A biochemical explanation for the success of mixotrophy in the flagellate <i>Ochromonas</i> sp.

Boëchat, Iola G.; Weithoff, Guntram; Krüger, Angela; Gücker, Björn; Adrian, Rita

doi:10.4319/lo.2007.52.4.1624

Cited by 39 publications

(42 citation statements)

References 40 publications

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“…Mixotrophy is a common strategy in oligotrophic environments, representing an ecological advantage (Boëchat et al, 2007). Also in oligotrophic Lake Tovel some dinoflagellates have phagotrophic mixotrophic feeding mechanisms (Moestrup et al, 2006;.…”

Section: Discussionmentioning

confidence: 99%

Eco-fingerprinting of the dinoflagellate Borghiella dodgei: experimental evidence of a specific environmental niche

et al. 2009

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In Lake Tovel, an oligotrophic and weakly stratified lake, the dinoflagellate Borghiella dodgei Moestrup, Hansen et Daugbjerg, showed a peculiar spatial-temporal pattern with highest abundances in the bottom of the shallow side bay (4 m) along with remarkable abundance variations fromyear to year. We investigated B. dodgei's growth in laboratory cultures and related results to their implication for bloom formation. B. dodgei was cultivated under different temperature, nutrient and light conditions. Growth rates, cell biovolume, cyst formation and pigment and mycosporine-like amino acids (MAAs) concentrations were determined. Experiments showed that this alga (i) had higher growth rates at low temperatures (\7°C) and high irradiance levels (*250 lmol m -2 s -1 ), (ii) produced higher yields with organic supplements such as peptone, (iii) did not grow in the dark even with organic supplements, (iv) survived for long periods without a light source, (v) synthesised MAAs, (vi) showed an increase in cell volume with nutrient shortage and increasing temperatures ([7°C) and (vii) had high encystment rates with temperatures [7°C. These laboratory fingerprints allowed us to construct a theoretical model defining the species' niche. Borghiella needed a mixture of low temperatures, high irradiance levels and sufficient quantities of dissolved organic nitrogen to form blooms. Such a strict combination was probably a transient situation and occurred in oligotrophic Lake Tovel only in early summers followed by heavy spring rains.

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Section: Discussionmentioning

confidence: 99%

Eco-fingerprinting of the dinoflagellate Borghiella dodgei: experimental evidence of a specific environmental niche

et al. 2009

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“…For example, the polyunsaturated fatty acid 18:5ω3 has a central function in the photosynthetic light reaction and is located in the glycolipids of the chloroplasts. Its concentration or that of other PUFAs thus relates to the autotrophic mode, exhibiting intermediate concentrations under mixotrophic mode and being absent when heterotrophically grown (ADOLF et al, 2007;BOËCHAT et al, (2007b). Under limiting conditions by those substances, mixotrophic protozoans should be of higher food quality than their heterotrophic counterparts.…”

Section: Mixotrophymentioning

confidence: 99%

Food Web Paradigms: The Biochemical View on Trophic Interactions

Müller-Navarra

2008

International Review of Hydrobiology

132

100

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Different metabolic pathways and requirements can lead to imbalances in the biochemical composition, e.g., between prokaryotes and eukaryotes and between heterotrophic and autotrophic organisms. In addition, heterotrophs cannot synthesize many of the required biochemical constituents themselves but rely in their provision on the feeding environment. If imbalances of essential biochemicals between heterotrophic consumers and their prey are large, those biochemicals can become limiting. The importance of essential ω3-poly unsaturated fatty acids (PUFAs) for heterotrophic organisms (zooplankton, fish) is well recognized. Especially the conversion of C 18 -PUFAs to C 20 or C 22 highly unsaturated fatty acids (HUFAs) are critical for heterotrophic protists and metazooplankton, and storage may be an adaptation to help overcome limitation. The ecological relevance of cholesterol, essential for arthropods, is still an open question as vertebrates and fungi may be important sources in aquatic systems. Less is known about essential amino acids being limiting. However protein limitation seems to be rare in plankton unless detritus contributes largely to the food. One ecological importance of autotrophs lies in the synthesis of essential biomolecules, promoting growth of heterotrophs. However, vitamin B 12 may preferentially originate from prokaryotes (bacteria, cyanobacteria), even limiting growth of certain eukaryotic algae. Measuring the relevant biochemicals, its environmental forcing and cycling (conservation versus alteration in the food web), going beyond food species affiliation and carbon as a unit, but taking the overall food concentration into account will enhance the characterization of C-cycling and energy flux, irrespectively of the "classical food chain" or "microbial loop", with implication to human nutrition.

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“…As mixotrophs, these organisms differ considerably from purely heterotrophic grazers by their photosynthetic machinery and the presence of several biochemical pathways typical of autotrophic organisms. For instance, in contrast to many heterotrophs, Ochromonas is able to synthesize long-chain polyunsaturated fatty acids (Boëchat et al 2007) and thus does not depend on the presence of these substances in its prey. However, Ochromonas might be susceptible to the other 2 mechanisms of grazer deterrence in Microcystis, e.g.…”

Section: Introductionmentioning

confidence: 99%

Microcystins do not provide anti-herbivore defence against mixotrophic flagellates

Wilken¹,

Wiezer²,

Huisman³

et al. 2010

Aquat. Microb. Ecol.

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While most experiments investigating zooplankton grazing on harmful cyanobacteria have been carried out with metazoan plankton, several protozoa can also feed efficiently on cyanobacteria. We investigated grazing by the mixotrophic flagellate Ochromonas sp. on the toxic cyanobacterium Microcystis aeruginosa. Ochromonas sp. grew rapidly on M. aeruginosa and had a strong impact on the population density of its prey. However, specific growth rates of Ochromonas sp. decreased over time, possibly indicating a negative impact on Ochromonas sp. mediated by M. aeruginosa. Grazing did not have any effect on the intracellular microcystin content of M. aeruginosa, and the ingested microcystins did not accumulate within Ochromonas sp. We studied the functional and numerical response of Ochromonas sp. grazing on the microcystin-producing strain M. aeruginosa PCC 7806 and its microcystin-deficient mutant. Ochromonas sp. showed a Type 3 functional response of very similar shape on both the toxic and non-toxic M. aeruginosa strain. Ingestion rates of Ochromonas sp. were even slightly higher on the toxic M. aeruginosa strain. We therefore found no indication of microcystins acting as a defence against mixotrophic flagellates.

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A biochemical explanation for the success of mixotrophy in the flagellate Ochromonas sp.

Cited by 39 publications

References 40 publications

Eco-fingerprinting of the dinoflagellate Borghiella dodgei: experimental evidence of a specific environmental niche

Eco-fingerprinting of the dinoflagellate Borghiella dodgei: experimental evidence of a specific environmental niche

Food Web Paradigms: The Biochemical View on Trophic Interactions

Microcystins do not provide anti-herbivore defence against mixotrophic flagellates

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