Demographic responses of <Emphasis Type="Italic">Daphnia magna</Emphasis> fed transgenic <Emphasis Type="Italic">Bt</Emphasis>-maize

The food/feed quality of a variety of genetically modified (GM) maize expressing Cry1Ab Bt-toxin was tested over the life-cycle of Daphnia magna, an arthropod commonly used as model organism in ecotoxicological studies. Demographic responses were compared between animals fed GM or unmodified (UM) near isogenic maize, with and without the addition of predator smell. Age-specific data on survival and birth rates were integrated and analysed using life tables and Leslie matrices. Survival, fecundity and population growth rate (PGR) data generally disfavoured transgenic Bt-maize as feed for D. magna compared to animals fed the unmodified (UM) near isogenic line of maize. Decomposition of age-specific effects revealed that the most important contributions to a reduced PGR in the GM-fed group came from both fecundity and survival differences early in life. We conclude that juvenile and young adult stages are the most sensitive experimental units and should be prioritized in future research. These stages are often omitted in toxicological/ecotoxicological studies and in feeding trials.     

Sub-lethal effects of acetone on <Emphasis Type="Italic">Daphnia magna</Emphasis>

There is increasing concern about the sub-lethal effect of hydrophobic chemicals in the water medium. Even though acetone is a commonly used solvent in toxicity testing, few studies have focussed on its chronic toxicity to Daphnia magna and the available results are often contradictory. In this study, acetone was tested on D. magna in a 21-day exposure experiment and the effects on mortality, fertility and morphology of exposed organisms (F₀) and offspring (F₁–F₂, reared without acetone) were evaluated. No significant reduction of survival was observed with increasing concentrations, and no significant reduction in fecundity in any treatment group in terms of average number of daphnids per mother was observed. Abnormal development of second antennae was observed on F₁ from F₀ exposed to 79 mg l⁻¹ solvent. The ET50 of acetone on the number of mothers that produced deformed offspring over time was 12.5 days. Our results suggest that the acetone concentration should not exceed 7.9 mg l⁻¹, which is 10 times less than the allowed concentration as determined by OECD chronic assays on D. magna. More attention should be paid to small, water-soluble molecules usually considered of low concern for chronic toxicity because they might affect other metabolic pathways.     

Joint toxicity of cadmium and SDBS on <Emphasis Type="Italic">Daphnia magna</Emphasis> and <Emphasis Type="Italic">Danio rerio</Emphasis>

Information on joint toxicity is limited. To clarify the joint toxicity and the interactions among toxicants on different aquatic organisms, we investigated the acute toxicity of cadmium and sodium dodecyl benzene sulfonate, two chemicals with high concerns in Chinese waters, on the immobilization of Daphnia magna (D. magna) and the swimming behavior of Danio rerio (D. rerio). Our results illustrated that cadmium and sodium dodecyl benzene sulfonate expressed a synergistic effect on the immobilization of D. magna; and an antagonistic effect on the swimming speed D. rerio, but a synergistic effect on its vertical position in the water column. Based on the observed data, we found the independent action model was more appropriate than the concentration addition model in the prediction of their joint toxicity. Our results gave an example of the joint toxicity investigation, and aided to comprehensive the toxicity action mode of chemical mixtures.     

Genetic and chemical comparison of Boi (<Emphasis Type="Italic">Sinomeni Caulis</Emphasis><Emphasis Type="Italic">et Rhizoma</Emphasis>) and Seifuto (<Emphasis Type="Italic">Caulis Sinomenii</Emphasis>)

