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Linda K Medlin - One of the best experts on this subject based on the ideXlab platform.
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an assessment of rna content in Prymnesium parvum Prymnesium polylepis cf chattonella sp and karlodinium veneficum under varying environmental conditions for calibrating an rna microarray for species detection
FEMS Microbiology Ecology, 2014Co-Authors: Gary R Mccoy, Jessica Kegel, Nicolas Touzet, Gerard T A Fleming, Linda K Medlin, Robin RaineAbstract:Traditional methods of identification and enumeration can be somewhat ambiguous when identifying phytoplankton that requires electron microscopic examination to verify specific morphological features. Members of the genus Prymnesium (division Haptophyta), members of the Raphidophyceae and naked dinoflagellates are examples of such phytoplankton whose identification can be difficult. One alternative to traditional microscopy-based methods of identification is to use molecular protocols to detect target species. Methods that measure cellular DNA and RNA content can be used to estimate the number of cells present in a sample. This study investigated the variation of RNA yields in Prymnesium parvum, P. polylepis, cf. Chattonella sp. and Karlodinium veneficum cells grown under different light, temperature, salinity and inorganic nutrient conditions. This information was used to calibrate the signal intensity of a variety of oligonucleotide probes spotted onto the microarrays for the detection of toxic algae (MIDTAL), which is being developed to aid national monitoring agencies and to provide a faster means of identifying and quantifying harmful phytoplankton in water column samples.
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automated detection and enumeration for toxic algae by solid phase cytometry and the introduction of a new probe for Prymnesium parvum haptophyta prymnesiophyceae
Journal of Plankton Research, 2006Co-Authors: Kerstin Tobe, Gundula Eller, Linda K MedlinAbstract:Harmful algal blooms have a severe impact on aquaculture and fishery and can be caused by toxic haptophytes and dinoflagellates. Different toxic species, which are not easy to distinguish from their morphologically similar and non-toxic relatives, occur in both groups. Sequencing of the large subunit ribosomal RNA of different strains and taxonomic relatives allowed the design of a probe specific to the toxic Prymnesium parvum spp. For the rapid detection and enumeration of Prymnesium and Alexandrium cells in cultures and environmental samples, respectively, protocols for fluorescence in situ hybridization were adapted for automated detection by a solid-phase cytometer, the ChemScan. This cytometer enables the automated counting of fluorescently labelled cells on a membrane filter and subsequently a microscopic verification of these results by the user, because the motorized stage of the microscope is driven to each positive signal by the computer software to localize that cell on the filter. With this fast detection method, it was possible to detect, enumerate and verify microalgal cells on a filter, with a detection limit of one cell per membrane filter.
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Phylogenetic reconstructions of the Haptophyta inferred from 18S ribosomal DNA sequences and available morphological data
Phycologia, 2000Co-Authors: Bente Edvardsen, J. C. Green, Wenche Eikrem, Robert A. Andersen, Seung Yeo Moon-van Der Staay, Linda K MedlinAbstract:Abstract Most haptophytes are unicellular, photosynthetic flagellates, although some have coccoid, colonial, amoeboid, or filamentous stages. Nearly all have a characteristic filamentous appendage, the haptonema, arising between the two flagella. The small subunit ribosomal RNA gene (l8S ribosomal DNA) from 18 haptophyte species has been sequenced, and the sequences aligned with those of more than 300 published and unpublished chlorophyll a + c algae. Phylogenies were constructed using maximum likelihood, neighbor-joining, and weighted maximum parsimony analyses. The high divergence (6%) between members of Pavlova and the remaining haptophytes supports the division of Haptophyta into two classes: Prymnesiophyceae and Pavlovophyceae. Three major clades that correspond to known taxa within the Prymnesiophyceae were identified: one clade embraces Phaeocystis spp.; the second includes members of the genera Chrysochromulina, Prymnesium, and Imantonia; and the third includes coccolithophorid genera and the genu...
