Project description:Prymnesium parvum is regarded as one of the most notorious harmful algal bloom (HAB) species worldwide. In recent years, it has frequently formed toxic blooms in coastal and brackish waters of America, Europe, Australia, Africa and Asia, causing large-scale mortalities of wild and cultured fish and other gill-breathing animals. In the last decade, blooms of P. parvum have expanded to inland fresh waters in the USA, presumably due to changes in environmental conditions. The aim of the experiment was to establish the gill transcriptomic responses to P. parvum in rainbow trout. We used 2 different concentrations of P. parvum and identified fish with low and moderate responses to the algae. Based on the dose of and the fish response, fish were classified into 4 groups with high exposure/moderate response (HM), high exposure/low response (HL), low exposure/low response (LL) and control group (C) with no exposure/no response. Gene expression profiling of the gill tissue was performed using a microarray platform developed and validated for rainbow trout.
Project description:Phytoplankton blooms provoke bacterioplankton blooms, from which bacterial biomass (necromass) is released via increased zooplankton grazing and viral lysis. While bacterial consumption of algal biomass during blooms is wellstudied, little is known about the concurrent recycling of these substantial amounts of bacterial necromass. We demonstrate that bacterial biomass, such as bacterial alpha-glucan storage polysaccharides, generated from the consumption of algal organic matter, is reused and thus itself a major bacterial carbon source in vitro and during a diatom-dominated bloom. We highlight conserved enzymes and binding proteins of dominant bloom-responder clades that are presumably involved in the recycling of bacterial alpha-glucan by members of the bacterial community. We furthermore demonstrate that the corresponding protein machineries can be specifically induced by extracted alpha-glucan-rich bacterial polysaccharide extracts. This recycling of bacterial necromass likely constitutes a large-scale intra-population energy conservation mechanism that keeps substantial amounts of carbon in a dedicated part of the microbial loop.
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:Phytoplankton blooms represent hotspots of primary production and lead to the formation of particulate organic matter composed of living and dead algal cells. These particles are characterized by steep chemical gradients, for instance in oxygen concentration, that provide diverse ecological niches for specifically adapted microbes to thrive. Particulate fractions were collected at almost daily intervals between early March and late May in 2018. Amplicon sequencing and Meta-omics was used to asses microbial community composition and functionality at different time points.
Project description:Lytic viruses have been implicated in the massive cellular lysis observed during algal blooms, through which they assume a prominent role in oceanic carbon and nutrient flows. Despite their impact on biogeochemical cycling, the transcriptional dynamics of these important oceanic events is still poorly understood. Here, we employ an oligonucleotide microarray to monitor host (Emiliania huxleyi) and virus (coccolithovirus) transcriptomic features during the course of E. huxleyi blooms induced in seawater-based mesocosm enclosures. Host bloom development and subsequent coccolithovirus infection was associated with a major shift in transcriptional profile. In addition to the expected metabolic requirements typically associated with viral infection (amino acid and nucleotide metabolism, as well as transcription- and replication-associated functions), the results strongly suggest that the manipulation of lipid metabolism plays a fundamental role during host-virus interaction. The results herein reveal the scale, so far massively underestimated, of the transcriptional domination that occurs during coccolithovirus infection in the natural environment. Six mesocosm enclosures were placed in the Raunefjorden (Western Norway coast) and filled with natural community water (in June 2008). Nutrient enrichment was applied in order to trigger the development of E. huxleyi blooms. The major transcriptomic features of those blooms and consequent viral infections were monitered through the use of an oligo microarray containing a total of 3571 gene probes; 2271 (63.6%) matching E. huxleyi ESTs, and 1300 (36.4%) matching EhV-86 and EhV-163 genomic sequences. Each microarray contains 5 technical replicates. Sampling of total RNA present in 2L of water (from each enclosure) was performed once a day from day 8 to day 16. For enclosures 2 and 3 other sampling points were taken, covering the complete dial-cycle (6h,12h,18h, and 24h).
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.