Inducible defence against a ciliate grazer<i>Pseudomicrothorax dubius</i>, in two strains of<i>Phormidium</i>(cyanobacteria)

Fiałkowska, Edyta; Pajdak‐Stós, Agnieszka

doi:10.1098/rspb.1997.0129

Cited by 34 publications

(41 citation statements)

References 11 publications

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“…Hoiczyk (1998) describes a sheath as a tube visible by phase contrast or differential inter-155 Aquat Microb Ecol 27: 149-157, 2002 ference contrast, which appears only in old cultures. Our experiment, using the strain of Phormidium described as Ph2 in a previous paper (Fia8kowska & Pajdak-Stós 1997), seems to confirm that under strong grazer pressure cyanobacteria are able to accelerate production of sheath-building materials.The density of 10 ciliates ml -1 is too low to induce any kind of defense. The pattern of trichome migration was similar to that in the control, and the ciliates remained satiated throughout the experiment, thanks to unlimited access to food (Fig.…”

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confidence: 61%

Dependence of cyanobacteria defense mode on grazer pressure

Fiałkowska

Pajdak‐Stós²

2002

Aquat. Microb. Ecol.

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In a series of experiments we investigated the ability of a cyanobacterium of the genus Phormidium to defend itself against the ciliate grazer Furgasonia blochmanni. The experiments showed that the cyanobacterium can employ different modes of defense, depending on grazer density. Under high grazer pressure, each mat of Phormidium instantly formed a dense clump surrounded by a mucilage layer. Trichomes remaining inside such clumps were completely inaccessible to ciliates. Under medium pressure, the defense reaction was slower and consisted in enhanced sheath production by individual trichomes. The effectiveness of such a defense was also very high, as clearly reflected in the condition of the ciliates. When the pressure was low, the cyanobacteria did not exhibit any form of defense, dispersing evenly all over the bottom in a pattern similar to that observed in control mats. We conclude that the cyanobacterium is able to modify its defense reaction according to the real grazing risk.KEY WORDS: Cyanobacteria · Anti-herbivore defense · Ciliate pressure Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 27: [149][150][151][152][153][154][155][156][157] 2002 and Ph2, revealed an inducible defense capability against ciliates by means of withdrawing inside the sheaths when disturbed by grazers. Trichomes ending in empty sheaths turned out to be completely inaccessible for the ciliates (Fia8kowska & Pajdak-Stós 1997). In Phormidium autumnale, the same purpose is served by a protective layer of extracellular polysaccharides (EPS) shielding the initial piece of mat in which filaments are embedded; the defense reaction is engaged in the presence of different grazer species (Pajdak-Stós et al. 2001). However, the phenomenon was investigated only at invariable grazer density. During closer observations of the cyanobacteria mats used for feeding our ciliate cultures, we noticed interesting changes in their appearance. We suspected that those changes might be related to different ciliate densities in the culture dishes and designed a set of experiments to determine whether the cyanobacteria mode of defense depends on grazer pressure. MATERIALS AND METHODSA strain of an unidentified species of the cyanobacterium Phormidium called Ph2 in our previous paper (Fia8kowska & Pajdak-Stós 1997) and a clone of a nassulinid ciliate Furgassonia blochmanni were used for experiments. This free-living, freshwater ciliate occurs naturally in ponds and puddles along with filamentous cyanobacteria like Ph2, which form mats on the sediment surface. F. blochmanni is equipped with a cytopharyngeal apparatus, a highly specialized structure that enables the ciliate to ingest long threads of cyanobacteria (Eisler & Bardele 1986, Vigues et al. 1999.Clonal populations of experimental organisms were obtained from a single filament (Phormidium sp.) and a single cell (Furgassonia blochmanni) taken from an aquarium maintained non-axenically at the Department of Hydrobiology, Jagiellonian University, ...

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confidence: 61%

Dependence of cyanobacteria defense mode on grazer pressure

Fiałkowska

Pajdak‐Stós²

2002

Aquat. Microb. Ecol.

