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Interaction of A. cryptophaga with volvocalean green algae. (A) Trophozoite attached to a colony of E. elegans before invading the mucilage. (B-G) Time series of A. cryptophaga invading E. elegans and successively phagocytosing single algal cells (arrowheads). Note that the amoeba first extracts a cell from the colony. (H) Trophozoite inside E. elegans feeding on daughter colonies. (I) Digestive cyst of A. cryptophaga residing in the mucilage of E. elegans next to an empty digestive cyst displaying two holes (asterisks) and brown digestive remnants. (J) Large plasmodial cell of A. cryptophaga with ingested Eudorina cells. (K) Dumbbell-shaped digestive cyst extending in two separate gelatinous colonies of E. elegans. (L-N) Arachnomyxa cryptophaga (arrows) feeding on other volvocalean algae, namely Volvox aureus (L), G. pectorale (M) and C. multitaeniata (N). Scale bars: 10 μm in A-I; 20 μm in J, K, M, N; 50 μm in L.
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Vampyrellid amoebae (Vampyrellida, Rhizaria) are widespread in freshwater, marine and terrestrial ecosystems and consume a wide range of eukaryotes, e.g. algae, fungi and micrometazoa. Environmental sequences indicate that only a small fraction of their genetic diversity is phenotypically characterised, emphasising the need to further explore unkno...
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... attack on the natural prey E. elegans, trophozoites of A. cryptophaga attached to the surface of the algal colony and retracted the filopodia, attaining a compact morphology (Fig. 4A). Subsequently, pseudopodia invaded the mucilage of the algal colony and searched for prey cells (Fig. 4B and C). Most often, the entire cell body then slipped through the outer mucilage layer of E. elegans, thus entering the internal space of the gelatinous colony, in which the algal cells reside (Fig. 4D-F). Internal trophozoites ...
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... attack on the natural prey E. elegans, trophozoites of A. cryptophaga attached to the surface of the algal colony and retracted the filopodia, attaining a compact morphology (Fig. 4A). Subsequently, pseudopodia invaded the mucilage of the algal colony and searched for prey cells (Fig. 4B and C). Most often, the entire cell body then slipped through the outer mucilage layer of E. elegans, thus entering the internal space of the gelatinous colony, in which the algal cells reside (Fig. 4D-F). Internal trophozoites surrounded single cells of E. elegans with sheetlike pseudopodia, pulled them out of their place and phagocytosed ...
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... attaining a compact morphology (Fig. 4A). Subsequently, pseudopodia invaded the mucilage of the algal colony and searched for prey cells (Fig. 4B and C). Most often, the entire cell body then slipped through the outer mucilage layer of E. elegans, thus entering the internal space of the gelatinous colony, in which the algal cells reside (Fig. 4D-F). Internal trophozoites surrounded single cells of E. elegans with sheetlike pseudopodia, pulled them out of their place and phagocytosed them (Fig. 4E and F). Depending on the size of the Eudorina colony, trophozoites engulfed a fraction or all algal cells and finally formed digestive cysts inside the algal colonies ( Fig. 4G and Video ...
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... and C). Most often, the entire cell body then slipped through the outer mucilage layer of E. elegans, thus entering the internal space of the gelatinous colony, in which the algal cells reside (Fig. 4D-F). Internal trophozoites surrounded single cells of E. elegans with sheetlike pseudopodia, pulled them out of their place and phagocytosed them (Fig. 4E and F). Depending on the size of the Eudorina colony, trophozoites engulfed a fraction or all algal cells and finally formed digestive cysts inside the algal colonies ( Fig. 4G and Video S2, Supporting Information). Occasionally, the extraction of a single cell from a colony and the external formation of a digestive cyst were observed (not ...
