Monoxenic culture of the anaerobic ciliate Trimyema compressum Lackey

Three species of marine, anaerobic free-living ciliates (Metopus contortus, Plagiopyla frontata and ParabZepkisina collare) were studied with respect to their relation to 02. Survival was adversely affected at O2 tensions exceeding 1-2% of atmospheric (air) saturation (atm. sat.): ParablepMsma c o k e survived for about 1 h at 100% atm. sat., while the other two species survived the treatment for up to 2 d. Survival in the presence of O2 depended on the composition of the medium; cells survived longer in clean seawater than in culture medium which, when exposed to O,, became toxic. This is probably related to peroxide production mediated by solutes in the culture medium: addition of catalase prolonged survival. The ciliates did not contain catalase. Two of the species harbour endosymbiotic methanogens; at 0, tensions exceeding 2% atm. sat. the bacteria were inactivated, but they remained viable even after more than 5 h exposure to atmospheric O2 tension. Metopus contortus and Plagiopyla frontata respired 0, at rates similar to those of aerobic species; this 0, uptake is not coupled to energy conservation since the ciliates do not contain cytochromes, and low O2 tensions do not stimulate growth. 0, consumption is probably a detoxification mechanism which can maintain an intracellular anaerobic environment at a low ambient O2 tension. Metopus contortus and Plagiopyla frontata showed chemosensory behaviour in response to 0,; this allowed them to find and remain within anaerobic microhabitats.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oxygen toxicity, respiration and behavioural responses to oxygen in free-living anaerobic ciliates

Fenchel

Finlay

1990

“…The electromigration device was identical to that described by Wagener et al (1986) except for the insertion of a loose cotton wool plug in the capillary tube through which the ciliates were forced to swim. The isolated ciliates were suspended in anoxic (purged with N2), dithionite-reduced mineral medium (Wagener & Pfennig, 1987;S. Wagener, personal communication) containing (g I-'): NaHCO, (l-O), and adjusted to pH 7.0.…”

Section: Methodsmentioning

confidence: 99%

The use of rRNA sequences and fluorescent probes to investigate the phylogenetic positions of the anaerobic ciliate Metopus palaeformis and its archaeobacterial endosymbiont

Roeder

et al. 1992

155

~ ~~The polymerase chain reaction (PCR) was used to amplify small-subunit ribosomal DNA from the anaerobic ciliated protozoon Metopus pdaeformis, and from its uncultured endosymbiotic bacteria. This was accomplished directly from total DNA extracted from protozoa without prior isolation or enrichment for symbiont cells. The double-stranded amplification products were precipitated and directly sequenced using the linear PCR reaction. Fluorescent oligonucleotide probes were designed and used in whole-cell hybridizations to provide direct visual evidence that the sequences originated from the host ciliate and from the endosymbiont. Phylogenetic analysis of the Metopus pdaeformis sequence consistently placed it as a deep-branching lineage near the root of the ciliate tree. However, the present data were insufficient to resolve the detailed relationship between Blepharisma and Metopus and thus to determine if the heterotrichs are mono-or paraphyletic. Phylogenetic analysis of the symbiont partial sequence clearly demonstrated that it is an archaeobacterium and that it is closely related to, but distinct from, Methanobacterium formicicum.

“…strain WoCblS as food bacteria (Wagener & Pfennig, 1987). For growth of the food bacteria the medium was supplemented with 5 mwtartaric acid.…”

Section: Methodsmentioning

confidence: 99%

Effect of fixation on activity and cytochemistry of hydrogenosomal enzymes in Trichomonas vaginalis

Goosen

Broers

Hombergen

et al. 1990

~~The effect of fixation on the activity of malate dehydrogenase (decarboxylating) and pyruvate synthase was investigated in Trichomonas vaginaIis. Subsequently a cytochemical staining method was developed for the demonstration of malate dehydrogenase activity in hydrogenosomes. After fixation of cells in low concentrations of glutaraldehyde and incubation in the presence of malate and the tetrazolium compound 2-(2'-benzothiazolyl)-5-styryl-3-(4'-phthalhydrazidyl)tetrazoliu chloride, an electron-dense deposit was produced in the hydrogenosomes. During the whole procedure strictly anaerobic conditions were required. Attempts to develop an analogous procedure for pyruvate synthase failed because even low concentrations of glutaraldehyde strongly inhibited enzyme activity. When cells were fixed in low concentrations of glycolaldehyde and acetaldehyde, a high enzyme activity was retained, but no staining could be achieved. Application of both staining methods to the sapropelic ciliates Trimyema compressurn and PIagiopyIa nasuta gave negative results.