Organisms Living on and in Protozoa

Ball, Gordon H.

doi:10.1016/b978-0-08-012339-4.50009-3

Cited by 68 publications

(25 citation statements)

References 180 publications

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“…The presence of endosymbiotic bacteria in many termite gut flagellates had already been recognized quite early (1,18). The cytoplasmic bacteria found in Trichonympha collaris (11) resemble the TG-1 bacteria described in the present study, although membranous extensions were not reported.…”

Section: Discussionmentioning

confidence: 99%

“ Endomicrobia ”: Cytoplasmic Symbionts of Termite Gut Protozoa Form a Separate Phylum of Prokaryotes

Stingl

Radek

Yang

et al. 2005

Appl Environ Microbiol

137

116

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Lignocellulose digestion by wood-feeding termites depends on the mutualistic interaction of unusual, flagellate protists located in their hindgut. Most of the flagellates harbor numerous prokaryotic endosymbionts of so-far-unknown identity and function. Using a full-cycle molecular approach, we show here that the endosymbionts of the larger gut flagellates of Reticulitermes santonensis belong to the so-called termite group 1 (TG-1) bacteria, a group of clones previously obtained exclusively from gut homogenates of Reticulitermes speratus that are only distantly related to other bacteria and are considered a novel bacterial phylum based on their 16S rRNA gene sequences. Fluorescence in situ hybridization with specifically designed oligonucleotide probes confirmed that TG-1 bacteria are indeed located within the flagellate cells and demonstrated that Trichonympha agilis (Hypermastigida) and Pyrsonympha vertens (Oxymonadida) harbor phylogenetically distinct populations of symbionts (<95% sequence similarity). Transmission electron microscopy revealed that the symbionts are small, spindle-shaped cells (0.6 m in length and 0.3 m in diameter) surrounded by two membranes and located within the cytoplasm of their hosts. The symbionts of the two flagellates are described as candidate species in the candidate genus "Endomicrobium." Moreover, we provide evidence that the members of the TG-1 phylum, for which we propose the candidate name "Endomicrobia," are phylogenetically extremely diverse and are present in and also restricted to the guts of all lower termites and wood-feeding cockroaches of the genus Cryptocercus, the only insects that are in an exclusive, obligately mutualistic association with such unique cellulose-fermenting protists.Digestive symbioses are most common among insects feeding on wood or other lignified plant materials. The most prominent example is that of wood-feeding termites (order Isoptera), where the symbiotic digestion of lignocellulose is a complex series of events involving both the host and its gut microbiota. While the events in foregut and midgut are due mainly to host activities, the digestive processes in the hindgut are largely controlled by the symbiotic gut microbiota (5, 7).In the evolutionarily lower termites, the bulk of the hindgut volume is occupied by unicellular eukaryotes which belong to several flagellate taxa that are unique to termites (14, 37). These oxygen-sensitive protozoa, which can make up more than one-third of the body weight of their host, are essential for wood digestion and represent the major source of cellulolytic and xylanolytic activities in the hindgut (14, 16).The gut flagellates are regularly colonized by prokaryotic epibionts attached to the surface and by endosymbionts located in the cytoplasm or in the nucleus (see, e.g., references 1, 8, and 18). Although up to 85% of the total prokaryotes in the termite gut are associated with the gut flagellates (2), only a few of the epibiotic bacteria have been identified by using molecular techniques (23,35,36). Wh...

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Section: Discussionmentioning

confidence: 99%

“ Endomicrobia ”: Cytoplasmic Symbionts of Termite Gut Protozoa Form a Separate Phylum of Prokaryotes

Stingl

Radek

Yang

et al. 2005

Appl Environ Microbiol

137

116

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“…A variety of heterotrophic protists including fungi (Ball 1969), sarcodines (Caron and Swanberg 1990;Swanberg and Caron 1991), dinoflagellates (Hansen 1991;Schnepf and Elbr~ichter 1992), and other ciliates (Dolan and Coats 1991 a, b) utilize ciliated protozoa as a food source. Even some typical phytoplankton species that were conventionally viewed as strict phototrophs are now known to feed on small choreotrich ciliates (Bockstahler and Coats 1993 a, b).…”

Section: Introductionmentioning

confidence: 99%

Dinoflagellate infections of Favella panamensis from two North American estuaries

et al. 1994

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Favella panamensis Kofoid and Campbell, 1929 is seasonally abundant in meso-to polyhaline waters of Chesapeake Bay and Indian River, Florida, USA, where it reaches densities of 103 cells 1-1 . During the summers of 1986-1992, F. panamensis populations of the two estuaries were commonly infected by the parasitic dinoflagellate Duboscquella aspida Cachon, 1964. The intracellular phase of the parasite reached maturity in -21 h (30 ~ and consumed -35% of the host's biomass. Infections were not typically lethal to F. panamensis, but sometimes forced the host from its lorica. Several D. aspida were found in the cytoplasm of many hosts, and the number of parasites infection -1 was directly related to infection level. Parasite prevalence averaged 24.0 and 11.5% with mean number of parasites infection -1 being 1.5 and 1.3 for Chesapeake Bay and Indian River samples, respectively. D. aspida was estimated to remove up to 68% of host standing stock d -1 with a mean of ~ 10% for all samples. The average impact of parasitism on F. panamensis populations was somewhat less than would be expected from copepod grazing.

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“…Bacterial endosymbionts are often found in protozoa (1). Some bacterial endosymbionts of paramecia, including all members of the genus Caedibacter, are toxic for susceptible strains of paramecia (2).…”

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confidence: 99%

Occurrence of fragmented 16S rRNA in an obligate bacterial endosymbiont of Paramecium caudatum.

Springer

Ludwig

Amann

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

111

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Organisms Living on and in Protozoa

Cited by 68 publications

References 180 publications

“ Endomicrobia ”: Cytoplasmic Symbionts of Termite Gut Protozoa Form a Separate Phylum of Prokaryotes

“ Endomicrobia ”: Cytoplasmic Symbionts of Termite Gut Protozoa Form a Separate Phylum of Prokaryotes

Dinoflagellate infections of Favella panamensis from two North American estuaries

Occurrence of fragmented 16S rRNA in an obligate bacterial endosymbiont of Paramecium caudatum.

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