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... cells reside (Fig. 4D-F). Internal trophozoites surrounded single cells of E. elegans with sheetlike pseudopodia, pulled them out of their place and phagocytosed them (Fig. 4E and F). Depending on the size of the Eudorina colony, trophozoites engulfed a fraction or all algal cells and finally formed digestive cysts inside the algal colonies ( Fig. 4G and Video S2, Supporting Information). Occasionally, the extraction of a single cell from a colony and the external formation of a digestive cyst were observed (not shown). Arachnomyxa cryptophaga was also able to engulf entire daughter colonies inside mature colonies of E. elegans (Fig. 4H). The mostly spherical digestive cysts of A. ...
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... formed digestive cysts inside the algal colonies ( Fig. 4G and Video S2, Supporting Information). Occasionally, the extraction of a single cell from a colony and the external formation of a digestive cyst were observed (not shown). Arachnomyxa cryptophaga was also able to engulf entire daughter colonies inside mature colonies of E. elegans (Fig. 4H). The mostly spherical digestive cysts of A. cryptophaga formed inside E. elegans measured 13-38 μm in diameter and lacked a discernible outer cyst envelope (Fig. 4I). As typical for known leptophryids, the ingesta accumulated in a central food vacuole. During digestion, the green contents became brown and the cytoplasm of A. ...
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... the external formation of a digestive cyst were observed (not shown). Arachnomyxa cryptophaga was also able to engulf entire daughter colonies inside mature colonies of E. elegans (Fig. 4H). The mostly spherical digestive cysts of A. cryptophaga formed inside E. elegans measured 13-38 μm in diameter and lacked a discernible outer cyst envelope (Fig. 4I). As typical for known leptophryids, the ingesta accumulated in a central food vacuole. During digestion, the green contents became brown and the cytoplasm of A. cryptophaga developed an intense orange to brick-red colour (Fig. 4I). Subsequently, small amoebae (often two or four) were released from the digestive cysts, in which brown ...
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... of A. cryptophaga formed inside E. elegans measured 13-38 μm in diameter and lacked a discernible outer cyst envelope (Fig. 4I). As typical for known leptophryids, the ingesta accumulated in a central food vacuole. During digestion, the green contents became brown and the cytoplasm of A. cryptophaga developed an intense orange to brick-red colour (Fig. 4I). Subsequently, small amoebae (often two or four) were released from the digestive cysts, in which brown food remnants were left behind ( Fig. 4I and Video S3, Supporting Information). The small trophozoites exited the digestive cyst through separate holes in its envelope (Fig. 4I). Plasmodia of A. cryptophaga displayed the capacity to ...
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... leptophryids, the ingesta accumulated in a central food vacuole. During digestion, the green contents became brown and the cytoplasm of A. cryptophaga developed an intense orange to brick-red colour (Fig. 4I). Subsequently, small amoebae (often two or four) were released from the digestive cysts, in which brown food remnants were left behind ( Fig. 4I and Video S3, Supporting Information). The small trophozoites exited the digestive cyst through separate holes in its envelope (Fig. 4I). Plasmodia of A. cryptophaga displayed the capacity to engulf more algal cells than uninucleate trophozoites (Fig. 4J), resulting in larger digestive cysts, which sometimes contained algal cells of ...
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... of A. cryptophaga developed an intense orange to brick-red colour (Fig. 4I). Subsequently, small amoebae (often two or four) were released from the digestive cysts, in which brown food remnants were left behind ( Fig. 4I and Video S3, Supporting Information). The small trophozoites exited the digestive cyst through separate holes in its envelope (Fig. 4I). Plasmodia of A. cryptophaga displayed the capacity to engulf more algal cells than uninucleate trophozoites (Fig. 4J), resulting in larger digestive cysts, which sometimes contained algal cells of different colonies and displayed a dumbbell-like morphology (Fig. 4K). Furthermore, plasmodia were able to engulf entire colonies of E. ...
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... four) were released from the digestive cysts, in which brown food remnants were left behind ( Fig. 4I and Video S3, Supporting Information). The small trophozoites exited the digestive cyst through separate holes in its envelope (Fig. 4I). Plasmodia of A. cryptophaga displayed the capacity to engulf more algal cells than uninucleate trophozoites (Fig. 4J), resulting in larger digestive cysts, which sometimes contained algal cells of different colonies and displayed a dumbbell-like morphology (Fig. 4K). Furthermore, plasmodia were able to engulf entire colonies of E. elegans resulting in free digestive cysts that were not surrounded by algal ...
