-
Current Biology : CB Oct 2018Although we often think of cells as small, simple building blocks of life, in fact they are highly complex and can perform a startling variety of functions. In our...
Although we often think of cells as small, simple building blocks of life, in fact they are highly complex and can perform a startling variety of functions. In our bodies, cells are programmed by complex differentiation pathways and are capable of responding to a bewildering range of chemical and physical signals. Free-living single-celled organisms, such as bacteria or protists, have to cope with varying environments, locate prey and potential mates, and escape from predators - all of the same tasks that a free-living animal is faced with. When animals face complex behavioral challenges, they rely on their cognitive abilities - the ability to learn from experience, to analyse a situation and choose an appropriate course of action. This ability is essential for survival and should, in principle, be a ubiquitous feature of all living things regardless of the complexity of the organism.
Topics: Cells; Ciliophora; Habituation, Psychophysiologic; Learning; Physarum
PubMed: 30352182
DOI: 10.1016/j.cub.2018.09.015 -
Bacterial symbiosis in ciliates (Alveolata, Ciliophora): Roads traveled and those still to be taken.The Journal of Eukaryotic Microbiology Sep 2022The diversity of prokaryotic symbionts in Ciliophora and other protists is fascinatingly rich; they may even include some potentially pathogenic bacteria. In this... (Review)
Review
The diversity of prokaryotic symbionts in Ciliophora and other protists is fascinatingly rich; they may even include some potentially pathogenic bacteria. In this review, we summarize currently available data on biodiversity and some morphological and biological peculiarities of prokaryotic symbionts mainly within the genera Paramecium and Euplotes. Another direction of ciliate symbiology, neglected for a long time and now re-discovered, is the study of epibionts of ciliates. This promises a variety of interesting outcomes. Last, but not least, we stress the new technologies, such as next generation sequencing and the use of genomics data, which all can clarify many new aspects of relevance. For this reason, a brief overview of achievements in genomic studies on ciliate's symbionts is provided. Summing up the results of numerous scientific contributions, we systematically update current knowledge and outline the prospects as to how symbiology of Ciliophora may develop in the near future.
Topics: Alveolata; Bacteria; Ciliophora; Phylogeny; Symbiosis
PubMed: 35006645
DOI: 10.1111/jeu.12886 -
Microbial Ecology Nov 2022Ciliophora is a phylum of unicellular eukaryotes that are common and have pivotal roles in aquatic environments. Sea ice is a marine habitat, which is composed of a...
Ciliophora is a phylum of unicellular eukaryotes that are common and have pivotal roles in aquatic environments. Sea ice is a marine habitat, which is composed of a matrix of solid ice and pockets of saline water in which Ciliophora thrive. Here, we used phylogenetic placement to identify Ciliophora 18S ribosomal RNA reads obtained from wintertime water and sea ice, and assigned functions to the reads based on this taxonomic information. Based on our results, sea-ice Ciliophora assemblages are poorer in taxonomic and functional richness than under-ice water and water-column assemblages. Ciliophora diversity stayed stable throughout the ice-covered season both in sea ice and in water, although the assemblages changed during the course of our sampling. Under-ice water and the water column were distinctly predominated by planktonic orders Choreotrichida and Oligotrichida, which led to significantly lower taxonomic and functional evenness in water than in sea ice. In addition to planktonic Ciliophora, assemblages in sea ice included a set of moderately abundant surface-oriented species. Omnivory (feeding on bacteria and unicellular eukaryotes) was the most common feeding type but was not as predominant in sea ice as in water. Sea ice included cytotrophic (feeding on unicellular eukaryotes), bacterivorous and parasitic Ciliophora in addition to the predominant omnivorous Ciliophora. Potentially mixotrophic Ciliophora predominated the water column and heterotrophic Ciliophora sea ice. Our results highlight sea ice as an environment that creates a set of variable habitats, which may be threatened by the diminishing extent of sea ice due to changing climate.
