Project description:This SuperSeries is composed of the following subset Series: GSE29854: Daphnia magna exposed to narcotics and polar narcotics - aniline GSE29856: Daphnia magna exposed to narcotics and polar narcotics - 4-chloroaniline GSE29857: Daphnia magna exposed to narcotics and polar narcotics - 3,5-dichloroaniline GSE29858: Daphnia magna exposed to narcotics and polar narcotics - 2,3,4-trichloroaniline GSE29862: Daphnia magna exposed to narcotics and polar narcotics - ethanol GSE29864: Daphnia magna exposed to narcotics and polar narcotics - isopropanol GSE29867: Daphnia magna exposed to narcotics and polar narcotics - methanol Refer to individual Series
Project description:In the past years, the research focus on the effects of microplastics (MP) on aquatic organisms extended from marine systems towards freshwater systems. An important freshwater model organism in the MP field is the cladoceran Daphnia, which plays a central role in lacustrine ecosystems and has been established as a test organism in ecotoxicology. To investigate the effects of MP on Daphnia magna, we performed a chronic exposure experiment with polystyrene MP under strictly standardized conditions. Chronic exposure of D. magna to PS microparticles led to a significant reduction in body length and number of offspring. To shed light on underlying molecular mechanisms induced by microplastic ingestion in D. magna, we assessed the effects of PS-MP at the proteomic level.
Project description:Comparison of female and male Daphnia magna gene expression with age. The sexes in Daphnia magna are genetically identical. The aim of this study was to identify possible differences in gene expression between genders with age.
Project description:This experiment was conducted to study the short-term (12h) transcriptional responses in Daphnia magna after exposure to the anti-sea lice chemical emamectin benzoate (EMB). The microarray results were further vefiried using qPCR. The gene exression responses were linked to adverse effects after 48h exposure, in order to supply knowledge for environmental hazard assessment of this chemical in non-target crustaceans. Neonatal (<24h) Daphnia magna were exposed to 7.8-2000 pM waterborne emamectin benzoate for 12h. Microarray analysis was performed using pooled whole-organism D. magna (8 individuals) and 4 biological replicates were analyzed for each treatment group.
Project description:Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physicochemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna. Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag+ release and underwent a significant morphological transformation within 1 h following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating, and solution chemistry. Ag+ release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag+ and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag+. Scanning electron microscopy imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology, and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna. Four replicates each of five toxicant exposure groups of ~20 animals and four replicates of control, unexposed animals. Each control was compared to each exposed data set for a total of 16 comparisons per chemical condition.
Project description:Mass developments of toxin-producing cyanobacteria are frequently observed in freshwater ecosystems due to eutrophication and global warming. These mass developments can partly be attributed to cyanobacterial toxins, such as protease inhibitors (PIs), which inhibit digestive serine proteases of Daphnia, the major herbivore of phytoplankton and cyanobacteria. To date, mechanisms of this inhibition in the gut of the crustacean Daphnia magna are not known. Here, we characterize a single serine protease, chymotrypsin 448 (CT448), which is present in the gut of the crustacean D. magna.
Project description:Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physicochemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna. Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag+ release and underwent a significant morphological transformation within 1 h following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating, and solution chemistry. Ag+ release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag+ and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag+. Scanning electron microscopy imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology, and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna.
Project description:Cadmium (Cd) is a toxic metal causing sublethal and chronic effects in crustaceans. Omic technologies offer unprecedented opportunities to better understand modes of toxicity by providing a holistic view of the molecular changes underlying physiological disruption. We sought to use gene expression and metabolomic analyses to reveal the processes leading to chronic Cd toxicity in the indicator species, Daphnia magna, after a 24-h sublethal exposure (18 ug/L, corresponding to 1/10 LC50). We first confirmed that metabolites can be detected and identified in small volumes (~3-6 ul) of D. magna hemolymph using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and NMR spectroscopy. We then compared the altered metabolite levels from a mass spectrometry metabolomics study to differentially expressed genes identified by a D. magna 44k oligonucleotide microarray. Metabolomics identified several essential amino acids, nucleotides and fatty acids as decreased in D. magna hemolymph following Cd exposure. Transcriptional changes included decreased levels of digestive enzymes and increased expression of genes related to embryonic development. The integration of metabolomic and transcriptomic profiles, as well as incorporation of results from previous studies, has enabled construction of a conceptual model detailing how sublethal Cd disrupts energy reserves and reproduction resulting in chronic toxicity. Daphnia magna were exposed to 18 micrograms/L Cadmium sulfate for 24 hours. RNA was extracted and hybridized to a custom Daphnia magna microarray to determine genes differentially expressed by the treatment. Two treament experiment:Unexposed and Cd treatment, 6 replicates for each condition