Search

The evolution of photosynthesis has been a major driver in eukaryotic diversification. Eukaryotes have acquired plastids (chloroplasts) either directly via the engulfment and integration of a photosynthetic cyanobacterium (primary endosymbiosis) or indirectly by engulfing a photosynthetic eukaryote (secondary or tertiary endosymbiosis). The timing and frequency of secondary endosymbiosis during eukaryotic evolution is currently unclear but may be resolved in part by studying cryptomonads, a group of single-celled eukaryotes comprised of both photosynthetic and non-photosynthetic species. While cryptomonads such as Guillardia theta harbor a red algal-derived plastid of secondary endosymbiotic origin, members of the sister group Goniomonadea lack plastids. Here, we present the genome of Goniomonas avonlea-the first for any goniomonad-to address whether Goniomonadea are ancestrally non-photosynthetic or whether they lost a plastid secondarily.We sequenced the nuclear and mitochondrial genomes of Goniomonas avonlea and carried out a comparative analysis of Go. avonlea, Gu. theta, and other cryptomonads. The Go. avonlea genome assembly is ~ 92 Mbp in size, with 33,470 predicted protein-coding genes. Interestingly, some metabolic pathways (e.g., fatty acid biosynthesis) predicted to occur in the plastid and periplastidal compartment of Gu. theta appear to operate in the cytoplasm of Go. avonlea, suggesting that metabolic redundancies were generated during the course of secondary plastid integration. Other cytosolic pathways found in Go. avonlea are not found in Gu. theta, suggesting secondary loss in Gu. theta and other plastid-bearing cryptomonads. Phylogenetic analyses revealed no evidence for algal endosymbiont-derived genes in the Go. avonlea genome. Phylogenomic analyses point to a specific relationship between Cryptista (to which cryptomonads belong) and Archaeplastida.We found no convincing genomic or phylogenomic evidence that Go. avonlea evolved from a secondary red algal plastid-bearing ancestor, consistent with goniomonads being ancestrally non-photosynthetic eukaryotes. The Go. avonlea genome sheds light on the physiology of heterotrophic cryptomonads and serves as an important reference point for studying the metabolic "rewiring" that took place during secondary plastid integration in the ancestor of modern-day Cryptophyceae.

We report a new heterotrophic cryptomonad Hemiarma marina n. g., n. sp. that was collected from a seaweed sample from the Republic of Palau. In our molecular phylogenetic analyses using the small subunit ribosomal RNA gene, H. marina formed a clade with two marine environmental sequences, and the clade was placed as a sister lineage of the freshwater cryptomonad environmental clade CRY1. Alternatively, in the concatenated large and small subunit ribosomal RNA gene phylogeny, H. marina was placed as a sister lineage of Goniomonas. Light and electron microscopic observations showed that H. marina shares several ultrastructural features with cryptomonads, such as flattened mitochondrial cristae, a periplast cell covering, and ejectisomes that consist of two coiled ribbon structures. On the other hand, H. marina exhibited unique behaviors, such as attaching to substrates with its posterior flagellum and displaying a jumping motion. H. marina also had unique periplast arrangement and flagellar transitional region. On the basis of both molecular and morphological information, we concluded that H. marina should be treated as new genus and species of cryptomonads.

Telomeres, ubiquitous and essential structures of eukaryotic chromosomes, are known to come in a variety of forms, but knowledge about their actual diversity and evolution across the whole phylogenetic breadth of the eukaryotic life remains fragmentary. To fill this gap, we employed a complex experimental approach to probe telomeric minisatellites in various phylogenetically diverse groups of algae. Our most remarkable results include the following findings: 1) algae of the streptophyte class Klebsormidiophyceae possess the Chlamydomonas-type telomeric repeat (TTTTAGGG) or, in at least one species, a novel TTTTAGG repeat, indicating an evolutionary transition from the Arabidopsis-type repeat (TTTAGGG) ancestral for Chloroplastida; 2) the Arabidopsis-type repeat is also present in telomeres of Xanthophyceae, in contrast to the presence of the human-type repeat (TTAGGG) in other ochrophytes studied, and of the photosynthetic alveolate Chromera velia, consistent with its phylogenetic position close to apicomplexans and dinoflagellates; 3) glaucophytes and haptophytes exhibit the human-type repeat in their telomeres; and 4) ulvophytes and rhodophytes have unusual telomere structures recalcitrant to standard analysis. To obtain additional details on the distribution of different telomere types in eukaryotes, we performed in silico analyses of genomic data from major eukaryotic lineages, utilizing also genome assemblies from our on-going genome projects for representatives of three hitherto unsampled lineages (jakobids, malawimonads, and goniomonads). These analyses confirm the human-type repeat as the most common and possibly ancestral in eukaryotes, but alternative motifs replaced it along the phylogeny of diverse eukaryotic lineages, some of them several times independently.

