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

The Cyst-Theca Relationship Of The Dinoflagellate Cyst Trinovantedinium Pallidifulvum, With Erection Of Protoperidinium Lousianensis Sp Nov And Their Phylogenetic Position Within The Conica Group

We establish the cyst-theca relationship of the dinoflagellate cyst species Trinovantedinium pallidifulvum Matsuoka 1987 based on germination experiments of specimens isolated from the Gulf of Mexico. We show that the motile stage is a new species, designated as Protoperidinium louisianensis. We also determine its phylogenetic position based on single-cell polymerase chain reaction (PCR) of a single cell germinated from the Gulf of Mexico cysts. To further refine the phylogeny, we determined the large subunit (LSU) sequence through single-cell PCR of the cyst Selenopemphix undulata isolated from Brentwood Bay (Saanich Inlet, BC, Canada). The phylogeny shows that P. louisianensis is closest to P. shanghaiense, the motile stage of T. applanatum, and is consistent with the monophyly of the genus Trinovantedinium. Selenopemphix undulata belongs to a different clade than Selenopemphix quanta (alleged cyst of P. conicum), suggesting that the genus Selenopemphix is polyphyletic. Trinovantedinium pallidifulvum is widely distributed with occurrences in the Gulf of Mexico, the North Atlantic, the northeast Pacific and southeast Asia. In addition, we illustrate the two other extant species, Trinovantedinium applanatum and Trinovantedinium variabile, and two morphotypes of Trinovantedinium. Geochemical analyses of the cyst wall of T. pallidifulvum indicate the presence of amide groups in agreement with other heterotrophic dinoflagellate species, although the cyst wall of T. pallidifulvum also includes some unique features

Minimal information for studies of extracellular vesicles 2018 (MISEV2018):a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points

Unraveling the chemical composition of modern, resistant, organic-walled dinoflagellate cysts via FTIR spectroscopy

The chemical nature of resistant, organic-walled dinoflagellate cysts (dinocysts) is highly understudied and the suite of resistant macromolecules (i.e. ‘dinosporin’) present in their walls is incompletely characterized. Past studies used microscopic Fourier transform infrared (micro-FTIR) spectroscopy to determine that dinosporin is different from other resistant biomolecules like sporopollenin (pollen and spores) and algaenan (green algae); that it is a strongly cross-linked carbohydrate-like polymer (somewhat similar to cellulose; Versteegh et al. 2012); that its composition slightly varies with the nutritional strategy of associated motile cells (heterotrophic cysts contain N, autotrophs do not; Bogus et al. 2014). Using a more robust spectral data collection method based on attenuated total reflectance micro-FTIR spectroscopy (Meyvisch et al. 2022), this study further explores the compositional diversity of dinosporin in modern dinocysts from surface sediments, characterizes it in more detail, and re-evaluates the previously established dietary relationship. A large dataset of 216 spectra (10 families, 25 genera, 51 species) from 17 locations across the Northern hemisphere reveals that dinosporin is more variable than previously thought, leading to the erection of four spectrochemical groups, some with striking similarities to sporopollenin and algaenan. It is also shown that pigments significantly contribute to the spectral composition of colored dinocysts, and that eumelanin is likely present in these forms acting as a sunscreen against harmful ultraviolet radiation. Finally, detailed spectral analyses suggest that N is present in all observed dinosporin types and that it originates from sunscreen pigments rather than through heterotrophic prey accumulation. Therefore, the previously established dietary relationship by Bogus et al. (2014) is evaluated to be ambiguous. This study provides a reference framework for a more systematic investigation of resistant biomolecules in dinocysts and other resting stages, as well as their associated ecological roles. Furthermore, the spectral dataset can be used for comparisons with fossil dinocysts and other microorganisms/-fossils with unknown affinities (i.e. acritarchs) in the light of chemotaxonomic studies. References — Bogus, K., Mertens, K.N., Lauwaert, J., Harding, I.C., Vrielinck, H., Zonneveld, K.A.F. & Versteegh, G.J.M. 2014. J Phycol. 50:254–66. — Meyvisch, P., Gurdebeke, P.R., Vrielinck, H., Mertens, K.N., Versteegh, G. & Louwye, S. 2022. Appl Spectrosc. 76. — Versteegh, G.J.M., Blokker, P., Bogus, K., Harding, I.C., Lewis, J., Oltmanns, S., Rochon, A. et al. 2012. Org Geochem. 43:92–102

Unraveling the chemical composition of modern, resistant, organic-walled dinoflagellate cysts via FTIR spectroscopy

