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  • 1
    Electronic Resource
    Electronic Resource
    Replacement and aging of chloroplasts inStrombidium capitatum (Ciliophora: Oligotrichida) (1990)
    Springer
    Marine biology 107 (1990), S. 491-502 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The planktonic ciliateStrombidium capitatum (Leegaard, 1915) Kahl, 1932 retains functional chloroplasts derived from ingested algal cells. Chloroplast replacement and aging were experimentally investigated in cultured ciliates provided with a cryptophyte (Pyrenomonas salina), a prymnesiophyte (Isochrysis galbana) and a prasinophyte (Pyramimonas sp.) as sources of plastids. All three algae were ingested and chloroplasts from all were retained by the ciliate. Within 15 min of exposure to the cryptophyte, this alga was taken up by the ciliates. Initially, most of the cryptophyte chloroplasts were in intact algal cells in ciliate vacuoles. By 2 h, cryptophyte plastids were commonly found free in the ciliate cytoplasm. WhenS. capitatum was switched from a diet containing cryptophytes to a non-cryptophyte diet, most cryptophyte chloroplasts were diluted out of the ciliates by cell division and/or replaced by non-cryptophyte chloroplasts within 9 h. When the ciliates are not provided with algae, they decrease in size and number. However, the starving ciliate cells contain some chloroplasts for as long as they live (40 h or more). Under these conditions, cryptophyte chloroplasts persist longer than the other chloroplast types. Our observations suggest that chloroplast retention times inS. capitatum depend on the type of chloroplast as well as the availability of phytoplankton containing suitable new chloroplasts, and probably also on the physiological states of the ingested algae and the ciliates. It is interesting that we were not able to grow this ciliate when we provided it only with prey that lacked chloroplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313434
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  • 2
    Electronic Resource
    Electronic Resource
    Respiration, photosynthesis and carbon metabolism in planktonic ciliates (1991)
    Springer
    Marine biology 108 (1991), S. 441-447 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Release of14C-labelled carbon dioxide from uniformly labelled cells was used to measure respiration by individual ciliates in 2-h incubations in 1989 and 1990. In a strictly heterotrophic ciliate,Strobilidium spiralis (Leegaard, 1915), release of labelled carbon dioxide was equivalent to ca. 2.8% of cell C h−1 at 20°C, and there was no difference between rates in the dark and light. In the chloroplast-retaining ciliatesLaboea strobila Lohmann, 1908,Strombidium conicum (Lohmann, 1908) Wulff, 1919 andStrombidium capitatum (Leegaard, 1915) Kahl, 1932, release of labelled carbon dioxide was less in the light than in the dark in experiments done at 15°C. InL. strobila release of radiolabel as carbon dioxide was equivalent to ca. 2.4% of cell C h−1 in the dark but ca. 1% at 50µE m−2 s−1, an irradiance limiting to photosynthesis. InS. conicum release of radiolabel as carbon dioxide was equivalent to ca. 4.4% of cell C h−1 in the dark, but at an irradiance saturating to photosynthesis (250 to 300µE m−2 s−1) there was no detectable release of labelled carbon dioxide. InS. capitatum release of radiolabel as carbon dioxide was equivalent to ca. 4.3% of cell C h−1 in the dark but at an irradiance saturating to photosynthesis was ca. 2.4% of cell C h−1. These data, combined with data from photosynthetic uptake experiments, indicate that14C uptake underestimates the total benefit of photosynthesis by 50% or more in chloroplastretaining ciliates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313654
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  • 3
    Electronic Resource
    Electronic Resource
    Efficient grazing and utilization of the marine cyanobacterium Synechococcus sp. by larvae of the bivalve Mercenaria mercenaria (1994)
    Springer
