Influence of Nano- and Small Microplastics on Ciliated Protozoan Spirostomum ambiguum (Müller, 1786) Ehrenberg, 1835

This study evaluated the uptake of secondary nano- and small microparticles by the protozoan Spirostomum ambiguum, comparing edible (baker’s yeasts) and inedible (red latex) particles. Secondary nano- and microplastic particles were prepared from household materials made of four different polymers and served to the protozoans separately and as two-component mixtures in different proportions. The number and content of food vacuoles formed by the protozoan were analyzed using a digital microscope. The microscopic results showed that the protozoans ingested the secondary microplastic particles to a similar degree as the latex microspheres but to a lesser extent compared to the nutritional food—baker’s yeasts. At the microplastic concentrations of 1000 and 10,000 particles mL–1, no food vacuoles were observed inside the cells, which may be a finding of great ecological importance. In the protozoans served two-component mixtures, both microplastics and yeasts were found in the vacuoles formed by the organisms. The egestion of two-component vacuoles by the protozoans was slower than that of vacuoles containing a single component.

Infection of Slugs with Theronts of the Ciliate Protozoan, Tetrahymena rostrata

Tetrahymena rostrata is a free-living ciliated protozoan and is a facultative parasite of some species of terrestrial mollusks. It is a potential biopesticide of pest slugs, such as the grey field slug, which cause considerable damage to crops. T. rostrata has several developmental forms. Homogeneous preparations of the feeding stage cells (trophonts) and excysted stage cells (theronts) were compared for their ability to infect and kill Deroceras reticulatum slugs. Theronts were more effective and remained viable and infective, even after prolonged starvation.

Swimming of the Trophont Zooid of Vorticella Convallaria

Vorticella convallaria is a ciliated protozoan found in freshwater habitats. In the sessile or stalked trophont form, V. convallaria is shaped somewhat like a balloon as it has a body or zooid (the head of the balloon) that is about 40 μm large with cilia around its oral part, and a stalk (the string of a balloon) anchoring the zooid to a solid surface. When a trophont zooid of V. convallaria detached from the stalk, the zooid swims around in water by creating water flow using its oral cilia. In contrast to the stalk contraction of V. convallaria that has been well studied, the swimming motility of V. convallaria is little known. In this study, we measured the swimming trajectories of the stalkless trophont zooid of V. convallaria using video microscopy and Hele-Shaw cells with a gap height of 25 μm, traced the swimming zooid using image processing, and analyzed the swimming motion in terms of swimming velocity and mean square displacement. The stalkless trophont zooid of V . convallaria was found to swim in circular patterns with intermittent ballistic motions in the confinement, and the average swimming speed ranged from 20 μm/s to 110 μm/s. Since the swimming pattern of V. convallaria appeared to be affected by the level of confinement, we will continue characterizing the ciliate’s swimming in the Hele-Shaw cell with different gap heights. Our study is expected to reveal the swimming motility of V. convallaria and to advance general understanding of swimming of microorganisms.

Characterization of ASF1 and GCN5 in the ciliated protozoan tetrahymena thermophila

One method of regulating accessibility of DNA is chromatin remodelling via histone post-translational modifications (PTM). Adding an acetyl group to the lysine residues (K) on the core histone H3 is one of these chemical modifications. Acetylation of H3 on lysine 56 (H3K56ac) is an important histone alteration that is conserved among most if not all eukaryotes including humans. Several histone acetyl transferases (HAT) have been shown to be responsible for H3K56ac in different organisms including Gen5 and p300/CPB in human cells and Rtt109 in fungi including the yeast Saccharomyces cerevisiae. In addition the histone chaperone ASf1, is also required for these modifications in yeast and human cells. The ciliated protozoan Tetrahymena thermophila is an effective model organism for studying the function of histone PTMs in certain processes including meiosis and RNA interference. Here, I show that tGen5 has H3 acetylation activity and that tAsf1 binds Histone H3.