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inter and intraspecific genetic variation in twelve Prymnesium haptophyceae clones
Journal of Phycology, 1997Co-Authors: Aud Larsen, Linda K MedlinAbstract:The haptophytes Prymnesium parvum Carter and Prymnesium patelliferum Green, Hibberd, and Pienaar are two closely related species, which can only be distinguished by minor differences in the morphology of their organic body scales. The two Prymnesium species are reported to coexist at several locations, including the Sands-fjord system in southwestern Norway. Comparisons of physiology and toxicity within the two species have failed to reveal differences that can add to the small morphological distinctions used to separate them. To investigate the genetic relationship between the two species, we compared the sequence of the first internal transcribed spacer region (ITS1)and length variation in one intron separating calmodulin genes for four P. parvum strains and eight P. patelliferum strains. Both the ITS1 sequence and the banding patterns obtained by PCR amplification of one intron in the calmodulin genes indicated that the Prymnesium isolates are related by their geographic origin instead of 4 their species affiliation. The results indicate that P. parvum and P. patelliferum are so closely related that they could be considered one species. Alternatively, we discuss the possibility that the two species might be joined in a heteromorphic haploid-diploid life cycle, as is now widely reported for other haptophycean algae.
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The identification of Chrysochromulina and Prymnesium species (Haptophyta, Prymnesiophyceae) using fluorescent or chemiluminescent oligonucleotide probes: a means for improving studies on toxic algae
European Journal of Phycology, 1997Co-Authors: Nathalie Simon, Joachim Brenner, Linda K MedlinAbstract:Chrysochromulina and Prymnesium are important bloom-forming organisms in marine and brackish waters, respectively. Both genera include toxic species, which are primarily implicated in fish kills. Previous analyses of small subunit (SSU) rDNA sequences from Chrysochromulina and Prymnesium spp. indicate that Chrysochromulina is paraphyletic. C. polylepis, which produced a spectacular, harmful bloom in 1988, is more closely related to toxic Prymnesium species than to most other Chrysochromulina species based on rDNA sequence comparisons. Signatures were identified in the SSU rRNA gene specific for a clade that comprised primarily toxic taxa (C. polylepis, P. parvum, P. patelliferum and P. calathiferum) and that recognized C. polylepis alone. Oligonucleotide probes complementary to these regions were designed, and their specificity tested using dot-blot hybridization on PCR products of the SSU rRNA gene from 28 strains of Chrysochromulina and Prymnesium. Whole-cell hybridizations were performed with FLUOS- as...
Bente Edvardsen - One of the best experts on this subject based on the ideXlab platform.
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characterisation of three novel giant viruses reveals huge diversity among viruses infecting prymnesiales haptophyta
Virology, 2015Co-Authors: Torill Vik Johannessen, Gunnar Bratbak, Bente Edvardsen, Wenche Eikrem, Aud Larsen, Hiroyuki Ogata, Elianne Sirnaes Egge, Ruthanne SandaaAbstract:We have isolated three novel lytic dsDNA-viruses from Raunefjorden (Norway) that are putative members of the Mimiviridae family, namely Haptolina ericina virus RF02 (HeV RF02), Prymnesium kappa virus RF01 (PkV RF01), and Prymnesium kappa virus RF02 (PkV RF02). Each of the novel haptophyte viruses challenges the common conceptions of algal viruses with respect to host range, phylogenetic affiliation and size. PkV RF01 has a capsid of ~310 nm and is the largest algal virus particle ever reported while PkV RF01 and HeV RF02 were able to infect different species, even belonging to different genera. Moreover, PkV RF01 and HeV RF02 infected the same hosts, but phylogenetic analysis placed them in different groups. Our results reveal large variation among viruses infecting closely related microalgae, and challenge the common conception that algal viruses have narrow host range, and phylogeny reflecting their host affiliation.