Dinoflagellates are unicellular protists that are – similar to other aquatic microalgal groups – capable of forming organic- walled cysts which allow them to survive periods with unfavorable environmental conditions. These dinocysts are often very resistant to physical and chemical degradation resulting in the occurrence of both modern and fossil forms which are commonly used in (paleo)ecological, (paleo)climatological, and (paleo)environmental studies. The chemical nature of dinocysts is highly understudied and the suite of resistant macromolecules (i.e. ‘dinosporin’) present in their walls is incompletely characterized. Past studies used microscopic Fourier transform infrared (micro- FTIR) spectroscopy to determine that dinosporin is different from other resistant biomolecules like sporopollenin (pollen and spores) and algaenan (green algae); that it is a strongly cross-linked carbohydrate-like polymer (somewhat similar to cellulose; Versteegh et al. 2012); that its composition slightly varies with the nutritional strategy of associated motile cells (heterotrophic cysts contain N, autotrophs do not; Bogus et al. 2014). Using a more robust spectral data collection method based on attenuated total reflectance micro-FTIR spectroscopy (Meyvisch et al. 2022), this study further explores the compositional diversity of dinosporin in modern dinocysts from surface sediments, characterizes it in more detail, and re-evaluates the previously established dietary relationship. A large dataset of 216 spectra (10 families, 25 genera, 51 species) from 17 locations across the Northern hemisphere reveals that dinosporin is more variable than previously thought, leading to the erection of four spectrochemical groups, some with striking similarities to sporopollenin and algaenan. It is also shown that pigments significantly contribute to the spectral composition of colored dinocysts, and that eumelanin is likely present in these forms acting as a sunscreen against harmful ultraviolet radiation. Finally, detailed spectral analyses suggest that N is present in all observed dinosporin types and that it originates from sunscreen pigments rather than through heterotrophic prey accumulation. Therefore, the previously established dietary relationship by Bogus et al. (2014) is evaluated to be ambiguous. This study provides a reference framework for a more systematic investigation of resistant biomolecules in dinocysts and other resting stages, as well as their associated ecological roles. Furthermore, the spectral dataset can be used for comparisons with fossil dinocysts and other microorganisms/-fossils with unknown affinities (i.e. acritarchs) in the light of chemotaxonomic studies. References - Bogus, K., Mertens, K.N., Lauwaert, J., Harding, I.C., Vrielinck, H., Zonneveld, K.A.F. & Versteegh, G.J.M. 2014. Differences in the chemical composition of organic-walled dinoflagellate resting cysts from phototrophic and heterotrophic dinoflagellates. J Phycol. 50:254–66. - Meyvisch, P., Gurdebeke, P.R., Vrielinck, H., Mertens, K.N., Versteegh, G. & Louwye, S. 2022. Attenuated Total Reflection (ATR) Micro-Fourier Transform Infrared (Micro-FT- IR) Spectroscopy to Enhance Repeatability and Reproducibility of Spectra Derived from Single Specimen Organic-Walled Dinoflagellate Cysts. Appl Spectrosc. 76. - Versteegh, G.J.M., Blokker, P., Bogus, K., Harding, I.C., Lewis, J., Oltmanns, S., Rochon, A. et al. 2012. Infra red spectroscopy, flash pyrolysis, thermally assisted hydrolysis and methylation (THM) in the presence of tetramethylammonium hydroxide (TMAH) of cultured and sediment-derived Lingulodinium polyedrum (Dinoflagellata) cyst walls. Org Geochem. 43:92–102

Coccolithophores as palaeoecological indicators for shifts of the ITCZ in the Cariaco Basin during the late Quaternary

Coccoliths were studied from the ODP Hole 1002C and core PL07-39PC in the Cariaco Basin. Increases in Emiliania huxleyi are synchronous with decreases of Gephyrocapsa oceanica and vice versa. A new index (GEX) based on the relative abundances of these two taxa is proposed, and correlates with various other proxies. It is shown that GEX can serve as upwelling proxy. This confirms that the Intertropical Convergence Zone shifted north during the Bølling/Allerød, south during the Younger Dryas and back north during the Preboreal. The upwelling proxy shows few discrepancies with the terrigenous record

Morphology, molecular phylogeny and azaspiracid profile of Azadinium poporum (Dinophyceae) from the Gulf of Mexico

Azadinium poporum produces a variety of azaspiracids and consists of several ribotypes, but information on its biogeography is limited. A strain of A. poporum (GM29) was incubated from a Gulf of Mexico sediment sample. Strain GM29 was characterized by a plate pattern of po, cp, x, 4′, 3a, 6″, 6C, 5S, 6‴, 2⁗, a distinct ventral pore at the junction of po and the first two apical plates, and a lack of an antapical spine, thus fitting the original description of A. poporum. The genus Azadinium has not been reported in waters of the United States of America before this study. Molecular phylogeny, based on large subunit ribosomal DNA (LSU rDNA) and internal transcribed spacer (ITS) sequences, reveals that strain GM29 is nested within the well-resolved A. poporum complex, but forms a sister clade either to ribotype B (ITS) or ribotype C (LSU). It is, therefore, designated as a new ribotype, termed as ribotype D. LSU and ITS sequences similarity among different ribotypes of A. poporum ranges from 95.4% to 98.2%, and from 97.1% to 99.2% respectively, suggesting that the LSU fragment is a better candidate for molecular discrimination. Azaspiracid profiles were analyzed using LC–MS/MS and demonstrate that strain GM29 produces predominantly AZA-2 with an amount of 45 fg/cell. The results suggest that A. poporum has a wide distribution and highlights the risk potential of azaspiracid intoxication in the United States

Average process length variation of the marine dinoflagellate cyst Operculodinium centrocarpum in the tropical and Southern Hemisphere Oceans: Assessing its potential as a palaeosalinity proxy

The study investigates the morphological variability of the dinoflagellate cyst Operculodinium centrocarpum (resting cyst of Protoceratium reticulatum) in core-top samples distributed over the Southern Hemisphere and the tropics in relation to sea-surface temperature (SST) and sea-surface salinity (SSS) at the corresponding sites. The process lengths show a moderate inverse relationship to summer SST (sSST) (R 2=0.44) and sSSS/sSST (R 2=0.4), however, lateral transport of cysts probably produced noise in the plots. After excluding tropical and Southern Hemisphere sites considered to have been affected by long distance lateral transport, the relationship between process length and density follows the equation sD=0.8422x+1016.9 (R 2=0.55) with a Root Mean Square Error=0.63kgm -3, while the negative correlation with sSST increases up to R 2=0.79. Next to salinity, this study thus highlights the importance of a second factor, temperature, affecting process length in the topics and the Southern Hemisphere oceans