Free-living stages of the life cycle of the parasitic dinoflagellate Ichthyodinium chabelardi Hollande et J. Cachon, 1952 (Alveolata: Dinoflagellata)

Шадрин, А. М.; Simdyanov, Timur G.; Pavlov, D.; Nguyen, Trang Hong

doi:10.1134/s0012496615020131

Cited by 3 publications

(1 citation statement)

References 8 publications

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“…Flow cytometer data showed a significant correlation between side scatter (SSC) and the forward scatter (FSC) parameters (R = 0.81; p < 0.01) as well as green autofluorescence (R = 0.71 and 0.94, for SSC and FSC respectively; p < 0.01). We frequently observed different populations of dinospores within a strain illustrated by distinct flow cytometry signatures, suggesting that dinospores could still be engaged in cell division during sporulation, as previously reported for syndinids 16,60 . FSC, SSC, and green autofluorescence differentiated strains belonging to the RIB2 from the rest, as their dinospores seemed to be brighter and larger when compared to other ribotypes (Mann-Whitney pairwise tests; p < 0.01) ( Fig.…”

Section: Resultssupporting

confidence: 81%

Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach

Cai

Kayal

Alves‐de‐Souza

et al. 2020

Sci Rep

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ecology and evolution. Thus, achieving a reliable delineation of cryptic species within parasitic protistan lineages is critical for gaining a better knowledge of their ecological niches and host range. The problem of species delineation is pervasive for parasitic lineages almost exclusively composed of environmental sequences, such as the Marine ALVeolate lineages (MALVs) 10,11. MALV represented one of the most hyperdiverse lineages (>1,000 OTUs) recovered in the metabarcoding dataset collected during the Tara Oceans expedition 5,12. However, only a handful of species representatives of the different MALV lineages have been formally described, all of them obligatory aplastidial parasites occurring as intracellular biotrophs (i.e., the host is maintained alive during the infection but eventually killed) and belonging to the order Syndiniales 11. Among them, Amoebophryidae (or MALV-II) were observed to have the highest rate of cladogenesis (i.e., speciation minus extinction rates) among 65 marine protist lineages 13 , making their classification even more challenging. The Amoebophrya ceratii species complex is a MALV-II clade with a worldwide distribution that can be isolated in culture 14,15. All A. ceratii reported to date were observed infecting a broad range of marine dinoflagellates 11,16. A single infected host produces within days hundreds of dinospores (i.e., free-living, flagellated infective propagules), each with a life span of few days 17. Dinospores frequently account for a substantial proportion (>25%) of the nanoplanktonic fraction (2-20 µm) in coastal waters 18 and can be readily consumed by microzooplankton grazers (20-200 µm) 19. Consequently, such parasites potentially constitute key trophic links between different compartments of the marine food web in the oceanic carbon cycle 20 , notably through population control of dinoflagellate blooms 21,22. Here, we explored the diversity of the A. ceratii species complex through an extensive sequencing effort of 76 strains in culture and 43 environmental single-cells from two close localities (the Penzé and Rance Estuaries, western Channel, France). We followed a polyphasic approach to provide the first comprehensive species boundaries delineation within the A. ceratii species complex. To do so, we combined (i) ribotyping (both of the SSU rDNA and ITS1-5.8S-ITS2 regions), (ii) k-mer analysis from whole-genome sequencing, (iii) analysis of the ITS2 compensatory base changes (CBCs), (iv) phenotypic characteristics of dinospores by flow cytometry, and (v) assessment of their host range through cross-infection culture experiments. Finally, we applied our novel species boundaries to answer the following questions: do these Amoebophrya cryptic species share the same ecological niches? Can we explain their fitness (maximal abundance and persistence in time) by their host range? For that, we explored the population dynamics of the newly-defined cryptic Amoebophrya species (considered here as ribotypes until formal descriptions are performed) during a three-year...

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Section: Resultssupporting

confidence: 81%

Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach

Cai

Kayal

Alves‐de‐Souza

et al. 2020

Sci Rep

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A review of the characteristics of the dinoflagellate parasite Ichthyodinium chabelardi and its potential effect on fin fish populations

Gleason

Nagarkar

Chambouvet

et al. 2019

Mar. Freshwater Res.

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This paper focuses on the biology and ecological impacts of Ichthyodinium chabelardi (phylum Dinophyta, class Syndiniophyceae, order Syndiniales), a virulent endobiotic parasite of yolk sacs and young larvae of many species of marine fin fish. Its infections have been observed in warm and temperate open oceanic environments and crowded marine fish tanks. The prevalence of I. chabelardi and the range of its host fishes is not well studied, and our understanding of its life cycle is incomplete. Here, we describe what is known about I. chabelardi infections in fish and we compare this with several other protistan parasites of fish, including Amyloodium ocellatum, Saprolegnia parasitica, Sphaerothecum destruens and the ‘X-cell’ clades Gadixcellia and Xcellia, all of which are considered emerging generalist parasites infecting a wide variety of fin fish species. Recent findings suggest that rising seawater temperatures might lead to higher infection rates in fishes, and we expect that these changing conditions could also expand the ranges of some of these parasitic species. Thus, it is essential that the fishing industry effectively monitors fish tanks and water in the surrounding environments for the presence of zoosporic parasites, including I. chabelardi, so as to take steps to prevent large losses in these fisheries.

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The ultrastructure of the zoospores of the parasitic dinoflagellate Ichthyodinium chabelardi Hollande et J. Cachon, 1952 (Alveolata: Dinoflagellata)

Simdyanov

Шадрин

Thanh³

2016

Dokl Biol Sci

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This is the first study on the ultrastructure of the zoospores of Ichthyodinium chabelardi, a parasitoid of the fish egg and early larval stages. The zoospores were characterized by the cell structure specific for dinoflagellates; particularly, cells contained large trichocysts and the "dinokaryon"-type nucleus. An unusual large electron-transparent zone was the only significant difference from the "classical" cell structure in Dinoflagellata. We did not find cell structures for the penetration to the host cell (microtubular basket, conoid, or secretory organelles such as rhoptries). The data on the fine structure of the zoospores of I. chabelardi agree with the results of molecular phylogeny; this allows us argue that excluding this species from Dinoflagellata and assigning it to Protalveolata was a mistake.

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Free-living stages of the life cycle of the parasitic dinoflagellate Ichthyodinium chabelardi Hollande et J. Cachon, 1952 (Alveolata: Dinoflagellata)

Cited by 3 publications

References 8 publications

Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach

Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach

A review of the characteristics of the dinoflagellate parasite Ichthyodinium chabelardi and its potential effect on fin fish populations

The ultrastructure of the zoospores of the parasitic dinoflagellate Ichthyodinium chabelardi Hollande et J. Cachon, 1952 (Alveolata: Dinoflagellata)

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