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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Large miliolid foraminifers of the subfamily Soritinae bear symbiotic dinoflagellates morphologically similar to the species of the “Symbiodinium” complex, commonly found in corals and other marine invertebrates. Soritid foraminifers are abundant in coral reefs and it has been proposed that they share their symbionts with other dinoflagellate-bearing reef dwellers. In order to test this hypothesis, we have analysed partial large subunit ribosomal DNA sequences from dinoflagellates symbionts obtained from 28 foraminiferal specimens, and compared them to the corresponding sequences of Symbiodinium-like endosymbionts from various groups of invertebrates. Phylogenetic analysis of our data shows that all soritid symbionts belong to the “Symbiodinium” species complex, within which they form seven different molecular types (Fr1–Fr7). Only one of these types (Fr1) branches within a group of invertebrate symbionts, previously described as type C. The remaining six types form sister groups to coral symbionts previously designed as types B, C, and D. Our data indicate a high genetic diversity and specificity of Symbiodinium-like symbionts in soritids. Except for type C, we have found no evidence for the transmission of symbionts between foraminifers and other symbiont-bearing invertebrates from the same localities. However, exchanges must have occurred frequently between the different species of Soritinae, as suggested by the lack of host specificity and some biogeographical patterns observed in symbiont distribution. Our data suggest that members of the subfamily Soritinae acquired their symbionts at least three times during their history, each acquisition being followed by a rapid diversification and independent radiation of symbionts within the foraminiferal hosts.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Studies of benthic Foraminifera typically rely on the morphological identification of dried specimens. This approach can introduce sampling bias against small, delicate, or morphologically ambiguous forms. To overcome this limitation, we extracted total DNA from sediment followed by PCR using group- and species-specific primers. Phylogenetic analyses revealed that approximately ninety percent of the PCR products represented previously undescribed sequence types that group with undersampled members of the allogromiid Foraminifera. We also used a modification of this technique to track individual species in sediment fractions too fine for normal morphological identification, and to confirm species placement of morphologically ambiguous foraminiferans. We were able to identify the DNA of several large foraminiferal species in fine fractions in a seasonally-dependent manner, indicating that in some seasons the majority of the standing stock of these species exists as gametes/juveniles. The approach outlined here represents a powerful strategy for exploring the total diversity of benthic foraminiferal communities.
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  • 3
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . A species of Amphidinium bloomed in a mariculture sedimentation pond that was used to grow bivalves near the Gulf of Eilat, Israel. Its overall length averaged 13 μm, the hypocone was 11 μm, and its width was 8μm. It has a ventral ridge. The sulcus begins at the longitudinal flagellar pore and does not project forward in the apex toward the transverse flagellar pore and left margin of the cingulum. The sulcus is a very shallow groove that projects variably about a third of the body length toward the antapex. The cingulum is a deep groove as it circles the cell from the left ventral side to the dorsal side and then becomes very shallow on the right ventral side as it arches posterior toward the longitudinal flagellar pore. Using a modified method for studying dinoflagellate chromosomes in the SEM, we observed 31 chromosomes. The plastid is dorsal and peripheral with 6 ventrally projecting peripheral digital lobes that wrap around the sides of the ventral and posterior nucleus. Amphidinium eilatiensis n. sp. is morphologically closest to Amphidinium carterae and Amphidinium rhynchocephalum, but it does not have the obvious thecal plates or polygonal units described for the former species. Instead, it has a series of spicules, bumps, and ridges on its surface. It differs from A. rhynchocephalum by two morphological characters: surface morphology and gross plastid architecture.The amplified fragments of the rDNA from A. eilatiensis n. sp. isolated from 2 separate sedimentation ponds in Eilat include the 3′-end of the SSU rDNA (about 100 nt), the whole ITS region (ITS1 + 5. 8S + ITS2) and the 5′-end of the LSU rDNA (about 900 nts). The total length of the sequences ranged from 1,460 nt. (A. eilatiensis isolate #1) to 1,461 nts. (A. eilatiensis isolate #2). The latter sequences are identical, the difference in length being due to three insertions. Amphidinium eilatiensis is genetically more closely related to A. carterae than to A. klebsii, with respectively 2. 36% and 6. 93% of sequence divergence.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 50 (2003), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Xenophyophorea are giant deep-sea rhizopodial protists of enigmatic origins. Although species were described as Foraminifera or sponges in the early literature, the xenophyophoreans are currently classified either as a class of Rhizopoda or an independent phylum. To establish the phylogenetic position of Xenophyophorea, we analysed the small subunit (SSU) rRNA gene sequence of Syringammina corbicula Richardson, a newly described xenophyophorean species from the Cape Verde Plateau. The SSUrDNA analyses showed that S. corbicula is closely related to Rhizammina algaeformis, a tubular deep-sea foraminiferan. Both species branch within a group of monothalamous (single-chambered) Foraminifera, which include also such agglutinated genera as Toxisarcon, Rhabdammina, and Saccammina, and the organic-walled genera Gloiogullmia and Cylindrogullmia. Our results are congruent with observations of similar cytoplasmic organisation in Rhizammina and Syringammina. Thus, the Xenophyophorea appear to be a highly specialised group of deep-sea Foraminifera.