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the ecophysiology and bloom dynamics of Prymnesium spp
Harmful Algae, 2012Co-Authors: Edna Granéli, Bente Edvardsen, Daniel L Roelke, Johannes A HagstromAbstract:Abstract Members of Prymnesium belong to the division Haptophyta, class Prymnesiophyceae, order Prymnesiales and family Prymnesiaceae. As most haptophytes, members of the genus Prymnesium are unicellular and planktonic. The most known of these species is the ichthyotoxic P. parvum, which may form nearly monospecific dense blooms in coastal and inland waters. This species possesses extraordinary plasticity concerning life survival strategies, and is specifically addressed in this review. Toxins produced by P. parvum have hemolytic properties, that not only kill fish but also co-existing plankton. These substances are allelopathic (when other algae are killed) and grazer deterrent (when grazers are killed). Allelopathy enables P. parvum to utilize inorganic nutrients present in the surrounding water without competition from other algal species; and by eliminating its grazers P. parvum reduces cell losses. The paralized microalgae and/or zooplankton, are therefter ingested by the P. parvum cells, a process called phagotrophy. P. parvum is also able of osmotrophy, i.e. utilization of dissolved organic matter. In this review, the cellular characteristics, life cycles, bloom formation, and factors affecting toxicity, allelopathy, phagotrophy, and osmotrophy of P. parvum are discussed.
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fine structure and systematics of Prymnesium radiatum sp nov prymnesiophyceae from false bay and franskraal south africa
European Journal of Phycology, 2011Co-Authors: Stuart D Sym, Bente Edvardsen, Richard N Pienaar, Elianne EggeAbstract:A novel colonial prymnesiophyte from the inshore waters of South Africa, which is reminiscent of the genus Corymbellus, is described at light and electron microscope levels. It differs from the only species of this genus, Corymbellus aureus, in scale structure, cell shape and colony morphology and has a complement of unusual morphological features that link it most with members of the Prymnesiales. Phylogenetic analyses of the nuclear-encoded SSU and LSU ribosomal DNA sequences indicate that this organism is closely related to members of the genus Prymnesium sensu lato and it is thus considered as a novel species, here named P. radiatum. The closest relative to P. radiatum in the SSU rDNA phylogenetic tree was Prymnesium neolepis (formerly Hyalolithus neolepis). The reconfiguration of the cytoskeleton during cell division in this organism is also novel, with a progressive elaboration of existing elements, rather than the massive reorganization expected in the prymnesiophytes.
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Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta)
European Journal of Phycology, 2011Co-Authors: Bente Edvardsen, Alberto G. Sáez, Ian Probert, Wenche Eikrem, Jahn Throndsen, Linda MedlinAbstract:Nucleotide sequences of the nuclear-encoded small subunit (18S rDNA) and partial large subunit (28S rDNA) ribosomal DNA were determined in 30 different species of the haptophyte genera Prymnesium, Chrysocampanula, Chrysochromulina, Imantonia and Platychrysis, all belonging to the order Prymnesiales. Phylogenies based on these and other available haptophyte 18S, 28S and plastid 16S rDNA sequences were reconstructed, and compared with available morphological and ultrastructural data. The rDNA phylogenies indicate that the genus Chrysochromulina is paraphyletic and is divided into two major clades. This is supported by ultrastructural and morphological data. There is a major split between Chrysochromulina species with a saddle-shaped cell form (clade B2) and the remaining species in the genus (clade B1). Clade B2 includes the type species C. parva and taxa belonging to this clade thus retain the name Chrysochromulina. The non-saddle-shaped Chrysochromulina species analysed are closely related to Hyalolithus, Prymnesium and Platychrysis species. Imantonia species are sister taxa to these species within clade B1. An amendment to the classification of the order Prymnesiales and the genera Prymnesium, Platychrysis and Chrysochromulina is proposed with one new and one emended family (Chrysochromulinaceae and Prymnesiaceae, respectively), two new genera (Haptolina and Pseudohaptolina), and one new species (Pseudohaptolina arctica). We suggest a revision of the taxonomy of the Prymnesiales that is in accordance with available molecular evidence and supported by morphological data.