The cryptomonads is a well-defined lineage of unicellular eukaryotes, composed of several marine and freshwater groups. However, the evolutionary relationships among these groups are unclear due to conflicting inferences between morphological and molecular phylogenies. Here, we have inferred the evolutionary relationships among marine and freshwater species in order to better understand the importance of the marine-freshwater boundary on the historical diversification patterns of cryptomonads. We have constructed improved molecular phylogenies by taking into account rate variation both across sites and across sequences (covarion substitutions), and by analysing the vast majority of publicly available cryptomonad 18S rRNA sequences and related environmental phylotypes. The resulting phylogenies included 55 sequences, and revealed two novel freshwater cryptomonad clades (CRY1 and CRY2) and a large hidden diversity of cryptomonads. CRY1 was placed deeply within the cryptomonad phylogeny together with all the major freshwater lineages (i.e. Goniomonas and Cryptomonas), while CRY2 was placed within a lineage of marine species identified as Plagioselmis-like with the aid of a new sequence generated from a cultured species. The inferred phylogenies suggest only few successful marine-freshwater transitions over the history of cryptomonads. Most of the transitions seem to have occurred from marine to fresh waters, but re-colonizations of marine habitats have also taken place. This implies that the differences in the biogeophysical conditions between marine and fresh waters constitute a substantial barrier for the cross-colonization of these environments by cryptomonads.

Planktonic heterotrophic flagellates are ubiquitous eukaryotic microorganisms that play a crucial role in carbon and nutrient fluxes through pelagic food webs. Here we illustrate for the first time a grazing model of planktonic dinoflagellate, Oxyrrhis marina, on the heterotrophic nanoflagellate Goniomonas amphinema, using the DNA-binding fluorescent dye Hoechst 33342. A solution of 1 microg/mL of the fluorochrome allowed viability of the prey for at least 48 hours, provided low fluorescence quenching, and labelled the flagellate without masking the cytoplasm. After 2 hours of contact between the fluorescent prey and the predator, O. marina population had preyed on live G. amphinema at an ingestion rate of 2.2 prey Oxyrrhis (-1) h(-1). Results show that this model is a time-effective and inexpensive approach for the direct observation of heterotrophic flagellate grazing. The fact that prey remain alive while predation occurs, as well as the low rate of quenching, could be of help in studying the fate of real-time trophic interactions between protists in microbial webs.

The fine structure and surface exopolymers of a coastal planktonic nanodiatom of the sparsely reported genus Extubocellulus were studied respectively by scanning electron microscopy and confocal microscopy in conjunction with fluorescent lectins. Monitoring the suitability of the species as prey food for other protists was also investigated by video microscopy coupled with digital film. Cells are rectangular in girdle view, with a pervalvar axis longer than the apical axis. Valves are almost circular with a diameter of 2.8 to 3.6 microm. The valve face bears randomly distributed areolae (ca. 50 in 10 microm), which may be either open or occluded. Two small raised ocelluli occur at the apices, with a rim devoid of perforations and about 6-7 porelli. Glucose and N-acetyl-glucosamine moieties present on the surface of the live diatom were labelled with fluorescent lectins, and a differential pattern of distribution for both carbohydrates was observed. The potential role of fluorescent lectins as cellular probes of taxonomic value in small diatoms is compared with that of nucleotide and antibody probes. We provide the first illustrative evidence of the presence of Extubocellulus sp. in the cytoplasm of the nanoflagellate Goniomonas amphinema and of the egestion of diatom frustules. Results obtained are discussed in the light of the present knowledge of the role of carbohydrate-protein interactions in phagocytosis of prey by free-living protozoa.

