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Heterotrophic protists Rotosphaerida, Thaumatomonadida, and centrohelid heliozoans are among the less studied silicified protists in terms of their biogeography and ecology. These organisms inhabit fresh and brackish water, and leave behind siliceous structural elements after death that are species‐specific and amenable to electron microscopic analysis. This paper is the first to present data on species richness and taxonomic structure of silica‐scaled heterotrophic protists—rotosphaerids, colorless free‐living thaumatomonad flagellates and centrohelid heliozoans—in the large continuous water system of Siberia connecting Lake Baikal to the Kara Sea. In the study area, electron microscopy revealed 21 centrohelid heliozoan species from the genera Raphidiophrys (1), Acanthocystis (7), Choanocystis (3), Raineriophrys (2), Raphidocystis (6), and Pterocystis (2), seven rotosphaerid species from the genera Pinaciophora (3), Turriplaca (2), Rabdiophrys (1), and Pompholyxophrys (1), and one thaumatomonad flagellate species Thaumatomastix. Two species of rotosphaerids, Rabdiophrys cf. anulifera and Pinaciophora tridentata, and two species of centrohelid heliozoans, Acanthocystis cf. tubata, and A. cf. cornuta, were found in the waters of Russia for the first time. The most widespread species in fresh water from Lake Baikal to the Lower Yenissei River were Pinaciophora fluviatilis and Raineriophrys cf. fortesca. These species disappeared from the protist assemblages of the Yenissei gulf of the Kara Sea due to higher salinity, with only three species, Acanthocystis cf. mylnikovi (at 3.12‰ salinity) and A. pectinata and Raphidocystis sp. 2 (at 8‰ salinity), found in the area. The sensitivity of silica‐scaled heterotrophic protists to changes in habitat parameters suggests that these microeukaryotes could be new indicator organisms. [ABSTRACT FROM AUTHOR]

Challengerids, phaeogromids rhizarian protists, are emblematic protists of the deep sea but are also enigmatic as they occur in very low concentrations. In previous studies, we reported on temporal changes in abundance at a near‐shore mesopelagic site, but only as part of sampling of the entire microplankton assemblage, not well‐suited for examining phaeogromids. Consequently, we turned to using a closing plankton net to provide material from large volumes of seawater, thus allowing for more robust estimates of concentrations and material for observations of living cells, to our knowledge the first made. Here, we report our results on the four most commonly occurring species: Challengeranium diadon, Challengereron willemoesii, Challengeria xiphodon, and Euphysetta lucani. In contrast to our previous report, we found that changes in concentrations were not related to water column stratification, and the four species roughly co‐varied with time. Observations of live cells revealed that all four species deploy tentacle‐like pseudopods and also very large unstructured webs of fine pseudopods. The similarities in feeding webs suggest similar prey are exploited, and the similar temporal changes in abundances suggest a common factor or factors (unknown at this time) govern their concentrations. Films of live cells are provided in Supplementary Files. [ABSTRACT FROM AUTHOR]

Periphytic ciliates play a vital role in the material cycle and energy flow of microbial food web, however, their taxonomy and biodiversity are inadequately studied given their high species richness. Two new and one little known species, viz. Derouxella lembodes gen. et sp. nov., Cyrtophoron multivacuolatum sp. nov., and Cyrtophoron apsheronica Aliev, 1991, collected from coastal waters of China, were investigated using modern methods. Derouxella gen. nov. can be recognized by having dorsoventrally flattened body, a podite, one fragmented preoral kinety, two parallel circumoral kineties, and somatic kineties progressively shortened from right to left. Morphological classification and phylogenetic analyses based on nuclear small subunit ribosomal RNA (nSSU rRNA) and mitochondrial small subunit ribosomal RNA (mtSSU rRNA) gene sequence data inferred that Derouxella gen. nov. occupies an intermediate position between Hartmannulidae and Dysteriidae. Cyrtophoron multivacuolatum sp. nov. is characterized by large body size, the numbers of somatic kineties and nematodesmal rods, and having numerous contractile vacuoles. The genus Cyrtophoron and the poorly known species C. apsheronica were redefined. Even with the addition of newly obtained nSSU rRNA and mtSSU rRNA gene sequences of Cyrtophoron, the family Chlamydodontidae was still recovered as a monophyletic group, the monophyly of Cyrtophoron was supported too. [ABSTRACT FROM AUTHOR]

