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- Elbrächter, Malte, et al.
(författare)
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Establishing an Agenda for Calcareous Dinoflagellate Research (Thoracosphaeraceae, Dinophyceae) including a nomenclatural synopsis of generic names
- 2008
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Ingår i: Taxon. - 0040-0262 .- 1996-8175. ; 57:4, s. 1289-1303
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Tidskriftsartikel (refereegranskat)abstract
- Calcareous dinoflagellates are considered to be a monophyletic group of peridinoid taxa that have the potential to produce calcified exoskeletal structures during the life cycle, or that derive from such forms. Frequently, these calcareous bodies are excellently preserved in the fossil record and have received increased attention during the past three decades with regard to their use in biostratigraphy, climate and environmental reconstruction. Fossil and extant taxa have been classified in various, partly concurring, systematic concepts, using character complexes of the theca, cyst wall ultrastructure and archaeopyle/operculum morphology. The significance of such character complexes is briefly discussed in the light of molecular data that have been accumulated during the past decade. Over the years, the number of published taxonomic names has increased, partly due to nomenclatural changes. We propose that the entirety of calcareous dinoflagellates, and non-calcareous relatives derived from them, is accommodated in a single family of the order Peridiniales, the Thoracosphaeraceae, combining the former segregated taxonomic units Calciodinelloideae, a subfamily within Peridiniaceae, and Thoracosphaerales, a separate dinoflagellate order. As a result of a meeting of calcareous dinoflagellate specialists, we outline major subjects that are in need of re-investigation and -evaluation (an Agenda for Calcareous Dinoflagellate Research). In order to contribute to a consistent and stable nomenclature and taxonomy of calcareous dinoflagellates, we list 97 published generic names assigned to known calcareous dinoflagellates in a nomenclatural synopsis, with species names indicating their types and information on type locality and stratigraphy. We evaluate the status of these names—whether validly published and, if so, whether legitimate—,a crucial first step for any revisionary work in the future.
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| 2. |
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| 3. |
- Godhe, Anna, 1967, et al.
(författare)
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Genetic and Microscopic Evidence for Sexual Reproduction in the Centric Diatom Skeletonema marinoi
- 2014
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Ingår i: Protist. - : Elsevier BV. - 1434-4610 .- 1618-0941. ; 165:4, s. 401-416
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Tidskriftsartikel (refereegranskat)abstract
- This study provides microscopic and molecular evidence for sexual reproduction in the homothallic centric diatom Skeletonema marinoi isolated from the Baltic Sea. The species is capable of restoring cell size asexually through an auxospore-like stage. However, cells were sexualized after shifting strains from low (6 PSU) to high (16 PSU) salinity. We observed flagellate male gametes and oogonia, with diameters of 3-4 and 3.2-6.3 m, respectively. Fertilization took place followed by the formation of round auxospores surrounded by thin siliceous incunabular scales. Auxosporulation was synchronized, and a maximum of auxospores was detected on day three following the salinity shift. The proportion of auxospores to vegetative cells ranged from 0.02 to 0.18. There was a significant correlation between auxosporulation success and inoculum cell density. At lower cell concentration (5,000 cells ml-1), pro- portionally fewer auxospores were formed. Auxospores were formed in single strains and in crosses of strains. The proportion of auxospores differed significantly among strains and crosses of strains. Additionally, we isolated single auxospores, obtained F1 strains and performed microsatellite based pedigree analysis of parental generations and their offspring. We proved that the auxospores were formed sexually, either by inter- or by intra-strain fertilization.
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| 4. |
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| 5. |
- Kremp, Anke, et al.
(författare)
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Species-specific encystment patterns in three Baltic cold-water dinoflagellates: The role of multiple cues in resting cyst formation
- 2009
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Ingår i: Limnology and Oceanography. - 1939-5590. ; 54:4, s. 1125-1138
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Tidskriftsartikel (refereegranskat)abstract
- The relationships among cellular nutrient status, environmental conditions (temperature and nutrient availability), and cyst production were studied in batch cultures of three cold-water dinoflagellates (Scrippsiella hangoei, Gymnodinium corollarium, and Woloszynskia halophila) isolated from the Baltic Sea. We tested the effect of increasing temperature while providing nutrient-replete conditions as well as the effect of ambient nutrient (N, P) deficiency. The results revealed different encystment cues and patterns in the three species. While depletion of ambient nitrogen and subsequent internal N stress were the primary factors behind cyst production of G. corollarium, higher temperature led to substantial encystment of S. hangoei and W. halophila without a direct link to cellular nutrient physiology. In W. halophila, N limitation induced a transition of the population to small cells presumably representing gametes, but this process was not followed by cyst formation. Phosphorus stress was not directly linked to cyst formation in any of the species. Our data indicate that both reliable token cues (such as temperature) and ultimate causes (for example, nutrient depletion) for encystment are likely involved in the cystformation process. Such duality might provide an explanation for multiple triggers inducing encystment in laboratory settings and the lack of evidence for a direct relationship between nutrient depletion and cyst formation in the field.
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| 6. |
- McNamee, Sara E., et al.