    Marine biology 119 (1994), S. 251-259 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Efficient grazing by marine bivalve larvae has been thought to be limited to particles larger than 4 μm in diameter, thereby eliminating photosynthetic and non-photosynthetic picoplankton as contributers to larval diets. Documentation of ingestion, carbon retention and growth of laboratory-reared larvae of the bivalve Mercenaria mercenaria L. on Synechococcus sp. (WH7803), a small unicellular cyanobacterium 1 μm in diameter, was facilitated using 14C-labelled cells in pulse/chase experiments and growth of larvae on diets of cell mixtures of both Synechococcus sp. and the haptophyte Isochrysis aff. galbana (TISO). Clearance rates on Synechococcus sp. ranged between 2 and 23 μl larva-1 h-1 depending on ambient cell concentration and larval age. Retention efficiency of cell carbon after gut evacuation was about 55% for both prey species. Growth rates of larvae fed on monocultures of Synechococcus sp. at typical summer concentrations in coastal waters (1×105 cells ml-1, ∼29 μg C l-1) was two-fold lower than on monocultures of Isochrysis galbana at 1×104 cells ml-1 (∼120 μg C l-1). Larval growth was inhibited and atrophy of the digestive gland was observed when Synechococcus sp. was offered at concentrations at or exceeding 8.6×105 cells ml-1. Larval growth was enhanced, however, in the presence of Synechococcus sp. (5×104 cells ml-1) when Isochrysis galbana was limiting. During the diurnal study of Synechococcus sp. population dynamics conducted by Waterbury et al. (1986) in Vinyard Sound, Massachusetts, the abundance of bivalve larvae was sufficient to account for 12 to 24% of the calculated grazing activity on Synechococcus sp. When nanoplankton are scarce, invertebrate larvae may exert considerable grazing pressure on Synechococcus sp. and derive benefit from ingestion of these cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349564
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  • 4
    Electronic Resource
    Electronic Resource
    Carbon content, dark respiration and mortality of the mixotrophic planktonic ciliate Strombidium capitatum (1996)
    Springer
    Marine biology 126 (1996), S. 415-422 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carbon content and rate of dark respiration was determined on individual Strombidium capitatum (Leegard) Kahl cells uniformly labelled with 14C in culture. Isolated individuals were incubated in sterile medium in the dark for periods of up to 24h, and cumulative respired 14CO2 was retained in an alkaline trap. Cell carbon varied by more than an order of magnitude and followed a bi-modal distribution. “Small” cells of 2 to 7 ng C cell-1 respired at specific rates of ∼3 to 5% cell C h-1, whereas “large” cells of 7 to 25 ng C cell-1 respired at ∼1 to 2% cell C h-1. Mortality was greater for small cells than for large ones, and was greatest during the first few hours. Small cells accounted for 40% of all cells at initial time, T 0, whereas none of these survived a 16 h incubation. It is proposed that the rates of carbon-specific dark respiration observed for small cells compromise their ability to survive more than a few hours in the dark without food. The combination of influence of size (carbon content) together with differential proportions of small cells resulting from mortality contributed to considerable variance in carbon-specific respiration rates. When smaller and larger modal groups were considered separately, this variance was significantly reduced for both groups. Using this “refined” data, there was no significant starvation-induced reduction in carbon-specific rates. The mean rate remained at between 1.1 and 1.4% cell C h-1 for large cells over the 24 h period, and between 3.8 and 4.1% cell C h-1 for small cells over the 8 h of their survival. This observation for a planktonic mixotrophic ciliate contrasts with published observations for heterotrophic protists which have reported reduction of carbon-specific respiration rate with starvation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00354623
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  • 5
    Electronic Resource
    Electronic Resource
    Food selection by young larval gulf menhaden (Brevoortia patronus) (1984)
    Springer
    Marine biology 80 (1984), S. 299-306 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Food selection by young larvae of the gulf menhaden (Brevoortia patronus) was studied in the laboratory at Beaufort, North Carolina (USA) in 1982 and 1983; this species is especially interesting, since the larvae began feeding on phytoplankton as well as microzooplankton. When dinoflagellates (Prorocentrum micans), tintinnids (Favella sp.), and N1 nauplii of a copepod (Acartia tonsa) were presented to laboratory-reared, larval menhaden (3.9 to 4.2 mm notochord length), the fish larvae ate dinoflagellates and tintinnids, but not copepod nauplii. Larvae showed significant (P〈0.001) selection for the tintinnids. Given the same mixture of food items, larger larvae (6.4 mm notochord length) ate copepod nauplii as well as the other food organisms. These feeding responses are consistent with larval feeding in the northern Gulf of Mexico, where