Project description:Elevated levels of adsorbable organic bromine compounds (AOBr) have been detected in German lakes, and cyanobacteria like Microcystis, which are known for the synthesis of microcystins, are one of the main producers of natural organobromines. However, very little is known about how environmental realistic concentrations of organobromines impact invertebrates. Here, the nematode C. elegans was exposed to AOBr-containing surface water samples and to a Microcystis aeruginosa enriched batch culture (MC-BA) and compared to single organobromines and microcystin-LR exposures. Stimulatory effects were observed in certain life trait variables, which were particularly pronounced in nematodes exposed to MC-BA. A whole genome DNA-microarray revealed that MC-BA led to the differential expression of more than 2000 genes, many of which are known to be involved in metabolic, neurologic, and morphologic processes. Moreover, the up-regulation of cyp- and the down-regulation of abu-genes suggested the presence of chronic stress. However, the nematodes were not marked by negative phenotypic responses. The observed difference in MC-BA and microcystin-LR (which impacted lifespan, growth and reproduction) exposed nematodes was hypothesized to be likely due to other compounds within the batch culture. Most likely the exposure to low concentrations of organobromines appears to buffer the effects of toxic substances, like microcystin-LR.
Project description:Elevated levels of adsorbable organic bromine compounds (AOBr) have been detected in German lakes, and cyanobacteria like Microcystis, which are known for the synthesis of microcystins, are one of the main producers of natural organobromines. However, very little is known about how environmental realistic concentrations of organobromines impact invertebrates. Here, the nematode C. elegans was exposed to AOBr-containing surface water samples and to a Microcystis aeruginosa enriched batch culture (MC-BA) and compared to single organobromines and microcystin-LR exposures. Stimulatory effects were observed in certain life trait variables, which were particularly pronounced in nematodes exposed to MC-BA. A whole genome DNA-microarray revealed that MC-BA led to the differential expression of more than 2000 genes, many of which are known to be involved in metabolic, neurologic, and morphologic processes. Moreover, the up-regulation of cyp- and the down-regulation of abu-genes suggested the presence of chronic stress. However, the nematodes were not marked by negative phenotypic responses. The observed difference in MC-BA and microcystin-LR (which impacted lifespan, growth and reproduction) exposed nematodes was hypothesized to be likely due to other compounds within the batch culture. Most likely the exposure to low concentrations of organobromines appears to buffer the effects of toxic substances, like microcystin-LR. Nematodes were exposed to filtrated samples of Lake Stößensee Berlin (August and October) and compared to the control-group (exposure to water). Furthermore, nematodes were exposed to filtrated M. aeruinosa batch culture samples and compared to another control-group (exposure to Z-Medium). Three samples (biological replicates) were prepared for each group.
Project description:As an essential primary producer, cyanobacteria play an important role in the global cycle for both carbon and nitrogen in the ecosystems. Though the influence of nanoplastics on the carbon metabolism of cyanobacteria, especial Microcystis aeruginosa, a dominant species causing cyanobacterial blooms, is well studied, little is known about nanoplastics affecting the nitrogen metabolism.
Project description:<p>Cyanobacterial harmful algal blooms (cHABs) dominated by <em>Microcystis aeruginosa</em> threaten the ecological integrity and beneficial uses of lakes globally. In addition to producing hepatotoxic microcystins (MC), <em>M. aeruginosa</em> exudates (MaE) contain various compounds with demonstrated toxicity to aquatic biota. Previously, we found that the ecotoxicity of MaE differed between MC-producing and MC-free strains at exponential (E-phase) and stationary (S-phase) growth phases. However, the components in these exudates and their specific harmful effects were unclear. In this study, we performed untargeted metabolomics based on liquid chromatography-mass spectrometry to reveal the constituents in MaE of a MC-producing and a MC-free strain at both E-phase and S-phase. A total of 409 metabolites were identified and quantified based on their relative abundance. These compounds included lipids, organoheterocyclic compounds, organic acid, benzenoids and organic oxygen compounds. Multivariate analysis revealed that strains and growth phases significantly influenced the metabolite profile. The MC-producing strain had greater total metabolites abundance than the MC-free strain at S-phase, whereas the MC-free strain released higher concentrations of benzenoids, lipids, organic oxygen, organic nitrogen and organoheterocyclic compounds than the MC-producing strain at E-phase. Total metabolites had higher abundance in S-phase than in E- phase in both strains. Analysis of differential metabolites (DMs) and pathways suggest that lipids metabolism and biosynthesis of secondary metabolites were more tightly coupled to growth phases than to strains. Abundance of some toxic lipids and benzenoids DMs were significantly higher in the MC-free strain than the MC-producing one. This study builds on the understanding of MaE chemicals and their biotoxicity, and adds to evidence that non-MC-producing strains of cyanobacteria may also pose a threat to ecosystem health.</p>
Project description:Microcystins are produced by the cyanobacteria, most commonly Microcystis aerµginosa. Upon ingestion, toxic microcystins are actively absorbed by fish, birds and mammals where they are primarily liver toxins. Groups of 4-6 rats were exposed to 0, 1, 10, 50 or 100 µg/kg microcystin-LR for 0.5, 1, 3 or 6 hours and gene expression analysis performed on liver with samples hybridized to whole rat genome RG230_2.0 GeneChip arrays (Affymetrix, CA).