Boi and its original plant Sinomenium acutum from Japan were compared with Seifuto and its botanical origins from China in terms of their internal transcribed spacer (ITS) sequences and major chemical components. Boi, Seifuto, and their botanical origins overall showed seven variable sites in the ITS sequence and six genotypes. Japanese S. acutum and Boi had one nucleotide variation at position 593 to show two genotypes (J1 and J2) and their heterozygote (J3). Seifuto samples and their botanical origins, S. acutum and S. acutum var. cinereum from China, showed three genotypes (C1, C2, and C3), which did not agree with the botanical classification, indicating that they cannot be distinguished according to their ITS sequences. All Seifuto samples from Henan market showed the same ITS genotype (C1). The Japanese and Chinese genotypes differed in the nucleotide position 424, which can be used to distinguish the country of origin of these materials. In the HPLC analysis of six major components, sinomenine (1), magnoflorine (2), menisperine (3), 6-O-methyllaudanosoline glucoside (4), liriodendrin (5), and menisdaurin (6), all were detected in Boi, whereas five (all except for menisdaurin) were detected in Seifuto. The main component in the rhizome of Seifuto was sinomenine, whereas magnoflorine was the main component in the rhizome and the climbing stem of Boi. The content of sinomenine in Seifuto was almost twice that in Boi. Although the individual content of alkaloids 1–4 differed between Boi and Seifuto, the total contents of these alkaloids were comparable between them both in the climbing stem and rhizome.     

The effect of lead from sediment bioturbation by <Emphasis Type="Italic">Lumbriculus variegatus</Emphasis> on <Emphasis Type="Italic">Daphnia magna</Emphasis> in the water column

The present study investigated the bioavailability and potential toxicity to Daphnia magna of lead released to the water column due to bioturbation by Lumbriculus variegatus. Experiments used microcosms with Pb-spiked sediment, with or without worms in the sediment, and with D. magna present in the water column. The daphniids were allowed free movement or were restricted to flow-through containers, in order to assess the influence of their direct contact with the contaminated sediment. A control group consisted of D. magna in clean moderately hard reconstituted water. At the end of the 12-day experiment, D. magna survival, reproduction, biomass, and Pb-bioaccumulation were determined. Water column turbidity and Pb levels were quantified to assess their influence on the Pb toxicity and bioaccumulation. The bioturbation by L. variegatus increased Pb levels and turbidity in the water column. While this resulted in an increased Pb bioaccumulation by the D. magna, the water column Pb levels and the Pb bioaccumulation were insufficient to bring about toxic effects for the survival, reproduction, and biomass of the daphniids. Contact of D. magna with the sediment resulted in an increase in their Pb bioaccumulation, with water turbidity and Pb data, suggesting that these crustaceans also acted as bioturbators. The increase in Pb bioaccumulation in D. magna as a consequence of bioturbation by L. variegatus demonstrates the potential for bioturbation to enhance contaminant toxicity to organisms in the water column, though this potential appeared relatively low in the case of lead.     

The mysid <Emphasis Type="Italic">Siriella armata</Emphasis> as a model organism in marine ecotoxicology: comparative acute toxicity sensitivity with <Emphasis Type="Italic">Daphnia magna</Emphasis>

Siriella armata (Crustacea, Mysidacea) is a component of the coastal zooplankton that lives in swarms in the shallow waters of the European neritic zone, from the North Sea to the Mediterranean. Juveniles of this species were examined as standard test organisms for use in marine acute toxicity tests. The effects of reference toxicants, three trace metals (Copper, Cadmium and Zinc), and one surfactant, sodium dodecyl sulfate (SDS) were studied on S. armata neonates (<24 h) reared in the laboratory. Acute toxicity tests were carried out with filtered sea water on individual chambers (microplate wells for metals or glass vials for SDS) incubated in an isothermal room at 20°C, with 16 h light: 8 h dark photoperiod for 96 h. Each neonate was fed daily with 10–15 nauplii of Artemia salina. Acute (96 h) LC₅₀ values, in increasing order, were 46.9 μg/L for Cu, 99.3 μg/L for Cd, 466.7 μg/L for Zn and 8.5 mg/L for SDS. The LC₁₀, NOEC and LOEC values were also calculated. Results were compared with Daphnia magna, a freshwater cladoceran widely used as a standard ecotoxicological test organism. Acute (48 h) LC₅₀ values were 56.2 μg/L for Cu, 571.5 μg/L for Cd, 1.3 mg/L for Zn and 27.3 mg/L for SDS. For all the reference toxicants studied, the marine mysid Siriella armata showed higher sensitivity than the freshwater model organism Daphnia magna, validating the use of Siriella mysids as model organisms in marine acute toxicity tests.     