Here we use phylogenomics with expressed sequence tag (EST) data from the ecologically important coccolithophore-forming alga Emiliania huxleyi and the plastid-lacking cryptophyte Goniomonas cf. pacifica to establish their phylogenetic positions in the eukaryotic tree. Haptophytes and cryptophytes are members of the putative eukaryotic supergroup Chromalveolata (chromists [cryptophytes, haptophytes, stramenopiles] and alveolates [apicomplexans, ciliates, and dinoflagellates]). The chromalveolates are postulated to be monophyletic on the basis of plastid pigmentation in photosynthetic members, plastid gene and genome relationships, nuclear "host" phylogenies of some chromalveolate lineages, unique gene duplication and replacements shared by these taxa, and the evolutionary history of components of the plastid import and translocation systems. However the phylogenetic position of cryptophytes and haptophytes and the monophyly of chromalveolates as a whole remain to be substantiated. Here we assess chromalveolate monophyly using a multigene dataset of nuclear genes that includes members of all 6 eukaryotic supergroups. An automated phylogenomics pipeline followed by targeted database searches was used to assemble a 16-protein dataset (6,735 aa) from 46 taxa for tree inference. Maximum likelihood and Bayesian analyses of these data support the monophyly of haptophytes and cryptophytes. This relationship is consistent with a gene replacement via horizontal gene transfer of plastid-encoded rpl36 that is uniquely shared by these taxa. The haptophytes + cryptophytes are sister to a clade that includes all other chromalveolates and, surprisingly, two members of the Rhizaria, Reticulomyxa filosa and Bigelowiella natans. The association of the two Rhizaria with chromalveolates is supported by the approximately unbiased (AU)-test and when the fastest evolving amino acid sites are removed from the 16-protein alignment.

The diversity of heterotrophic flagellates was examined at marine sediments around Cape Tribulation, Australia. The species described belong to the Alveolates, Apusomonadidae, Cercomonadida, Choanoflagellida, Cry ptomonadida, Diplomonadida, Euglenozoaincertae sedis, Kathablepharidae, Kinetoplastida, Pedinellids, Stephanopogonidae, Stramenopiles, Stramenopilesincertae sedis, Thaumatomonadidae and Protistaincertae sedis. Among the 51 species from 38 genera encountered in this study is one new taxon:Glissandra similis n. sp., and two new names are introduced:Goniomonas abrupta (Skvortzov 1924) nomen nodum andCercomonas skvortzovi (Skvortzov 1977) nomen nodum. There was little evidence for endemism because most flagellates including one new taxon described here have been reported.

The communities of heterotrophic flagellates from intertidal sediments and from samples of surface water collected at coastal sites in Darwin (Northern Territory, Australia) were surveyed as part of a study on the geographic distribution of marine heterotrophic flagellates. Seventy two species were identified from the genera: Acanthocorbis, Acanthoeca, Actinomonas, Amastigomonas, Ancyromonas, Anisonema, Apheloecion, Bicosoeca, Bicosta, Bodo, Bordnamonas, Caecitellus, Cafeteria, Calliacantha, Calotheca, Campyloacantha, Carpediemonas, Ciliopkrys, Cosmoeca, Crucispina, Diaphanoeca, Dinema, Diplotheca, Do-Hum, Goniomonas, Heteronema, Jenningsia, Kiitohsia, Massisteria, Metopion, Metromonas, Ministeria, Nannoeca, Notosolenus, Paraphysomonas, Pendulomonas, Percolomonas, Petalomonas, Platypleura, Pleurasiga, Ploeotia, Protaspis, Pseudobodo, Pseudophyllomitus, Rhynchobodo, Rhynchomonas, Rhynchopus, Salpingoeca, Stephanoeca and Telonema. Two new species, Percolomonas similis and Ploeotia amygdala, are rep...

