Assessment of microbial plankton diversity as an ecological indicator in the NW Mediterranean coast

High-throughput sequencing of microbial assemblages has been proposed as an alternative methodology to the traditional ones used in marine monitoring and environmental assessment. Here, we evaluated pico- and nanoplankton diversity as ecological indicators in NW Mediterranean coastal waters by comparing their diversity in samples subjected to varying degrees of continental pressures. Using metabarcoding of the 16S and 18S rRNA genes, we explored whether alphadiversity indices, abundance of Operational Taxonomic Units and taxonomic groups (and their ratios) provide information on the ecological quality of coastal waters. Our results revealed that only eukaryotic diversity metrics and a limited number of prokaryotic and eukaryotic taxa displayed potential in assessing continental influences in our surveyed area, resulting thus in a restrained potential of microbial plankton diversity as an ecological indicator. Therefore, incorporating microbial plankton diversity in environmental assessment could not always result in a significant improvement of current marine monitoring strategies.Preprint2,35

The role of morbid obesity in the promotion of metabolic disruptions and non-alcoholic steatohepatitis by Helicobacter Pylori

Helicobacter pylory (HP) infection has been associated to an increased rate of type 2 diabetes (T2D) and liver disease through its effect on insulin resistance and systemic inflammation. However, results are inconstant and no studies exist in morbidly obese patients, in which both insulin resistance and inflammation coexist

On Imprimitive Representations of Finite Reductive Groups in Non-defining Characteristic

In this paper, we begin with the classification of Harish-Chandra imprimitive representations in non-defining characteristic. We recall the connection of this problem to certain generalizations of Iwahori-Hecke algebras and show that Harish-Chandra induction is compatible with the Morita equivalence by Bonnaf\'{e} and Rouquier, thus reducing the classification problem to quasi-isolated blocks. Afterwards, we consider imprimitivity of unipotent representations of certain classical groups. In the case of general linear and unitary groups, our reduction methods then lead to results for arbitrary Lusztig series

Marine zoosporic parasites of dinoflagellates

2nd Plankton Chytridiomycosis Workshop, 15-17 September 2016, Skagaströnd, IcelandPeer Reviewe

Life-cycle, ultrastructure, and phylogeny of Parvilucifera corolla sp. nov. (Alveolata, Perkinsozoa), a parasitoid of dinoflagellates

Recent studies of marine protists have revealed parasites to be key components of marine communities. Here we describe a new species of the parasitoid genus Parvilucifera that was observed infecting the dinoflagellate Durinskia baltica in salt marshes of the Catalan coast (NW Mediterranean). In parallel, the same species was detected after the incubation of seawater from the Canary Islands (Lanzarote, NE Atlantic). The successful isolation of strains from both localities allowed description of the life cycle, ultrastructure, and phylogeny of the species. Its infection mechanism consists of a free-living zoospore that penetrates a dinoflagellate cell. The resulting trophont gradually degrades the dinoflagellate cytoplasm while growing in size. Once the host is consumed, schizogony of the parasitoid yields a sporocyte. After cytokinesis is complete, the newly formed zoospores are released into the environment and are ready to infect new host cells. A distinguishing feature of the species is the radial arrangement of its zoospores around the central area of the sporocyte during their formation. The species shows a close morphological similarity with other species of the genus, including P. infectans, P. sinerae, and P. rostrata.Postprin

Parasitoid chytridiomycete Ericiomyces syringoforeus gen. et sp. nov. has unique cellular structures to infect the host

15 pages, 8 figures, 1 table, supplementary information https://doi.org/10.1007/s11557-020-01652-xThis is a post-peer-review, pre-copyedit version of an article published in Karpov, S.A., Reñé, A., Vishnyakov, A.E. et al. Parasitoid chytridiomycete Ericiomyces syringoforeus gen. et sp. nov. has unique cellular structures to infect the host. Mycol Progress 20:, 95-109 (2021). The final authenticated version is available online at: http://dx.doi.org/10.1007/s11557-020-01652-xMany fungi have been identified as pathogens of marine algae. Among them, Chytridiomycota have been revealed as relatively highly abundant, but much of the diversity known within these groups is almost entirely based on environmental sequencing data. Here, we present a novel chytridiomycete genus and species, characterized by light microscopical observations, ultrastructure, and molecular phylogenetic analysis of the parasitic chytrid of brackish-water dinoflagellate Kryptoperidinium foliaceum from the Baltic Sea. Phylogenetic analysis of rDNA sequences and the ultrastructure of the strain reveals that it represents a new family in the order Rhizophydiales. Ericiomyces syringoforeus gen. et sp. nov. is a parasitoid with a life cycle composed by zoospores, which attach to the host, encyst, and produce a rhizoidal system (haustorium). Unlike typical Rhizophydiales chytrids, sporangium develops as a lateral outgrowth of the encysted zoospore. The ultrastructural study revealed at least two unique traits: the syringe-like organelle in the cyst, which supposed to paralyze the host, and funnel-shaped structure anchoring sporangium in the host wall. Sporangium matures and produces new zoospores within 3 days. Multiple infections are common and then the life cycle is 1–2 days shorter compared to the duration when a single infection occurred. Cross-infection experiments showed that E. syringoforeus could only infect dinoflagellates, being K. foliaceum highly susceptible to infection by the chytrid parasitoid. The effects of some fungal epidemics on populations of Kryptoperidinium are discussedLight and electron microscopic studies and manuscript writing were supported by Russian Scientific Foundation grant 16-14-10302. SK and AV thank the Research Resource Centre for Molecular and Cell Technologies (RRC MCT) at St. Petersburg State University (SPbSU) for access to the EM facilities. EG, EA, and AR were supported by MINECO COPAS “Understanding top-down control in coastal bloom-forming protists” (CTM2017-86121-R). MK and KS were supported by JSPS KAKENHI grants 15KK0026 & 16H02943. AK and AP were supported by grant 251564 from Academy of FinlandWith the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)Peer reviewe