Characterization of ASF1 and GCN5 in the ciliated protozoan tetrahymena thermophila

One method of regulating accessibility of DNA is chromatin remodelling via histone post-translational modifications (PTM). Adding an acetyl group to the lysine residues (K) on the core histone H3 is one of these chemical modifications. Acetylation of H3 on lysine 56 (H3K56ac) is an important histone alteration that is conserved among most if not all eukaryotes including humans. Several histone acetyl transferases (HAT) have been shown to be responsible for H3K56ac in different organisms including Gen5 and p300/CPB in human cells and Rtt109 in fungi including the yeast Saccharomyces cerevisiae. In addition the histone chaperone ASf1, is also required for these modifications in yeast and human cells. The ciliated protozoan Tetrahymena thermophila is an effective model organism for studying the function of histone PTMs in certain processes including meiosis and RNA interference. Here, I show that tGen5 has H3 acetylation activity and that tAsf1 binds Histone H3.

Genetic and Proteomic Analysis of Rna Polymerase Ii-Interacting Complexes Mediator and Integrator in the Ciliated Protozoan Tetrahymena Thermophila

In most eukaryotes, the largest subunit of RNAPII, Rpb1, contains a conserved carboxyterminal domain (CTD) containing a canonical structure of heptapeptide repeats. Two protein complexes of interest, Mediator and Integrator, are known to interact with this CTD in all eukaryotic models they have been described in to date. Recently, orthologs of Mediator and Integrator subunits have been identified within the ciliated protozoan Tetrahymena thermophila; one of the few eukaryotic lineages to lack a canonically organized CTD. To begin to characterize putative Mediator and Integrator complexes within T. thermophila, I engineered appropriate macronuclear tagging and knockout cassettes. Although the Tetrahymena MED31 ortholog was unable to rescue the slow growth phenotype of a yeast MED31 knockout, or co-purify with yeast Med8-TAP, I identified subunit Med3 as a member of the Med31 interactome in T. thermophila through tandem affinity purification coupled with mass spectrometry. I also targeted the Tetrahymena INTS6 locus for knockout as determined by colony PCR. If Mediator and Integrator exist in Tetrahymena despite its divergent CTD of Rpb1, perhaps these complexes have CTD-independent functions beyond what can be effectively studied using conventional model systems.

Genetic and Proteomic Analysis of Rna Polymerase Ii-Interacting Complexes Mediator and Integrator in the Ciliated Protozoan Tetrahymena Thermophila

In most eukaryotes, the largest subunit of RNAPII, Rpb1, contains a conserved carboxyterminal domain (CTD) containing a canonical structure of heptapeptide repeats. Two protein complexes of interest, Mediator and Integrator, are known to interact with this CTD in all eukaryotic models they have been described in to date. Recently, orthologs of Mediator and Integrator subunits have been identified within the ciliated protozoan Tetrahymena thermophila; one of the few eukaryotic lineages to lack a canonically organized CTD. To begin to characterize putative Mediator and Integrator complexes within T. thermophila, I engineered appropriate macronuclear tagging and knockout cassettes. Although the Tetrahymena MED31 ortholog was unable to rescue the slow growth phenotype of a yeast MED31 knockout, or co-purify with yeast Med8-TAP, I identified subunit Med3 as a member of the Med31 interactome in T. thermophila through tandem affinity purification coupled with mass spectrometry. I also targeted the Tetrahymena INTS6 locus for knockout as determined by colony PCR. If Mediator and Integrator exist in Tetrahymena despite its divergent CTD of Rpb1, perhaps these complexes have CTD-independent functions beyond what can be effectively studied using conventional model systems.

Endosymbiotic Ciliated Protozoan Biota of Dromedary Camels and Domestic Cattle in Tunisia

Species concentration and composition of endosymbiotic ciliates were investigated in the forestomach contents of 12 dromedary camels (Camelus dromedarius) and the ruminal contents of 16 domestic cattle (Bos taurus taurus) living in Ben Gardane, Tunisia. Sixteen species and 8 morphotypes, belonging to 8 genera, were identified from dromedary camels, and 18 species and 13 morphotypes, belonging to 8 genera, were identified from domestic cattle. This is the first report on the endosymbiotic ciliated protozoan biota of dromedary camels and cattle living in Tunisia. The mean density (± SD) of ciliates in the forestomach samples of dromedary camels and the ruminal samples of domestic cattle was 65.4 ± 69.4 × 104 cells mL–1 and 54.2 ± 55.8 × 104 cells mL–1, respectively. Diplodinium cameli and Blepharoconus krugerensis were detected for the first and second time, respectively, from the ruminal contents of cattle. Caloscolex camelinus and B. krugerensis were studied in detail with a scanning electron microscope.