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  • 5
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Percolomonas cosmopolitus is a common free-living flagellate of uncertain phylogenetic position that was placed within the Heterolobosea on the basis of ultrastructure studies. To test the relationship between Percolomonas and Heterolobosea, we analysed the primary structure of the actin and small-subunit ribosomal RNA (SSU rRNA) genes of P. cosmopolitus as well as the predicted secondary structure of the SSU rRNA. Percolomonas shares common secondary structure patterns of the SSU rRNA with heterolobosean taxa, which, together with the results of actin gene analysis, confirms that it is closely related to Heterolobosea. Phylogenetic reconstructions based on the sequences of the SSU rRNA gene suggest Percolomonas belongs to the family Vahlkampliidae. The first Bayesian analysis of a large taxon sampling of heterolobosean SSU rRNA genes clarifies the phylogenetic relationships within this group.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 39 (1992), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . A new foraminiferan species, Rotaliella elatiana n. sp., was isolated in the Gulf of Elat, where it lives in association with a macrophytic green alga, Enteromorpha. The agamont of this tiny new species has a transparent test composed of a bilocular embryonic chamber followed by six to seven trochospirally coiled inflated chambers. The spiral sutures are undulated. The umbilical side has numerous denticules and has radial grooves. The gamont has only one inflated chamber. Rotaliella elatiana has a classical, heterophasic life cycle, with a regular alternation of diploid agamontic phase and haploid gamontic phase. The gamontic phase of the life cycle is exceptionally reduced and the uninucleated gamonts pair immediately after they build their first chamber. A few cases of autogamic reproduction were observed. R. elatiana is a heterocaryotic species; agamonts have one somatic and two to three generative nuclei.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 50 (2003), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Sediment-dwelling protists are among the most abundant meiobenthic organisms, ubiquitous in all types of aquatic ecosystems. Yet, because their isolation and identification are difficult, their diversity remains largely unknown. In the present work, we applied molecular methods to examine the diversity of freshwater Foraminifera, a group of granuloreticulosan protists largely neglected until now. By using specific PCR primers, we detected the presence of Foraminifera in all sediment samples examined. Phylogenetic analysis of amplified SSU rDNA sequences revealed two distinct groups of freshwater foraminiferans. All obtained sequences branched within monothalamous (single-chambered), marine Foraminifera, suggesting a repeated colonization of freshwater environments. The results of our study challenge the traditional view of Foraminifera as essentially marine organisms, and provide a conceptual framework for charting the molecular diversity of freshwater granuloreticulosan protists.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Large miliolid foraminifers bear various types of algal endosymbionts including chlorophytes, dinoflagellates, rhodophytes, and diatoms. Symbiosis plays a key role in the adaptation of large foraminifera to survival and growth in oligotrophic seas. The identity and diversity of foraminiferal symbionts, however, remain largely unknown. In the present work we use ribosomal DNA (rDNA) sequences to identify chlorophyte endosymbionts in large miliolid foraminifera of the superfamily Soritacea. Partial 18S and complete Internal Transcribed Spacer (ITS) rDNA sequences were obtained from symbionts of eight species representing all genera of extant chlorophyte-bearing Soritacea. Phylogenetic analysis of the sequences confirms the previous fine structure-based identification of these endosymbionts as belonging to the genus Chlamydomonas. All foraminiferal symbionts form a monophyletic group closely related to Chlamydomonas noctigama. The group is composed of seven types identified in this study, including one previously morphologically described species, Chlamydomonas hedleyi. Each of these types can be considered as a separate species, based on the comparison of genetic differences observed between other established Chlamydomonas species. Several foraminiferal species share the same symbiont type, but only one species, Archaias angulatus, was found to bear more than one type.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 46 (1999), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Reticulomyxa filosa is a freshwater protist possessing fine granular, branching and anastomosing pseudopodia and therefore traditionally placed in the class Granuloreticulosea, order Athalamida, as a sister group to the order Foraminiferida. Recent studies have revealed remarkable similarities in pseudopodial motility and ultrastructure between R. filosa and foraminifera (e.g. Allogromia laticollaris), prompting us to conduct a molecular phylogenetic analysis of these seemingly disparate organisms. We sequenced the complete small-subunit of the ribosomal DNA of the cultured strain of R. filosa and compared it to the corresponding sequences of other protists including 12 species of foraminifera. We also sequenced and analyzed the actin coding genes from R. filosa and two species of foraminifera, Allogromia sp. and Ammonia sp. the analysis of both data sets clearly shows that R. filosa branches within the clade of foraminifera, suggesting that R. filosa is in fact a freshwater naked foraminiferan.
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