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... trophozoites exited the digestive cyst through separate holes in its envelope (Fig. 4I). Plasmodia of A. cryptophaga displayed the capacity to engulf more algal cells than uninucleate trophozoites (Fig. 4J), resulting in larger digestive cysts, which sometimes contained algal cells of different colonies and displayed a dumbbell-like morphology (Fig. 4K). Furthermore, plasmodia were able to engulf entire colonies of E. elegans resulting in free digestive cysts that were not surrounded by algal ...
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... stagnophila (details in Table S1, Supporting Information). The amoebae invaded the mucilaginous colonies of a wide morphological range of Volvocales, including Gonium, Eudorina, Pleodorina and Volvox, and fed on the algal cells as described above (Fig. 4L and M). Furthermore, A. cryptophaga consumed single-celled representatives such as C. multitaeniata by phagocytosis, resulting in digestive cysts that adhered to the bottom of the culture vessels (Fig. 4N). Arachnomyxa cryptophaga did not grow on Zygnematophyceae and Euglenophyceae, except Euglena viridis. The phagocytosis of Eu. schmitzii, ...
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... of a wide morphological range of Volvocales, including Gonium, Eudorina, Pleodorina and Volvox, and fed on the algal cells as described above (Fig. 4L and M). Furthermore, A. cryptophaga consumed single-celled representatives such as C. multitaeniata by phagocytosis, resulting in digestive cysts that adhered to the bottom of the culture vessels (Fig. 4N). Arachnomyxa cryptophaga did not grow on Zygnematophyceae and Euglenophyceae, except Euglena viridis. The phagocytosis of Eu. schmitzii, Trachelomonas sp. and Monomorphina pyrum was very rarely observed, but did not lead to growth of the ...
Citations
... The same was observed for Leptophrys vorax. L. vorax is able to engulf single algae cells, to engulf algae colonies or to invade them [15]. The order Vampyrellida includes several genera [16], and some examples are Leptophrys [17], Platyreta [18] and Theratromyxa [19]. ...
... In contrast, the ingestion of the spores of the fungus Fusarium culmorum and subsequent protist growth was not possible [29]. Perhaps, as already observed for hyphae [29], the BghA6 spores were too large to be phagocytosed by A. castellanii, and there was no secondary consumption pattern as in vampyrellid amoebae [14,15]. Despite these observations in the liquid culture experiment, all isolates were able to influence the BghA6 spores within five days and to survive on the barley's leaf surface (Fig. 3). ...
The obligate biotrophic fungal pathogen Blumeria graminis causes the powdery mildew disease of cereals, which results in large crop losses. Control of B. graminis in barley is mainly achieved by fungicide treatment and by breeding resistant varieties. Vampyrellid amoebae, just like mycophagous protists, are able to consume a variety of fungi. To reveal the impact of some selected fungus-consuming protists on Blumeria graminis f. sp. hordei (Bgh), and to evaluate the possibility of using these protists as biological agents in the future, their feeding behaviour on B. graminis spores on barley leaves was investigated. An experiment was carried out with five different protist isolates (Leptophrys vorax, Platyreta germanica, Theratromyxa weberi U 11, Theratromyxa weberi G7.2 and Acanthamoeba castellanii) and four matched controls, including the food sources of the cultures and the medium. Ten-day-old leaves of barley (Hordeum vulgare cv. Golden Promise) were first inoculated with Blumeria graminis (f. sp. hordei race A6) spores, then treated with protists and fungal colonies on the leaf surfaces were counted under the microscope after 5 days. The isolates L. vorax, P. germanica, and T. weberi U11 did not show a significant reduction in the number of powdery mildew colonies whereas the isolates T. weberi G7.2 and A. castellanii significantly reduced the number of powdery mildew colonies on the leaf surfaces compared to their respective controls. This indicates that these two isolates are capable of reducing B. graminis colonies on barley leaves and are suitable candidates for further investigation for possible use as biological agents. Nevertheless, the susceptibility to dryness and the cell division rate should be considered during the optimisation of the next steps like application procedure and whole plant treatment.