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Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta
2011Co-Authors: Bente Edvardsen, Ian Probert, Wenche Eikrem, Jahn Throndsen, Alberto G. Sáez, K. MedlinAbstract:Nucleotide sequences of the nuclear-encoded small subunit (18S rDNA) and partial large subunit (28S rDNA) ribosomal DNA were determined in 30 different species of the haptophyte genera Prymnesium, Chrysocampanula, Chrysochromulina, Imantonia and Platychrysis, all belonging to the order Prymnesiales. Phylogenies based on these and other available hapto-phyte 18S, 28S and plastid 16S rDNA sequences were reconstructed, and compared with available morphological and ultrastructural data. The rDNA phylogenies indicate that the genus Chrysochromulina is paraphyletic and is divided into two major clades. This is supported by ultrastructural and morphological data. There is a major split between Chrysochromulina species with a saddle-shaped cell form (clade B2) and the remaining species in the genus (clade B1). Clade B2 includes the type species C. parva and taxa belonging to this clade thus retain the name Chrysochromulina. The non-saddle-shaped Chrysochromulina species analysed are closely related to Hyalolithus, Prymnesium and Platychrysis species. Imantonia species are sister taxa to these species within clade B1. An amendment to the classification of the order Prymnesiales and the genera Prymnesium, Platychrysis and Chrysochromulina is proposed with one new and one emended family (Chrysochromulinaceae and Prymnesiaceae, respectively), two new genera (Haptolina and Pseudohaptolina), and one new species (Pseudohaptolina arctica). We suggest a revision of the taxonomy of the Prymnesiales that is in accordance with available molecular evidenc
Edna Granéli - One of the best experts on this subject based on the ideXlab platform.
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The effects of aeration on growth and toxicity of Prymnesium parvum grown with and without algal prey
Harmful Algae, 2014Co-Authors: Nayani K. Vidyarathna, Emanuela Fiori, Veronica M. Lundgren, Edna GranéliAbstract:We investigated the effects of aeration on growth and toxicity of the haptophyte Prymnesium parvum in the presence and absence of the algal prey Rhodomonas salina. Batch monocultures of P-limited P ...
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the ecophysiology and bloom dynamics of Prymnesium spp
Harmful Algae, 2012Co-Authors: Edna Granéli, Bente Edvardsen, Daniel L Roelke, Johannes A HagstromAbstract:Abstract Members of Prymnesium belong to the division Haptophyta, class Prymnesiophyceae, order Prymnesiales and family Prymnesiaceae. As most haptophytes, members of the genus Prymnesium are unicellular and planktonic. The most known of these species is the ichthyotoxic P. parvum, which may form nearly monospecific dense blooms in coastal and inland waters. This species possesses extraordinary plasticity concerning life survival strategies, and is specifically addressed in this review. Toxins produced by P. parvum have hemolytic properties, that not only kill fish but also co-existing plankton. These substances are allelopathic (when other algae are killed) and grazer deterrent (when grazers are killed). Allelopathy enables P. parvum to utilize inorganic nutrients present in the surrounding water without competition from other algal species; and by eliminating its grazers P. parvum reduces cell losses. The paralized microalgae and/or zooplankton, are therefter ingested by the P. parvum cells, a process called phagotrophy. P. parvum is also able of osmotrophy, i.e. utilization of dissolved organic matter. In this review, the cellular characteristics, life cycles, bloom formation, and factors affecting toxicity, allelopathy, phagotrophy, and osmotrophy of P. parvum are discussed.
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Nitrogen uptake kinetics of Prymnesium parvum (Haptophyte)
Harmful Algae, 2011Co-Authors: Elin Lindehoff, Edna Granéli, Patricia M. GlibertAbstract:Abstract The uptake rates of different nitrogen (N) forms (NO 3 − , urea, and the amino acids glycine and glutamic acid) by N-deficient, laboratory-grown cells of the mixotrophic haptophyte, Prymnesium parvum , were measured and the preference by the cells for the different forms determined. Cellular N uptake rates ( ρ cell , fmol N cell −1 h −1 ) were measured using 15 N-labeled N substrates. P. parvum showed high preference for the tested amino acids, in particular glutamic acid, over urea and NO 3 − under the culture nutrient conditions. However, extrapolating these rates to Baltic Seawater summer conditions, P. parvum would be expected to show higher uptake rates of NO 3 − and the amino acids relative to urea because of the difference in average concentrations of these substrates. A high uptake rate of glutamic acid at low substrate concentrations suggests that this substrate is likely used through extracellular enzymes. Nitrate, urea and glycine, on the other hand, showed a non-saturating uptake over the tested substrate concentration (1–40 μM-N for NO 3 − and urea, 0.5–10 μM-N for glycine), indicating slower membrane-transport rates for these substrates.