The alternative nutritional strategies in protists that were addressed during the symposium by that name at the 2010 annual meeting of the International Society of Protistologists and here in contributed papers, include a range of mechanisms that combine photosynthesis with heterotrophy in a single organism. Often called mixotrophy, these multiple trophic level combinations occur across a broad range of organisms and environments. Consequently, there is great variability in the physiological abilities and relative importance of phototrophy vs. phagotrophy and/or osmotrophy in mixotrophic protists. Recently, research papers addressing ecological questions about mixotrophy in marine systems have been more numerous than those that deal with freshwater systems, a trend that is probably partly due to a realization that many harmful algal blooms in coastal marine systems involve mixotrophic protists. After an introduction to the symposium presentations, recent studies of mixotrophy in freshwater systems are reviewed to encourage continuing research on their importance to inland waters. [ABSTRACT FROM AUTHOR]

Labyrinthulomycetes are mostly fungus‐like heterotrophic protists that absorb nutrients in an osmotrophic or phagotrophic manner. Members of order Labyrinthulida produce unique membrane‐bound ectoplasmic networks for movement and feeding. Among the various types of labyrinthulids' food substrates, diatoms play an important role due to their ubiquitous distribution and abundant biomass. We isolated and cultivated new diatom consuming Labyrinthulida strains from shallow coastal marine sediments. We described Labyrinthula diatomea n. sp. that differs from all known labyrinthulids in both molecular and morphological features. We provided strain delimitation within the genus Labyrinthula based on ITS sequences via haplotype network construction and compared it with previous phylogenetic surveys. [ABSTRACT FROM AUTHOR]

The deep sea has long been a mysterious and attractive habitat for protistologists. However, logistical difficulties severely limit sampling opportunities. Consequently, our knowledge of the protists in the deep sea, (arguably the largest habitat on earth), is relatively sparse. Here, we present a unique time‐series concerning three different protist taxa that share only the characteristics of being relatively large, robust to sampling, and easily identifiable to species level using light microscopy: tintinnid ciliates, phaeogromid cercozoans (e.g. Challengerids) and amphisolenid dinoflagellates. We sampled a near‐shore deep water site in the N.W. Mediterranean Sea at 250 m depth over a 2‐yr period at approximately weekly intervals from January 2017 to December 2018. To our knowledge, no previous studies have employed sampling on a similar time scale. We found taxa that appear to be restricted to deep waters, distinct seasonal patterns of abundance in some taxa, and in others nonseasonal successional patterns. Based on data from sampling following a flash flood event, the Challengerid population appeared to respond positively to a pulse of terrigenous input. Some of the distinct mesopelagic tintinnid ciliates and amphisolinid dinoflagellates were also found in two samples from the North Atlantic mesopelagic gathered from near the Azores Islands in September 2018. We conclude that there are a variety of protist taxa endemic to the mesopelagic, that the populations are dynamic, and they may be widely distributed in the deep waters of the world ocean. [ABSTRACT FROM AUTHOR]

Protist community composition and seasonal dynamics are of major importance for the production of higher trophic levels, such as zooplankton and fish. Our aim was to reveal how the protist community in the Skagerrak changes through the seasons by combining high‐throughput sequencing and microscopy of plankton collected monthly over two years. The V4 region of the 18S rRNA gene was amplified by eukaryote universal primers from the total RNA/cDNA. We found a strong seasonal variation in protist composition and proportional abundances, and a difference between two depths within the euphotic zone. Highest protist richness was found in late summer‐early autumn, and lowest in winter. Temperature was the abiotic factor explaining most of the variation in diversity. Dinoflagellates was the most abundant and diverse group followed by ciliates and diatoms. We found about 70 new taxa recorded for the first time in the Skagerrak. The seasonal pattern in relative read abundance of major phytoplankton groups was well in accordance with microscopical biovolumes. This is the first metabarcoding study of the protist plankton community of all taxonomic groups and through seasons in the Skagerrak, which may serve as a baseline for future surveys to reveal effects of climate and environmental changes. [ABSTRACT FROM AUTHOR]

