Tracing hydrological millennial-scale cycles in the late Quaternary of the Cariaco Basin and the southern Gulf of Cádiz using coccoliths and dinoflagellate cysts

Climate fluctuations in tropical to subtropical regions are coupled to hydrological changes. The reconstruction of these hydrological changes during rapid late Quaternary climate oscillations is crucial for climate change study. The present study demonstrates that coccoliths and dinoflagellate cysts are very useful as paleoclimatological indicators for the elucidation or a better understanding of the late Quaternary regional and global palaeoclimate. This study also reveals new insights in coccolithophore and dinoflagellate palaeoecology. At the outset, two fundamental studies were undertaken to strengthen dinoflagellate cysts as a proxy for paleoecological studies. Since so-called ‘standard’ palynological processing methods are still very variable and inflict damage on organic-walled microfossils to a certain extent, the effect on the determination of dinoflagellate cyst concentrations needed to be sorted out. Furthermore, since there were indications that process length variation of Lingulodinium machaerophorum is related to salinity, there was a need to assess its use for quantitative palaeosalinity reconstruction, which is of critical importance for better understanding of global climate change. Two locations were chosen for a high-resolution micropalaeontological study of hydrological millennial-scale cycles during Late Quaternary times: the Cariaco Basin, an anoxic basin offshore Venezuela and the Southern Gulf of Cádiz, offshore Morocco. Because of the high sedimentation rates, both sites contain a relatively undisturbed Late Quaternary climate record. Both record rapid, large climatic oscillations related to major hydrological changes caused by respectively the intertropical convergence zone (ITCZ) and the North Atlantic Oscillation (NAO). Results of the micropalaeontological analysis indicate that the changes in the dominance of river influx or upwelling cause important variations in plankton productivity in both locations. These variations are reflected in both assemblage changes and absolute abundance variation. Apart from the productivity reconstruction, changes in assemblage or morphology reflect changes in temperature and salinity. The seasonal and multi-year changes between upwelling and river dominated ecosystems, related in both regions to climatological shifts of respectively the ITCZ and NAO, can be extended to millennial-scale cycles and results in specific productivities, temperatures and salinities. Since millennial-scale shifts of both phenomena occur during the same periods (e.g. Younger Dryas), future work should elucidate the precise timing of both phenomena by comparing detailed multi-proxy records from north-south transects

Islandinium pacificum sp. nov., a new dinoflagellate cyst from the upper Quaternary of the northeast Pacific

Round brown process-bearing cysts (RBPC) produced by dinoflagellates (Dinophyceae) occur as an important part of assemblage diversities in seafloor sediments worldwide. Here a new species, Islandinium pacificum, is described from surface sediment samples from coastal waters of British Columbia (Canada). Additional observations are made on material from the Holocene of Kyuquot Sound (Vancouver Island, Canada) and the Eemian of the Voring Plateau (North Atlantic). The cysts have a smooth wall and bear acuminate processes with barbs. Incubation experiments reveal an affinity with the motile stage Protoperidinium mutsuense. The ecology of the new species is specified

Equilibrium Existence and Approximation for Incomplete Market Models with Substantial Heterogeneity

This paper contains an analysis of incomplete market models with finitely but arbitrarily many heterogeneous agents. We discuss the mathematical foundation for equilibrium conditions which leads to two findings. First, we establish existence of equilibria for small and large risks. Second, we develop a simple but general solution technique which handles many state and choice variables for each agent and thus an extremely high-dimensional state space. The method is based on perturbations around a point at which the solution is known. The novel idea is to exploit the symmetry of the problem to overcome the curse of dimensionality. We use the analysis to demonstrate the impact of heterogeneity on macroeconomic quantities and the pricing of risk. Furthermore, we set our technique apart from the standard method used in the literature

Hiddenocysta matsuokae gen. nov. et sp. nov. from the Holocene of Vancouver Island, British Columbia, Canada

A new dinoflagellate cyst genus and species are described here as Hiddenocysta gen. nov. and Hiddenocysta matsuokae sp. nov. from Holocene sediments in a core from the west coast of Vancouver Island (British Columbia, Canada). The genus Hiddenocysta encompasses spherical to ovoid skolochorate cysts, characterized by a gonyaulacoid plate pattern and a 2P precingular archeopyle. The species H. matsuokae is characterized by a granular wall and slender trifurcate processes with heavily perforated process bases. Two end members are described here based on process morphology and number of processes (formas 1 and 2). Cyst wall chemistry is analyzed using micro-Fourier transform infrared (FTIR) spectroscopy and reveals a unique dinosporin composition consistent with a gonyaulacoid autotrophic feeding strategy

