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  • 1
    Electronic Resource
    Electronic Resource
    Multiple Fission in Allogromia sp., Strain NF (Foraminiferida): Release, Dispersal, and Ultrastructure of Offspring (1984)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 31 (1984), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The release, dispersal, and ultrastructure of juveniles arising through multiple fission in the benthic foraminiferan Allogromia sp., strain NF (Lee & Pierce, 1963) has been examined by light and electron microscopy. An extensive reticulopodial network participates in the dispersal of fully differentiated young as they emerge from the fragmented parental test. During the earliest stages of release, offspring are of two classes—aroused and unaroused. Unaroused juveniles, which have not extended pseudopods, attach externally to the network and are transported bidirectionally along its surface. Aroused juveniles, which have extended pseudopods and are in protoplasmic continuity with the network, move quickly to the periphery of the network. Within 24 h, juveniles establish a communal “feeding reticulum” in which dispersed individuals are in protoplasmic continuity with neighbors via a common reticulopodial network. At the ultrastructural level, the cell body cytoplasm of unaroused juveniles contains numerous patches of a paracrystalline material, which disappears as their pseudopodia are extended to join the communal feeding reticulum. This paracrystalline material therefore appears to be a temporary reservoir of precursors required for pseudopod construction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1984.tb02959.x
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  • 2
    Electronic Resource
    Electronic Resource
    Towards a Non-Terminal Viability Assay for Foraminiferan Protists (1995)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 42 (1995), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Epifluorescence microscopy and spectrofluorimetry were investigated as possible non-terminal methods to distinguish live from dead foraminifera. Seven fluorogenic probes (diacetates of fluorescein [FDA], carboxyfluorescein, dichlorofluorescein, and carboxyeosin; AM-esters of biscarboxyethylcarboxyfluorescein [BCECF-AM], calcein, and calcein blue) were tested on Allogromia laticollaris. The probes that consistently produced the brightest fluorescence signals (BCECF-AM and FDA) were judged non-toxic to Allogromia, on the basis of short-term pseudopodial deployment and long-term reproduction assays. Once protocols were established, these two probes were tested on 13 additional benthic foraminiferal species. We found that BCECF-AM is the most suitable probe for direct epifluorescence microscopy of metabolically active foraminifera, especially tectinous and transparent calcareous species. Using spectrofluorimetry, FDA showed promise for opaque species because fluorescence is detected in the incubation media after its release from the cell. However, both approaches could only be used with confidence in light of appropriate controls established for each species examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1995.tb01594.x
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  • 3
    Electronic Resource
    Electronic Resource
    Invasive Activity of Allogromia Pseudopodial Networks: Skyllocytosis of a Gelatin/Agar Gel (1985)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Time-lapse phase-contrast videomicroscopy revealed that the psudopodial network of two allogromiid foraminiferense display an invasive behaviour, previously undescribed, which I term Skyllocytosis (Greek: skylo—to rend, tear, pluck). When these networks encounter an interface between a gelatin/agar overlay and a glass substratum, portions of the overlay are penetrated and partly surrounded by reticulopodia. By the coordinated activity and contraction of these reticulopodia, small segments of the overlay are ripped away. Manageable portions of the overlay are subsequently transported towords the cell body. In carnivorous foraminifera skyllocytosis may account for the removal of soft, autolysed tissues from dead invertebrate prey.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1985.tb03005.x
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  • 4
    Electronic Resource
    Electronic Resource
    Structure, Bioadhesive Distribution and Elastic Properties of the Agglutinated Test of Astrammina rara (Protozoa: Foraminiferida) (1993)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 40 (1993), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . The fine structure, elastic properties, and distribution of the fibrous, meshlike cement (bioadhesive) were studied for the test of the antarctic agglutinated foraminiferan Astrammina rara. Grain-size analysis of particles incorporated into the test compared with adjacent sediment indicates that A. rara is grain-size selective. Fractured tests curl inward, suggesting that the test is under tension—an impression substantiated by micromanipulation observations. Changes in test appearance were examined by scanning electron microscopy after sequential chemical treatments combined with ultrasonication. Organic fibrils securing fine-grained particulates on the test exterior were removed during initial sonication. A veil of fibrous organic material lining the test interior (i.e. inner organic lining) was removed by treatment with a nonionic detergent, revealing ligamentous cables of bioadhesive securely joining large grains. These cables are partially disrupted by treatment with sodium dodecyl sulfate, and further disrupted by disulfide reducing agents, suggesting that protein is an integral adhesive component. The large detrital grains incorporated into the test are arranged in an interlocked, optimally packed fashion. Together, these observations indicate that the seemingly simple spherical architecture of A. rara's test is in fact quite complex, consisting of large grains compressed by tensile cables of a proteinaceous bioadhesive, with additional rigidity supplied by fine particulate “mortar” deposited externally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1993.tb04891.x
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  • 5
    Electronic Resource
    Electronic Resource
