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Lophomonas blattarum is a facultative commensal gut dweller of common pest cockroaches. Its cells are roughly spherical in shape with an apical tuft of ~50 flagella. Controversially, it has been implicated in human respiratory infections based on light microscopic observations of similarly shaped cells in sputum or bronchoalveolar lavage fluid. Here, we have sequenced the 18S rRNA gene of L. blattarum and its sole congener, Lophomonas striata, isolated from cockroaches. Both species branch in a fully supported clade with Trichonymphida, consistent with a previous study of L. striata, but not consistent with sequences from human samples attributed to L. blattarum. [ABSTRACT FROM AUTHOR]

Sorodiplophrys stercorea is a sorocarpic organism that utilizes filose pseudopodia for locomotion and absorptive nutrition. It has traditionally been considered to be a member of the Labyrinthulae based on its morphology. Its closest relatives were thought to be species in the taxon Diplophrys. Since the genus Diplophrys has been shown to be paraphyletic and S. stercorea has pseudopodia similar to some members of Rhizaria, we examined its relationship with other eukaryotes. We obtained four isolates from the dung of cow and horse, brought each into monoeukaryotic culture, and sequenced their SSU rRNA gene for phylogenetic analysis. All our isolates were shown to form a monophyletic group in the Labyrinthulae, nested in the Amphifiloidea clade. Our results demonstrate that Sorodiplophrys is more closely related to species of the genus Amphifila than to Diplophrys and represents an additional independent origin of sorocarpic multicellularity among eukaryotes. This study represents the first confirmed sorocarpic lifestyle in the Stramenopiles. [ABSTRACT FROM AUTHOR]

A wide diversity of organisms utilize faecal habitats as a rich nutrient source or a mechanism to traverse through animal hosts. We sequenced the 18S rRNA genes of the coprophilic, fruiting body-forming amoeba Guttulinopsis vulgaris and its non-fruiting relatives Rosculus 'ithacus' CCAP 1571/3, R. terrestris n. sp. and R. elongata n. sp. and demonstrate that they are related to the coprophilic flagellate Helkesimastix in a strongly supported, but highly divergent 18S sister clade. PCR primers specific to both clades were used to generate 18S amplicons from a range of environmental and faecal DNA samples. Phylogenetic analysis of the cloned sequences demonstrated a high diversity of uncharacterised sequence types within this clade, likely representing previously described members of the genera Guttulinopsis, Rosculus and Helkesimastix, as well as so-far unobserved organisms. Further, an Illumina MiSeq sequenced set of 18S V4-region amplicons generated from faecal DNAs using universal eukaryote primers showed that core-cercozoan assemblages in faecal samples are as diverse as those found in more conventionally examined habitats. These results reveal many novel lineages, some of which appear to occur preferentially in faecal material, in particular cercomonads and glissomonads. More broadly, we show that faecal habitats are likely untapped reservoirs of microbial eukaryotic diversity. [ABSTRACT FROM AUTHOR]

Summary Over the last 15 years classical culturing and environmental PCR techniques have revealed a modest number of genuinely new major lineages of protists; however, some new groups have greatly influenced our understanding of eukaryote evolution. We used culturing techniques to examine the diversity of free-living protists that are relatives of diplomonads and retortamonads, a group of evolutionary and parasitological importance. Until recently, a single organism, Carpediemonas membranifera, was the only representative of this region of the tree. We report 18 new isolates of Carpediemonas-like organisms (CLOs) from anoxic marine sediments. Only one is a previously cultured species. Eleven isolates are conspecific and were classified within a new genus, Kipferlia n. gen. The remaining isolates include representatives of three other lineages that likely represent additional undescribed genera (at least). Small-subunit ribosomal RNA gene phylogenies show that CLOs form a cloud of six major clades basal to the diplomonad-retortamonad grouping (i.e. each of the six CLO clades is potentially as phylogenetically distinct as diplomonads and retortamonads). CLOs will be valuable for tracing the evolution of diplomonad cellular features, for example, their extremely reduced mitochondrial organelles. It is striking that the majority of CLO diversity was undetected by previous light microscopy surveys and environmental PCR studies, even though they inhabit a commonly sampled environment. There is no reason to assume this is a unique situation - it is likely that undersampling at the level of major lineages is still widespread for protists. [ABSTRACT FROM AUTHOR]

