Pocheina and Acrasis are two genera of heterolobosean sorocarpic amoebae within Acrasidae that have historically been considered close relatives. The two genera were differentiated based on their differing fruiting body morphologies. The validity of this taxonomic distinction was challenged when a SSU rRNA phylogenetic study placed an isolate morphologically identified as "Pocheina" rosea within a clade of Acrasis rosea isolates. The authors speculated that pocheinoid fruiting body morphology might be the result of aberrant Ac. rosea fruiting body development, which, if true, would nullify this taxonomic distinction between genera. To clarify Acrasidae systematics, we analyzed SSU rRNA and ITS region sequences from multiple isolates of Pocheina, Acrasis, and Allovahlkampfia generated by Polymerase Chain Reaction (PCR) and transcriptomics. We demonstrate that the initial SSU sequence attributed to "P. rosea" originated from an Ac. rosea DNA contamination in its amplification reaction. Our analyses, based on morphology, SSU and 5.8S rRNA gene phylogenies, as well as comparative analyses of ITS1 and ITS2 sequences, resolve Acrasidae into three major lineages: Allovahlkampfia and the strongly supported clades comprising Pocheina and Acrasis. We confirm that the latter two genera can be identified by their fruiting body morphologies.
- Klíčová slova
- Acrasis, Allovahlkampfia, Guttulina, acrasid, amoeba, cellular slime mold, multicellularity, protist, social amoeba, sorocarpic amoeba,
- MeSH
- Amoebozoa klasifikace genetika MeSH
- fylogeneze * MeSH
- mezerníky ribozomální DNA genetika MeSH
- protozoální DNA * genetika MeSH
- ribozomální DNA genetika MeSH
- RNA ribozomální 18S genetika MeSH
- sekvenční analýza DNA MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- mezerníky ribozomální DNA MeSH
- protozoální DNA * MeSH
- ribozomální DNA MeSH
- RNA ribozomální 18S MeSH
Nodular gill disease (NGD) is an emerging condition associated with amoeba trophozoites in freshwater salmonid farms. However, unambiguous identification of the pathogens still must be achieved. This study aimed to identify the amoeba species involved in periodic NGD outbreaks in two rainbow trout (Oncorhynchus mykiss) farms in Northeastern Italy. During four episodes (February-April 2023), 88 fish were euthanized, and their gills were evaluated by macroscopic, microscopic and histopathological examination. The macroscopic and microscopic severity of the lesions and the degree of amoebae infestation were scored and statistically evaluated. One gill arch from each animal was put on non-nutrient agar (NNA) Petri dishes for amoeba isolation, cultivation and subsequent identification with SSU rDNA sequencing. Histopathology confirmed moderate to severe lesions consistent with NGD and mild to moderate amoeba infestation. The presence of amoebae was significantly correlated with lesion severity. Light microscopy of cultured amoebae strains and SSU rDNA analysis revealed the presence of a previously characterized amoeba Naegleria sp. strain GERK and several new strains: two strains from Hartmannelidae, three vannelid amoebae from the genus Ripella and cercozoan amoeba Rosculus. Despite the uncertainty in NGD etiopathogenesis and amoebae pathogenic role, identifying known and new amoebae leans towards a possible multi-aetiological origin.
- Klíčová slova
- Oncorhynchus mykiss, Italy, SSU rDNA, amphizoic amoeba, nodular gill disease (NGD), rainbow trout,
- MeSH
- amébiáza * veterinární parazitologie MeSH
- Amoeba genetika izolace a purifikace klasifikace MeSH
- Amoebozoa genetika izolace a purifikace klasifikace fyziologie MeSH
- fylogeneze MeSH
- nemoci ryb * parazitologie epidemiologie MeSH
- Oncorhynchus mykiss * parazitologie MeSH
- vodní hospodářství MeSH
- žábry * parazitologie patologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Itálie MeSH
Amoeboid protists are extremely abundant and diverse in natural systems where they often play outstanding ecological roles. They can be found in almost all major eukaryotic divisions, and genomic approaches are bringing major changes in our perception of their deep evolutionary relationships. At fine taxonomic levels, the generalization of barcoding is revealing a considerable and unsuspected specific diversity that can be appreciated with careful morphometric analyses based on light and electron microscopic observations. We provide examples on the difficulties and advances in amoeboid protists systematics in a selection of groups that were presented at the VIIIth ECOP/ISOP meeting in Rome, 2019. We conclude that, in all studied groups, important taxonomical rearrangements will certainly take place in the next few years, and systematics must be adapted to incorporate these changes. Notably, nomenclature should be flexible enough to integrate many new high level taxa, and a unified policy must be adopted to species description and to the establishment of types.