Environmental sequences have become a major source of information. High‐throughput sequencing (HTS) surveys have been used to infer biogeographic patterns and distribution of broad taxa of protists. This approach is, however, more questionable for addressing low‐rank (less inclusive) taxa such as species and genera, because of the increased chance of errors in identification due to blurry taxonomic boundaries, low sequence divergence, or sequencing errors. The specious ciliate genus Euplotes partially escapes these limitations. It is a ubiquitous, monophyletic taxon, clearly differentiated from related genera, and with a relatively well‐developed internal systematics. It has also been the focus of several ecological studies. We present an update on Euplotes biogeography, taking into consideration for the first time environmental sequences, both traditional (Sanger) and HTS. We inferred a comprehensive small subunit rRNA gene phylogeny of the genus including a newly described marine species, Euplotes enigma, characterized by a unique question mark‐shaped macronucleus. We then added available environmental sequences to the tree, mapping associated metadata. The resulting scenario conflicts on many accounts with previously held views, suggesting, for example, that a large diversity of anaerobic Euplotes species exist, and that marine representatives of mainly freshwater lineages (and vice‐versa) might be more common than previously thought. [ABSTRACT FROM AUTHOR]

Presents several abstracts of papers submitted at The Society of Protozoologists East Coast Section 11th East Coast Protozoology Conference. "Protistan Communities of the Great Barrier Reef," by G. A. Langlois; "Production of Ammonia by Tritirichomonas Foetus and Trichomonas Vaginalis," by Y. Kleydman, N. Yarlett and T. Gorrell; "Viral Lysis vs. Protistan Predation: A Long-term Study of Bacerial Losses in Two Lakes of Different Trophic Status," by Y. Bettarel, T. Sime-Ngando and C. Amblard; "Epidemiology of Zoonotic Protozoa in Dairy Cattle and Wildlife in Eastern United States," by M. Santin-Duran, R. Fayer and J. M. Trout.

Presents several abstracts of papers presented at the Society of Protozoologists North American Section 55th Annual Meeting held at Gleneden Beach, Oregon. "The Growing Contributions of Molecular Biology and Immunology to Protistan Ecology: Molecular Signatures as Ecological Tools," by David C. Caron; "Why the World Needs Protists!," by John O. Corliss; "Viral Control of Phytoplankton," by C. Brussaard; "Excavata: Evolutionary Relationships Amongst Supposedly Early-Diverging Eukaryotes," by Alastair G. B. Simpson.

This revision of the classification of eukaryotes follows that of Adl et al., 2012 [J. Euk. Microbiol. 59(5)] and retains an emphasis on protists. Changes since have improved the resolution of many nodes in phylogenetic analyses. For some clades even families are being clearly resolved. As we had predicted, environmental sampling in the intervening years has massively increased the genetic information at hand. Consequently, we have discovered novel clades, exciting new genera and uncovered a massive species level diversity beyond the morphological species descriptions. Several clades known from environmental samples only have now found their home. Sampling soils, deeper marine waters and the deep sea will continue to fill us with surprises. The main changes in this revision are the confirmation that eukaryotes form at least two domains, the loss of monophyly in the Excavata, robust support for the Haptista and Cryptista. We provide suggested primer sets for DNA sequences from environmental samples that are effective for each clade. We have provided a guide to trophic functional guilds in an appendix, to facilitate the interpretation of environmental samples, and a standardized taxonomic guide for East Asian users. [ABSTRACT FROM AUTHOR]

Abstract: Two events have helped to shape protozoology/protistology as a specific scientific discipline. The first such event was the creation of the Society of Protozoologists in the U.S. in 1947 (and of its Journal of Protozoology, first published in 1954), the second event was the First International Conference on Protozoology, held in 1961 in Prague. The history of the Society of Protozoologists was comprehensively treated by Corliss (1998); the history of the Prague Conference is presented here as reminiscences and personal interpretation of events of the author, who was one of the conference organizers and a member of the organization committee. Special attention is given to the personality and scientific accomplishments of Otto Jírovec, the 1961 conference spiritual father and president. It is concluded that the Prague Conference, while establishing the tradition of protistology meetings, helped protistology to attain its present status as a fundamental science discipline, which discovers and interprets the web of life at one of its, basic, “microbial” levels. Protists literally permeate the earth biosphere and in a way represent the “dark matter” of the living world, still awaiting many discoveries. [ABSTRACT FROM AUTHOR]

Presents an overview on the taxonomy and phylogeny of protists. Kinds of biotic interactions; Role of protists in support of all life on the planet Earth; Influence of protists in restricting bacterial and fungal growth in such habitats; Role of anoxic protists in altering Earth's environment chemically.

