The genus Polytomella: A review of classification, morphology, life cycle, metabolism, and motility

We investigated the recently described colpodid ciliate Bromeliothrix metopoides in a series of laboratory experiments to reveal the environmental factors that constrain this species to its peculiar habitat, i.e. the tanks of bromeliads. Our results demonstrated that the various life stages of this ciliate (bacterivorous theronts and microstome trophonts, flagellate-feeding macrostomes) have specific demands in terms of food quality and quantity. Bromeliothrix required a high food threshold (>1.4 mg C L−1) in order to thrive. Food quality also affected resting cyst formation of B. metopoides when the experimental containers dried out. Its maximum growth rates (μmax = 4.71 d−1, i.e. 6.8 doublings d−1) belong to the highest ones recorded thus far for free-living ciliates. The pH niche of B. metopoides was relatively wide (pH ∼4 to >9) under optimal food conditions. However, its high sensitivity to unfavourable environmental conditions let the population collapse within several hours. We conclude that B. metopoides is a boom and bust ciliate that is specifically adapted to its peculiar habitat but virtually unviable in other environments.

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“…(de la Cruz and Gittleson 1981) may possess and phototrophic flagellates such as Cryptomonas sp. do not.…”

Section: Discussionmentioning

confidence: 99%

Bromeliothrix metopoides, a boom and bust ciliate (Ciliophora, Colpodea) from tank bromeliads

Weisse

Scheffel

Štádler

et al. 2013

European Journal of Protistology

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“…In particular, apicomplexan parasites, former algae with a non-photosynthetic plastid, which cause devastating diseases in animals and humans (malaria, toxoplasmosis), have been extensively studied [47]. Photosynthesis was also lost from some parasitic plants [48], free-living green algae such as Polytomella [49], parasitic green algae such as Helicosporidum [50,51], parasitic rhodophytes [52], and osmotrophic euglenophytes (e.g., Euglena longa, [53]). Furthermore, about half of the dinoflagellates are secondarily heterotrophic, many of them being phagotrophic (e.g., Oxyrrhis marina , [54]).…”

Section: Secondary Heterotrophy and Parasitism In Algaementioning

confidence: 99%

Endosymbiotic Evolution of Algae, Secondary Heterotrophy and Parasitism

Oborník

2019

Biomolecules

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Photosynthesis is a biochemical process essential for life, serving as the ultimate source of chemical energy for phototrophic and heterotrophic life forms. Since the machinery of the photosynthetic electron transport chain is quite complex and is unlikely to have evolved multiple independent times, it is believed that this machinery has been transferred to diverse eukaryotic organisms by endosymbiotic events involving a eukaryotic host and a phototrophic endosymbiont. Thus, photoautotrophy, as a benefit, is transmitted through the evolution of plastids. However, many eukaryotes became secondarily heterotrophic, reverting to hetero-osmotrophy, phagotrophy, or parasitism. Here, I briefly review the constructive evolution of plastid endosymbioses and the consequential switch to reductive evolution involving losses of photosynthesis and plastids and the evolution of parasitism from a photosynthetic ancestor.

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“…is a nonphotosynthetic, motile, unicellular protist that is believed to have evolved from a photosynthetic algal ancestor (16,41). Polytomella sp.…”

mentioning

confidence: 99%

Enzymes of the Heme Biosynthetic Pathway in the Nonphotosynthetic Alga Polytomella sp

2005

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Heme biosynthesis involves a number of enzymatic steps which in eukaryotes take place in different cell compartments. Enzyme compartmentalization differs between photosynthetic and nonphotosynthetic eukaryotes. Here we investigated the structures and subcellular localizations of three enzymes involved in the heme pathway in Polytomella sp., a colorless alga evolutionarily related to the green alga Chlamydomonas reinhardtii. Functional complementation of Escherichia coli mutant strains was used to isolate cDNAs encoding three heme biosynthetic enzymes, glutamate-1-semialdehyde aminotransferase, protoporphyrinogen IX oxidase, and ferrochelatase. All three proteins show highest similarity to their counterparts in photosynthetic organisms, including C. reinhardtii. All three proteins have N-terminal extensions suggestive of intracellular targeting, and immunoblot studies indicate their enrichment in a dense cell fraction that is enriched in amyloplasts. These results suggest that even though the plastids of Polytomella sp. are not photosynthetically active, they are the major site of heme biosynthesis. The presence of a gene for glutamate-1-semialdehyde aminotransferase suggests that Polytomella sp. uses the five-carbon pathway for synthesis of the heme precursor 5-aminolevulinic acid.

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The genus Polytomella: A review of classification, morphology, life cycle, metabolism, and motility

Cited by 11 publications

References 68 publications

Bromeliothrix metopoides, a boom and bust ciliate (Ciliophora, Colpodea) from tank bromeliads

Bromeliothrix metopoides, a boom and bust ciliate (Ciliophora, Colpodea) from tank bromeliads

Endosymbiotic Evolution of Algae, Secondary Heterotrophy and Parasitism

Enzymes of the Heme Biosynthetic Pathway in the Nonphotosynthetic Alga Polytomella sp

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