- Klíčová slova
- Cercozoa, Lobose amoebae, Myxomycetes, Taxonomy, Testate amoebae,
- MeSH
- Amoebozoa klasifikace MeSH
- biodiverzita MeSH
- klasifikace * MeSH
- terminologie jako téma MeSH
- výzkum trendy MeSH
- Publikační typ
- kongresy MeSH
Neoparamoeba perurans is the aetiological agent of amoebic gill disease (AGD) in salmonids, however multiple other amoeba species colonise the gills and their role in AGD is unknown. Taxonomic assessments of these accompanying amoebae on AGD-affected salmon have previously been based on gross morphology alone. The aim of the present study was to document the diversity of amoebae colonising the gills of AGD-affected farmed Atlantic salmon using a combination of morphological and sequence-based taxonomic methods. Amoebae were characterised morphologically via light microscopy and transmission electron microscopy, and by phylogenetic analyses based on the 18S rRNA gene and cytochrome oxidase subunit I (COI) gene. In addition to N. perurans, 11 other amoebozoans were isolated from the gills, and were classified within the genera Neoparamoeba, Paramoeba, Vexillifera, Pseudoparamoeba, Vannella and Nolandella. In some cases, such as Paramoeba eilhardi, this is the first time this species has been isolated from the gills of teleost fish. Furthermore, sequencing of both the 18S rRNA and COI gene revealed significant genetic variation within genera. We highlight that there is a far greater diversity of amoebae colonising AGD-affected gills than previously established.
- Klíčová slova
- AGD, Amoebozoa, Aquaculture, Atlantic salmon, Discosea, Tubulinea,
- MeSH
- amébiáza parazitologie veterinární MeSH
- Amoebozoa klasifikace genetika ultrastruktura MeSH
- biodiverzita * MeSH
- fylogeneze MeSH
- mikroskopie MeSH
- nemoci ryb parazitologie MeSH
- respirační komplex IV genetika MeSH
- RNA ribozomální 18S genetika MeSH
- Salmo salar parazitologie MeSH
- transmisní elektronová mikroskopie MeSH
- žábry parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- respirační komplex IV MeSH
- RNA ribozomální 18S MeSH
Two amoeboid organisms of the genera Sappinia Dangeard, 1896 and Rosculus Hawes, 1963 were identified in a sample containing king penguin guano. This sample, collected in the Subantarctic, enlarges the list of fecal habitats known for the presence of coprophilic amoebae. The two organisms were co-isolated and subcultured for over 6 mo, with continuous efforts being invested to separate each one from the mixed culture. In the mixed culture, Rosculus cells were fast growing, tolerated changes in culturing conditions, formed cysts, and evidently were attracted by Sappinia trophozoites. The separation of the Rosculus strain was accomplished, whereas the Sappinia strain remained intermixed with inseparable Rosculus cells. Sappinia cell populations were sensitive to changes in culturing conditions; they improved with reduction of Rosculus cells in the mixed culture. Thick-walled cysts, reportedly formed by Sappinia species, were not seen. The ultrastructure of both organisms was congruent with the currently accepted generic characteristics; however, some details were remarkable at the species level. Combined with the results of phylogenetic analyses, our findings indicate that the ultrastructure of the glycocalyx and the presence/absence of the Golgi apparatus in differential diagnoses of Sappinia species require a critical re-evaluation.