A nuclearl8S rDNA phylogeny for cryptomonad algae is presented, including 11 species yet to be investigated by molecular means. The phylogenetic positions of the cryptomonad genera Campylomonas and Plagioselmis are assessed for the first time. Campylomonas groups most closely with morphologically similar species with the same accessory pigment from the genus Cryptomonas. Plagioselmis groups with the genera Teleaulax and Geminigera forming a clade whose members are united by unusual thylakoid arrangement. Nuclear 18S rDNA phylogeny divides cryptomonads into seven major lineages, two of which consist of the monospecific genera Proteomonas and Falcomonas. Analysis of nuclearl8S rDNA sequence supports suggestions that a Falcomonas-like cryptomonad gave rise to all other blue-green cryptomonads. New sequence from the plastid-lacking cryptomonad genus Goniomonas is also included, and the order of divergence of the major cryptomonad lineages is discussed. The morphology, number, and pigmentation of the cryptomonad plastidial complex are congruent with nuclear 18S rDNA phylogenies. Host cell features, such as periplast type, furrow/ gullet system, and cell shape, can be more variable and may be markedly different in species that are closely related by nuclear 18S rDNA phylogeny. Conversely, some species that are not closely related by molecular phylogeny may display a very similar, possibly primitive, periplast and furrow morphology.

The sensitivity to ultraviolet radiation (UVR, 280-400 nm) of ten species of freshwater and marine phagotrophic protists was assessed in short-term (4 h) laboratory experiments. Changes in the motility and morphology of the cells, as well as direct quantification of DNA damage, were evaluated. The net amount of cyclobutane pyrimidine dimers formed after exposure of the organisms to a weighted dose (Setlow DNA normalized at 300 nm) of 1.7 kJ m(-2) was quantified by an immunoassay using a monoclonal specific antibody directed against thymine dimers (TTs). This is the first application of this method to aquatic protists. The results indicated that marine and freshwater heterotrophic nanoflagellates, representatives from the order Kinetoplastida (Bodo caudatus and Bodo saltans, respectively) accumulate significantly higher DNA damage than protists representatives of the orders Chrysomonadida, Cryptomonadida or Scuticociliatida. The high proportion of A:T bases in the unique kinetoplast DNA, may explain the higher accumulation of TTs found in bodonids. Experiments made with B. saltans to study the dynamics of DNA damage accumulation in the presence of UVR and photorepairing light, indicated that the mechanisms of DNA repair in this species are very inefficient. Furthermore, the dramatic changes observed in the cell morphology of B. saltans probably compromise its recovery. Our results show that sensitivity to UVR among aquatic phagotrophic protists is species-specific and that different cell targets are affected differently among species. While DNA damage in B. saltans was accompanied by motility reduction, altered morphology, and finally mortality, this was not observed in other bodonids as well as in the other species tested.

The Cryptophyta comprise photoautotrophic protists with complex plastids which harbor a remnant eukaryotic nucleus (nucleomorph) and a few heterotrophic taxa which either lack a plastid (Goniomonas) or contain a complex plastid devoid of pigments (Ieucoplast; Chilomonas). To resolve the phylogenetic relationships between photosynthetic, leucoplast-containing and aplastidial taxa, we determined complete nuclear-encoded SSU rRNA-sequences from 12 cryptophyte taxa representing the genera Cryptomonas, Chilomonas, Rhodomonas, Chroomonas, Hemiselmis, Proteomonas and Teleaulax and, as an outgroup taxon, Cyanoptyche gloeocystis (Glaucocystophyta). Phylogenetic analyses of SSU rRNA sequences from a total of 24 cryptophyte taxa rooted with 4 glaucocystophyte taxa using distance, parsimony and likelihood methods as well as LogDet transformations invariably position the aplastidial genus Goniomonas as a sister taxon to a monophyletic lineage consisting of all plastid containing cryptophytes including Chilomonas. Among the plastid-containing taxa, we identify six major clades each supported by high bootstrap values: clade I (Cryptomonas and Chilomonas), clade II (Rhodomonas, Pyrenomonas, Rhinomonas and Storeatula), clade III (Guillardia and the 'unidentified cryptophyte' strain CCMP 325), clade IV (Teleaulax and Geminigera), clade V (Proteomonas) and clade VI (Hemiselmis, Chroomonas and Komma). Clade I (Cryptomonas and Chilomonas) represents a sister group to clades II-VI which together form a monophyletic lineage; the phylogenetic relationships between clades II-VI remain largely unresolved. Chilomonas is positioned within the Cryptomonas clade and thus presumably evolved from a photosynthetic taxon of this genus. In our analysis the characters blue and red pigmentation do not correspond with a basal subdivision of the phylum, thus rejecting this character for higher-level classification of cryptophytes. However, different spectroscopic subtypes of phycoerythrin (PE I-III) and phycocyanin (PC II-IV) represent informative characters at a lower taxonomic level. Phycocyanin types are confined to the later diverging clade VI and within Hemiselmis, a species with phycocyanin is monophyletic with two species containing phycoerythrin. This supports previous molecular studies which demonstrated that the β subunit of all cryptophyte biliproteins, regardless of spectroscopic type, is phylogenetically derived from the red algal β-phycoerythrin gene family, therefore the cryptophyte phycocyanins presumably originated by chromophore replacement from phycoerythrin. Our phylogenetic analysis does not support a previous suggestion that the aplastidial cryptophyte Goniomonas evolved from an ancestor containing a complex cryptomonadtype plastid by nucleomorph and plastid loss.