Highlights the important trends in the field of protistology. Controversy over the origin of the eukaryotic cells; Emergence of complete genome sequencing in the field of parasitology; Role of protists in global carbon and sulfur cycles.

Information about the papers presented at the joint meetings of the 9th International Workshop on Opportunistic Protists and the 57th annual meetings of the International Society of Protistologists. Among the papers presented were studies on Trypanosome antigenic variation and host-pathogenic interactions. One of the studies proposed that the diversity in variant surface glyco-protein might also function to overcome herd immunity by allowing transmission into cured hosts.

Species determination is crucial in biodiversity research. In tintinnids, identification is based almost exclusively on the lorica, despite its frequent intraspecific variability and interspecific similarity. We suggest updated procedures for identification and, depending on the aim of the study, further steps to obtain morphological, molecular, and ecological data. Our goal is to help improving the collection of information (e.g. species re-/descriptions and DNA barcodes) that is essential for generating a natural tintinnid classification and a reliable reference for environmental surveys. These suggestions are broadly useful for protistologists because they exemplify data integration, quality/effort compromise, and the need for scientific collaborations. [ABSTRACT FROM AUTHOR]

The genus Entamoeba includes anaerobic lobose amoebae, most of which are parasites of various vertebrates and invertebrates. We report a new Entamoeba species, E. marina n. sp. that was isolated from a sample of tidal flat sediment collected at Iriomote Island, Okinawa, Japan. Trophozoites of E. marina were 12.8-32.1 μm in length and 6.8-15.9 μm in width, whereas the cysts were 8.9-15.8 μm in diam. and contained four nuclei. The E. marina cells contained a rounded nucleus with a small centric karyosome and uniformly arranged peripheral chromatin. Although E. marina is morphologically indistinguishable from other tetranucleated cyst-forming Entamoeba species, E. marina can be distinguished from them based on the combination of molecular phylogenetic analyses using SSU rDNA gene and the difference of collection sites. Therefore, we propose E. marina as a new species of the genus Entamoeba. [ABSTRACT FROM AUTHOR]

Microalgae in the division Haptophyta may be difficult to identify to species by microscopy because they are small and fragile. Here, we used high-throughput sequencing to explore the diversity of haptophytes in outer Oslofjorden, Skagerrak, and supplemented this with electron microscopy. Nano- and picoplanktonic subsurface samples were collected monthly for 2 yr, and the haptophytes were targeted by amplification of RNA/cDNA with Haptophyta-specific 18S ribosomal DNA V4 primers. Pyrosequencing revealed higher species richness of haptophytes than previously observed in the Skagerrak by microscopy. From ca. 400,000 reads we obtained 156 haptophyte operational taxonomic units (OTUs) after rigorous filtering and 99.5% clustering. The majority (84%) of the OTUs matched environmental sequences not linked to a morphological species, most of which were affiliated with the order Prymnesiales. Phylogenetic analyses including Oslofjorden OTUs and available cultured and environmental haptophyte sequences showed that several of the OTUs matched sequences forming deep-branching lineages, potentially representing novel haptophyte classes. Pyrosequencing also retrieved cultured species not previously reported by microscopy in the Skagerrak. Electron microscopy revealed species not yet genetically characterised and some potentially novel taxa. This study contributes to linking genotype to phenotype within this ubiquitous and ecologically important protist group, and reveals great, unknown diversity. [ABSTRACT FROM AUTHOR]

Studies of microbial communities in areas of the world where permanent marine water column oxyclines exist suggest they are 'hotspots' of microbial activity, and that these water features and the anoxic waters below them are inhabited by diverse protist taxa, including ciliates. These communities have minimal taxonomic overlap with those in overlying oxic water columns. Some ciliate taxa have been detected in multiple locations where these stable water column oxyclines exist; however, differences in such factors as hydrochemistry in the habitats that have been studied suggest local selection for distinct communities. We compare published data on ciliate communities from studies of deep marine water column oxyclines in Caricao Basin, Venezuela, and the Black Sea, with data from coastal, shallower oxycline waters in Framvaren and Mariager fjords, and from several deep-sea hypersaline anoxic basins in the Eastern Mediterranean Sea. Putative symbioses between Bacteria, Archaea, and ciliates observed along these oxyclines suggests a strategy of cooperative metabolism for survival that includes chemosynthetic autotrophy and exchanges of metabolic intermediates or end products between hosts and their prokaryotic partners. [ABSTRACT FROM AUTHOR]