Topics: Ice Cover; Phylogeny; Ciliophora; Ecosystem; Seasons
PubMed: 34748071
DOI: 10.1007/s00248-021-01915-4 -
European Journal of Protistology Oct 2017This paper first reviews the concept of functional diversity in general terms and then applies it to free-living aquatic ciliates. Ciliates are extremely versatile... (Review)
Review
This paper first reviews the concept of functional diversity in general terms and then applies it to free-living aquatic ciliates. Ciliates are extremely versatile organisms and display an enormous functional diversity as key elements of pelagic food webs, acting as predators of bacteria, algae, other protists and even some metazoans. Planktonic ciliates are important food for zooplankton, and mixotrophic and functionally autotrophic species may significantly contribute to primary production in the ocean and in lakes. The co-occurrence of many ciliate species in seemingly homogenous environments indicates a wide range of their ecological niches. Variation in space and time may foster co-occurrence and prevent violating the competitive exclusion principle among ciliates using the same resources. Considering that many ciliates may be dormant and/or rare in many habitats, ciliate species diversity must be higher than can be deduced from simple sampling techniques; molecular methods of identification clearly point to this hidden diversity. From a functional point of view, the question is how much of this diversity represents redundancy. A key challenge for future research is to link the ecophysiological performance of naturally co-occurring ciliates to their functional genes. To this end, more experimental research is needed with with functionally different species.
Topics: Biodiversity; Ciliophora; Fresh Water
PubMed: 28623024
DOI: 10.1016/j.ejop.2017.04.001 -
The Journal of Eukaryotic Microbiology Sep 2022As single cells, ciliates build, duplicate, and even regenerate complex cortical patterns by largely unknown mechanisms that precisely position organelles along two... (Review)
Review
As single cells, ciliates build, duplicate, and even regenerate complex cortical patterns by largely unknown mechanisms that precisely position organelles along two cell-wide axes: anterior-posterior and circumferential (left-right). We review our current understanding of intracellular patterning along the anterior-posterior axis in ciliates, with emphasis on how the new pattern emerges during cell division. We focus on the recent progress at the molecular level that has been driven by the discovery of genes whose mutations cause organelle positioning defects in the model ciliate Tetrahymena thermophila. These investigations have revealed a network of highly conserved kinases that are confined to either anterior or posterior domains in the cell cortex. These pattern-regulating kinases create zones of cortical inhibition that by exclusion determine the precise placement of organelles. We discuss observations and models derived from classical microsurgical experiments in large ciliates (including Stentor) and interpret them in light of recent molecular findings in Tetrahymena. In particular, we address the involvement of intracellular gradients as vehicles for positioning organelles along the anterior-posterior axis.
Topics: Cell Division; Ciliophora; Tetrahymena thermophila
PubMed: 35075744
DOI: 10.1111/jeu.12890 -
Current Biology : CB Sep 2014
Topics: Ciliophora; Genes, Protozoan; Models, Animal; Morphogenesis; Regeneration; Wound Healing
PubMed: 25202864
DOI: 10.1016/j.cub.2014.06.044 -
Cold Spring Harbor Perspectives in... Dec 2013Research using ciliates revealed early examples of epigenetic phenomena and continues to provide novel findings. These protozoans maintain separate germline and somatic... (Review)
Review
Research using ciliates revealed early examples of epigenetic phenomena and continues to provide novel findings. These protozoans maintain separate germline and somatic nuclei that carry transcriptionally silent and active genomes, respectively. Examining the differences in chromatin within distinct nuclei of Tetrahymena identified histone variants and established that transcriptional regulators act by modifying histones. Formation of somatic nuclei requires both transcriptional activation of silent chromatin and large-scale DNA elimination. This somatic genome remodeling is directed by homologous RNAs, acting with an RNA interference (RNAi)-related machinery. Furthermore, the content of the parental somatic genome provides a homologous template to guide this genome restructuring. The mechanisms regulating ciliate DNA rearrangements reveal the surprising power of homologous RNAs to remodel the genome and transmit information transgenerationally.