Project description:Cyanobacteria produce various cyanotoxins, which can cause severe effects to other organisms. Microcystins, one group of such toxins, primarily produced by species of Microcystis, are strong hepatotoxins and inhibit potently protein phosphatases 1 and 2A. Microcystin is the most studied cyanotoxin, however, others are not investigated. Eutrophication of water bodies promotes the occurrence of toxic algal blooms and since a anthropogenic caused increase in eutrophication events can be observed, it is becoming increasingly important to study the consequences and to increase the knowledge on toxins associated with algal blooms. Recently a new cyanobacteria toxin from a Microcystis strain, CP1020, was described. CP1020 belongs to the class of cyanopeptolins and its toxicity was shown to be comparable to that of microcystin (Gademann et al., 2009). It is a strong protease inhibitor inhibiting trypsin in the picomolar range (IC50 = 670 pM) and effects survival of the freshwater crustacean Thamnocephalus platyurus (LC50) 8.8 μM (Gademann et al., 2009). Nothing is known, however, about the toxicity of CP1020 to fish. Furthermore, no information is available on the toxic modes of action, in addition to the proteinase activity. Consequently our study has the aim to elucidate the modes of action of CP1020 on zebrafish eleuthero-embryos. By using a microarray technique, we will analyse alterations of global gene expression by CP1020 at two different concentrations. Thereby, we hope to elucidate the whole array of affected biological pathways to elucidate the mechanisms by which CP1020 affect fish.
Project description:Microcystis aeruginosa cells were treated with phosphorus repletion, depletion and starvation. Isobaric tags for relative and absolute quantitation (iTRAQ) proteomic method was employed to explore to the effects of phosphorus limitation on Microcystis aeruginosa cells at the protein level. This investigation would contribute to the understanding of global cellular responses of Microcystis to phosphorus limitation and provide theoretical basis for deciding whether it is an effective way to control Microcystis blooms by phosphorus reduction.
Project description:Cyanobacteria produce various cyanotoxins, which can cause severe effects to other organisms. Microcystins, one group of such toxins, primarily produced by species of Microcystis, are strong hepatotoxins and inhibit potently protein phosphatases 1 and 2A. Microcystin is the most studied cyanotoxin, however, others are not investigated. Eutrophication of water bodies promotes the occurrence of toxic algal blooms and since a anthropogenic caused increase in eutrophication events can be observed, it is becoming increasingly important to study the consequences and to increase the knowledge on toxins associated with algal blooms. Recently a new cyanobacteria toxin from a Microcystis strain, CP1020, was described. CP1020 belongs to the class of cyanopeptolins and its toxicity was shown to be comparable to that of microcystin (Gademann et al., 2009). It is a strong protease inhibitor inhibiting trypsin in the picomolar range (IC50 = 670 pM) and effects survival of the freshwater crustacean Thamnocephalus platyurus (LC50) 8.8 M-NM-<M (Gademann et al., 2009). Nothing is known, however, about the toxicity of CP1020 to fish. Furthermore, no information is available on the toxic modes of action, in addition to the proteinase activity. Consequently our study has the aim to elucidate the modes of action of CP1020 on zebrafish eleuthero-embryos. By using a microarray technique, we will analyse alterations of global gene expression by CP1020 at two different concentrations. Thereby, we hope to elucidate the whole array of affected biological pathways to elucidate the mechanisms by which CP1020 affect fish. Gene expression in zebrafish eleuthero-embryos was measured after exposure for 96h to 100 ug/L and 1000 ug/L CP1020 or to the respective controls. A total of 12 arrays (Agilent 4 M-CM-^W 44 K Zebrafish microarray) were used, including four for the solvent control group, four for the 100 M-NM-<g/L and four for the 1000 M-NM-<g/L CP1020 dose group.