The marine phototrophic dinoflagellate Gymnodinium smaydae n. sp. is described from cells prepared for light, scanning, and transmission electron microscopy. Also, sequences of the small (SSU) and large subunits (LSU) and the internal transcribed spacer region (ITS1-5.8S-ITS2) of ribosomal DNA were analyzed. This newly isolated dinoflagellate possessed nuclear chambers, nuclear fibrous connective, an apical groove running in a counterclockwise direction around the apex, and a major accessory pigment peridinin, which are four key features for the genus Gymnodinium. The epicone was conical with a round apex, while the hypocone was ellipsoid. Cells growing photosynthetically were 6.3-10.9 μm long and 5.1-10.0 μm wide, and therefore smaller than any other Gymnodinium species so far reported except Gymnodinium nanum. Cells were covered with polygonal amphiesmal vesicles arranged in 11 horizontal rows, and the vesicles were smaller than those of the other Gymnodinium species. This dinoflagellate had a sharp and elongated ventral ridge reaching half way down the hypocone, unlike other Gymnodinium species. Moreover, displacement of the cingulum was 0.4-0.6 × cell length while in other known Gymnodinium species it is less than 0.3 × cell length. In addition, the new species possessed a peduncle, permanent chloroplasts, pyrenoids, trichocysts, pusule systems, and small knobs along the apical furrow, but it lacked an eyespot, nematocysts, and body scales. The sequence of the SSU, ITS1-5.8S-ITS2, and LSU r DNA region differed by 1.5-3.8%, 6.0-17.4%, and 9.1-17.5%, respectively, from those of the most closely related species. The phylogenetic trees demonstrated that the new species belonged to the Gymnodinium clade at the base of a clade consisting of Gymnodinium acidotum, Gymnodinium dorsalisulcum, Gymnodinium eucyaneum, etc. Based on morphological and molecular data, we suggest that the taxon represents a new species, Gymnodinium smaydae n. sp. [ABSTRACT FROM AUTHOR]

Using morphological, morphometrical, and molecular methods, we describe Leptopharynx bromelicola n. sp. from tank bromeliads of Jamaica. We add significant data to Leptopharynx costatus and briefly characterize and review the genus Leptopharynx, including four new combinations. Nine species can be distinguished when applying the following main features and assuming that most or all have the ability to produce macrostomes (MAs): distinct ridges along the right side ciliary rows; special features like spines or wings on the body and of the oral basket; dikinetids present vs. absent from somatic kinety 3; number of kinetids in kinety 6 as two for the c ostatus pattern and ≥ five for the bromelicola pattern; beginning and structure of kinety 9 as either underneath or far underneath the adoral membranelles and with or without dikinetids; postoral complex present vs. absent; and preoral kinety 4 continuous vs. discontinuous. The 18S rDNA sequences of L. bromelicola and L. costatus differ by 1.7% and show that Leptopharynx forms a distinct clade within the Nassophorea . Leptopharynx bromelicola is possibly closely related to Leptopharynx euglenivora, which, however, lacks the basket nose so typical of the former. Leptopharynx forms thin-walled, non-kinetosome-resorbing resting cysts maintaining most of the trophic organelles. [ABSTRACT FROM AUTHOR]

The 11th in the series of International Workshops on Opportunistic Protists (IWOP-11) was held in August 2010 on the Big Island of Hawaii. These meetings are devoted to agents of infections that cause serious problems in AIDS patients and other individuals with defective immune systems. International Workshops on Opportunistic Protists serves as a forum for exchange of current research information on Pneumocystis, Cryptosporidium and the Microsporidia, Toxoplasma, free-living amoebae, kinetoplastid flagellates and other pathogens that are particularly pathogenic in immunodeficient hosts. Studies on interactions between host and pathogen, especially host responses, were highlighted in this year's symposium. The lack of in vitro cultivation methods for luxuriant growth of Pneumocystis, Cryptosporidium and the Enterocytozoon bieneusi remains a major hindrance to understanding the basic biology of these organisms and precludes genetic manipulations. However, slow but steady progress is being achieved by hard work including data mining of some completed or partially completed genome sequencing of several IWOP organisms. Of great concern is evidence for dramatic decline in research funding for these pathogens and the lack of appreciation by the larger scientific community concerning the state of art and challenges faced by researchers working on these organisms that can provide critical insight into emerging and reemerging pathogens. [ABSTRACT FROM AUTHOR]

