed trout was significantly correlated with (1) bile and blood plasma test concentration, (2) acid treatment of bile and blood plasma (hydrolysis of metal-plasma and metal-bile complexes) and (3) sediment concentration of metals during exposure of trout. In order to significantly detect the magnitude of the exposure to a xenobiotic the biomarker must respond in a dose- or time-dependent manner. Therefore, the potential use of bile toxicity as a biomarker of heavy metal exposure in fish is probably limited by the low bioconcentration of many of these toxicants in bile.

Toxicity Evaluations of Wastewaters in Austria with Conventional and Cost-Effective Bioassays

The acute toxicity of 42 samples of different types of domestic and industrial discharges was assessed with a battery of tests comprising the standard Daphnia magna bioassay and three cost-effective new microbiotests (cyst-based Toxkits): the Rotoxkit F with the freshwater rotifer Brachionus calyciflorus and the Streptoxkit F and Thamnotoxkit F tests with the freshwater fairy shrimps Streptocephalus proboscideus and Thamnocephalus platyurus, respectively. Chemical analyses were performed for conventional water quality parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD5), NO2, NH2, NH4+, O2, and pH. Toxicity of the samples, expressed as German regulatory G-values, was found to vary between 1 and 128. The results of these toxicity tests indicate that the Toxkit bioassays were as sensitive as the D. magna acute test. The crustacean T. platyurus was in 75% of the toxic samples more sensitive than D. magna. Relationships between the chemical composition and the toxicity of the discharges could be established in some cases, but not in others, which confirms the difficulties of extrapolating toxic hazards of complex wastes from (mostly restricted) chemical analyses. This study demonstrates the potential of cost-effective bioassays (such as, e.g., cyst-based Toxkits) as attractive alternatives to (expensive) conventional bioassays for routine monitoring of effluents and wastes.

Cyst-based toxicity tests X: comparison of the sensitivity of the acute Daphnia magna test and two crustacean microbiotests for chemicals and wastes

This paper statistically evaluates the sensitivity of the acute Daphnia magna bioassay in comparison to that of two crustacean microbiotests: the Streptoxkit F and Thamnotoxkit F, which make use of larvae of the anostracans Streptocephalus proboscideus and Thamnocephalus platyurus respectively, hatched from cysts. Regression equations were calculated for 146 data pairs, taken from 5 different studies dealing with the acute toxicity of pure chemicals, effluents, river sediments, solid wastes and monitoring wells, and sludges. All comparisons show that there is a significant relationship (p< 0.05) between the acute effects found with the D.magna and the two crustacean microbiotests; correlation coefficients ranged from 0.84 to 0.92. In the majority of cases, effect ratios between the conventional D.magna and the microbiotests were within a factor 2 for both pure chemicals and environmental samples. Variation coefficients for repeated tests on the reference chemical potassium dichromate indicate a good precision and hence a good degree of standardization of the microbiotest procedures. The evidence provided in this paper demonstrates that the new crustacean microbiotests can be used as low cost alternatives to the conventional D.magna acute assay.

Mutagenicity and toxicity assessment of pulp mill effluent

Data are presented on the mutagenic and toxic properties of both whole and fractionated bleached kraft mill effluent. Mutagenic properties were measured using the Ames test and the SOS Chromotest. Toxic properties were measured using the Microtox and Daphnia magna bioassays. The D. magna bioassays were performed only on four samples, and the information on mutagenicity represent the main emphasis of this study. Various fractionation procedures, including filtration, centrifugation and XAD resin adsorption procedures were employed. Bleached kraft mill effluent (BKME) was found to be mutagenic with the majority of activity associated with polar compounds. Polar material adsorbed by XAD-4 and XAD-8 resins contained a mutagenic potency equivalent to that measured directly in the effluent. Whole effluent samples were non-toxic (Microtox bioassay), but the polar fractions were toxic (Microtox and Daphnia magna bioassays) while particulate associated materials were toxic just to the Microtox bioassay. This paper also comments on the chemical characteristics of mutagenetic materials in these effluent fractions.