High-throughput screening of cellulase F mutants from multiplexed plasmid sets using an automated plate assay on a functional proteomic robotic workcell

<p>Abstract</p> <p>Background</p> <p>The field of plasmid-based functional proteomics requires the rapid assay of proteins expressed from plasmid libraries. Automation is essential since large sets of mutant open reading frames are being cloned for evaluation. To date no integrated automated platform is available to carry out the entire process including production of plasmid libraries, expression of cloned genes, and functional testing of expressed proteins.</p> <p>Results</p> <p>We used a functional proteomic assay in a multiplexed setting on an integrated plasmid-based robotic workcell for high-throughput screening of mutants of cellulase F, an endoglucanase from the anaerobic fungus <it>Orpinomyces </it>PC-2. This allowed us to identify plasmids containing optimized clones expressing mutants with improved activity at lower pH. A plasmid library of mutagenized clones of the <it>celF </it>gene with targeted variations in the last four codons was constructed by site-directed PCR mutagenesis and transformed into <it>Escherichia coli</it>. A robotic picker integrated into the workcell was used to inoculate medium in a 96-well deep well plate, combining the transformants into a multiplexed set in each well, and the plate was incubated on the workcell. Plasmids were prepared from the multiplexed culture on the liquid handler component of the workcell and used for <it>in vitro </it>transcription/translation. The multiplexed expressed recombinant proteins were screened for improved activity and stability in an azo-carboxymethylcellulose plate assay. The multiplexed wells containing mutants with improved activity were identified and linked back to the corresponding multiplexed cultures stored in glycerol. Spread plates were prepared from the glycerol stocks and the workcell was used to pick single colonies from the spread plates, prepare plasmid, produce recombinant protein, and assay for activity. The screening assay and subsequent deconvolution of the multiplexed wells resulted in identification of improved CelF mutants and corresponding optimized clones in expression-ready plasmids.</p> <p>Conclusion</p> <p>The multiplex method using an integrated automated platform for high-throughput screening in a functional proteomic assay allows rapid identification of plasmids containing optimized clones ready for use in subsequent applications including transformations to produce improved strains or cell lines.</p

Adding new pieces to the Azadinium (Dinophyceae) diversity and biogeography puzzle: Non-toxigenic Azadinium zhuanum sp. nov. from China, toxigenic A. poporum from the Mediterranean, and a non-toxigenic A. dalianense from the French Atlantic

The marine planktonic dinophyceaen genus Azadinium is a primary source of azaspiracids, but due to their small size its diversity may be underestimated and information on its biogeography is still limited. A new Azadinium species, A. zhuanum was obtained from the East China Sea and Yellow Sea of China by incubating surface sediments. Five strains were established by isolating single germinated cells and their morphology was examined with light microscopy and scanning electron microscopy. Azadinium zhuanum was characterized by a plate pattern of Po, cp, X, 4′, 2a, 6′′, 6C, 5S, 6′′′, 2′′′′, by a distinct ventral pore at the junction of Po, the first and fourth apical plates, and a conspicuous antapical spine. Moreover, Azadinium poporum was obtained for the first time from the Mediterranean by incubating surface sediment collected from Diana Lagoon (Corsica) and a new strain of Azadinium dalianense was isolated from the French Atlantic. The morphology of both strains was examined. Small subunit ribosomal DNA (SSU rDNA), large subunit ribosomal DNA (LSU rDNA) and internal transcribed spacer (ITS) sequences were obtained from cultured strains. In addition, LSU sequences were obtained by single cell sequencing of two presumable A. poporum cells collected from the French Atlantic. Molecular phylogeny based on concatenated SSU, LSU and ITS sequences revealed that A. zhuanum was closest to A. polongum. French A. poporum from Corsica (Mediterranean) and from the Atlantic showed some genetic differences but were nested within one of the A. poporum ribotypes together with other European strains. Azadinium dalianense from France together with the type strain of the species from China comprised a well resolved clade now consisting of two ribotypes. Azaspiracid profiles were analyzed for the cultured Azadinium strains using LC–MS/MS and demonstrate that the Mediterranean A. poporum strain produced AZA-2 and AZA-2 phosphate with an amount of 0.44 fg cell−1. Azadinium zhuanum and A. dalianense did not produce detectable AZA. Results of the present study support the view of a high diversity and wide distribution of species belonging to Azadinium. The first record of AZA-2 producing A. poporum from the Mediterranean suggests that this species may be responsible for azaspiracid contaminations in shellfish from the Mediterranean Sea

Dinoflagellate fossils: Geological and biological applications

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