We surveyed a variety of studies that have used single-cell polymerase chain reaction (SC-PCR) to examine the gene sequences of a diversity of unicellular protists. Representatives of all the Super-Groups of eukaryotes have been subjected to SC-PCR with ciliates and dinoflagellates being most commonly examined. The SC-PCR was carried out either by directly amplifying a single lysed cell or by first extracting DNA and following this with amplification of the DNA extract. Cell lysis methods included heating, freezing, mechanical rupture, and enzyme digestion. Cells fixed or preserved with ethanol, methanol, and Lugol's have also been used successfully. Heminested or seminested PCR might follow the initial PCR, whose products were then directly sequenced or cloned and then sequenced. The methods are not complicated. This should encourage protistologists to use SC-PCR in the description of new or revised taxa, especially rare and unculturable forms, and it should also enable the probing of gene expression in relation to life history stages. [ABSTRACT FROM AUTHOR]

Larger symbiont-bearing foraminifera are prominent and important producers of calcium carbonate in modern tropical environments. With an estimated production of at least 130 million tons of CaCO3 per year, they contribute almost 5% of the annual present-day carbonate production in the world's reef and shelf areas (0–200 m) and approximately 2.5% of the CaCO3 of all oceans. Together with non-symbiont-bearing smaller foraminifera, all benthic foraminifera are estimated to annually produce 200 million tons of calcium carbonate worldwide. The majority of foraminiferal calcite in modern oceans is produced by planktic foraminifera. With an estimated annual production of at least 1.2 billion tons, planktic foraminifera contribute more than 21% of the annual global ocean carbonate production. Total CaCO3 of benthic and planktic foraminifera together amounts to 1.4 billion tons of calcium carbonate per year. This accounts to almost 25% of the present-day carbonate production of the oceans, and highlights the importance of foraminifera within the CaCO3 budget of the world's oceans. [ABSTRACT FROM AUTHOR]

The article highlights the 9th International Workshops on Opportunistic Protists which focus on AIDS-related protistan pathogens. The author offers information about the keynote speakers, organizers, and the topic discussed during the workshops. They have also presented the themes and overviews of every workshop.

A new heterotrophic flagellate ( Andalucia godoyi n. gen. n. sp.) is described from soil. Earlier preliminary 18S rRNA analyses had indicated a relationship with the phylogenetically difficult-to-place jakobid Jakoba incarcerata. Andalucia godoyi is a small (3–5 μm) biflagellated cell with a ventral feeding groove. It has tubular mitochondrial cristae. There are two major microtubular roots (R1, R2) and a singlet root associated with basal body 1 (posterior). The microtubular root R1 is associated with non-microtubular fibres “I,”“B,” and “A,” and divides in two parts, while R2 is associated with a “C” fibre. These structures support the anterior portion of the groove. Several features of A. godoyi are characteristic of jakobids: (i) there is a single dorsal vane on flagellum 2; (ii) the C fibre has the jakobid multilaminate substructure; (iii) the dorsal fan of microtubules originates in very close association with basal body 2; and (iv) there is no “R4” microtubular root associated with basal body 2. Morphological analyses incorporating the A. godoyi data strongly support the monophyly of all jakobids. Our 18S rRNA phylogenies place A. godoyi and J. incarcerata as a strong clade, which falls separately from other jakobids. Statistical tests do not reject jakobid monophyly, but a specific relationship between Jakoba libera and J. incarcerata and/or A. godoyi is rejected. Therefore, we have established a new genus Andalucia n. gen. with the type species Andalucia godoyi n. sp., and transfer Jakoba incarcerata to Andalucia as Andalucia incarcerata n. comb. [ABSTRACT FROM AUTHOR]