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factors influencing allelopathy and toxicity in Prymnesium parvum
Journal of The American Water Resources Association, 2010Co-Authors: Edna Granéli, Paulo S SalomonAbstract:Graneli, Edna and Paulo S. Salomon, 2010. Factors Influencing Allelopathy and Toxicity in Prymnesium parvum. Journal of the American Water Resources Association (JAWRA) 46(1):108-120. Abstract: Some microalgae are able to kill or inhibit nutrient-competing microalgae, a process called allelopathy. Inhibiting or killing competitors enable these species to monopolize limiting resources, such as nitrogen and phosphorus. Prymnesium parvum is known to produce such allelopathic compounds, substances that seem identical to the ichthyotoxins identified from this species. Biotic and abiotic environmental factors influence not only growth rates but also toxin/allelopathic compounds production by P. parvum cells. Toxin production, as well as allelopathy, including grazer deterrence, increases dramatically in light, temperature, or nutrient stressed P. parvum cells. Correspondingly, toxicity and allelopathy may decrease, or cease completely, if cells are grown with high amounts of N and P in balanced proportions. However, even under nutrient (N and P) sufficient conditions, P. parvum is able to produce toxins/allelopathic compounds, with negative effects on other phytoplankton species or grazers, if cells densities of P. parvum are high relative to other species. This negative effect might shift the plankton community to more toxin resistant species. Filtrates from nutrient-deficient P. parvum cultures have almost the same strong negative effect on grazers and other phytoplankton species as when Prymnesium cells are grown together with the target organisms. Eutrophication, the increased input of N and P to aquatic ecosystems, besides increasing nutrient concentrations, is usually provoking unbalanced N:P condition for the optimal growth of phytoplankton, deviating from the Redfield ratio, i.e., the phytoplankton cellular nitrogen to phosphorus ratio, N:P = 16:1 (by atoms) or 7.2:1 (by weight). Eutrophication thus both enhances P. parvum growth and increases production of toxins and allelopathic compounds. Supplying N-deficient or P-deficient P. parvum cells with the deficient nutrient reduces toxicity to less than half within 24 h after additions. As P. parvum is mixotrophic, uptake of dissolved or particulate organic N (DON or PON) can also reduce toxicity and allelopathy in the same manner as addition of inorganic N to N-starved cells. In conclusion, P. parvum, by increasing its toxicity and allelopathic ability under poor environmental conditions, outcompetes the co-occurring phytoplankton species.
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influence of prey and nutritional status on the rate of nitrogen uptake by Prymnesium parvum haptophyte
Journal of The American Water Resources Association, 2010Co-Authors: Elin Lindehoff, Edna Granéli, Patricia M. GlibertAbstract:Lindehoff, Elin, Edna Graneli, and Patricia M. Glibert, 2010. Influence of Prey and Nutritional Status on the Rate of Nitrogen Uptake by Prymnesium parvum (Haptophyte). Journal of the American Water Resources Association (JAWRA) 46(1):121-132. DOI: 10.1111/j.1752-1688.2009.00396.x Abstract: We studied how the specific nitrogen (N) uptake rates of nitrate (NO3−), urea, and the amino acids, glutamic acid and glycine, by Prymnesium parvum were affected by (1) the change from N-deficient status to N-sufficient status of the P. parvum cells, (2) presence of prey from a natural Baltic Sea plankton community, and (3) the composition of prey as affected by additions of terrestrial originated dissolved organic matter (DOM) or inorganic nutrients. Nitrogen-deficient P. parvum (16 μM NO3− and 4 μM PO4−, molar N:P ratio of 4:1) were mixed with a natural Baltic plankton community and given PO43− and (1) NO3− (control) or (2) high molecular weight DOM, >1 kDa concentrated from sewage effluent (+DOM), in a molar N:P ratio of 9-10:1. With additions of 15N-enriched substrates, rates of N uptake from NO3−, urea, and the amino acids glycine and glutamic acid were measured every 24 h for 72 h. Initial N-deficient P. parvum were highly toxic (3.7 ± 0.9 × 10−4 mg Sap equiv/cell) and toxic allelochemicals were released into the medium causing the natural plankton community to lyse. Rates of N uptake differed between the “control” and the “+DOM” treatments over time; total (sum of the N substrates measured) absolute uptake rates (ρcell, fmol N/cell/h) at ambient culture conditions were significantly higher (ANOVA, p < 0.05) in the more toxic “control” treatments compared with the “+DOM” treatments after 48 h. In the “control” treatment, the total ρcell increased significantly (ANOVA, p < 0.01) from time 0 to 48 h, while in the “+DOM” treatment there was no significant increase. Released organic nutrients from the lysed plankton cells may have increased uptake rates of amino acids and urea by P. parvum. All uptake rates declined in all treatments by 72 h. Total dissolved N uptake rates at ambient culture conditions were estimated to make up about 10% of the N P. parvum are potentially capable of ingesting from particulate prey.
