Sergey A. Karpov

Zoological Institute

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David Moreira

Centre National de la Recherche Scientifique

Purificación López‐García

Centre National de la Recherche Scientifique

Igor R. Pozdnyakov

Zoological Institute

Alexander P. Mylnikov

Institute of Biology of Inland Waters named Ivan Dmitrievich Papanin

Vladimir V. Aleoshin

Lomonosov Moscow State University

Maria A. Mamkaeva

St Petersburg University

Denis V. Tikhonenkov

Institute of Biology of Inland Waters named Ivan Dmitrievich Papanin

Andrey E. Vishnyakov

St Petersburg University

Guifré Torruella

Centre National de la Recherche Scientifique

Kirill V. Mikhailov

Lomonosov Moscow State University

Cooperative Institutions

St Petersburg University

Centre National de la Recherche Scientifique

Mae Fah Luang University

University of British Columbia

Russian Academy of Sciences

Sorbonne Université

Zoological Institute

Qujing Normal University

Canadian Institute for Advanced Research

Lomonosov Moscow State University

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Flagellar apparatus structure of choanoflagellates

Cilia (2016)

Sergey A. Karpov

Phylum choanoflagellata is the nearest unicellular neighbor of metazoa at the phylogenetic tree. They are single celled or form the colonies, can be presented by naked cells or live in theca or lorica, but in all cases they have a flagellum surrounded by microvilli of the collar. They have rather uniform and peculiar flagellar apparatus structure with flagellar basal body (FB) producing a flagellum, and non-flagellar basal body (NFB) lying orthogonal to the FB. Long flagellar transition zone contains a unique structure among eukaryotes, the central filament, which connects central microtubules to the transversal plate. Both basal bodies are composed of triplets and interconnected with fibrillar bridge. They also contain the internal arc-shaped connectives between the triplets. The FB has prominent transitional fibers similar to those of chytrid zoospores and choanocytes of sponges, and a radial microtubular root system. The ring-shaped microtubule organizing center (MTOC) produces radial root microtubules, but in some species a MTOC is represented by separate foci. The NFB has a narrow fibrillar root directed towards the Golgi apparatus in association with membrane-bounded sac. Prior to cell division, the basal bodies replicate and migrate to poles of elongated nucleus. The basal bodies serve as MTOCs for the spindle microtubules during nuclear division by semiopen orthomitosis.

Basal body

Microtubule organizing center

Centriole

Motile cilium

10.1186/s13630-016-0033-5

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Citations (19)

A comparative study of zoospore cytoskeleton in Symphytocarpus impexus, Arcyria cinerea and Lycogala epidendrum (Eumycetozoa)

Protistology (2003)

Sergey A. Karpov Yuri K. Novozhilov Ludmila V. Chistiakova

Zoospore

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Citations (8)

Newly identified diversity of Dinomycetaceae (Rhizophydiales, Chytridiomycota), a family of fungal parasites of marine dinoflagellates

European Journal of Protistology (2024)

Alan Denis Fernández‐Valero Sergey A. Karpov Nagore Sampedro Jordina Gordi Natàlia Timoneda

We identified two new parasite species of Chytridiomycota isolated during blooms of the dinoflagellate Alexandrium minutum in the coastal Mediterranean Sea. Light and electron microscopy together with molecular characterization of the nuclear 18S, ITS, and 28S rDNA regions led to their identification as two new species, Dinomyces gilberthii and Paradinomyces evelyniae, both belonging to the family Dinomycetaceae, order Rhizophydiales. Dinomyces gilberthii differs from the previously described D. arenysensis by the presence of discharge papillae and the development of a drop-shaped sporangium. Paradinomyces evelyniae differs from the previously described P. triforaminorum by the prominent lipid globule present in early sporangia and the pointed end producing a rhizoid. The two chytrids differed in their geographical distribution. Dinomyces gilberthii was detected in several Mediterranean habitats, including harbours and beaches, and was particularly prevalent during summer dinoflagellate blooms. This widespread occurrence in coastal ecosystems suggested a high level of adaptability in this environment. Paradinomyces evelyniae had a more restricted distribution in the coastal-marine environment, occurring in harbour sediments and only occasionally in the water column during winter and early spring. Paradinomyces evelyniae has previously been detected in the Baltic Sea, suggesting that its distribution encompasses contrasting coastal environments, although its presence is rare.