An understanding of large-scale eukaryotic evolution is beginning to crystallise, as molecular and morphological data demonstrate that eukaryotes fall into six major groups. However, there are several taxa of which the affinities are yet to be resolved, and for which there are only either molecular or morphological data. One of these is the amoeboid flagellate Mastigamoeba invertens. This organism was originally misidentified and studied as a pelobiont using molecular data. We present its first light microscopical and ultrastructural characterisation. We demonstrate that it does not show affinities to the amoebozoan pelobionts, because unlike the pelobionts, it has a double basal body and two flagellar roots, a classical Golgi stack, and a large branching double membrane-bound organelle. Phylogenetic analyses of small subunit ribosomal RNA suggest an affinity with the apusomonads, when a covariotide correction for rate heterogeneity is used. We suggest that previous molecular results have been subject to artefacts from an insufficient correction for rate heterogeneity. We propose a new name for the taxon, Breviata anathema; and the unranked, apomorphy-based name “Breviates” for Breviata and its close relatives. [ABSTRACT FROM AUTHOR]

The planktonic ciliate Parastrombidinopsis shimi n. gen., n. sp. is described from both living cells and quantitative protargol-stained (QPS) preparations and the sequence of the small subunit rDNA (SSU rDNA) is reported. This species is almost oval when the cells are alive; when stained, it is cylindrical for the upper two-fifths, half-bowl shaped for the middle two-fifths, and narrow rodshaped for the lower one-fifth. The ranges (and mean±standard deviation, n=20) of cell length, cell width, and oral diameter of living cells were 112–221 μm (168±39), 88–176 μm (121±30), and 53–110 μm (80±14), respectively, while those of the QPS-stained specimens (n=54) were 88–225 μm (162±29), 55–163 μm (102±19), and 53–98 μm (69±9), respectively. Thirty-six to 48 external oral polykinetids had cilia 25–40 μm long. However, unlike Strombidinopsis species sensu stricto, P. shimi has an external oral polykinetid zone that is an open circle. This species has two shorter polykinetids associated with the end of the oral polykinetid zone, deep in the oral cavity. Like Strombidinopsis species in the subclass Choreotrichia, 36–50 somatic kineties were equally spaced around the cell body and extended from the oral to the posterior regions with 68–105 dikinetids per kinety. Both kinetosomes of each kinetid bore cilia 3–10 μm long. Parastrombidinopsis shimi had 2 (1–4) ovoid macronuclei of 20–82 × 15–32 μm. When properly aligned, the sequence of the SSU rDNA of P. shimi (GenBank Accession No. AJ786648) was approximately 5% different from that of Strobilidium caudatum and 6% different from that of two Strombidinopsis species. Based both on morphology and gene sequence divergence, we establish this is as a new species in a new genus belonging to the family Strombidinopsidae. [ABSTRACT FROM AUTHOR]

This revision of the classification of unicellular eukaryotes updates that of Levine et al. (1980) for the protozoa and expands it to include other protists. Whereas the previous revision was primarily to incorporate the results of ultrastructural studies, this revision incorporates results from both ultrastructural research since 1980 and molecular phylogenetic studies. We propose a scheme that is based on nameless ranked systematics. The vocabulary of the taxonomy is updated, particularly to clarify the naming of groups that have been repositioned. We recognize six clusters of eukaryotes that may represent the basic groupings similar to traditional “kingdoms.” The multicellular lineages emerged from within monophyletic protist lineages: animals and fungi from Opisthokonta, plants from Archaeplastida, and brown algae from Stramenopiles. [ABSTRACT FROM AUTHOR]

Describes the ultrastructure of a new microsporidian species Microgemma vivaresi causing liver cell xenoma formation in sea scorpions, Taurulus bubalis. Stages of merogony, sporogony and sporogenesis mixed in the central cytoplasm of developing xenomas; All stages with unpaired nuclei; Broadly ovoid spores; Polaroplast with up to 40 membranes arranged in pairs.

Presents the first results from the protistan diversity component of the Microbial Observatory of Caterpillars project. Goal of exploring prokaryotic and eukaryotic microbial diversity in the tropical forest using the caterpillar as a focal point; Discovery of two protests; Ciliate Colpoda isolated from the frass of Rothschildia lebeau; Flagellate Heteromita from an enrichment of gut contents of R. lebeau.