    Extracellular Matrix Augments Mechanical Properties of Pseudopodia in the Carnivorous Foraminiferan Astrammina rara: Role in Prey Capture (1992)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 39 (1992), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The seemingly delicate, strand-like pseudopodia of Astrammina rara, a carnivorous benthic foraminiferan, adhere to and withstand the rigorous movements of meiofaunal prey. Previous electron microscopic studies identified two novel structures that might account for the unusual tensile properties of these pseudopodia: 1) an extensive, coiled microtubule cytoskeleton and 2) a fibrous extracellular matrix vesting the pseudopodial surface. In the present study, we found that pseudopodial networks microsurgically removed from A. rara's cell body captured Artemia metanauplii as efficiently as intact organisms, and therefore used them to test the role of microtubules and extracellular matrix components in augmenting pseudopodial strength. Agents that specifically disassemble micro-tubules (1 mM colchicine or 20 μM nocodazole) or generally disrupt pseudopodial integrity (heat, 10 mM formaldehyde, 1 mg/ml saponin) failed to inhibit prey capture. All of these treatments left the extracellular matrix intact as revealed by immunofluorescence and scanning electron microscopy. The elastic and tensile properties of the extracellular matrix, isolated by solubilization of pseudopodial cytonhsm using the nonionic detergent Triton X-100, were similar to those of intact pseudopodial networks when assayed with calibrated microneedles or a flexible rubber substrate. These observations indicate that A. rara uses a fibrous extracellular matrix to augment cytoplasmic tensile properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1992.tb04455.x
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  • 6
    Electronic Resource
    Electronic Resource
    Microtubule-Dependent Reticulopodial Surface Motility: Reversible Inhibition on Plasma Membrane Blebs (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 466 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb38478.x
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  • 7
    Electronic Resource
    Electronic Resource
    Divergent β-tubulins from foraminifera: Implications for microtubule assembly (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Foraminifera utilize an unusual and very rapid microtubule assembly/disassembly system: a state transition between microtubules and helical filaments. The helical filament is an assembly polymorph that forms when the microtubule lattice uncoils into a ribbon of tubulin dimers connected only by lateral subunit/subunit bonds. An unusual β-tubulin sequence, which may be implicated in this process, has previously been reported from the foraminiferan Reticulomyxa filosa. In order to determine the taxonomic distribution and possible significance of this tubulin isoform, we sequenced and analyzed β-tubulin genes from a broad taxonomic range of foraminifera. These genes contain a large number of substitutions, conserved within the group, which may alter the biochemical properties of β-tubulin, especially in regions involved in subunit/subunit binding between α- and β-tubulin in the microtubule lattice. In particular, the M-loop, which is intimately involved in lateral subunit binding, shows only 30% homology to the consensus sequence for eukaryotic β-tubulins. Multiple regions identified to be involved in longitudinal contacts with α-tubulin are also highly substituted. In contrast, the foraminiferal α-tubulin is well conserved with its homologs in other organisms. We suggest that these alterations to the consensus eukaryotic β-tubulin sequence may help to explain the unusual assembly properties of foraminiferal microtubules.This work was supported by NSF OPP0003639.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_82.x
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  • 8
    Electronic Resource
    Electronic Resource
    Predicted Secondary Structure of the Foraminiferal SSU 3′ Major Domain Reveals a Molecular Synapomorphy for Granuloreticulosean Protists (2004)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The small subunit ribosomal RNA genes of foraminiferal protists are the largest and most divergent of any eukaryote. We demonstrate that this foraminiferal sequence alteration represents a substantial modification to the small subunit ribosomal RNA structure, including a large (up to 350 nt) novel helix in a very well-conserved portion of the head domain. This modification dates from the beginning of the foraminiferal radiation and, within modern orders, is partially conserved at the sequence level, suggesting that it is a functional part of the ribosome. The pattern of conservation makes it particularly useful for determining lower-taxon relationships in morphologically ambiguous allogromiid foraminifera.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00397.x
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  • 9
    Electronic Resource
    Electronic Resource
    Saccamminid foraminifers from anoxic sediments: implications for Proterozoic ecosystem dynamics (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Eukaryote origin and earliest diversification occurred in the Proterozoic when Earth's atmosphere was undoubtedly different from that of today. Atmospheric oxygen levels were increasing from the primordial anoxic atmosphere due, for example, to cyanobacterial oxygenic photosynthesis. Late Proterozoic (∼0.6–0.9 Gya) deep-ocean oxygen concentrations are less certain, but geochemical evidence suggests anoxia and hydrogen-sulfide enrichment. It can, therefore, be postulated that initial eukaryotic diversification occurred in oxygen-depleted, sulfide-enriched environments. Foraminifera are aerobes and, thus, not expected in anoxic settings. Recently, however, we found a saccamminid allogromian in a deep-water anoxic, sulfidic setting. Samples were collected from Santa Barbara Basin (California) when bottom-water oxygen was undetectable and sediments smelled strongly of hydrogen sulfide. Foraminiferal SSU rDNA sequences recovered from sediments included one from a previously uncharacterized saccamminid. Ultrastructural analysis indicated the presence of intact Golgi, mitochondria, and prokaryotic endobionts. Saccamminid occurrence in environmental conditions known to exist during the Proterozoic supports the possibility of their origin early in eukaryotic evolution. Extant saccamminids could have competed well in the prokaryote-dominated Proterozoic benthic ecosystem given their diet includes bacteria, bacterial biofilms and unicellular algae. Thus, Proterozoic foraminifers may have been top carnivores.Funded by NASA NRA-01-01-EXB-057, the Geological Society of America's W. Storrs Cole Memorial Research Award, and NSF OPP0003639.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_12.x
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  • 10
    Electronic Resource
    Electronic Resource
    Unexpected Foraminiferal Diversity Revealed by Small-subunit rDNA Analysis of Antarctic Sediment (2004)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00542.x
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