Supplementary Information
The online version contains supplementary material available at 10.1007/s00284-023-03497-5.
... It was also shown that this amoeba belongs to the rhizarian protists (and not the Amoebozoa) -relatively closely related to the genus Vampyrella (Bass et al., 2009a;Hess et al., 2012). During the past 10 years, the vampyrellid amoebae have been extensively explored by cultivation and molecular methods (Hess et al., 2012;Berney et al., 2013;Gong et al., 2015;Hess, 2017aHess, , 2017bMore et al., 2018More et al., , 2021Zhang et al., 2022), but these studies mainly focused on aquatic representatives. For the terrestrial vampyrellids preying on fungi and animals, we still lack the link between in-depth ecological observations and the genetic identity of particular species. ...
In the context of the soil food web, the transfer of plant-fixed energy and carbon to higher trophic levels has
traditionally been attributed to two main energy channels: the fungal energy channel and the bacterial energy
channel. Historically, protists were overlooked in the fungal energy channel, which was believed to be controlled
by fungivorous microarthropods and nematodes. In this study, we investigated fungivorous protists in the
rhizosphere of Arabidopsis thaliana. Our findings revealed a notable abundance and diversity of protists that have
developed specialized strategies to overcome the protective cell wall of fungi. Among the identified species were
two Vampyrellida (Rhizaria) species, namely Theratromyxa weberi and Platyreta germanica, as well as one
Arcellinida (Amoebozoa) species, called Cryptodifflugia oviformis. While T. weberi typically consumed entire
fungal cells, the other two species perforated fungal cell walls and extracted the cellular contents. We elucidate
the feeding strategies and dietary ranges of the amoebae, highlighting the non-uniform nature of fungivory in
protists, as different taxa have evolved distinct approaches to access fungi as a food source. Moreover, we provide
publicly available cultures of these protists to facilitate further experimental investigations within the research
community.
... The Leptophryidae were well supported (100/1.00); however, as previously reported (Hess, 2017b) the internal branching of this family remained largely unresolved. The strains VC.01 and VC.02 formed a clade within the family Leptophryidae with maximum support, most closely related to environmental sequences with no associated phenotype. ...
... Leptophrys, Kinopus, Vernalophrys, Planctomyxa), colony invasion (e.g. Arachnomyxa), or prey on micrometazoa (Theratromyxa; Gong et al., 2015;Hess, 2017b;Hess et al., 2012;Weber et al., 1952;Zhang et al., 2022;Zwillenberg, 1953). Considering our findings on Pseudovampyrella, the Leptophryidae exhibit a stunning diversity of feeding strategies and prey types, highlighting the ecological versatility of this family. ...
Vampyrellid amoebae are predatory protists, which consume a variety of eukaryotic prey and inhabit freshwater, marine and terrestrial ecosystems. Although they have been known for almost 150 years, much of their diversity lacks an in‐depth characterization. To date, environmental sequencing data hint at several uncharacterized lineages, to which no phenotype is associated. Furthermore, there are numerous historically described species without any molecular information. This study reports on two new vampyrellid strains from moorlands, which extract the protoplasts of Closterium species (Zygnematophyceae). Our data on morphology, prey range specificity and feeding strategy reveal that the studied vampyrellids are very similar to the historically described Vampyrella closterii . However, phylogenetic analyses demonstrate that the two strains do not belong to the genus Vampyrella and, instead, form a distinct clade in the family Leptophryidae. Hence, we introduce a new genus of algivorous protoplast extractors, Pseudovampyrella gen. nov., with the species P. closterii (= V. closterii ) and P. minor . Our findings indicate that the genetic diversity of morphologically described vampyrellid species might be hugely underrated.