Examines microbial eukaryote diversity in a natural seawater sample from the coastal western North Atlantic Ocean using two molecular biological approaches. Cloning and sequencing of ribosomal RNA genes; Fragment analysis of these genes using the terminal restriction fragment length polymorphism method; Indication of the high diversity of protistan taxa in the seawater sample.

Discusses the mixotrophy in the phototrophic harmful alga Cochlodinium (C.) polykrikoides and investigation of the kinds of prey species and the effects of prey concentration on the growth and ingestion rates of C. polykrikoides. Calculation of the grazing coefficients by the combination of field data on abundances of C. polykrikoides; Increase in growth rates of C. polykrikoides on a cryptophyte; Growth and ingestion rates of C. polykrikoides; Grazing impact of C. polykrikoides on populations of cryptophytes.

Examines the interactions between planktonic microalgae and protozoan grazers by researchers from Bremerhaven, Germany. Recognition for the dominance of microzooplankton in consuming phytoplankton; Diversity of feeding strategies and behavior used by heterotrophic protists to access phytoplankton species; Defense strategies used by algae against protozoan grazers.

Studies the viral control of phytoplankton populations by researchers from the Netherlands. Influence of physical, chemical and biological variables in the dynamics of phytoplankton population; Role of zooplankton grazing and sinking on the loss factors for phytoplankton; Significance of viral infection in the regulation of phytoplankton populations.

Reports on a study conducted by researchers in Italy, which represents the first extended report on a species of the ciliate genus Peritromus. Determination of the small subunit rDNA gene sequence of the ciliates; Description of the different stages of contraction of Peritromus kahli.

The article presents instructions to authors to submit articles regarding new taxa of unicellular protists to be published by the journal.

Reports on a workshop entitled, "Frontiers in Genomics: Insights into Protist Evolutionary Biology," at the University of Iowa on June 19-21, 2004. Goals of the workshop; Definition of the role of genomics in the eukaryotic tree of life; Identification of the challenges in characterizing protist genomes; Proposal of specific solutions to these challenges.

The article presents abstracts of the papers submitted at the annual meeting of the International Society of Protistologists held at Lisbon, Portugal from June 20-24, 2006. They include "Studies of protistan diversity in Antarctica," "Antigenic variation in ciliates" and "Structure, evolution, and expression of Pneumocystis gene families that encode variable surface proteins."

The article presents abstracts of papers presented at the annual meeting of the International Society of Protistologists held in Czech Republic from April 24-28, 2006. They include "The susceptibility of suckling rabbits to infection with coccidia," "Cysteine and aspartic peptidases from the gut of the tick Ixodes ricinus" and "Phlebotomine sand flies in an endemic focus of cutaneous leishmaniasis in Turkey: identification of the vector."

The article presents abstracts of papers discussed at the annual meeting of the Groupement des Protistologues de Langue Francaise (GPLF) held in Dakar Senegal, France from May 22-26, 2006. They include "Structure of the sub-terminal regions of Encephalitozoon cuniculi chromosomes," "Research of structural homology between the spores proteins of Myxobolus episquamalis (Myxosporidia) and Encephalitozoon cuniculi (Microsporidia)" and "Microsporidia of marine fishes from Senegal."

ABSTRACT. Polymyxa betae is a soil-borne protist and an obligate parasite of sugar beet that transmits the beet necrotic yellow vein virus. Sugar beet hairy roots, transformed by Agrobacterium rhizogenes, were inoculated with surface-sterilized root fragments infected by P. betae. After 10 wk in a liquid medium, typical structures of P. betae were observed in this in vitro system. This first in vitro culture of P. betae in liquid medium will contribute to a better understanding of this protist's biology through providing a way to conserve and produce purified isolates of the protist. [ABSTRACT FROM AUTHOR]

Points out that while researchers have amassed a tremendous amount of information on the diversity, life histories, genetics and physiologies of protests, there are a number of glaring omissions in some aspects of their ecology. Methodological limitations; Rapid and substantive advances in molecular biology and immunology which have made available novel approaches and techniques for ecological research.

Presents a decadal review of the contents of "The Journal of Protozoology/Journal of Eukaryotic Microbiology from Volume 1 to Volume 50. Highlights of the continued and broad relevance of protozoa and protists to biology; Demonstration of the increasing importance of molecular approaches to the ecological study of the protists; Discussion of several advances in the field of protistology.