- Klíčová slova
- Coprophilic amoebae, HGR clade, free-living amoebae, molecular phylogeny, polar region, ultrastructure,
- MeSH
- Amoebozoa klasifikace genetika izolace a purifikace ultrastruktura MeSH
- Cercozoa klasifikace genetika izolace a purifikace ultrastruktura MeSH
- ekosystém MeSH
- feces parazitologie MeSH
- fylogeneze MeSH
- Spheniscidae parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Georgia MeSH
Five amoeboid organisms of different origin (isolated from fish organs, soil and digestive tract of earthworm) that shared light microscopical and ultrastructural features including type and arrangement of mitochondrial cristae were subjected to phylogenetic analyses based on sequences of SSU rDNA and protein coding genes (actin, cytochrome oxidase I, and eukaryotic elongation factor 2). The reconstruction of multigene phylogeny of the strains studied (i) revealed that they belong to the same single-genus Copromyxa clade; (ii) strongly supported position of Copromyxa cantabrigiensis (syn. Hartmannella cantabrigiensis) within the genus; (iii) together with comparisons of light and electron microscopy data justified reclassification of Cashia limacoides (syn. Vexillifera expectata) to Copromyxa limacoides n. comb., and (iv) justified description of a new species, Copromyxa laresi n. sp.
- Klíčová slova
- Euamoebida, free-living amoebae, limax amoebae, phylogeny, ultrastructure,
- MeSH
- aktiny genetika MeSH
- Amoeba MeSH
- Amoebozoa klasifikace genetika izolace a purifikace ultrastruktura MeSH
- dánio pruhované parazitologie MeSH
- druhová specificita MeSH
- elektronová mikroskopie MeSH
- fylogeneze * MeSH
- kinasa elongačního faktoru 2 genetika MeSH
- Lobosea klasifikace genetika izolace a purifikace ultrastruktura MeSH
- mitochondrie parazitologie ultrastruktura MeSH
- Oligochaeta parazitologie MeSH
- organely parazitologie ultrastruktura MeSH
- protozoální DNA genetika MeSH
- protozoální proteiny genetika MeSH
- půda parazitologie MeSH
- respirační komplex IV genetika MeSH
- ribozomální DNA genetika MeSH
- sekvence nukleotidů MeSH
- sekvenční seřazení MeSH
- žábry parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
- Španělsko MeSH
- Názvy látek
- aktiny MeSH
- kinasa elongačního faktoru 2 MeSH
- protozoální DNA MeSH
- protozoální proteiny MeSH
- půda MeSH
- respirační komplex IV MeSH
- ribozomální DNA MeSH
A new amoebozoan species, Vermistella arctica n. sp., is described from marine habitats in the central part of Svalbard archipelago. This is the first report on Arctic amoebae belonging to the genus Vermistella Moran and Anderson, 2007, the type species of which was described from the opposite pole of the planet. Psychrophily proved in the new strains qualifies the genus Vermistella as a bipolar taxon. Molecular phylogenetic analyses based on 18S rDNA and actin sequences did not show any affinity of the genus Vermistella to Stygamoeba regulata ATCC(®) 50892(™) strain. A close phylogenetic relationship was found between Vermistella spp. and a sequence originating from an environmental sample from Cariaco basin, the largest marine permanently anoxic system in the world. Possible mechanisms of bipolar distribution are discussed.