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“…For example, Lampert et al (1994) revealed that the induction of colony formation in Scenedesmus depends on the concentration of infochemicals released from Daphnia grazers. A study by Fiałkowska and Pajdak-Stó s (1997) suggested that a high density of the ciliate grazer Furgasonia blochmanni triggers Phorimidium cyanobacteria to congregate into dense clumps surrounded by a mucilage layer. This phenomenon has been observed in ciliated protozoan interactions as well.…”

Section: Discussionmentioning

confidence: 99%

“…A well-studied example of induced defenses in freshwater algae is the morphological changes observed in coenobial green algae and filamentous blue-green algae in water containing Daphnia (Fiałkowska and Pajdak-Stó s 1997;Lü rling and van Donk 2000). Chemicals in water that contains zooplankton may function as infochemicals, and induced antipredator morphological defenses have been shown to depend on consumer density and to be triggered by infochemical cues (Lampert et al 1994;van Donk et al 1999), although the identity of these chemicals is still under debate.…”

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confidence: 99%

Changes in microcystin production in cyanobacteria exposed to zooplankton at different population densities and infochemical concentrations

Jang

Jung²,

Takamura

2007

Limnology & Oceanography

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We investigated microcystin (MC) production by four cyanobacterial strains (three Microcystis aeruginosa and one Planktothrix agardhii) in response to different grazer densities (direct exposure: zero, two, four, or eight individuals per 300 mL) and infochemical concentrations (indirect exposure: 0%, 10%, 25%, and 50%) of Daphnia magna and Moina macrocopa. MC production increased after direct exposure to both zooplankton species and was higher with increasing concentration of infochemicals. This MC production was significantly different among the control and three zooplankton treatment levels. Upon direct and indirect exposure of cyanobacteria to zooplankton, intracellular MC peaked on days 3 and 4. In most cyanobacterial strains, the peak MC contents were significantly higher in direct treatment with the highest zooplankton density and in indirect treatment with the highest concentration of zooplankton culture media filtrate than with treatments with the lowest density and concentration, respectively. Extracellular MC concentrations were much lower than intracellular ones, but both showed similar temporal patterns over the course of the experiment. Cyanobacteria directly exposed to Daphnia released greater amounts of extracellular MC than did those exposed to Moina. This is the first study to provide evidence of an induced defense of increased MC production by cyanobacteria in response to increasing zooplankton grazer density and increased concentrations of infochemicals released by zooplankton. In addition to the induction of tolerance in Daphnia to toxic Microcystis, we discuss how these reciprocal defenses may explain the coexistence of zooplankton and toxic cyanobacteria in eutrophic freshwaters.

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“…A comparison of the cyanobacteria mats subjected to high grazer pressure with those in the control wells suggests that the defensive reaction of the cyanobacteria was induced by the presence of ciliates attacking trichomes. In our previous work on 2 other species of Phormidium (Fia8kowska & Pajdak-Stós 1997) we described a mechanism of inducible defense based on the production of stiff, strong sheaths and the ability of the trichomes to withdraw inside them. Unlike those species, P. autumnale produces much softer sheaths and a considerable amount of extracellular material in the form of mucilage.…”

Section: Discussionmentioning

confidence: 99%

“…Recently it was reported that simple organisms such as filamentous cyanobacteria are able to generate an induced defense against ciliate grazers (Fia8kowska & Pajdak-Stós 1997). The defense mechanism is based on the trichomes' ability to withdraw inside their sheaths, most likely supplemented by accelerated production of sheath material in the presence of ciliates.…”

Section: Introductionmentioning

confidence: 99%

Phormidium autumnale (Cyanobacteria) defense against three ciliate grazer species

Pajdak‐Stós¹,

Fiałkowska²,

Fyda³

2001

Aquat. Microb. Ecol.

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Investigations of the effects of grazing by 3 species of ciliates -Pseudomicrothorax dubius Peck, Nassula citrea Kahl and Furgasonia blochmanni Faure-Fremiet -on mats of Phormidium autumnale (Agardh) Gomont showed that the cyanobacterium was capable of surviving very strong grazer pressure, thanks to both an extracellular polysaccharide (EPS) layer and behavioral defense. In the presence of ciliates, cyanobacteria trichomes were confined to a protective layer of extracellular material enclosing the mat. Trichomes attacked by a ciliate usually escaped by retreating within the EPS layer. The effectiveness of this kind of defense was reflected in dramatic changes in the condition of the ciliates: within 30 h of the start of the experiments a significant fraction was starved because they were unable to reach trichomes hidden within the shielding EPS layer.

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Inducible defence against a ciliate grazerPseudomicrothorax dubius, in two strains ofPhormidium(cyanobacteria)

Cited by 34 publications

References 11 publications

Dependence of cyanobacteria defense mode on grazer pressure

Dependence of cyanobacteria defense mode on grazer pressure

Changes in microcystin production in cyanobacteria exposed to zooplankton at different population densities and infochemical concentrations

Phormidium autumnale (Cyanobacteria) defense against three ciliate grazer species

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