... They are known for an obligatory digestive cyst stage in the life history and their peculiar modes of feeding (9). The recorded algal preys were diverse, including haptophytes (10), euglenids (11), cryptophytes (12), diatoms (13), and cyanobacteria (14,15), as well as chlorophytes and streptophytes in unicellular forms (16), fusiform (17), gelatinous colonies (16), and filamentous forms (18). ...
... They are known for an obligatory digestive cyst stage in the life history and their peculiar modes of feeding (9). The recorded algal preys were diverse, including haptophytes (10), euglenids (11), cryptophytes (12), diatoms (13), and cyanobacteria (14,15), as well as chlorophytes and streptophytes in unicellular forms (16), fusiform (17), gelatinous colonies (16), and filamentous forms (18). ...
... Moreover, Platyreta readily forms plasmodia with highly branched or reticulate cells (27), but K. chlorellivorus never does. The shapes of the trophozoites and pseudopodia of other genera within the family Leptophryidae (namely, Leptophrys [9], Planctomyxa [16], Arachnomyxa [16], and Vernalophrys [17]) resemble Kinopus ( Fig. 2A and B). Leptophrys and Planctomyxa both fed on various Euglenophyceae (e.g., Euglena, Monomorphina, Phacus, Trachelomonas) (16), while Kinopus favored Chlorella. ...
The large-scale culture of low-cost algal biomass can be significantly affected by microbial grazing on the algae. To minimize the impact, it is necessary to manage the predators. In this study, we describe a new genus and species of vampyrellid amoeba, Kinopus chlorellivorus, which caused the loss of Chlorella sorokiniana in large-scale cultures. We assigned it to the family Leptophryidae (Vampyrellida) based on morphology and small-subunit (SSU) rRNA gene sequence comparisons. Using transmission electron microscopy, we found spherical lucent inclusions, which have not been reported for any leptophryids or other vampyrellids. The gene sequence of SSU rRNA did not match any recognized genera or species and contained four characteristic regions. K. chlorellivorus preys on algae by engulfment. Laboratory feeding experiments confirmed that its grazing rate was as high as 131 Chlorella cells day-1 individual-1. Results of prey-range experiments demonstrated that it could consume other chlorophyte microalgae (e.g., Scenedesmus, Coelastrella, and Haematococcus) but with a strong feeding ability on Chlorella spp., with ingestion rates ranging from 2.67 to 3.15 prey predator-1 h-1 and growth rates of the amoeba ranging from 0.039 to 0.045 h-1. On the basis of its high grazing ability on Chlorella, capacity to form large populations in a short period of time, and capacity to form resistant resting stages, this contaminant has the potential to cause serious problems in large-scale Chlorella culture and should be of concern to operators of algal production facilities. IMPORTANCE The vampyrellids (Vampyrellida, Rhizaria) are a major group of predatory amoebae that have attracted significant attention because of their diversity of feeding strategies. The crucial roles they play in important processes such as suppressing soil disease and controlling aquatic algae, and as microbial contaminants in outdoor large-scale algal cultures, have also received increasing attention. In this study, a new genus and species of algivorous vampyrellid amoeba, Kinopus chlorellivorus, is described as a significant grazer responsible for losses in outdoor industrial Chlorella cultures. We found that the amoeba's detrimental effects on Chlorella cultures may be related to its specific feeding characteristics. This study provides phenotypic and genetic information on a previously unknown vampyrellid, emphasizes the impact of contaminating vampyrellids in commercial microalgal cultures, and will contribute to the development of management strategies for predicting this kind of contaminant in large-scale microalgal cultivation.
... The majority of the Rhizaria ASVs were Cercozoans which are most likely bacterial grazers (Burki and Keeling, 2014) which could survive in an oligotrophic environment. There were also ASVs classified as Vampyrellida, also known as predatory amoebae that parasitize other microeukaryotes (Hess, 2017;More et al., 2019) and Plasmodiophorida best known as plant parasites (Hwang et al., 2012). Rhizaria were reported as a significant component of microbial mats collected in the Movile cave but they were not the predominant group, except in a cultured sample (Reboul et al., 2019). ...