- Klíčová slova
- SSU, actin, biogeography, bipolar distribution, free-living amoebae, phylogeny, polar regions,
- MeSH
- aktiny genetika MeSH
- Amoeba genetika MeSH
- Amoebozoa klasifikace genetika izolace a purifikace ultrastruktura MeSH
- fylogeneze MeSH
- fylogeografie MeSH
- Lobosea MeSH
- mořská voda parazitologie MeSH
- protozoální DNA genetika MeSH
- ribozomální DNA genetika MeSH
- RNA ribozomální 16S genetika MeSH
- studené klima MeSH
- transmisní elektronová mikroskopie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Arktida MeSH
- Svalbard MeSH
- Názvy látek
- aktiny MeSH
- protozoální DNA MeSH
- ribozomální DNA MeSH
- RNA ribozomální 16S MeSH
The genus Rhizomastix is a poorly known group of amoeboid heterotrophic flagellates living as intestinal commensals of insects, amphibians or reptiles, and as inhabitants of organic freshwater sediments. Eleven Rhizomastix species have been described so far, but DNA sequences from only a single species have been published. Recently, phylogenetic analyses confirmed a previous hypothesis that the genus belongs to the Archamoebae; however, its exact position therein remains unclear. In this study we cultured nine strains of Rhizomastix, both endobiotic and free-living. According to their light-microscopic morphology and SSU rRNA and actin gene analyses, the strains represent five species, of which four are newly described here: R. bicoronata sp. nov., R. elongata sp. nov., R. vacuolata sp. nov. and R. varia sp. nov. In addition, R. tipulae sp. nov., living in the intestine of crane flies, is separated from the type species, R. gracilis. We also examined the ultrastructure of R. elongata sp. nov., which revealed that it is more complicated than the previously described R. libera. Our data show that either the endobiotic lifestyle of some Rhizomastix species has arisen independently from other endobiotic archamoebae, or the free-living members of this genus represent a secondary switch from the endobiotic lifestyle.
- Klíčová slova
- Archamoebae, morphology, phylogeny, ultrastructure,
- MeSH
- aktiny genetika MeSH
- Amoebozoa klasifikace genetika izolace a purifikace ultrastruktura MeSH
- druhová specificita MeSH
- fylogeneze MeSH
- geny rRNA MeSH
- geologické sedimenty parazitologie MeSH
- mikroskopie MeSH
- protozoální DNA analýza MeSH
- sekvence nukleotidů MeSH
- sekvenční analýza DNA MeSH
- sladká voda parazitologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- aktiny MeSH
- protozoální DNA MeSH
A total of 109 sea urchins from 3 species collected in 2 localities off the coast of Tenerife Island, Spain, were examined for the presence of free-living amoebae in their coelomic fluid. Amoeba trophozoites were isolated exclusively from moribund individuals of long-spined sea urchins Diadema aff. antillarum (Philippi) (Echinoidea, Echinodermata) that manifested lesions related to sea urchin bald disease on their tests (16 out of 56 examined). No amoebae were detected in Arbacia lixula (L.) and Paracentrotus lividus (Lamarck). From the former sea urchin species, 8 strains, established from 10 primary isolates, were identified as Neoparamoeba branchiphila Dyková et al., 2005 using morphological and molecular methods. Results of this study (limited to the screening for free-living amoebae) together with data on agents of sea urchin mortalities reported to date justify the hypothesis that free-living amoebae play an opportunistic role in D. aff. antillarum mortality. The enlargement of the dataset of SSU rDNA sequences brought new insight into the phylogeny of Neoparamoeba species.
- MeSH
- Amoebozoa klasifikace genetika izolace a purifikace MeSH
- fylogeneze MeSH
- ježovky parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Atlantský oceán MeSH
- Španělsko MeSH
Testate amoebae (TA) are a group of free-living protozoa, important in ecology and paleoecology. Testate amoebae taxonomy is mainly based on the morphological features of the shell, as examined by means of light microscopy or (environmental) scanning electron microscopy (SEM/ESEM). We explored the potential applications of confocal laser scanning microscopy (CLSM), two photon excitation microscopy (TPEM), phase contrast, differential interference contrast (DIC Nomarski), and polarization microscopy to visualize TA shells and inner structures of living cells, which is not possible by SEM or environmental SEM. Images captured by CLSM and TPEM were utilized to create three-dimensional (3D) visualizations and to evaluate biovolume inside the shell by stereological methods, to assess the function of TA in ecosystems. This approach broadens the understanding of TA cell and shell morphology, and inner structures including organelles and endosymbionts, with potential implications in taxonomy and ecophysiology.