Summary The flagellates of an Australian garden soil were studied by placing coverslips on wet soil and subsequently examining the coverslips by light microscopy. A number of genera and species were found which have not previously been reported from soil samples. Besides the three new species, Apusomonas australiensis sp. nov., Peltomonas hanelisp. nov., and Sciviamonas terricola gen. nov. sp. nov. they include species from the genera Amastigomonas, Cryptaulax, Paraphysomonas, and Protaspis. Among genera which have been reported from soils, we recorded a number of species previously unreported from soils: Petalomonas pusilla, Bicosoeca epiphytica, Bicosoeca mignotii, and Ancyromonas sigmoides. In addition, we extracted a number of forms which have been found in soil but which are usually not considered as members of the soil flagellate community. They are: Codosiga botrytis, Salpingoeca amphoridium, and Goniomonas truncata. Only a minority of the taxa recorded are thought of as common and widespread in soils, they include: Apusomonas proboscidea, and species of Cercomonas and Spumella. At least part of the difference between communities of flagellates from freshwaters and those of soils are due to different sampling methods and not only to the existence of different communities.

Summary The communities of heterotrophic flagellates from four sites of differing salinity (from marine to saturated brine) from the Shark Bay region in Western Australia were examined. A total of 46 species were identified, seven of which are described for the first time. New names are Ancyromonas melba n. sp. Bodo cygnus n. sp., Colpodella unguis n. sp., Glissandra innuerende n. gen. n. sp., Pleurostomum turgidum n. sp., Ploeotia azurina n. sp., Rhynchobodo simius n. sp. and Palustrimonas n. gen. The majority of the new species were from hypersaline sites. There was a degree of overlap in the communities present at the different sites, especially between the three lowest salinity sites. Some species, such as Rhynchomonas nasuta, Bodo saltans and B. designis , have been found over a wide range of salinities. There was little evidence for any endemism in the marine site, with all species observed having been recorded previously from at least one other location geographically remote from Shark Bay.

Summary Heterotrophic flagellates were identified from the littoral sediments of One Tree Island (Great Barrier Reef, Australia) by light microscopy. A total of 37 species are described of which 3 are new to science. The new species are: Peranema macrostoma, Ploeotia plumosa , and Anehmia exotica , the latter also representing a new genus. One species previously described as Percolomonas membranifera was assigned to a new genus Carpediemonas . The similarities of the species composition from One Tree Island and other locations world-wide were compared using the program PRIMER. The community from One Tree Island shows considerable overlap from other marine benthic sites world-wide. Communities from littoral benthic sites form a cluster separate from pelagic communities — although there is considerable overlap in the species of smaller heterotrophic and/or bacterivorous flagellates. Most species from the benthic community of heterotrophic flagellates appear to have a world-wide distribution, and there is little evidence of endemism.