Chytridiomycota

Dinoflagellate

Oomycete

10.1016/j.ejop.2024.126053

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Citations (1)

Author response for "The nature of ‘jaws’: a new predatory representative of Provora and the ultrastructure of nibbling protists"

Artem O. Belyaev Sergey A. Karpov Patrick J. Keeling Denis V. Tikhonenkov

10.1098/rsob.240158/v3/response1

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New Lineage of Microbial Predators Adds Complexity to Reconstructing the Evolutionary Origin of Animals

SSRN Electronic Journal (2020)

Denis V. Tikhonenkov Kirill V. Mikhailov Elisabeth Hehenberger Sergey A. Karpov Kristina Prokina

The origin of animals is one of the most intensely studied evolutionary events, and our understanding of this transition was greatly advanced by analyses of unicellular protist relatives of animals, which have shown many “animal-specific” genes actually arose in protistan ancestors long before the emergence of animals. These genes have sometimes complex distributions and the protists have diverse lifestyles, so understanding their evolutionary significance requires both a robust phylogeny of animal relatives, and a detailed understanding of their biology. But discoveries of new animal-related lineages are rare and biased to bacteriovores and parasites. Here, we characterize the morphology, life cycle and transcriptome content of a new animal-related lineage, represented by the predatory flagellate, Tunicaraptor unikontum. Although it survives by preying on other eukaryotes, Tunicaraptor is an extremely small (3-5 μm) and morphologically simple cell; closely resembling some fungal zoospores. The Tunicaraptor transcriptome encodes a full complement of flagellar genes, which are only common to predatory animal relatives and missing in microbial parasites and grazers. Tunicaraptor also encodes several major classes of animal cell adhesion molecules and transcription factors and proteins involved in neurodevelopment that have not been found in other animal-related lineages. Phylogenomics including Tunicaraptor challenges the existing framework used to reconstruct the evolution of “animal specific” genes, and emphasizes that the diversity of animal-related lineages may be better understood only once the smaller, more inconspicuous animal-related lineages are better studied.

Lineage (genetic)

10.2139/ssrn.3606769

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Genomic analysis reveals cryptic diversity in aphelids and sheds light on the emergence of Fungi

Current Biology (2022)

Kirill V. Mikhailov Sergey A. Karpov Peter M. Letcher Philip A. Lee Maria D. Logacheva

Multicellular organism

Comparative Genomics

10.1016/j.cub.2022.08.071

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Citations (20)

Kinetid structure in Choanocytes of Sponges (Heteroscleromorpha): Toward the ancestral Kinetid of Demospongiae

Journal of Morphology (2016)

Igor R. Pozdnyakov Sergey A. Karpov

ABSTRACT Every large clade of Eukarya has its own pattern of kinetid (flagellar apparatus) structure, which is stable and specific within the group, thereby being a good phylogenetic marker. The kinetid structure of sponge choanocytes might be a candidate for such marker for the phylogeny of Porifera. Kinetids of two heteroscleromorphs, Halichondria sp. (Suberitida) and Crellomima imparidens (Poecilosclerida), have been investigated here for the first time, and a reconstruction of the kinetid for each species is provided. The kinetids of both species comprise a flagellar kinetosome with a nuclear fibrillar root, a basal foot and satellite producing microtubules; a centriole is absent. Good resolution images reveal a new thin structure, the axial granule, in the flagellar transition zone which might be present in other sponges. The comparison of kinetids in investigated sponges revealed three types of kinetid in Demospongiae, and their distribution in the taxon has been shown on a molecular phylogenetic tree. Kinetid characters of the common ancestor of Demospongiae are discussed. J. Morphol. 277:925–934, 2016. © 2016 Wiley Periodicals, Inc.