Comparative ecotoxicity of suspended sediment in the lower Rhone River using algal fractionation, Microtox® and Daphnia magna bioassays

The toxicity associated with suspended sediments from the Rhone River (Switzerland-France) was determined with three acute bioassays. Large volume water samples were centrifuged for recovery of suspended solids in November 1989; one sample was taken as a control upstream from Lake Geneva and the 9 remainder downstream from Geneva to the Mediterranean Sea, with a single sample of the major tributary the Saone at Lyon. Heavy metals (Hg, Cd, Cr, Cu, Ni, Pb, Zn) and organic contaminants (OCs, PCBs, PAHs) bound to sediment were analysed and extracted by elutriation with filtered lake water and by organic solvent (dichloromethane). Sediment water elutriates were tested with algal fractionation bioassays (AFB) using Lake Geneva ambient phytoplankton, with Daphnia magna and Microtox® acute toxicity tests, whereas organic extracts were utilized in the latter two bioassays to evaluate the potential sediment toxicity.

Interclonal variation in the performance of Daphnia magna straus in chronic bioassays

AbstractAs an ecotoxicological test organism, Daphnia magna Straus has a long history and is now used extensively. Despite this, considerable variation in interlaboratory bioassays using the same reference toxicant has been reported. Using a standard quantitative genetics approach, the relative tolerance of different genotypes of Daphnia magna to two toxicants (sodium bromide and 3,4‐dichloroaniline) was assessed. As expected, the environmental component of variability dominated the chronic response with a significant component of interaction. Differences between genotypes, although significant, were not large. It was concluded that genotype‐environment interactions played a key role in determining chronic responses of Daphnia magna to both compounds. Some suggestions are given to improve the level of repeatability in Daphnia magna bioassays.

Correlation between heavy metal acute toxicity values in Daphnia magna and fish.

In the toxicant bioassays, invertebrates with special reference to aquatic arthropod species have been of recent interest as test models due to the need for developing nonmammalian tests system. The cladoceran Daphnia magna bioassays have several practical advantages. D. magna has been used as a useful test species and its sensitivity to environmental pollutants have been recognized as a general representative of other freshwater zooplankton species. The objectives of this study were to determine the acute toxicity of various heavy metals to Daphnia magna for 48 h of exposure and to compare these values with the existing LC50 values for rainbow trout (Salmo gairdneri); which is commonly used as a test animal in aquatic bioassay studies.

Effects of chronic exposure to coal‐derived oil on freshwater ecosystems: I. Microcosms

AbstractSixteen 67‐liter freshwater microcosms were treated for 8 weeks with an unrefined coal‐oil in amounts ranging from 0.03 to 7 ml per week. Phenols make up 95% of the water‐soluble compounds in this oil, and dissolved phenol concentrations averaged &lt;0.01 mg L−1 in the lowest dose and 10 mg L−1 in the highest. The microcosms were severely damaged at the highest treatment level; macrophytes, zooplankton and insects were eliminated, and the ecosystems became anaerobic. Microcosms did not recover to pretreatment conditions within 5 months. At lower dosages there were temporary effects on ecosystem metabolism, water chemistry and community structure. The most sensitive indices—community respiration, production/respiration ratio, pH and cladoceran zooplankton numbers—were affected at phenol concentrations below the lowest observable effect concentration of a chronic Daphnia magna bioassay.

Foam fractionation of spent sulphite liquor: Part II: Separation of toxic components

AbstractFoam fractionation was used as a unit operation for the reduction of toxicity in spent sulphite liquor. Toxicity was measured quantitatively using a Daphnia magna bioassay. The optimum pH for the operation was 10 and no toxicity removal was possible at pH values less than 8. The maximum decrease in the toxicant concentration was 40%. The collapsed foam was very toxic to D. magna indicating that toxicants were concentrated in the foam which contained 20% of the original liquid charged to the column. A relationship between surfactant and toxicant concentration was shown to exist.