Background: Elongation factor-1α (EF-1α) and elongation factor-like (EFL) proteins are functionally homologous to one another, and are core components of the eukaryotic translation machinery. The patchy distribution of the two elongation factor types across global eukaryotic phylogeny is suggestive of a ‘differential loss’ hypothesis that assumes that EF-1α and EFL were present in the most recent common ancestor of eukaryotes followed by independent differential losses of one of the two factors in the descendant lineages. To date, however, just one diatom and one fungus have been found to have both EF-1α and EFL (dual-EF-containing species). Results: In this study, we characterized 35 new EF-1α/EFL sequences from phylogenetically diverse eukaryotes. In so doing we identified 11 previously unreported dual-EF-containing species from diverse eukaryote groups including the Stramenopiles, Apusomonadida, Goniomonadida, and Fungi. Phylogenetic analyses suggested vertical inheritance of both genes in each of the dual-EF lineages. In the dual-EF-containing species we identified, the EF-1α genes appeared to be highly divergent in sequence and suppressed at the transcriptional level compared to the co-occurring EFL genes. Conclusions: According to the known EF-1α/EFL distribution, the differential loss process should have occurred independently in diverse eukaryotic lineages, and more dual-EF-containing species remain unidentified. We predict that dual-EF-containing species retain the divergent EF-1α homologues only for a sub-set of the original functions. As the dual-EF-containing species are distantly related to each other, we propose that independent re-modelling of EF-1α function took place in multiple branches in the tree of eukaryotes.

We describe a new species of cryptomonad, Goniomonas avonlea sp. nov., using molecular phylogeny and comprehensive microscopic investigation. G. avonlea is a marine bacterivorous flagellate, measuring 8-11 μm long and 6-7 μm wide, with two subequal flagella that are directed anteriorly and posteriorly. G. avonlea is morphologically and genetically distinct from three other Goniomonas species that have been described to date. SEM and TEM show that G. avonlea shares ultrastructural features with other Goniomonas and cryptomonads, including the presence of bipartite ejectisomes, double septa in the transition region, flat mitochondrial cristae, a furrow complex, a rhizostyle, rectangular periplast plates, and the infundibulum. The discharged large ejectisome is straight and has a unique loose, reticulate layer. The flagellar apparatus includes non-tubular roots, microtubular roots, and a compound root that is reminiscent of the multilayered structure (MLS) observed in the flagellate cells of streptophytes and a few other eukaryotes. Molecular phylogenies based on 18S and 28S rRNA genes suggest a specific affiliation of G. avonlea to marine Goniomonas species, and support the monophyly of Goniomonas to the exclusion of plastid-bearing cryptomonads. Our study adds to a growing body of evidence for the high level of diversity and antiquity of the genus Goniomonas.

Several species of flagellates (genera Bodo, Cercomonas, Cryptaulax, Cyathomonas, Goniomonas, Spumella) have been identified in cultures from a plume of organic contamination (treated sewage effluent) within an aquifer on Cape Cod, Massachusetts. Amoebae and numerous unidentifiable 2‐ to 3‐μm flagellates have also been observed. As a rule, flagellates were associated with solid surfaces, or were capable of temporary surface attachment, corroborating earlier observations from in situ and column transport experiments suggesting that protists in the Massachusetts aquifer have a high propensity for association with sediment grain surfaces. Based on the fact that cultures from the uncontaminated part of the aquifer yielded only a few species of protists, it is hypothesized that the greater abundance and variety of food sources in the contaminant plume is capable of supporting a greater number of protistan species.

Grazing mortality of the marine phytoplankton Synechococcus is dominated by planktonic protists, yet rates of consumption and factors regulating grazer- Synechococcus interactions are poorly understood. One aspect of predator-prey interactions for which little is known are the mechanisms by which Synechococcus avoids or resists predation and, in turn, how this relates to the ability of Synechococcus to support growth of protist grazer populations. Grazing experiments conducted with the raptorial dinoflagellate Oxyrrhis marina and phylogenetically diverse Synechococcus isolates (strains WH8102, CC9605, CC9311, and CC9902) revealed marked differences in grazing rates—specifically that WH8102 was grazed at significantly lower rates than all other isolates. Additional experiments using the heterotrophic nanoflagellate Goniomonas pacifica and the filter-feeding tintinnid ciliate Eutintinnis sp. revealed that this pattern in grazing susceptibility among the isolates transcended feeding guilds and grazer taxon. Synechococcus cell size, elemental ratios, and motility were not able to explain differences in grazing rates, indicating that other features play a primary role in grazing resistance. Growth of heterotrophic protists was poorly coupled to prey ingestion and was influenced by the strain of Synechococcus being consumed. Although Synechococcus was generally a poor-quality food source, it tended to support higher growth and survival of G. pacifica and O. marina relative to Eutintinnis sp., indicating that suitability of Synechococcus varies among grazer taxa and may be a more suitable food source for the smaller protist grazers. This work has developed tractable model systems for further studies of grazer- Synechococcus interactions in marine microbial food webs.