The purpose of this study was to survey the eukaryotic microbiome of two karst caves in the Valley and Ridge physiographic region of the Appalachian Mountains. Caves are known to harbour eukaryotic microbes but their very low densities and small cell size make them difficult to collect and identify. Microeukaryotes were surveyed using two methodologies, filtering water and submerging glass microscope slides mounted in periphytometers in cave pools. The periphyton sampling yielded 13.5 times more unique amplicon sequence variants (ASVs) than filtered water. The most abundant protist supergroup was Alveolata with large proportions of the ASVs belonging to dinoflagellate, ciliate and apicomplexan clades. The next most abundant were Rhizarians followed by Stramenopiles (diatoms and chrysophytes) and Ameobozoans. Very few of the ASVs, 1.5%, matched curated protist sequences with greater than 99% identity and only 2.5% could be identified from surface plankton samples collected in the same region. The overall composition of the eukaryotic microbiome appears to be a combination of bacterial grazers and parasitic species that could possibly survive underground as well as cells, cysts and spores probably transported from the surface.
... Protists (Parabistichella sp., Platyreta sp. 1, sp. 2, Rhogostomidae sp. 2, and Intramacronucleata sp. 3) were probably eaten from cryoconite by chance, because they are not typical food for tardigrades (at least not known until now). Platyreta sp. is an amoeba known as parasite of algae species but also nematodes [80]. On glaciers, it can live as a predator or parasite of ice algae, or parasite of tardigrades, but such a relationship is highly speculative without additional testing. ...
Insights into biodiversity and trophic webs are important for understanding ecosystem functions. Although the surfaces of glaciers are one of the most productive and biologically diverse parts of the cryosphere, the links between top consumers, their diet and microbial communities are poorly understood. In this study, for the first time we investigated the relationships between bacteria, fungi and other microeukaryotes as they relate to tardigrades, microscopic metazoans that are top consumers in cryoconite, a biologically rich and productive biogenic sediment found on glacier surfaces. Using metabarcoding (16S rDNA for bacteria, ITS1 for fungi, and 18S rDNA for other microeukaryotes), we analyzed the microbial community structures of cryoconite and compared them with the community found in both fully fed and starved tardigrades. The community structure of each microbial group (bacteria, fungi, microeukaryotes) were similar within each host group (cryoconite, fully fed tardigrades and starved tardigrades), and differed significantly between groups, as indicated by redundancy analyses. The relative number of operational taxonomic units (ZOTUs, OTUs) and the Shannon index differed significantly between cryoconite and tardigrades. Species indicator analysis highlighted a group of microbial taxa typical of both fully fed and starved tardigrades (potential commensals), like the bacteria of the genera Staphylococcus and Stenotrophomonas , as well as a group of taxa typical of both cryoconite and fully fed tardigrades (likely part of the tardigrade diet; bacteria Flavobacterium sp., fungi Preussia sp., algae Trebouxiophyceae sp.). Tardigrades are consumers of bacteria, fungi and other microeukaryotes in cryoconite and, being hosts for diverse microbes, their presence can enrich the microbiome of glaciers.
... Many predatory protists feeding on other eukaryotes, for example, heliozoa and certain vampyrellids, rely on long and slender cell extensions increasing the chance of prey contact (e.g. Hess, 2017;Hülsmann, 1993;Patterson & Hausmann, 1981;Suzaki et al., 1980). The amoebae of I. vortex contain an elaborate microtubular cytoskeleton that is clearly separate from the F-actinrich domains. ...