John W La Claire - One of the best experts on this subject based on the ideXlab platform.
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transcriptome analysis of the euryhaline alga Prymnesium parvum prymnesiophyceae effects of salinity on differential gene expression
Phycologia, 2016Co-Authors: Aimee Talarski, Schonna R Manning, John W La ClaireAbstract:Abstract: There is limited information on the underlying physiological responses and molecular mechanisms involved in the ability of the ichthyotoxic alga, Prymnesium parvum, to tolerate a broad range of salinities. We report an RNA sequencing analysis of the transcriptome of P. parvum, including a de novo assembly generating 47,289 transcripts. Of them, 35.4% were identifiable, and 30.4% and 16.8% were classified into gene ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, respectively. Cultures were grown in media at salinities of 5 and 30 practical salinity units (psu), and the differential expression of 2507 transcripts (5.3%) was detected. Specifically, 1507 (3.2%) and 1000 (2.1%) transcripts were up- and downregulated, respectively, at 30 vs 5 psu. Relevant candidate genes identified included those whose products are involved in osmolyte production, salinity stress, ion transport, and acetate metabolism. Thirty-two different polyketide synthase (PKS) transcripts we...
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isolation of polyketides from Prymnesium parvum haptophyta and their detection by liquid chromatography mass spectrometry metabolic fingerprint analysis
Analytical Biochemistry, 2013Co-Authors: Schonna R Manning, John W La ClaireAbstract:Abstract Prymnesium parvum is a microalga that forms blooms coupled with the presence of potent exotoxins; however, no chemical standards are currently available for the toxins. Streamlined methods are presented for the separation and enrichment of polyketide toxins, prymnesin-1 (prym1) and prymnesin-2 (prym2). Prymnesins were separated by reversed-phase chromatography and detected by positive-mode electrospray ionization MS to generate a unique metabolic fingerprint. More than 10 ions were detected and mass assignments were in agreement with predicted isotopic distributions for the intact compounds and related fragments; ions occurred as multiply protonated species and with common salt adducts. The most prevalent ion was observed at 919.88 m / z , which represents the aglycone [prym agly + 2H] 2+ backbone structure common to both molecules. Expanded mass spectra for this and related ions were in excellent agreement ( P. parvum .
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Prymnesins: toxic metabolites of the golden alga, Prymnesium parvum Carter (Haptophyta).
Marine drugs, 2010Co-Authors: Schonna R Manning, John W La ClaireAbstract:Increasingly over the past century, seasonal fish kills associated with toxic blooms of Prymnesium parvum have devastated aquaculture and native fish, shellfish, and mollusk populations worldwide. Protracted blooms of P. parvum can result in major disturbances to the local ecology and extensive monetary losses. Toxicity of this alga is attributed to a collection of compounds known as prymnesins, which exhibit potent cytotoxic, hemolytic, neurotoxic and ichthyotoxic effects. These secondary metabolites are especially damaging to gill-breathing organisms and they are believed to interact directly with plasma membranes, compromising integrity by permitting ion leakage. Several factors appear to function in the activation and potency of prymnesins including salinity, pH, ion availability, and growth phase. Prymnesins may function as defense compounds to prevent herbivory and some investigations suggest that they have allelopathic roles. Since the last extensive review was published, two prymnesins have been chemically characterized and ongoing investigations are aimed at the purification and analysis of numerous other toxic metabolites from this alga. More information is needed to unravel the mechanisms of prymnesin synthesis and the significance of these metabolites. Such work should greatly improve our limited understanding of the physiology and biochemistry of P. parvum and how to mitigate its blooms.