Sensitivity of <Emphasis Type="Italic">Scenedesmus obliquus</Emphasis> and <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> to atrazine: effects of acclimation and mixed cultures,and their removal ability

Atrazine is an herbicide frequently detected in watercourses that can affect the phytoplankton community, thus impacting the whole food chain. This study aims, firstly, to measure the sensitivity of monocultures of the green alga Scenedemus obliquus and toxic and non-toxic strains of the cyanobacteria Microcystis aeruginosa before, during and after a 30-day acclimation period to 0.1?µM of atrazine. Secondly, the sensitivity of S. obliquus and M. aeruginosa to atrazine in mixed cultures was evaluated. Finally, the ability of these strains to remove atrazine from the media was measured. We demonstrated that both strains of M. aeruginosa had higher growth rate-based EC₅₀ values than S. obliquus when exposed to atrazine, even though their photosynthesis-based EC₅₀ values were lower. After being exposed to 0.1?µM of atrazine for 1?month, only the photosynthesis-based EC₅₀ of S. obliquus increased significantly. In mixed cultures, the growth rate of the non-toxic strain of M. aeruginosa was higher than S. obliquus at high concentrations of atrazine, resulting in a ratio of M. aeruginosa to total cell count of 0.6. This lower sensitivity might be related to the higher growth rate of cyanobacteria at low light intensity. Finally, a negligible fraction of atrazine was removed from the culture media by S. obliquus or M. aeruginosa over 6?days. These results bring new insights on the acclimation of some phytoplankton species to atrazine and its effect on the competition between S. obliquus and M. aeruginosa in mixed cultures.     

The individual and population effects of tetracycline on <Emphasis Type="Italic">Daphnia magna</Emphasis> in multigenerational exposure

Multigenerational exposure of Daphnia magna to tetracycline was carried out through four consecutive generations. The effects of tetracycline on the survival, reproduction and growth of D. magna were assessed over a period of 21 days per generation. The evaluated endpoints were overall fecundity (total mean neonates per female over 21 days), time to first reproduction, longevity, molting number and somatic growth, such as body weight and body length. Using the results obtained for reproduction and survival rates, the intrinsic population growth rate (PGR) was calculated and compared throughout the generations. Reproductive impairment was observed in all generations and magnified with increasing generation number. The value of no observed effect concentration on D. magna also markedly decreased with increasing generation number. This subsequently resulted in a reduction of the PGR value. In addition, the PGR value was decreased with increasing exposure concentration, decreasing by about 30 and 60% at 0.1 and 5.0 mg/L tetracycline, respectively. On the other hands, somatic growth increased with increasing generation number, because the remaining input energy from the reduced reproduction was mainly used for body maintenance. As a result, the somatic growth and reproduction showed reversed trends on continuous exposure of tetracycline to four generations. In conclusion, multigenerational exposure of tetracycline can induce overall responses on reproduction and the somatic growth of D. magna. Moreover, the PGR value of D. magna exposed to tetracycline was reduced with increasing generation number; thereby, inhibiting the long term propagation of D. magna.     

<Emphasis Type="Italic">ent</Emphasis>-Abietane diterpenoids from <Emphasis Type="Italic">Isodon xerophilus</Emphasis>

Three new ent-abietanoids, named xerophilusins XIV–XVI, and four known analogues, as well as four known chemical constituents were isolated from the leaves of Isodon xerophilus. Their structures were elucidated by extensive spectroscopic studies, and comparison with literature data. In addition, the cytotoxic activity of the ent-abietanoids against chronic myelogenous leukemia (K562), stomach adenocarcinoma (MKN45), and hepatocellular carcinoma (HepG2) human cell lines was investigated and no activities were observed.     