The Cutosea represent a deep‐branching lineage within the phylum Amoebozoa that is still relatively poorly explored. Currently, there are four cutosean representatives known – the monotypic genera Armaparvus, Idionectes, Sapocribrum and Squamamoeba – with marked genetic distances. Idionectes vortex is the deepest‐branching species and differs markedly from the other Cutosea in ecology, life history, and, most importantly, in its ability to form a flagellated swarmer with an exceptional swimming mechanism. As far as we know, the other Cutosea lack flagella and rather represent small, marine amoebae with a characteristic cell coat. The present paper focuses on the amoeboid life history stage of the algivorous amoeboflagellate Idionectes vortex to provide data for a first in‐depth comparison with other Cutosea and to document structural specialties. The amoeboid stage of Idionectes is mainly associated with the specific feeding process, i.e. the interaction with algal prey cells and phagocytosis of protoplast material. Yet, the present data from time‐lapse microscopy, cytochemical stainings and electron microscopy demonstrate clear similarities with the other cutosean species concerning amoeboid locomotion and cell coat ultrastructure. Furthermore, Idionectes amoebae exhibit a well‐developed microtubular cytoskeleton, and an unusual basal apparatus that seems to undergo marked changes during the life history of this exceptional amoebozoan.
... VAMPYRELLIDS (order Vampyrellida) are predatory, naked amoebae that form a genetically diverse clade within Rhizaria, most closely related to the parasitic Phytomyxea (Bass et al., 2009;Hess, 2017a;Hess et al., 2012;Sierra et al., 2016). Known vampyrellids typically feed on other eukaryotes by extracting the protoplast or engulfing the entire prey cell, and have an obligatory "digestive cyst" stage in which cell division takes place (Cienkowski, 1865;Hess, 2017b;Hess et al., 2012;Hülsmann, 1993;More et al., 2019;Zopf, 1885). Currently, there are three well-defined vampyrellid families, namely Vampyrellidae Zopf, 1885, Leptophryidae Hess et al., 2012, and Placopodidae Jahn, 1928 (the latter containing only the genus Placopus; More et al., 2019), plus the genus Thalassomyxa, which represents a separate clade in SSU rRNA gene phylogenies (More et al., 2019). ...
... Their members differ markedly in gross morphology and locomotive behavior, and can be assigned to one or more of the three established vampyrellid morphotypes (Hess et al., 2012). "Isodiametric" amoebae (known Vampyrellidae, some Leptophryidae) have a spherical morphology and tend to float in the water column (Hess, 2017b;Hess et al., 2012;Hülsmann, 1985), while "expanded" amoebae (some Leptophryidae, Thalassomyxa) may be branched, network-forming, or sheet-like, and creep over surfaces (Berney et al., 2013;Grell, 1992;Hess, 2017b). "Filoflabellate" amoebae (Placopus) are characterized by the formation of a pseudopodial lamella and a peculiar rolling locomotion (Hertwig & Lesser, 1874;Hess, 2017a;More et al., 2019). ...
... Their members differ markedly in gross morphology and locomotive behavior, and can be assigned to one or more of the three established vampyrellid morphotypes (Hess et al., 2012). "Isodiametric" amoebae (known Vampyrellidae, some Leptophryidae) have a spherical morphology and tend to float in the water column (Hess, 2017b;Hess et al., 2012;Hülsmann, 1985), while "expanded" amoebae (some Leptophryidae, Thalassomyxa) may be branched, network-forming, or sheet-like, and creep over surfaces (Berney et al., 2013;Grell, 1992;Hess, 2017b). "Filoflabellate" amoebae (Placopus) are characterized by the formation of a pseudopodial lamella and a peculiar rolling locomotion (Hertwig & Lesser, 1874;Hess, 2017a;More et al., 2019). ...
The vampyrellids (Vampyrellida, Rhizaria) are an order of naked amoebae of considerable genetic diversity. Three families have been well defined (Vampyrellidae, Leptophryidae, Placopodidae), but most vampyrellid lineages detected by environmental sequencing are poorly known or completely uncharacterised. In the brackish sediment of Lake Bras D’Or, Nova Scotia, Canada, we discovered an amoeba with a vampyrellid-like life history that was morphologically dissimilar from known vampyrellid taxa. We established a culture of this amoeba, studied its feeding behaviour and prey range specificity, and characterized it with molecular phylogenetic methods and light and electron microscopy. The amoeba was a generalist predator (i.e. eukaryotroph), devouring a range of marine microalgae, with a strong affinity for some benthic diatoms and Chroomonas. Interestingly, the amoeba varied its feeding strategy depending on the prey species. Small diatoms were engulfed whole, while larger species were fed on through extraction with an invading pseudopodium. The SSU rRNA gene phylogenies robustly placed the amoeba in the most basal, poorly described lineage (‘clade C’) of the Vampyrellida. Based on the phylogenetic position and the distinct morphology of the studied amoeba, we here describe it as Sericomyxa perlucida gen. et sp. nov., and establish the new vampyrellid family Sericomyxidae for ‘clade C’.