Uwe John - One of the best experts on this subject based on the ideXlab platform.
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transcriptomic response of the toxic prymnesiophyte Prymnesium parvum n carter to phosphorus and nitrogen starvation
Harmful Algae, 2012Co-Authors: Sara Beszteri, Gernot Glöckner, Allan Cembella, Ines Yang, Nina Jaeckisch, Urban Tillmann, Stephan Frickenhaus, Uwe JohnAbstract:The ichthyotoxic and mixotrophic prymnesiophyte Prymnesium parvum is known to produce dense virtually monospecific blooms in marine coastal, brackish, and inshore waters. Fish-killing Pyrmnesium blooms are often associated with macronutrient imbalanced conditions based upon shifts in ambient nitrogen (N):phosphorus (P) ratios. We therefore investigated nutrient-dependent cellular acclimation mechanisms of this microalga based upon construction of a normalized expressed sequence tag (EST) library. We then profiled the transcriptome of P. parvum under nutrient-replete conditions as well as under nitrogen (N) and phosphorus (P) limitation via microarray analyses. Twenty-three genes putatively involved in acclimation to low nutrient levels were identified, among them three phosphate transporters, which were highly upregulated under P-starvation. In contrast, the expression of genes involved in transport and acquisition of ammonium or nitrate/nitrite was unaltered in N-starved cells. We propose that genes upregulated under P- or N-starvation lend themselves as potential tools to monitor nutrient limitation effects at the cellular level and indirectly the potential for initiation and maintenance of toxic blooms of P. parvum.
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effects of physiological shock treatments on toxicity and polyketide synthase gene expression in Prymnesium parvum prymnesiophyceae
European Journal of Phycology, 2011Co-Authors: Michael Freitag, Sara Beszteri, Heiko Vogel, Uwe JohnAbstract:The toxic prymnesiophyte Prymnesium parvum has been linked to massive fish kills worldwide. The toxic blooms have been shown to be derived from a seed population, abiotic conditions such as temperature, salinity and water turbulence having encouraged massive growth of the Prymnesium population. Within its highly fluctuating coastal marine niche, P. parvum must acclimate rapidly to changing conditions. Although studies on the physiology and toxicity of P. parvum exist, examination of gene expression in such analyses is novel. In this study we investigate (1) relative toxicity (intracellular vs. extracellular) and (2) differential gene expression of three polyketide synthase (PKS) transcripts via real-time PCR (qPCR). It was hypothesized that these genes play a role in the production of the toxic compounds prymnesin-1 and -2 produced by P. parvum. We found that low salinity shock and high irradiation shock increase different aspects of Prymnesium's toxicity (intra- vs. extracellular). Furthermore, we found ...
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Genomic characterisation of the ichthyotoxic prymnesiophyte Chrysochromulina polylepis, and the expression of polyketide synthase genes in synchronized cultures
European Journal of Phycology, 2010Co-Authors: Uwe John, Linda Medlin, Sara Beszteri, Gernot Glöckner, Rama K. Singh, Allan CembellaAbstract:The widely distributed prymnesiophyte species Chrysochromulina polylepis is prominent and well known for occasional formation of ichthyotoxic blooms. The chemical structure of the C. polylepis toxin(s) has not yet been elucidated, but the associated haemolytic activity, potent membrane disruption interactions and toxicity to finfish and protists have led to the suggestion that they may be similar to the prymnesins of Prymnesium parvum. Such polyether toxins are presumably formed partially or completely via polyketide biosynthetic pathways. In this genetic study of C. polylepis, we generated and analysed a genomic DNA and a normalized cDNA library. We estimated a genome size of approximately 230 mbp based upon analysis of >1000 genomic library clones. Of the cDNA library, 3839 clones were partially sequenced and annotated, representing approximately 2900 unique contigs. We detected several genes putatively related to toxin synthesis. Thirteen putative polyketide synthase (PKS)-related gene sequences were i...