Stereoselective Taurine Conjugation of (<Emphasis Type="Italic">R</Emphasis>)-Benoxaprofen Enantiomer in Rats: <Emphasis Type="Italic">In Vivo</Emphasis> and <Emphasis Type="Italic">in Vitro</Emphasis> Studies Using Rat Hepatic Mitochondria and Microsomes

No HeadingPurpose. Identify (R)-BOP-T in rat bile after administration of (R)-BOT over a 12 h period.Methods. Each benoxaprofen (BOP) enantiomer was administered i.v. to bile duct-cannulated rats at a dose of 5 mg/kg. The optical isomers of BOP and its metabolites in plasma, urine, and bile were quantified using a chiral HPLC column. The amounts of BOP glucuronide (BOP-G), BOP taurine conjugate (BOP-T), and BOP enantiomers excreted into the bile over 12 h after administration of (R)-BOP were as follows: (R)-BOP-G and (S)-BOP-G, 2.1 ± 0.5 and 6.2 ± 1.4% of the dose; (R)-BOP-T and (S)-BOP-T, 5.6 ± 1.8 and 0.7 ± 0.3% of the dose; (R)-BOP and (S)-BOP, 0.7 ± 0.1 and 1.7 ± 0.2% of the dose, respectively, whereas after (S)-BOP administration, (S)-BOP-G and (S)-BOP were mainly excreted into the bile (14.3 ± 1.8 and 3.0 ± 0.4% of the dose, respectively). Only after (R)-BOP administration was the taurine conjugate of BOP found in the bile, and the configuration was R. BOP-T could not be found in the bile after (S)-BOP administration. To investigate the stereoselectivity of the conjugation enzymes responsible for BOP-T formation, in vitro studies were performed using rat hepatic organelles.Results. When (R)-BOP was used as a substrate, rat hepatic mitochondrial and microsomal fractions exhibited stereoselective BOP-T formation activity, with microsomal activity approximately 3.0 times greater than that of the mitochondria. That of (S)-BOP was approximately 2.1. Mean (R)/(S) ratios of BOP enantiomer for BOP-T formation in the mitochondrial and microsomal incubations were approximately 1.7 and 2.4, respectively.Conclusion. Although in the in vivo studies, only (R)-BOP-T originated from (R)-BOP was found in the bile, the configuration of BOP-T formed by the incubations of (R)-BOP or (S)-BOP with rat hepatic mitochondria or microsomes was S for both.     

Ecotoxicological assessment of pesticides towards the plant growth promoting activities of Lentil (<Emphasis Type="Italic">Lens</Emphasis><Emphasis Type="Italic">esculentus</Emphasis>)-specific <Emphasis Type="Italic">Rhizobium</Emphasis> sp. strain MRL3

This study was designed to evaluate the effect of the selected pesticides [herbicides (metribuzin and glyphosate), insecticides (imidacloprid and thiamethoxam) and fungicides (hexaconazole, metalaxyl and kitazin)] at the recommended and the higher dose rates on plant growth promoting traits of Rhizobium sp. strain MRL3 isolated from lentil-nodules. Strain MRL3 was explicitly selected owing to its high pesticide-tolerance ability and substantial production of indole acetic acid, siderophores (salicylic acid and 2, 3 dihydroxy benzoic acid), exo-polysaccharides, HCN and ammonia. A trend of pesticide-concentration dependent progressive-decline for plant growth promoting properties of Rhizobium sp. strain MRL3 was observed excluding exo-polysaccharides which was regularly augmented on exceeding the concentration of each tested pesticide from the recommended dose. Commonly, the maximum toxicity to plant growth promoting traits of Rhizobium was shown by glyphosate, imidacloprid and hexaconazole at three times the recommended rate among herbicides, insecticides and fungicides, respectively.     

Impairment of trophic interactions between zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) and midge larvae (<Emphasis Type="Italic">Chironomus riparius</Emphasis>) by chlorpyrifos

The effects of chemicals on biotic interactions, such as competition and predation, have rarely been investigated in aquatic ecotoxicology. This study presents a new approach for the investigation of predator–prey interactions between zebrafish (Danio rerio) and midge larvae (Chironomus riparius) impaired by chlorpyrifos (CHP), a neurotoxic insecticide. With a simple experimental design including four different treatments: (1) control, (2) predator exposed, (3) prey exposed and (4) both, predator and prey, exposed, we were able to detect by visual observation an increase in the feeding rate of zebrafish preying on exposed chironomids after acute (2 h) exposure to 6 μg/l CHP. Previously, a decrease in the burrowing behaviour of exposed chironomid larvae was observed. However, when pre-exposing simultaneously both predators and prey, no significant differences in the feeding rate of zebrafish were observed. This suggests an impairment in prey recognition of the exposed zebrafish. At a lower CHP concentration (1 μg/l), no differences in feeding rate of zebrafish were observed. We therefore propose the use of trophic interactions as parameters in higher tier studies for chemical testing and evaluation of ecotoxicological risk assessment.     

