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  • 1980-1984  (5)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Fine Structure of Yellow-Brown Symbionts (Prymnesiida) in Solitary Radiolaria and Their Comparison with Similar Acantharian Symbionts (1983)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 30 (1983), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Yellow-brown, algal symbionts varying in diameter from approximately 5 μ m to 20 μ m, associated with solitary Radiolaria with spongiose skeletons (i.e. Spongodrymus sp.), exhibit fine structural features resembling the Prymnesiida (botanical class, Prymnesiophyceae). A large central vacuole is surrounded by a thin layer of cytoplasm containing plastids with lamellae composed of three thylakoids and granular pyrenoids with internal tubules immersed between the thylakoids. The pyrenoids lack internal thylakoid membranes. The nucleus is surrounded by a dilated cisterna of the nuclear envelope that also encloses the plastids and gives rise to saccules of the endoplasmic reticulum. The algal symbionts appear coccoid; hence no flagella nor surface scales were observed. The symbiont fine structure is compared to similar yellow-brown symbionts associated with Acantharia. Thus far, three kinds of algal symbionts have been observed to be associated with solitary Radiolaria: dinoflagellate, prasinomonad, and this apparent prymnesiomonad.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1983.tb05351.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Biochemical and fine structure evidence for cellular specialization in a large spumellarian radiolarian Thalassicolla nucleata (1983)
    Springer
    Marine biology 72 (1983), S. 235-241 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thalassicolla nucleata is a skeletonless, large spumellarian radiolarian (ca 3 mm diameter) occurring abundantly in the surface water of the Sargasso Sea. It has a complex cellular organization consisting of (1) a well-defined central capsule surrounded by a non-living capsular wall perforated by numerous cytoplasmic strands and (2) an extracapsulum containing a frothy layer of alveolate cytoplasm penetrated by numerous rhizopodia. Evidence is presented for physiological specialization complementing this structural compartmentalization. Acid acryl phosphatase activity (a digestive vacuole marker enzyme) is approximately 3 times greater in the extracapsulum compared to the intracapsulum; whereas, cytochrome oxidase (a respiratory marker enzyme) is approximately 1.5 times greater in the intracàpsulum compared to the extracapsulum. Furthermore, cytochemical and electron microscopic evidence indicates that the extracapsulum, containing large vacuoles and copious amounts of acid phosphatase reaction product, is a major site of catabolism; while the intracapsulum, containing the nucleus, numerous Golgi bodies, and a rich supply of mitochondria, is a substantial site of anabolism, lysosomal secretory activity, and food product storage. This marked level of cellular specialization in T. nucleata may enhance its biological efficiency and thus partially account for its abundance in oligotrophic environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396828
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Assimilation of symbiont-derived photosynthates in some solitary and colonial radiolaria (1983)
    Springer
    Marine biology 77 (1983), S. 265-269 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evidence for host assimilation of 14C-labeled symbiont photosynthates is presented from laboratory studies of the solitary radiolarian Thalassicolla nucleata and the colonial species Collosphaera huxleyi. The amount of 14C-labeled product assimilated in the central capsule of T. nucleata is directly related to the amount of 14C incorporated by the symbionts. In C. huxleyi central capsules, the percentage of 14C-label occurring in the water-soluble fraction is 38% and in the lipid-soluble fraction is 20%, the remainder being in insoluble products. Within the lipid-soluble fraction, a substantial percentage of the 14C activity is associated with the triglyceride and wax ester fractions. The significance of these findings is discussed in relation to the possible physiological role of symbionts in sustaining the host and stabilizing the host-symbiont association.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395815
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  • 4
    Electronic Resource
    Electronic Resource
    An estimate of predation rate and relative preference for algal versus crustacean prey by a spongiose skeletal radiolarian (1984)
    Springer
    Marine biology 78 (1984), S. 205-207 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Solitary radiolarians (Spongodrymus sp.) in laboratory cultures consumed 14C-labeled Amphidinium carteri and Coccolithus huxleyi more than Isochrysis galbana or Thalassiosira fluviatilis. The ratio of A. carteri protein consumed per unit time to the amount of Artemia sp. nauplius protein consumed (P/Z) was 6.7×10-2 indicating that these omnivorous radiolarians tend to consume more zooplankton protein than phytoplankton protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394702
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of symbiont elimination and reinfection on the life processes of the planktonic foraminifer Globigerinoides sacculifer (1982)
    Springer
    Marine biology 70 (1982), S. 73-86 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Laboratory experiments were carried out to determine the influence of symbiotic dinoflagellates (zooxanthellae) on the shell growth, longevity, and reproductive potential of Globigerinoides sacculifer (Brady). Its symbionts were eliminated by 72-h treatment with a photosynthetic inhibitor (DCMU). Symbiont elimination resulted in earlier gametogenesis (shortened survival time) and smaller shell sizes of G. sacculifer when compared to untreated foraminifera grown in sea water. Individuals kept in continuous darkness in untreated sea water also exhibited early gametogenesis, short survival times and small shell sizes. Aposymbiotic foraminifera formed on the average one or two chambers fewer per individual and their rate of shell size increase is slower than symbiont-bearing foraminifera. Symbionts were lysed within perialgal vacuoles of G. sacculifer when subjected to DCMU treatment or kept in continuous darkness. One DCMU-treated group was reinfected with symbionts from crushed G. sacculifer donors. Soon after reinfection, these foraminifera resumed a shell growth rate and exhibited developmental stages that were nearly equivalent to those of untreated individuals, as deduced from their shell size, frequency of sac-like chambers, rate of gametogenesis, and survival time. Our experiments indicate that the symbionts aid in calcification and that elimination of symbionts triggers gametogenesis, thus shortening the life span of the foraminiferal host. The results imply that shell growth in symbiont-bearing planktonic foraminifera occurs mainly in the euphotic zone and that they do not survive for long periods below it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397298
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