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Ruminal ciliates are linked to methane production and nitrogen utilization efficiency in ruminants due to their association with other ruminal microorganisms. However, research on the specific interplay between ruminal bacteria and ciliates is still limited, particularly in different dietary conditions. This study examines the effect of the forage-to-concentrate (F:C) ratio on the ruminal bacteriome in vitro , focusing on bacteria associated with Isotricha spp. and small entodinia. The rumen fluid used as the inoculum for this experiment was collected from two cannulated Hanwoo cows. Dietary treatments included high-forage ( HF , F:C of 7:3), high-concentrate ( HC , F:C of 3:7), and control ( CON , F:C of 5:5). After 24-hour incubation, fractions for entodinia-associated bacteria ( EAB ), Isotricha -associated bacteria ( IAB ), and total bacteria ( TB ) were collected for bacteriome analysis using QIIME2 with full-length 16S rRNA gene sequences on the PacBio system. All fermentation parameters, except for NH 3 -N, showed linear changes with increasing F:C ratios (p  ≤  0.05). F:C ratio affected Isotricha spp. and Dasytricha spp. counts. Ciliate-associated bacterial fractions were significantly less diverse than the total bacterial group, as indicated by richness, phylogenetic diversity, and evenness indices. This suggests potential specific associations within ciliate-provided microhabitats. Both diet and ciliate fractions significantly influenced the overall bacteriome (p  ≤  0.05). More bacteriome features were differentially abundant due to the ciliate fraction effect rather than diet (q ≤ 0.05). Our newly proposed washing procedure, using higher ciliate cell counts and minimal bacterial contamination, effectively removed free-living or loosely associated bacteria. This allows focus on ciliate-associated bacterial populations, which may include potential symbionts or engulfed bacteria of host ruminal ciliates. Verifying these associations could provide insights into rumen microbiome dynamics, nitrogen utilization, hydrogen balance, and microbiome variation under different F:C ratios.

Changes in the biodiversity of aquatic environments over time and space due to human activities are a topic of theoretical and conservational interest in ecology. Thus, variation in taxonomic beta diversity of the planktonic ciliates community was investigated along a temporal and spatial gradient in two subsystems of a Neotropical floodplain, one impacted by dams (Paraná) and the other free of them along its course (Ivinhema). For the spatial analysis, the Paraná subsystem did not show a significant decrease in beta diversity, presenting a pattern like that observed for the Ivinhema subsystem. Therefore, biotic homogenization was not observed for the ciliate's community downstream of the dams. It was noted that there was a fluctuation in the relevance of the components of beta diversity, regardless of the subsystem analyzed. For the temporal analysis there was a significant change in species composition from the first to the last year investigated, essentially for the subsystem impacted by dams, and that this was determined mainly by species loss. Although spatial beta diversity remained high without a clear process of biotic homogenization, dams promoted remarkable changes in ciliate species composition over the years mainly by continuous loss of species.

Background Ciliates constitute a vital component of eukaryotic diversity, playing an essential trophic role in aquatic ecosystems by mediating carbon and nutrient cycling. As specialized primary consumers in biofilms, cyrtophorian ciliates (Class Phyllopharyngea de Puytorac et al., 1974) are ubiquitous in periphytic habitats; yet, their biodiversity remains significantly underestimated compared to well-studied model groups. Here we document three species from the urban-adjacent coastal waters in East China. Integrative studies suggest that one of them represents a novel species and the other two are rare species. Results Morphological and molecular investigations were conducted on three species belonging to the order Dysteriida Deroux, 1976, Dysteria armata Huxley, 1857, Dysteria bella sp. nov., and Orthotrochilia agamalievi Deroux, 1976. For Dysteria armata (the type species of the genus), detailed morphometric data and an improved diagnosis are provided based on a Chinese population. The new species is characterized by size in vivo 75–110 × 40–60 μm, body long obovate, and seven right kineties including five frontoventral kineties. The SSU rRNA gene sequences were first obtained for all three species. Phylogenetic analyses reveal that Dysteria bella sp. nov. and D. armata form a fully supported sister clade. Consistent with morphological diversity, the molecular topology shows the non-monophyly of the genus Dysteria . Furthermore, the first molecular data for Orthotrochilia confirms its evolutionary distinctiveness from the genus Trochilioides . Conclusions By providing detailed morphological and molecular characterizations of one new and two poorly known marine cyrtophorian species, this work not only advances our knowledge of the biodiversity within this specialized ciliate group but also resolves the systematic placement of the type species D. armata . Additionally, the acquisition of these sequences supplies essential genetic markers, filling critical gaps in molecular databases.

Mitochondrial energy conversion requires an intricate architecture of the inner mitochondrial membrane 1 . Here we show that a supercomplex containing all four respiratory chain components contributes to membrane curvature induction in ciliates. We report cryo-electron microscopy and cryo-tomography structures of the supercomplex that comprises 150 different proteins and 311 bound lipids, forming a stable 5.8-MDa assembly. Owing to subunit acquisition and extension, complex I associates with a complex IV dimer, generating a wedge-shaped gap that serves as a binding site for complex II. Together with a tilted complex III dimer association, it results in a curved membrane region. Using molecular dynamics simulations, we demonstrate that the divergent supercomplex actively contributes to the membrane curvature induction and tubulation of cristae. Our findings highlight how the evolution of protein subunits of respiratory complexes has led to the I–II–III 2 –IV 2 supercomplex that contributes to the shaping of the bioenergetic membrane, thereby enabling its functional specialization. A supercomplex comprising all four respiratory chain components contributes to the induction of mitochondrial membrane curvature and tubulation of cristae.