In the course of a large-scale global survey of mycetozoans, amoeboid organisms that form fruiting bodies, a new species of Acrasis was discovered from several subtropical locales in Hawaii, Australia, Bermuda, and South Africa. We isolated four strains from dead, still attached, plant material, and one strain from attached bark of a tree. Each isolate forms simple uniseriate multicellular fruiting bodies typically consisting of two bottle-shaped, basal stalk cells and a chain of <20 spores. The isolate from Bermuda often forms dichotomous simple branches, each consisting of <10 spores. Amoebae from these new isolates are limax with eruptive pseudopodial formation and display rapid locomotion—characters indicative of amoebae in the excavate taxon Heterolobosea. These isolates form simpler fruiting bodies than is typical of the well-known Acrasis rosea. Although in the original description, A. rosea is known to form uniseriate fruiting bodies similar to our isolates, A. rosea isolates typically form more complex fruiting structures along side simple ones, but never strictly simple ones. Nuclear-encoded 18S rRNA gene phylogenies demonstrate that our five isolates form a highly supported clade that is sister to A. rosea. Given the differences both in gene sequences and fruiting body morphology between our isolates and A. rosea, we propose the new species, Acrasis helenhemmesae n. sp. [ABSTRACT FROM AUTHOR]

Unicellular eukaryotes that lack mitochondria typically contain related organelles such as hydrogenosomes or mitosomes. To characterize the evolutionary diversity of these organelles, we conducted an expressed sequence tag (EST) survey on the free-living amoeba Mastigamoeba balamuthi, a relative of the human parasite Entamoeba histolytica. From 19 182 ESTs, we identified 21 putative mitochondrial proteins implicated in protein import, amino acid interconversion and carbohydrate metabolism, two components of the iron–sulphur cluster (Fe-S) assembly apparatus as well as two enzymes characteristic of hydrogenosomes. By immunofluorescence microscopy and subcellular fractionation, we show that mitochondrial chaperonin 60 is targeted to small abundant organelles within Mastigamoeba. In transmission electron micrographs, we identified double-membraned compartments that likely correspond to these mitochondrion-derived organelles, The predicted organellar proteome of the Mastigamoeba organelle indicates a unique spectrum of functions that collectively have never been observed in mitochondrion-related organelles. However, like Entamoeba, the Fe-S cluster assembly proteins in Mastigamoeba were acquired by lateral gene transfer from ε-proteobacteria and do not possess obvious organellar targeting peptides. These data indicate that the loss of classical aerobic mitochondrial functions and acquisition of anaerobic enzymes and Fe-S cluster assembly proteins occurred in a free-living member of the eukaryote super-kingdom Amoebozoa. [ABSTRACT FROM AUTHOR]

The genus Sappinia, a taxon of free-living amoebae with trophozoites that typically have two closely appressed nuclei, contains two named species, Sappinia pedata, the type species, and S. diploidea. The amoebae of both species are essentially identical according to the literature. The two species are distinguished by S. pedata having a standing amoeba stage, incorrectly interpreted as a cyst, and S. diploidea having sessile, bicellular cysts. Using four isolates of S. pedata collected from around the world, we present detailed light micrographic illustrations of all stages of its life cycle. We confirm that the standing amoeba lacks a cell wall. In two isolates of S. pedata, there are bicellular cysts indistinguishable from those of S. diploidea. Using sequence data from the nuclear small subunit ribosomal RNA gene, we conclude that S. pedata and the published neotype of S. diploidea are congeneric but not conspecific. The genus branches within Thecamoebidae. Sequencing of the actin gene confirms the inclusion of Sappinia in Thecamoebidae. Resolving the taxonomy of Sappinia is gaining importance because it has recently been attributed as an opportunistic human pathogen. [ABSTRACT FROM AUTHOR]

Studies ellobiopsids of the genus Thalassomyces by researchers from Los Angeles, California. Nutrient absorbing root possessed by the multinucleate protist parasites of aquatic crustaceans; Protrusion of its reproductive structures through the carapace of the host; Affiliation of the ellobiopsids with fungi, colorless algae and dinoflagellates.

Giardia lamblia must encyst to survive in the environment and subsequently infect new hosts. We investigated the expression of glucosamine-6-phosphate isomerase (Gln6PI), the first enzyme required for biosynthesis of N -acetylgalactosamine, for the major cyst wall polysaccharide. We isolated two Gln6PI genes that encode proteins with large areas of identity, but distinctive central and terminal regions. Both recombinant enzymes have comparable kinetics. Interestingly, these genes have distinct patterns of expression. Gln6PI-A has a conventional, short 5′ untranslated region (UTR), and is expressed at a low level during vegetative growth and encystation. The Gln6PI-B gene has two transcripts — one is expressed constitutively and the second species is highly upregulated during encystation. The non-regulated Gln6PI-B transcript has the longest 5′-UTR known for Giardia and is 5′ capped or blocked. In contrast, the Gln6PI-B upregulated transcript has a short, non-capped 5′-UTR. A small promoter region (< 56 bp upstream from the start codon) is sufficient for the regulated expression of Gln6PI-B. Gln6PI-B also has an antisense overlapping transcript that is expressed constitutively. A shorter antisense transcript is detected during encystation. This is the first report of a developmentally regulated promoter in Giardia , as well as evidence for a potential role of 5′ RNA processing and antisense RNA in differential gene regulation. [ABSTRACT FROM AUTHOR]