Sponge

10.1002/jmor.20546

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Citations (9)

Kinetid structure in sponge choanocytes of Spongillida in the light of evolutionary relationships within Demospongiae

Zoological Journal of the Linnean Society (2018)

Igor R. Pozdnyakov Agniya M. Sokolova Alexander Ereskovsky Sergey A. Karpov

With the advent of molecular phylogenetics, the morphology-based classification of Porifera has been cardinally changed. However, the relationships between some clusters of Demospongiae, the most diverse sponge class, remain uncertain. An analysis of sponge cell ultrastructures, in particular the flagellar apparatus (kinetid) of choanocytes, may help clarify the evolutionary links in Demospongiae. We studied the kinetid structure of the sponges Spongilla lacustris, Ephydatia fluviatilis and Lubomirskia baikalensis, which belong to the recently established order Spongillida (Heteroscleromorpha). In these sponges, the kinetid of the choanocytes have a uniform structure, consisting of a single kinetosome (without centriole) encircled with a ring of electron-dense bodies producing lateral microtubules. The flagellar transition zone contains a transverse plate with an axosome and a coiled filament. This type of kinetid is similar to that of Haplosclerida representatives, whose morphologic similarities with Spongillida representatives were still not explained. We also discussed the nuclear location in the choanocyte (basal or apical), which correlates to the kinetid structure in Demospongiae. Only three types of flagellar apparatus have been found in Demospongiae up to now, implying that the kinetid is one of the most conservative structures in sponge evolution.

Sponge

Morphology

10.1093/zoolinnean/zlx109

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Citations (8)

Morphology, phylogeny, and ecology of the aphelids (Aphelidea, Opisthokonta) and proposal for the new superphylum Opisthosporidia

Frontiers in Microbiology (2014)

Sergey A. Karpov Maria A. Mamkaeva Vladimir V. Aleoshin Elena Nassonova Osu Lilje

The aphelids are a small group of intracellular parasitoids of common species of eukaryotic phytoplankton with three known genera Aphelidium, Amoeboaphelidium, and Pseudaphelidium, and ten valid species, which form along with related environmental sequences a very diverged group. The phyla Microsporidia and Cryptomycota, and the class Aphelidea have recently been considered to be а deep branch of Holomycota lineage forming the so called the ARM-clade which is sister to the fungi. In this review we reorganize the taxonomy of ARM-clade, and establish a new superphylum Opisthosporidia with three phyla: Aphelida phyl. nov., Cryptomycota and Microsporidia. We discuss here all aspects of aphelid investigations: history of our knowledge, life cycle peculiarities, the morphology (including the ultrastructure), molecular phylogeny, ecology, and provide a taxonomic revision of the phylum supplied with a list of species. We compare the aphelids with their nearest relatives, the species of Rozella, and improve the diagnosis of the phylum Cryptomycota.

Lineage (genetic)

10.3389/fmicb.2014.00112

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Citations (209)

Molecular Phylogeny of Paraphelidium letcheri sp. nov. (Aphelida, Opisthosporidia)

Journal of Eukaryotic Microbiology (2016)

Sergey A. Karpov Guifré Torruella David Moreira Maria A. Mamkaeva Purificación López-Garcı́a

Abstract Aphelids remain poorly known parasitoids of algae and have recently raised considerable interest due to their phylogenetic position at the base of Holomycota. Together with Cryptomycota (Rozellosporidia) and Microsporidia, they have been recently re‐classified as the Opisthosporidia, which constitutes the sister group to the fungi within the Holomycota. Molecular environmental studies have revealed a huge diversity of aphelids, but only four genera have been described: Aphelidium, Amoeboaphelidium, Paraphelidium , and Pseudaphelidium . Here, we describe the life cycle of a new representative of Aphelida, Paraphelidium letcheri sp. nov., and provide the 18S rRNA gene sequence for this species. Molecular phylogenetic analysis indicates that P. letcheri is sister to Paraphelidium tribonemae and together they form a monophyletic cluster which is distantly related to both, Aphelidium, with flagellated zoospores, and Amoebaphelidium, with amoeboid zoospores.

Monophyly

Molecular Phylogenetics

Sister group

10.1111/jeu.12389

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Citations (26)