(författare)
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Distribution, occurrence and biotoxin composition of the main shellfish toxin producing microalgae within European waters : A comparison of methods of analysis
- 2016
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Ingår i: Harmful Algae. - : Elsevier BV. - 1568-9883 .- 1878-1470. ; 55, s. 112-120
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Tidskriftsartikel (refereegranskat)abstract
- Harmful algal blooms (HABs) are a natural global phenomena emerging in severity and extent. Incidents have many economic, ecological and human health impacts. Monitoring and providing early warning of toxic HABs are critical for protecting public health. Current monitoring programmes include measuring the number of toxic phytoplankton cells in the water and biotoxin levels in shellfish tissue. As these efforts are demanding and labour intensive, methods which improve the efficiency are essential. This study compares the utilisation of a multitoxin surface plasmon resonance (multitoxin SPR) biosensor with enzyme-linked immunosorbent assay (ELISA) and analytical methods such as high performance liquid chromatography with fluorescence detection (HPLC-FLD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for toxic HAB monitoring efforts in Europe. Seawater samples (n = 256) from European waters, collected 2009-2011, were analysed for biotoxins: saxitoxin and analogues, okadaic acid and dinophysistoxins 1/2 (VDU /DTX2) and domoic acid responsible for paralytic shellfish poisoning (PSP), diarrheic shellfish poisoning (DSP) and amnesic shellfish poisoning (ASP), respectively. Biotoxins were detected mainly in samples from Spain and Ireland. France and Norway appeared to have the lowest number of toxic samples. Both the multitoxin SPR biosensor and the RNA microarray were more sensitive at detecting toxic HABs than standard light microscopy phytoplankton monitoring. Correlations between each of the detection methods were performed with the overall agreement, based on statistical 2 x 2 comparison tables, between each testing platform ranging between 32% and 74% for all three toxin families illustrating that one individual testing method may not be an ideal solution. An efficient early warning monitoring system for the detection of toxic HABs could therefore be achieved by combining both the multitoxin SPR biosensor and RNA microarray. (C) 2016 Elsevier B.V. All rights reserved.
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| 7. |
- Medlin, Linda K., et al.
(författare)
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MIDTAL (Microarrays for the Detection of Toxic Algae)
- 2013
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Ingår i: Phytotaxa. - : Magnolia Press. - 1179-3155 .- 1179-3163. ; 127:1, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- Microalgae in marine and brackish waters of Europe regularly cause harmful effects, considered from the human perspective, in that they cause economic damage to fisheries and tourism. Cyanobacteria cause similar problems in freshwaters. These episodes encompass a broad range of phenomena collectively referred to as harmful algal blooms (HABs). For adequate management of these phenomena, monitoring of microalgae is required. However, present day monitoring is time consuming and based on morphology as determined by light microscopy, which may be insufficient to give definitive species and toxin attribution. In the European Union (EU) FP7 project MIDTAL (microarrays for the detection of toxic algae), we will first target rapid species identification using rRNA genes. The variable regions of the rRNA genes can be used for probe design to recognize species or even strains. Second, a toxin based microarray will be developed that includes antibody reactions to specific toxins produced by these microalgae because even when cell numbers are low, toxins can be present and can accumulate in the shellfish. Microarrays are the state of the art technology in molecular biology for the processing of bulk samples for detection of target RNA/DNA sequence. Existing rRNA probes and antibodies for toxic algal species/strains and their toxins will be adapted and optimized for microarray use. The purpose of MIDTAL is to support the common fisheries policy and to aid the national monitoring agencies by providing new rapid tools for the identification of toxic algae and their toxins so they can comply with EU directive 91/1491/CEE to monitor for toxic algae, and reduce the need for the mouse bioassay.
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| 8. |
- Tesson, Sylvie V.M., et al.
(författare)
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Mendelian Inheritance Pattern and High Mutation Rates of Microsatellite Alleles in the Diatom Pseudo-nitzschia multistriata.
- 2012
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Ingår i: Protist. - : Elsevier BV. - 1434-4610.
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Tidskriftsartikel (refereegranskat)abstract
- The diatom Pseudo-nitzschia multistriata exhibits a diplontic life cycle composed of an extensive phase of vegetative cell division and a brief phase of sexual reproduction. To explore genotypic stability, we genotyped seven polymorphic microsatellite loci in 26 monoclonal strains over 3-16 months in a culture maintenance regime. Moreover, to assess inheritance patterns of the microsatellite alleles, we genotyped 246 F1 strains resulting from four mating experiments between parental strains of know genotype. Results generally conformed expectations according to Mendelian inheritance patterns, but deviations were detected indicating mutations during sexual reproduction. A total of forty-two mutations were detected in the clonal cultures over time. Microsatellites with more core-repeats accumulated mutations faster. The mutation rate varied significantly across loci and strains. A binomial mass function and a computer simulation showed that the mutation rate was significantly higher during the first months of culture (μ≈3×10(-3) per locus per cell division) and decreased to μ≈1×10(-3) in the strains kept for 16 months. Our results suggest that genetic mutations acquired in both the vegetative phase and sexual reproduction add to the allelic diversity of microsatellites, and hence to the genotypic variation present in a natural population.
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