Identification of medicinal <Emphasis Type="Italic">Dendrobium</Emphasis> species by phylogenetic analyses using <Emphasis Type="Italic">matK</Emphasis> and <Emphasis Type="Italic">rbcL</Emphasis> sequences

Species identification of five Dendrobium plants was conducted using phylogenetic analysis and the validity of the method was verified. Some Dendrobium plants (Orchidaceae) have been used as herbal medicines but the difficulty in identifying their botanical origin by traditional methods prevented their full modern utilization. Based on the emerging field of molecular systematics as a powerful classification tool, a phylogenetic analysis was conducted using sequences of two plastid genes, the maturase-coding gene (matK) and the large subunit of ribulose 1,5-bisphosphate carboxylase-coding gene (rbcL), as DNA barcodes for species identification of Dendrobium plants. We investigated five medicinal Dendrobium species, Dendrobium fimbriatum, D. moniliforme, D. nobile, D. pulchellum, and D. tosaense. The phylogenetic trees constructed from matK data successfully distinguished each species from each other. On the other hand, rbcL, as a single-locus barcode, offered less species discriminating power than matK, possibly due to its being present with little variation. When results using matK sequences of D. officinale that was deposited in the DNA database were combined, D. officinale and D. tosaense showed a close genetic relationship, which brought us closer to resolving the question of their taxonomic identity. Identification of the plant source as well as the uniformity of the chemical components is critical for the quality control of herbal medicines and it is important that the processed materials be validated. The methods presented here could be applied to the analysis of processed Dendrobium plants and be a promising tool for the identification of botanical origins of crude drugs.     

A new <Emphasis Type="Italic">Erythrina</Emphasis> alkaloid from <Emphasis Type="Italic">Erythrina herbacea</Emphasis>

A new Erythrina alkaloid, 10-hydroxy-11-oxoerysotrine (1), has been isolated from the flowers of Erythrina herbacea together with five known compounds: erytharbine (2), 10,11-dioxoerysotrine (3), erythrartine (4), erysotramidine (5) and erysotrine-N-oxide (6). The structure of the new compound was elucidated on the basis of its spectral data, including 2-D NMR and mass (MS) spectra. The new compound is a rare C-10 oxygenated Erythrina alkaloid. The antioxidant activities of the isolated compounds 1–6 were evaluated by scavenging with peroxynitrite.     

<Emphasis Type="Italic">In Vitro</Emphasis> hepatoprotective compounds from <Emphasis Type="Italic">Suaeda glauca</Emphasis>

Bioassay-guided fractionation of the MeOH extract of Suaeda glauca yielded four phenolic compounds, methyl 3,5-di-O-caffeoyl quinate (1) and 3,5-di-O-caffeoyl quinic acid (2), isorhamnetin 3-O-beta-D-galactoside (3), and quercetin 3-O-beta-D-galactoside (4). Compounds 1 and 2 were hepatoprotective against tacrine-induced cytotoxicity in human liver-derived Hep G2 cells with the EC(50) values of 72.7+/-6.2 and 117.2+/-10.5 microM, respectively. Silybin as a positive control showed an EC(50) value of 82.4+/-4.1 microM.     

MDMA induces <Emphasis Type="Italic">Per1</Emphasis>, <Emphasis Type="Italic">Per2</Emphasis> and <Emphasis Type="Italic">c-fos</Emphasis> gene expression in rat suprachiasmatic nuclei

Rationale  

±3,4-Methylenedioxymethamphetamine (MDMA, ‘ecstasy’) is a psychoactive drug that has marked effects on the serotonergic system. Serotonergic agonists are known to interact with the circadian pacemaker located in the suprachiasmatic nuclei (SCN).