The new chytridiomycete Paradinomyces triforaminorum gen. et sp. nov. co-occurs with other parasitoids during a Kryptoperidinium foliaceum (Dinophyceae) bloom in the Baltic Sea

Special issue Marine Benthic Harmful Algal Blooms.-- 11 pages, 5 figures, supplementary materials https://doi.org/10.1016/j.hal.2022.102352.-- Data availability: Data will be made available on requestA new chytrid genus and species was isolated and cultured from samples obtained in the Baltic Sea during a dinoflagellate bloom event. This species is characterized by having a spherical sporangium without papillae and zoospores of 2–3 µm in diameter that are released through 3 discharge pores. Molecular phylogeny based on ribosomal operon showed its sister position to the Dinomyces cluster in Rhizophydiales. Zoospores lack fenestrated cisternae but contain a paracrystalline inclusion, found in a Rhizophydiales representative for the first time. Additionally, the kinetid features are uncommon for Rhizophydiales and only observed in Dinomyces representatives so far. These morphological features and its phylogenetic relationships justify the description of the new genus and speciesParadinomyces triforaminorum gen. nov. sp. nov. belonging to the family Dinomycetaceae. The chytrid was detected during a high-biomass bloom of the dinoflagellate Kryptoperidinium foliaceum. Laboratory experiments suggest this species is highly specific and demonstrate the impact it can have on HAB development. The chytrid co-occurred with three other parasites belonging to Chytridiomycota (Fungi) and Perkinsea (Alveolata), highlighting that parasitic interactions are common during HABs in brackish and marine systems, and these multiple parasites compete for similar hostsAR and EG were funded by the Spanish MICINN Project SMART PID2020-112978GB-I00. This work was partly supported by the Russian Science Foundation grant no. 21–74–20089 (writing, microscopy analysis), the infrastructure of SAK's laboratory was supported by ZIN RAS program 1021051402849–1, and the C7 strain was incorporated in CCPP ZIN RAS collection supported by a grant 075–15–2021–1069 of the Ministry of Science and Higher Education of the Russian Federation. AK was supported by the Academy of Finland, grant 310,449. MK was supported by JSPS KAKENHI 19H05667. EA was supported by The Royal Society (UK) under the Newton International Fellowship (grant number NF170346, call 2017)With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe

Host-released dimethylsulphide activates the dinoflagellate parasitoid Parvilucifera sinerae

4 pages, 2 figuresParasitoids are a major top-down cause of mortality of coastal harmful algae, but the mechanisms and strategies they have evolved to efficiently infect ephemeral blooms are largely unknown. Here, we show that the generalist dinoflagellate parasitoid Parvilucifera sinerae (Perkinsozoa, Alveolata) is activated from dormancy, not only by Alexandrium minutum cells but also by culture filtrates. We unequivocally identified the algal metabolite dimethylsulphide (DMS) as the density-dependent cue of the presence of potential host. This allows the parasitoid to alternate between a sporangium-hosted dormant stage and a chemically-activated, free-living virulent stage. DMS-rich exudates of resistant dinoflagellates also induced parasitoid activation, which we interpret as an example of coevolutionary arms race between parasitoid and host. These results further expand the involvement of dimethylated sulphur compounds in marine chemical ecology, where they have been described as foraging cues and chemoattractants for mammals, turtles, birds, fish, invertebrates and plankton microbesSupport was provided by the (former) Spanish Ministry of Science and Innovation through projects PARAL (to E.G.) and SUMMER (to R.S.). K.P. acknowledges a grant from Australian Endeavour Foundation (Australian Government). We thank Beatriz Garriz for the drawing of the infection cyclePeer reviewe