Marine goniomonads have a worldwide distribution but ultrastructural information has not been available so far. An isolate of the heterotrophic marine nanoflagellate Goniomonas (G. aff. amphinema) from North Wales (UK) has been studied, providing information on its morphology and cellular structure using video, electron, laser scanning confocal microscopy (LSCM), and atomic force microscopy. Here, we describe a new feature, a granular area, potentially involved in particle capture and feeding. The binding of the lectin wheat germ agglutinin to the granular area of cells with discharged ejectisomes indicates the adhesive nature of this novel feature. The presence of a microtubular intracellular cytopharynx, apparently also used for feeding, has been revealed by LSCM. The small subunit rRNA gene of the isolate has been sequenced (1,788 bp). Phylogenetic results corroborate significant genetic divergence within the marine members of Goniomonas. This work highlights the need for integrated morphological, ultrastructural, and molecular investigation when describing and studying heterotrophic nanoflagellates.

A recently identified GTPase, elongation factor-like (EFL) protein is proposed to bear the principal functions of translation elongation factor 1alpha (EF-1alpha). Pioneering studies of EF-1alpha/EFL evolution have revealed the phylogenetically scattered distribution of EFL amongst eukaryotes, suggesting frequent eukaryote-to-eukaryote EFL gene transfer events and subsequent replacements of EF-1alpha functions by EFL. We here determined/identified seven new EFL sequences of the photosynthetic cryptomonad Cryptomonas ovata, the non-photosynthetic cryptomonad (goniomonad) Goniomonas amphinema, the foraminifer Planoglabratella opecularis, the haptophyte Chrysochromulina sp., the centroheliozoan Raphidiophrys contractilis, and two red algae Chondrus crispus and Gracilaria changii. The analyses of these EFL sequences successfully brought new insights into lateral EFL gene transfer amongst eukaryotes. Of most interest is a complex EFL evolution in a monophyletic assemblage comprised of cryptomonads and haptophytes. Since our analyses rejected any phylogenetic affinity amongst the EFL sequences from Goniomonas, photosynthetic cryptomonads, and haptophytes, the EFL genes of the three lineages most likely originated from different phylogenetic sources.

Summary An account is given of the diversity of heterotrophic flagellates in Port Jackson (New South Wales, Australia) and is discussed in relation to the geographic patchiness of the marine communities of these organisms. Close to 100 taxa are reported. We report and document 86 species and 51 genera. None of these species are new, although we draw attention to some difficulties with the application of the morphological species concept. Of the species reported here, 50 have been previously recorded from Australia. We find no evidence for an endemic community here — or by extrapolation — elsewhere. However, the matter is contingent upon the validity of the morphological species concept.

Flagellates of different nutrition modes (hetero-, mixo-, osmo-, autotrophic) from batch cultures and natural freshwater samples were examined for abundance, cell size and biovolume changes after fixation and staining. The methods used were formaldehyde fixation and staining with 4,6-diamidino-2-phenylindole (DAPI) or fixation with Bouin's solution combined with a quantitative protargol stain (QPS). The values estimated with these protocols were compared to a live drop counting method and inspection of living organisms. Cell dimensions were measured with a semi-automatic image analysis system. We observed cultured species of Bodo saltans, Chilomonas paramaecium-group, Cryptomonas sp., Entosiphonomonas cf. sulcatum, Goniomonas cf. truncata and Paraphysomonas cf. vestita. Chemical treatment caused cell loss of up to 56%. In contrast lower abundance of field samples was determined via live counting than via formaldehyde and DAPI treatment. The number of living flagellates