gulf menhaden larvae between 3 and 5 mm in notochord length frequently ate large numbers of dinoflagellates (mostly P. micans and P. compressum) and tintinnids (mostly Favella sp.), but did not eat copepod nauplii. As larvae grew, copepod nauplii and other food organisms became important, while dinoflagellates and tintinnids became relatively less important in the diet. Since the tintinnids and nauplii used in the laboratory feeding experiments were similar in size as well as carbon and nitrogen contents, the feeding selectivity and dietary ontogeny that we observed were likely due to a combination of prey capturability and larval fish maturation and learning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392825
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  • 6
    Electronic Resource
    Electronic Resource
    Taxonomic Descriptions of One New Species and Redescription of Four Species in the Family Strombidiidae (Ciliophora, Oligotrichida) (1988)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 35 (1988), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Five ciliate species collected from the Woods Hole area were examined by protargol silver impregnation and scanning electron microscopy. These ciliates have been shown to sequester and use chloroplasts obtained from flagellate prey. One new species, Strombidium chlorophilum, is described. Four other species, Strombidium capitatum (Leegaard, 1915) Kahl, 1932, Strombidium conicum (Lohmann, 1908) Wulff, 1919, Strombidium acutum (Leegaard, 1915) Kahl, 1932, and Laboea strobila Lohmann, 1908, are redescribed. Characters used in describing the Strombidiidae include cell size and shape, anterior and ventral polykinetids, macronuclear shape and size, the kinetid “girdle,” the ventral kinety, the trichites, and the paroral kinety. The rationale for using these characters as taxonomic criteria is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1988.tb04322.x
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of copper and zinc on two planktonic ciliates (1986)
    Springer
    Marine biology 92 (1986), S. 21-29 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The interactive effects of copper and zinc on two estuarine planktonic ciliates, Favella sp. and Balanion sp., were determined in seawater media in which the free metal ion activities were controlled by nitrilotriacetic acid (NTA) trace metal ion buffer systems. Cupric ion activities of 10-10 M caused abnormal motility in both ciliates in shortterm (5 h) tests, and cupric ion activities as low as 10-12.8 M decreased the growth rates of both species in longer-term experiments. In the short-term tests, zinc ion activity by itself did not affect the motility of the ciliates, but there were significant interactions between copper and zinc. In the longer-term experiments, the growth of Favella sp. was optimal at the lowest cupric ion activity (10-13 M) and the two lowest zinc ion activities (10-12 and 10-13 M) and the two lowest zinc ion activities (10-12 and 10-11 M), and copper and zinc inhibited growth at activities above these values. By contrast, optimal growth rate of Balanion sp. occurred at the highest zinc ion activity (10-10 M) and the lowest cupric ion activities (10-13 to 10-12 M) and growth rate was reduced at zinc ion activities ≦10-11 M. There was an antagonism between copper and zinc which was particularly pronounced in Balanion sp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392741
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  • 8
    Electronic Resource
    Electronic Resource
    Obligate mixotrophy inLaboea strobila, a ciliate which retains chloroplasts (1988)
    Springer
    Marine biology 99 (1988), S. 415-423 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The planktonic ciliateLaboea strobila Lohmann sequesters photosynthetically functional chloroplasts derived from ingested algae. The chloroplasts lie free in the cytoplasm and are most abundant just under the pellicle of the ciliate. The maximum rate of photosynthesis (Pmax) was 925 pg C ciliate-1h-1 (3.7 pg C pg chl.a -1h-1). At saturating irradiance, the amount of carbon fixed h-1 equaled 12.6% of the body carbon of the ciliate. To grow,L. strobila requires both light and algal food. In the absence of food, survival ofL. strobila is significantly longer in the light than in the dark. Based on ingestion rate and photosynthetic rate, we calculate that photosynthesis can make an important contribution to this ciliate's carbon budget even when algal food is plentiful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02112135
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