The spatial patterns of planktonic ciliate communities were studied from May to June 2019 in the Nile Delta’s Damietta region, southeastern Mediterranean. The ciliate communities were sampled from twenty-five sites of five stressed domains with spatial gradients of environmental status. A total of 32 ciliate taxa with six dominant species were identified, comprising 21 tintinnids and 11 aloricate ciliates. The abundance and richness of each ciliate group varied geographically and were most strongly influenced by salinity variations; tintinnid ciliates attained high abundance and richness at high salinity sites in the harbour and coastal region and decreased within the estuary upstream. Aloricate ciliates were poorly represented at most sites but were a substantial proportion of upstream estuarine sites. Multivariate/univariate analyses demonstrated that spatial patterns of the ciliate communities were significantly correlated with environmental variables, especially salinity, chlorophyll-a, and nutrients, either alone or in combination with one another. These results indicate that the ciliates can be useful bioindicators in stressed environments while also allowing the detection of impacts on short time scales by rapidly responding to environmental variations.

The paired review papers in Parts I and II describe the 50-year history of research on the biomechanics of swimming microorganisms and its prospects in the next 50 years: Part I explains the behaviour of individual microorganisms, and Part II explains collective behaviour. Since the discovery of microorganisms by van Leeuwenhoek in the 17th century, many natural scientists have been interested in their motility because it is directly associated with biological function. A research upsurge occurred in the 1970s, with the elucidation of swimming mechanisms among individual microorganisms and the theoretical derivation of swimming speeds. Various swimming strategies of three types of microorganisms, i.e. bacteria, ciliates and microalgae, are explained in this Part I. We show that some of the behaviours of microorganisms can be described by biomechanical equations and are to some extent predictable. Recent researches have revealed the behaviour of microorganisms in more complex environments and more realistic settings, which are also reviewed in the paper. Last, we provide future prospects for research on microbial behaviour.

Losses and gains in species diversity affect ecological stability 1 – 7 and the sustainability of ecosystem functions and services 8 – 13 . Experiments and models have revealed positive, negative and no effects of diversity on individual components of stability, such as temporal variability, resistance and resilience 2 , 3 , 6 , 11 , 12 , 14 . How these stability components covary remains poorly understood 15 . Similarly, the effects of diversity on overall ecosystem stability 16 , which is conceptually akin to ecosystem multifunctionality 17 , 18 , remain unknown. Here we studied communities of aquatic ciliates to understand how temporal variability, resistance and overall ecosystem stability responded to diversity (that is, species richness) in a large experiment involving 690 micro-ecosystems sampled 19 times over 40 days, resulting in 12,939 samplings. Species richness increased temporal stability but decreased resistance to warming. Thus, two stability components covaried negatively along the diversity gradient. Previous biodiversity manipulation studies rarely reported such negative covariation despite general predictions of the negative effects of diversity on individual stability components 3 . Integrating our findings with the ecosystem multifunctionality concept revealed hump- and U-shaped effects of diversity on overall ecosystem stability. That is, biodiversity can increase overall ecosystem stability when biodiversity is low, and decrease it when biodiversity is high, or the opposite with a U-shaped relationship. The effects of diversity on ecosystem multifunctionality would also be hump- or U-shaped if diversity had positive effects on some functions and negative effects on others. Linking the ecosystem multifunctionality concept and ecosystem stability can transform the perceived effects of diversity on ecological stability and may help to translate this science into policy-relevant information. Species richness was found to increase temporal stability but decrease resistance to warming in an experiment involving 690 micro-ecosystems consisting of 1 to 6 species of bacterivorous ciliates that were sampled over 40 days.

Bacterivorous ciliates and lytic bacteriophages are two major predators in aquatic environments, competing for the same type of prey. This study investigated the possible interaction of these different microorganisms and their influence on the activity of each other. Therefore, two bacterivorous ciliates, Paramecium sp. RB1 and Tetrahymena sp. RB2, were used as representative ciliates; a T4-like Escherichia coli targeting lytic bacteriophage as a model virus; and E. coli ATCC 25922 as a susceptible bacterial host and prey. The growth of the two ciliates with E. coli ATCC 25922 as prey was affected by the presence of phage particles. The grazing activity of the two ciliates resulted in more than a 99% reduction of the phage titer and bacterial cell numbers. However, viable phage particles were recovered from individual washed cells of the two ciliates after membrane filtration. Therefore, ciliates such as Paramecium sp. RB1 and Tetrahymena sp. RB2 can remove bacteriophages present in natural and artificial waters by ingesting the viral particles and eliminating bacterial host cells required for viral replication. The ingestion of phage particles may marginally contribute to the nutrient supply of the ciliates. However, the interaction of phage particles with ciliate cells may contribute to the transmission of bacteriophages in aquatic environments.

The present study deals with the synthesis of selenium nanoparticles (SeNPs) using Nilgirianthus ciliatus leaf extracts, characterized by UV–Vis spectrophotometer, XRD, FTIR, FE-SEM, HR-TEM, DLS, and zeta potential analysis. The antimicrobial activity against Staphylococcus aureus (MTCC96), Escherichia coli (MTCC443), and Salmonella typhi (MTCC98) showed the remarkable inhibitory effect at 25 µl/mL concentration level. Furthermore, the characterized SeNPs showed a great insecticidal activity against Aedes aegypti in the early larval stages with the median Lethal Concentration (LC50) of 0.92 mg/L. Histopathological observations of the SeNPs treated midgut and caeca regions of Ae. aegypti 4th instar larvae showed damaged epithelial layer and fragmented peritrophic membrane. In order to provide a mechanistic approach for further studies, molecular docking studies using Auto Dock Vina were performed with compounds of N. ciliatus within the active site of AeSCP2. Overall, the N. ciliates leaf-mediated biogenic SeNPs was promisingly evidenced to have potential larvicidal and food pathogenic bactericidal activity in an eco-friendly approach.