Topics: Animals; Cell Nucleus; Ciliophora; Epigenesis, Genetic; Gene Rearrangement; Genome, Protozoan; Germ Cells; Histones; RNA Interference; Transcription, Genetic
PubMed: 24296171
DOI: 10.1101/cshperspect.a017764 -
European Journal of Pharmacology Sep 2014Ca(2+)-signaling pathways and intracellular Ca(2+) channels are present in protozoa. Ancient origin of inositol 1,4,5-trisphosphate receptors (IP3Rs) and other... (Review)
Review
Ca(2+)-signaling pathways and intracellular Ca(2+) channels are present in protozoa. Ancient origin of inositol 1,4,5-trisphosphate receptors (IP3Rs) and other intracellular channels predates the divergence of animals and fungi as evidenced by their presence in the choanoflagellate Monosiga brevicollis, the closest known relative to metazoans. The first protozoan IP3R cloned, from the ciliate Paramecium, displays strong sequence similarity to the rat type 3 IP3R. This ciliate has a large number of IP3- and ryanodine(Ry)-like receptors in six subfamilies suggesting the evolutionary adaptation to local requirements for an expanding diversification of vesicle trafficking. IP3Rs have also been functionally characterized in trypanosomatids, where they are essential for growth, differentiation, and establishment of infection. The presence of the mitochondrial calcium uniporter (MCU) in a number of protozoa indicates that mitochondrial regulation of Ca(2+) signaling is also an early appearance in evolution, and contributed to the discovery of the molecular nature of this channel in mammalian cells. There is only sequence evidence for the occurrence of two-pore channels (TPCs), transient receptor potential Ca(2+) channels (TRPCs) and intracellular mechanosensitive Ca(2+)-channels in Paramecium and in parasitic protozoa.
Topics: Animals; Calcium Channels; Ciliophora; Intracellular Space; Parasites; Protozoan Proteins
PubMed: 24291099
DOI: 10.1016/j.ejphar.2013.11.015 -
Journal of Molecular Biology Jul 2020Ciliates are an interesting model system for investigating diverse functions of noncoding RNAs, especially in genome defence pathways. During sexual development, the... (Review)
Review
Ciliates are an interesting model system for investigating diverse functions of noncoding RNAs, especially in genome defence pathways. During sexual development, the ciliate somatic genome undergoes massive rearrangement and reduction through removal of transposable elements and other repetitive DNA. This is guided by a multitude of noncoding RNAs of different sizes and functions, the extent of which is only recently becoming clear. The genome rearrangement pathways evolved as a defence against parasitic DNA, but interestingly also use the transposable elements and transposases to execute their own removal. Thus, ciliates are also a good model for the coevolution of host and transposable element, and the mutual dependence between the two. In this review, we summarise the genome rearrangement pathways in three diverse species of ciliate, with focus on recent discoveries and the roles of noncoding RNAs.
Topics: Ciliophora; DNA Transposable Elements; Gene Rearrangement; Genome, Protozoan; RNA, Protozoan; RNA, Untranslated
PubMed: 31926952
DOI: 10.1016/j.jmb.2019.12.042 -
Annals of the New York Academy of... Jul 2019Genome architecture is well diversified among eukaryotes in terms of size and content, with many being radically shaped by ancient and ongoing genome conflicts with... (Review)
Review
Genome architecture is well diversified among eukaryotes in terms of size and content, with many being radically shaped by ancient and ongoing genome conflicts with transposable elements (e.g., the large transposon-rich genomes common among plants). In ciliates, a group of microbial eukaryotes with distinct somatic and germ-line genomes present in a single cell, the consequences of these genome conflicts are most apparent in their developmentally programmed genome rearrangements. This complicated developmental phenomenon has largely overshadowed and outpaced our understanding of how germ-line and somatic genome architectures have influenced the evolutionary dynamism and potential in these taxa. In our review, we highlight three central concepts: how the evolution of atypical ciliate germ-line genome architectures is linked to ancient genome conflicts; how the complex, epigenetically guided transformation of germline to soma during development can generate widespread genetic variation; and how these features, coupled with their unusual life cycle, have increased the rate of molecular evolution linked to genome architecture in these taxa.
Topics: Animals; Ciliophora; Epigenesis, Genetic; Evolution, Molecular; Humans
PubMed: 31074010
DOI: 10.1111/nyas.14108