... In comparison with other studies [14,67], the family Leptophryidae and sm27-lineage (from the order Vampyrellidea) were more abundant in the grassland biocrusts than the dune biocrusts with 10% and 3% of the sequence reads, respectively. The vast majority of studied Vampyrellidea are obligatory algivores, although there is scattered laboratorybased evidence that some species may feed on fungi or soil mesofauna [68][69][70][71]. Many Vampyrellidea are known to be able to perforate cell walls and are thus able to prey on filamentous green algae, a food source that is inaccessible for most phagotrophic protists. ...
Biological soil crusts (biocrusts) accommodate diverse communities of phototrophic and heterotrophic microorganisms. Heterotrophic protists have critical roles in the microbial food webs of soils, with Cercozoa and Endomyxa often being dominant groups. Still, the diversity, community composition, and functions of Cercozoa and Endomyxa in biocrusts have been little explored. In this study, using a high-throughput sequencing method with taxon-specific barcoded primers, we studied cercozoan and endomyxan communities in biocrusts from two unique habitats (subarctic grassland and temperate dunes). The communities differed strongly, with the grassland and dunes being dominated by Sarcomonadea (69%) and Thecofilosea (43%), respectively. Endomyxa and Phytomyxea were the minor components in dunes. Sandonidae, Allapsidae, and Rhogostomidae were the most abundant taxa in both habitats. In terms of functionality, up to 69% of the grassland community was constituted by bacterivorous Cercozoa. In contrast, cercozoan and endomyxan communities in dunes consisted of 31% bacterivores, 25% omnivores, and 20% eukaryvores. Facultative and obligate eukaryvores mostly belonged to the families Rhogostomidae, Fiscullidae, Euglyphidae, Leptophryidae, and Cercomonadidae, most of which are known to feed mainly on algae. Biocrust edaphic parameters such as pH, total organic carbon, nitrogen, and phosphorus did not have any significant influence on shaping cercozoan communities within each habitat, which confirms previous results from dunes.
... Protoplast feeding a predatory mode whereby microbial eukaryotes, namely vampyrellid amoebae (Vampyrellidae, Rhizaria) and the Viridiraptoridae (Filosa, Rhizaria), locally dissolve the cell wall of their prey-primarily algae, as well as fungal spores and hyphae [149]-to phagocytose the entire protoplast without engulfing the entire cell [150]. ...
Phagocytosis, or ‘cell eating’, is a eukaryote-specific process where particulate matter is engulfed via invaginations of the plasma membrane. The origin of phagocytosis has been central to discussions on eukaryogenesis for decades, where it is argued as being either a prerequisite for, or consequence of, the acquisition of the ancestral mitochondrion. Recently, genomic and cytological evidence has increasingly supported the view that the pre-mitochondrial host cell—a bona fide archaeon branching within the ‘Asgard’ archaea—was incapable of phagocytosis and used alternative mechanisms to incorporate the alphaproteobacterial ancestor of mitochondria. Indeed, the diversity and variability of proteins associated with phagosomes across the eukaryotic tree suggest that phagocytosis, as seen in a variety of extant eukaryotes, may have evolved independently several times within the eukaryotic crown-group. Since phagocytosis is critical to the functioning of modern marine food webs (without it, there would be no microbial loop or animal life), multiple late origins of phagocytosis could help explain why many of the ecological and evolutionary innovations of the Neoproterozoic Era (e.g. the advent of eukaryotic biomineralization, the ‘Rise of Algae’ and the origin of animals) happened when they did.
